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Discussion Starter #1
I’ve been lurking for about 2 years , quietly soaking up information and knowledge, while building my 91 JDM GTO. I’m at the point of frustration, and looking for hints and guidance to get out of the “mud”.

My goal at the start and to date was to bring the car up to the 450 to 500 HP threshold , with bolt on mods. The car was well maintained and running before I started the upgrades. I am aware of the limitations of the1st generation 2 bolt girdle and cast crankshaft, and therefor trying to be conservative with my build . Reliability is more important to me, than pushing the limits of the drivetrain.

I have updated the turbos to 19T Kinugawas with the much respected Ooh Noo SMIC’s doing the cooling. I’ve done the required supporting upgrades as well, including; 2” IC piping and new Y, pre- cat deletes, 3” down pipe, Hi-Flow Cat , 3” custom Dual Magnaflow Exhaust, Hot Wired Walbro 400 Fuel Pump, AEM Fuel Regulator w/ Gauge at manifold, Denso 660 Fuel Injectors, colder NGK Iridium spark plugs ( forget actual plug # at moment), 8mm Wires, InkDual Port BOV ( plumbed back into intake side), oil catch can, Vaccum hose Reduction, K/N Air Filter in custom built air box, with custom duct feeding stock supply side hoses to turbos, cold air duct supplying air to filter, AEM Wideband, AEM Boost Controller, AEM Oil Pressure, AEM Water Temp, AEM Voltage , Chrome v2 ECU , Tactrix Cable w/ OBD1 to OBD2 adapter, laptop running EvoScan & ECU Flash, 3” GM MAF installed after Y , and MAF Translator installed in armrest storage. The car already had a Turbo Timer installed and 3SX under drive pulley , when I Purchased it. Being a JDM version, the EGR was already deleted. The Timing belt has been changed , and the car currently has 72,000 miles on it ( converted from Km) .

After spending nearly 2 years figuring out all these upgrades , the car did start up on the first attempt. I use the term “start” up loosely, as it fires and will run for a bit . Was running longer when I first started , but now after several attempts, and messing with settings, the most I can keep it going is about 10 seconds . The car is “clearly” running way too rich, as evidenced by wet plugs and extremely low numbers on the Wideband ( single digits ) . I struggled with figuring out the EvoScan & ECU flash software , but that is all working now , and I can datalog and read ECU Rom , and reflash as needed, but now I can keep the car running long enough to get any usable data. I’ve read up on the instructions, tables, and settings for the MAF controller, but something just doesn’t seem right. I recently experimented with incrementally changing the AUX, Base, Idle, Mid, And WOT settings, but just when I think I might be getting close to leaning out Fuel Ratio , I fail. I’ve pulled the front 3 plugs and have found them fouled . To be honest , I haven’t had the “will” to go through pulling the intake off to remove the rear plugs . I’ve been trying to burn off the excess fuel after failed attempts by removing the fuel pump fuse, which works , but admittedly, may not be the best way to address the plugs. The fuel pressure setting appears to be set @ 43 psi , but again it hasn’t been running long enough to fine tune the actual setting.
I’ve researched how to test the GM MAF , but I need it to be running to do that ( unless there is better way) The ECU appears to have the default 99 rom version loaded . I did play with the injector scaling , but it didn’t seem to have any effect. I keep feeling if I could get the RPM’s up , the motor would keep running, but increasing the throttle just floods it.

Really , I just want to get the car running, and drivable, so I can turn it over to an experienced shop that can tune it properly. I’m not opposed to just giving up , and flatbedding it , but these car’s are rare in Massachusetts , and I’ve yet to find a shop familiar with them. Maybe someone reading this knows one?
 

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Mechanical and electrical work aside, post a datalog. There may or may not be something obvious that stands out.

-sent from my Galaxy Note 9
 

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Discussion Starter #3
Mechanical and electrical work aside, post a datalog. There may or may not be something obvious that stands out.

-sent from my Galaxy Note 9
I will try to capture something soon, thanks! I failed to mention that I have not loaded excel on my laptop yet, so I haven’t seen files in proper form. I converted to MacBooks many years ago, so my car’s laptop is the only IBM machine I’ve got.
 

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Discussion Starter #4
I’ve been lurking for about 2 years , quietly soaking up information and knowledge, while building my 91 JDM GTO. I’m at the point of frustration, and looking for hints and guidance to get out of the “mud”.

My goal at the start and to date was to bring the car up to the 450 to 500 HP threshold , with bolt on mods. The car was well maintained and running before I started the upgrades. I am aware of the limitations of the1st generation 2 bolt girdle and cast crankshaft, and therefor trying to be conservative with my build . Reliability is more important to me, than pushing the limits of the drivetrain.

I have updated the turbos to 19T Kinugawas with the much respected Ooh Noo SMIC’s doing the cooling. I’ve done the required supporting upgrades as well, including; 2” IC piping and new Y, pre- cat deletes, 3” down pipe, Hi-Flow Cat , 3” custom Dual Magnaflow Exhaust, Hot Wired Walbro 400 Fuel Pump, AEM Fuel Regulator w/ Gauge at manifold, Denso 660 Fuel Injectors, colder NGK Iridium spark plugs ( forget actual plug # at moment), 8mm Wires, InkDual Port BOV ( plumbed back into intake side), oil catch can, Vaccum hose Reduction, K/N Air Filter in custom built air box, with custom duct feeding stock supply side hoses to turbos, cold air duct supplying air to filter, AEM Wideband, AEM Boost Controller, AEM Oil Pressure, AEM Water Temp, AEM Voltage , Chrome v2 ECU , Tactrix Cable w/ OBD1 to OBD2 adapter, laptop running EvoScan & ECU Flash, 3” GM MAF installed after Y , and MAF Translator installed in armrest storage. The car already had a Turbo Timer installed and 3SX under drive pulley , when I Purchased it. Being a JDM version, the EGR was already deleted. The Timing belt has been changed , and the car currently has 72,000 miles on it ( converted from Km) .

After spending nearly 2 years figuring out all these upgrades , the car did start up on the first attempt. I use the term “start” up loosely, as it fires and will run for a bit . Was running longer when I first started , but now after several attempts, and messing with settings, the most I can keep it going is about 10 seconds . The car is “clearly” running way too rich, as evidenced by wet plugs and extremely low numbers on the Wideband ( single digits ) . I struggled with figuring out the EvoScan & ECU flash software , but that is all working now , and I can datalog and read ECU Rom , and reflash as needed, but now I can keep the car running long enough to get any usable data. I’ve read up on the instructions, tables, and settings for the MAF controller, but something just doesn’t seem right. I recently experimented with incrementally changing the AUX, Base, Idle, Mid, And WOT settings, but just when I think I might be getting close to leaning out Fuel Ratio , I fail. I’ve pulled the front 3 plugs and have found them fouled . To be honest , I haven’t had the “will” to go through pulling the intake off to remove the rear plugs . I’ve been trying to burn off the excess fuel after failed attempts by removing the fuel pump fuse, which works , but admittedly, may not be the best way to address the plugs. The fuel pressure setting appears to be set @ 43 psi , but again it hasn’t been running long enough to fine tune the actual setting.
I’ve researched how to test the GM MAF , but I need it to be running to do that ( unless there is better way) The ECU appears to have the default 99 rom version loaded . I did play with the injector scaling , but it didn’t seem to have any effect. I keep feeling if I could get the RPM’s up , the motor would keep running, but increasing the throttle just floods it.

Really , I just want to get the car running, and drivable, so I can turn it over to an experienced shop that can tune it properly. I’m not opposed to just giving up , and flatbedding it , but these car’s are rare in Massachusetts , and I’ve yet to find a shop familiar with them. Maybe someone reading this knows one?
Just for the hell of it , I’m going to see what happens if I unplug MAF . One of the frustrating things for me is I store the car in a garage at my place of work, so often I have to wait to try ideas that come to mind.
 

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It sounds like your settings are too far off and you aren’t hardly doing any correction for your larger injectors since it is running super rich. You will have to change out the rear plugs but not necessarily right away to make sure it will run and do some light acceleration.

You need to download the ROM off your ECU, go into the injector scaling and change it to 660 as well as change the injector battery offset values. You will probably have to do a search on the Evo forums for Denso 660 injectors and see what injector data you come up with for the battery offset table. After that, set your MAFT to 360cc injector size with the base and aux knobs. The other three will remain zero. The car should start up with those settings and be close enough that you can drive it around. You’ll need to alter the fuel based on your AFR values you see at idle, cruise, and WOT after that. It would be preferred to do this in Chrome with the VE smoothing table. You can select the Hz ranges for idle, cruising, and WOT. Select the range you see for each and then hit + or - on the keyboard to increase or decrease the whole range by 1%. This is where datalogging your fuel trims comes in handy because the low and mid trims show you how much fuel the ecu is adding or subtracting.

Anyways, I don’t want to get into too much detail because it may become overwhelming and confusing but it isn’t that difficult to setup the tune on your car. You could completely tune it with the MAFT only by setting it for 660 injectors and then using the other three knobs to add/subtract fuel at idle, cruise, and WOT but since you have Chrome it would be better for ignition timing to let it do most of the work.
 

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Discussion Starter #6
It sounds like your settings are too far off and you aren’t hardly doing any correction for your larger injectors since it is running super rich. You will have to change out the rear plugs but not necessarily right away to make sure it will run and do some light acceleration.

You need to download the ROM off your ECU, go into the injector scaling and change it to 660 as well as change the injector battery offset values. You will probably have to do a search on the Evo forums for Denso 660 injectors and see what injector data you come up with for the battery offset table. After that, set your MAFT to 360cc injector size with the base and aux knobs. The other three will remain zero. The car should start up with those settings and be close enough that you can drive it around. You’ll need to alter the fuel based on your AFR values you see at idle, cruise, and WOT after that. It would be preferred to do this in Chrome with the VE smoothing table. You can select the Hz ranges for idle, cruising, and WOT. Select the range you see for each and then hit + or - on the keyboard to increase or decrease the whole range by 1%. This is where datalogging your fuel trims comes in handy because the low and mid trims show you how much fuel the ecu is adding or subtracting.

Anyways, I don’t want to get into too much detail because it may become overwhelming and confusing but it isn’t that difficult to setup the tune on your car. You could completely tune it with the MAFT only by setting it for 660 injectors and then using the other three knobs to add/subtract fuel at idle, cruise, and WOT but since you have Chrome it would be better for ignition timing to let it do most of the work.

Thanks for response , I actually did the first part of what you mentioned , with regards to the ROM file, but I did not consider or even know to consider the battery offset table. It does seem somewhat overwhelming , but mostly because I'm trying to self teach, and there is certainly a learning curve to overcome here. Thank you for the input.

I did follow up on the idea I had earlier today, and that has turned out to be fruitful. I unplugged the harness from. the MAF sensor and the car started right up and ran reasonably well, although still a bit rich , as is to be expected, being in "Limp Mode" the AFR #'s looked to be around 8 or so. I shut it down after a minute or 2 , as the laptop needs charging. In a little bit , I'm going to run some datalogs in limp mode just to have something to start with. Clearly though , I've got an issue with either the MAF sensor, the way I wired it , or the Translator. But I am somewhat relieved to be able to narrow it down, as the car otherwise wants to run. I haven't even started to play with boost, as I have been just focusing on getting it to idle, before I add that to the mix.
 

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Before you go any further, I would try some settings within Chrome. You are way too rich at idle, are diluting the oil with fuel being washed down the cylinders, and continued use will result in a spun bearing.

It looks like Injector Rehab has latency values for Denso 660s so try inputting those into Chrome with the 660 scaling.https://injector-rehab.com/knowledge-base/fuel-injector-lag-times/

Your MAFT knob values should be base 2 aux 8. That sets it for 360cc stock injectors since chrome is doing the injector correction. Keep the idle, mid, and WOT knobs set at zero.

Both of those things alone should make the car run and not be overly rich. Do you have a MAFT gen 2 since it’s in the armrest vs the small little black box MAFT? That would make a difference on settings and you’ll have to go through some menus instead.
 

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Discussion Starter #8
Before you go any further, I would try some settings within Chrome. You are way too rich at idle, are diluting the oil with fuel being washed down the cylinders, and continued use will result in a spun bearing.

It looks like Injector Rehab has latency values for Denso 660s so try inputting those into Chrome with the 660 scaling.https://injector-rehab.com/knowledge-base/fuel-injector-lag-times/

Your MAFT knob values should be base 2 aux 8. That sets it for 360cc stock injectors since chrome is doing the injector correction. Keep the idle, mid, and WOT knobs set at zero.

Both of those things alone should make the car run and not be overly rich. Do you have a MAFT gen 2 since it’s in the armrest vs the small little black box MAFT? That would make a difference on settings and you’ll have to go through some menus instead.

Thanks for your reply. Appreciate the advice on MAFT settings and that Chrome can handle scaling. I was confused about that. I believe I have MAF Translator 2G3S . I know it's not the Gen II. I had the wiring extension that allowed enough length to run box into armrest. I have all the knobs ( AUX, BASE, IDLE,MID WOT ) Black Box w/lid (4 screws)

I am going to look up the values you mentioned
 

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Thanks for your reply. Appreciate the advice on MAFT settings and that Chrome can handle scaling. I was confused about that. I believe I have MAF Translator 2G3S . I know it's not the Gen II. I had the wiring extension that allowed enough length to run box into armrest. I have all the knobs ( AUX, BASE, IDLE,MID WOT ) Black Box w/lid (4 screws)

I am going to look up the values you mentioned
It sounds like you need to set the mode switches on the MAFT also. I am assuming you did nothing else but plug it in. Switches 1&2 should all be set to off if you’re running a 3” aluminum LS1 MAF in blow-thru and switches 3&4 will be off as well since those features chrome will be handling instead. Give the manual a quick read as well if you haven’t. Translator 2G3S Rev 2.08-1.doc
 

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Discussion Starter #10
It sounds like you need to set the mode switches on the MAFT also. I am assuming you did nothing else but plug it in. Switches 1&2 should all be set to off if you’re running a 3” aluminum LS1 MAF in blow-thru and switches 3&4 will be off as well since those features chrome will be handling instead. Give the manual a quick read as well if you haven’t. Translator 2G3S Rev 2.08-1.doc

I had actually set the mode switches all to off , as per the manual ( which I have read ) . I was playing around with turning the 3rd switch on after making changes to the dials. I was confused by " turn ON to enable startup enrichment"

I just edited my ROM file and set the injector size to 661 (closest value to 660 I can enter) and changed the Injector Battery Voltage Latency Compensation Table to reflect the Latency #'s off Injector Rehab's site. Because they only supplied values at 10V, 11V, 12V, 13V, 14V, 15V ( 6 increments) , I left the first set of numbers from the original map ( 4.69 V - 3.825 MS ) in so the table still has 7 increments . The resulting graph is very similar and smooth but obviously adjusted upward slightly ( which is the whole point , right?)

Is there anything else I should adjust on the ROM file before I flash it back to the ECU ? The MAF size is 288.4 g/s . I haven't figured out what determines that number, but I am assuming I should leave it alone.

I was able to start the car with MAF unplugged , but the next thing i will try is this new ROM file flashed , MAF plugged back in with MAF Box Knobs at AUX=8 , Base= 2 , Idle, Mid, Wot , all set at 0, and pins 1-4 all OFF . Hopefully , it will start and run long enough to get a useful datalog.
 

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It used to be that the MAF size was related to which MAF you were using - stock vs Jester/EVO/Montero, but come to find out it wasn’t at all related to that but actually engine size according to what Greg found out. I would just leave it alone since you don’t need to change it and you are also only using the GM MAFT setup as an upgrade and direct translate. Chrome will do the rest of the tuning.

What you can end up doing after that for fuel adjustments is to look at your fuel trim Hz ranges, change the range if need be to reflect the shift/shrink the MAFT may do(little if any change from what a stock ecu sees), and then go into your MAF smoothing VE table. You’ll have airflow Hz ranges that correspond to idle, cruising, and WOT that off the top of my head were 0-100Hz, 100-500Hz, and 500+Hz. When you datalog your airflow you’ll see where you are at but basically you can treat those as the fueling area for idle, cruising, and WOT respectively. Datalog your long term fuel trims and see how much fuel the ecu is compensating +\-12.5% after it averages out the trims with four 4 min cycles for both idle and cruising. Add or subtract that much fuel in the VE table for the corresponding fuel trim load Hz area and rinse and repeat the process. It’s time consuming but that will dial it in.
 

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Discussion Starter #12
It used to be that the MAF size was related to which MAF you were using - stock vs Jester/EVO/Montero, but come to find out it wasn’t at all related to that but actually engine size according to what Greg found out. I would just leave it alone since you don’t need to change it and you are also only using the GM MAFT setup as an upgrade and direct translate. Chrome will do the rest of the tuning.

What you can end up doing after that for fuel adjustments is to look at your fuel trim Hz ranges, change the range if need be to reflect the shift/shrink the MAFT may do(little if any change from what a stock ecu sees), and then go into your MAF smoothing VE table. You’ll have airflow Hz ranges that correspond to idle, cruising, and WOT that off the top of my head were 0-100Hz, 100-500Hz, and 500+Hz. When you datalog your airflow you’ll see where you are at but basically you can treat those as the fueling area for idle, cruising, and WOT respectively. Datalog your long term fuel trims and see how much fuel the ecu is compensating +\-12.5% after it averages out the trims with four 4 min cycles for both idle and cruising. Add or subtract that much fuel in the VE table for the corresponding fuel trim load Hz area and rinse and repeat the process. It’s time consuming but that will dial it in.

Thanks for the Help! I appreciate the guidance! I'll post back when I have chance to try again.
 

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Sorry I do not know much about the Chrome ecu, but if I may say get rid of that Maft setup. Its nothing but a nightmare on the cars. I used them back in my dsm days and they never ran correctly even when the car seemed fine. My car had one on it and one of the first thing I got rid of. I know the Evo ecu uses open source like Chrome does but my advice is go to a map sensor and covert to speed density. It will make your life so much easier and easier to tune in chrome being your not fighting the maft.
 
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Sorry I do not know much about the Chrome ecu, but if I may say get rid of that Maft setup. Its nothing but a nightmare on the cars. I used them back in my dsm days and they never ran correctly even when the car seemed fine. My car had one on it and one of the first thing I got rid of. I know the Evo ecu uses open source like Chrome does but my advice is go to a map sensor and covert to speed density. It will make your life so much easier and easier to tune in chrome being your not fighting the maft.
The MAFT actually works very well with stock ecu or even a flashable ecu. There’s plenty of people that have gotten it to work well including myself. It’s rather easy to setup if you have a mechanically solid car. As old as these cars are they usually have issues and you can’t chase them away with the tune because it’ll leave you frustrated. It’s better to return the car to stock MAF and injectors, get it running good, and then install the tuning/fuel mods.

Also, Chrome can’t do speed density and it will never be coded to do it within the ecu itself like the Tephra mod the evos have. Nobody wants to program it or spend the time testing; however, there is a Jester add-on device coming that will allow you to run speed density with chrome. I still think it’s more feasible to run AEM if you do want SD by the time you add the costs up.
 

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Discussion Starter #15
I’m highly suspicious I’ve got a bum MAF ( 2 actually) . I reflashed the ECU with correct injector latency values and 660 scaling . Car still will not start with MAF plugged in. When I attempt to, I have to pull the fuel pump fuse, upon which it kicks over for a second, burning the excess fuel off. Runs almost normal idling , off MAF , but still rich with readings @ 8.5 afr. Any touch of the gas pedal will stall the car. Eventually, afr reading starts to drop as fuel builds, then it needs to be shut down. I double checked all my wiring, both on diagrams I wrote out, and what is in car , and it’s all correct. Checked continuity between oem MAF connector and Maft controller box , and it’s all good. Did tests for 12v & ground to the GM MAF and both were fine. Can’t run test for signal on frequency wire as car won’t run on MAF. Also , I need to get a tester that displays Hz. It dawned on me to disconnect MAF connector at maft box , instead of the connector at MAF , which is a bitch to get fingers on. Started car off MAF , and the second I plug connector back together it dies . I bought this stuff second hand , and I’m questioning that decision . Researched which MAF is correct for this application , and it points to the one on GM’s 3.4 L V6. Purchased a refurbished AC Delco version online from Rock Auto tonight, for @ 100 plus core. There are $30 Chinese Knock-offs available , but clearly that would not be wise . I know 3SX has 3.0 MAF for @ 140, but I know I’ll have the RA one sooner, and it will be a Legit AC Delco Part, made in USA. I still have faith that Maft box is not the culprit, but, I’m not ruling that out yet either . I need to find a way to test MAF off the car ?
Is there anything obvious I’m still overlooking?
 

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Discussion Starter #16
I’m highly suspicious I’ve got a bum MAF ( 2 actually) . I reflashed the ECU with correct injector latency values and 660 scaling . Car still will not start with MAF plugged in. When I attempt to, I have to pull the fuel pump fuse, upon which it kicks over for a second, burning the excess fuel off. Runs almost normal idling , off MAF , but still rich with readings @ 8.5 afr. Any touch of the gas pedal will stall the car. Eventually, afr reading starts to drop as fuel builds, then it needs to be shut down. I double checked all my wiring, both on diagrams I wrote out, and what is in car , and it’s all correct. Checked continuity between oem MAF connector and Maft controller box , and it’s all good. Did tests for 12v & ground to the GM MAF and both were fine. Can’t run test for signal on frequency wire as car won’t run on MAF. Also , I need to get a tester that displays Hz. It dawned on me to disconnect MAF connector at maft box , instead of the connector at MAF , which is a bitch to get fingers on. Started car off MAF , and the second I plug connector back together it dies . I bought this stuff second hand , and I’m questioning that decision . Researched which MAF is correct for this application , and it points to the one on GM’s 3.4 L V6. Purchased a refurbished AC Delco version online from Rock Auto tonight, for @ 100 plus core. There are $30 Chinese Knock-offs available , but clearly that would not be wise . I know 3SX has 3.0 MAF for @ 140, but I know I’ll have the RA one sooner, and it will be a Legit AC Delco Part, made in USA. I still have faith that Maft box is not the culprit, but, I’m not ruling that out yet either . I need to find a way to test MAF off the car ?
Is there anything obvious I’m still overlooking?
With all this hassle , I’m starting to consider going with the AEM setup, but honestly, I can’t justify spending another $2K just yet. COVID is throwing a monkey in the Jones Family budget this year with the kids schooling from home, and my wife being between jobs.
 

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I’m highly suspicious I’ve got a bum MAF ( 2 actually) . I reflashed the ECU with correct injector latency values and 660 scaling . Car still will not start with MAF plugged in. When I attempt to, I have to pull the fuel pump fuse, upon which it kicks over for a second, burning the excess fuel off. Runs almost normal idling , off MAF , but still rich with readings @ 8.5 afr. Any touch of the gas pedal will stall the car. Eventually, afr reading starts to drop as fuel builds, then it needs to be shut down. I double checked all my wiring, both on diagrams I wrote out, and what is in car , and it’s all correct. Checked continuity between oem MAF connector and Maft controller box , and it’s all good. Did tests for 12v & ground to the GM MAF and both were fine. Can’t run test for signal on frequency wire as car won’t run on MAF. Also , I need to get a tester that displays Hz. It dawned on me to disconnect MAF connector at maft box , instead of the connector at MAF , which is a bitch to get fingers on. Started car off MAF , and the second I plug connector back together it dies . I bought this stuff second hand , and I’m questioning that decision . Researched which MAF is correct for this application , and it points to the one on GM’s 3.4 L V6. Purchased a refurbished AC Delco version online from Rock Auto tonight, for @ 100 plus core. There are $30 Chinese Knock-offs available , but clearly that would not be wise . I know 3SX has 3.0 MAF for @ 140, but I know I’ll have the RA one sooner, and it will be a Legit AC Delco Part, made in USA. I still have faith that Maft box is not the culprit, but, I’m not ruling that out yet either . I need to find a way to test MAF off the car ?
Is there anything obvious I’m still overlooking?
You’ve got something seriously wrong with your car beyond the tune and I suspect it is multiple mechanical issues, failures, etc. Things are not adding up on the ecu side. You said you are disconnecting it at the car MAF harness connector, which completely bypasses the MAFT and GM MAF altogether, and the car will run albeit super rich in the 8s. Even in limp mode the car should be able to idle at 14.7:1 stoich. With it being in the 8s AFR it’s like the ecu is barely doing any correction.

Honestly, you need to backtrack and start over with some things because you are just going to keep chasing your tail adding parts, swapping, testing this and that, and so on. I’ve seen too many people be there. You need to start with a known good base before adding the mods. At this point there could be a bunch of things wrong or maybe only one or two but now we don’t know what is good so it’s just shooting in the air guessing. I would recommend you swap the stock 360cc injectors back in with the stock MAF. That will take less time than the testing you have already done. Your flashed ecu is highly likely to be good so flash it back to the stock chrome ROM. Fire up the car and see how it behaves. You can go from there and find out what’s wrong but currently you are throwing way too much fuel at it and will ruin your engine if you keep going. If it doesn’t dilute the oil enough with fuel you’ll lower your compression little by little as you continue to wash the cylinder walls down with more fuel.

It sounds like you’re running blow thru right now and would need another 3” MAF. I was going to recommend the 3.75” Z06 MAF because it fits in the stock rubber bubble without any spacers but that’s for a draw-thru configuration. You will want a LS1 3” MAF to replace yours if you stay in blow-thru. To put the stock MAF back in you’ll have to convert back to draw-thru.
 

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The MAFT actually works very well with stock ecu or even a flashable ecu. There’s plenty of people that have gotten it to work well including myself. It’s rather easy to setup if you have a mechanically solid car. As old as these cars are they usually have issues and you can’t chase them away with the tune because it’ll leave you frustrated. It’s better to return the car to stock MAF and injectors, get it running good, and then install the tuning/fuel mods.

Also, Chrome can’t do speed density and it will never be coded to do it within the ecu itself like the Tephra mod the evos have. Nobody wants to program it or spend the time testing; however, there is a Jester add-on device coming that will allow you to run speed density with chrome. I still think it’s more feasible to run AEM if you do want SD by the time you add the costs up.
Thanks for the info. I was not aware that Chrome did not do speed density. My fathers car we found out has a jester ecu in it. Being Chrome is opensource I wonder if Tephra would work on it being it looks liek the same code. I am no computer programmer by any means but just out of curiosity. I was unaware that it wouldn't do speed density. I agree on the standalone aspect of it. That was the first thing I did with my car was put a Haltech on it and started learning about tuning and setting up the ecu. So much easier.
 

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Discussion Starter #19
You’ve got something seriously wrong with your car beyond the tune and I suspect it is multiple mechanical issues, failures, etc. Things are not adding up on the ecu side. You said you are disconnecting it at the car MAF harness connector, which completely bypasses the MAFT and GM MAF altogether, and the car will run albeit super rich in the 8s. Even in limp mode the car should be able to idle at 14.7:1 stoich. With it being in the 8s AFR it’s like the ecu is barely doing any correction.

Honestly, you need to backtrack and start over with some things because you are just going to keep chasing your tail adding parts, swapping, testing this and that, and so on. I’ve seen too many people be there. You need to start with a known good base before adding the mods. At this point there could be a bunch of things wrong or maybe only one or two but now we don’t know what is good so it’s just shooting in the air guessing. I would recommend you swap the stock 360cc injectors back in with the stock MAF. That will take less time than the testing you have already done. Your flashed ecu is highly likely to be good so flash it back to the stock chrome ROM. Fire up the car and see how it behaves. You can go from there and find out what’s wrong but currently you are throwing way too much fuel at it and will ruin your engine if you keep going. If it doesn’t dilute the oil enough with fuel you’ll lower your compression little by little as you continue to wash the cylinder walls down with more fuel.

It sounds like you’re running blow thru right now and would need another 3” MAF. I was going to recommend the 3.75” Z06 MAF because it fits in the stock rubber bubble without any spacers but that’s for a draw-thru configuration. You will want a LS1 3” MAF to replace yours if you stay in blow-thru. To put the stock MAF back in you’ll have to convert back to draw-thru.
Going back to stock MAF is going to be an issue , went all in with filter adapter I fabricated from CF to feed factory turbo inlet hoses . Ignore the tilted MAF, I know it’s skewed about 30 degrees in this photo
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