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Funfoot
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Discussion Starter #1
KNOCKS(12-21)ABOUT 3000RPMS WITH WOT AND CODES P0125 AND P0170, BUT RUNS GOOD? Wonderful '92vr4 with almost all the bolt-ons available (560 inj and billet turbos), Chrome and semi-complete rebuilt by Mit mechanic who is not a tuner. Knocks(12-21 as measured on the lcdbc, from the beginning and codes came on after a couple thousand miles). Don't want to hurt car. Tried larger direct wired fuel pump with new fuel pressure regulator, Race gas and changing duty cycle on lcdbc only helped a little(per suggestions from an Evo mechanic). No apparent vacum leaks. Need tuner near Los Angeles that understands vr4's, Black Stealth lcdbc and Chrome. In the meantime any ideas? Would appreciate any help. Thanks
 

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P0125 means it took too long to go into closed loop... P0170 means bank 1 fuel trim is out to lunch. Bank 2 may not be far behind it, but hasn't set a code yet.

Is it a stock airflow meter? have you tested for boost leaks? What are the injector size and latency settings?

Al Sison (username Bboyalan on here) is a great tuner, but he's in San Diego.
 

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Funfoot
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Discussion Starter #3 (Edited)
Hi RealMcCoy,
Yes...I've been reading about these 2 codes. I actually showed my research to the Mit. mechanic and he nixed them all. He feels we need a tuner that understands Chrome and the Black Stealth lcdbc. About 3k miles ago we put all new/rebuilt parts under the hood except the lower which checked out fine. We had no codes until now, but from the beginning we have been fighting rough starting and knocking at WOT. The airflow meter is new and is from a corvette Z06. We have found no vacum leaks. The injectors are 560's, are rebuilt and came with the proper paperwork that they were 100%. I don't know what the latency settings are, but we went over them with Jester from Chrome. I have heard great things about Al from San Diego. Is there some way I could get his help if I drove to San Diego? Could you help me with an introduction? Thanks for the imput, it's appreciated.
 

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Hi RealMcCoy,
Yes...I've been reading about these 2 codes. I actually showed my research to the Mit. mechanic and he nixed them all. He feels we need a tuner that understands Chrome and the Black Stealth lcdbc. About 3k miles ago we put all new/rebuilt parts under the hood except the lower which checked out fine. We had no codes until now, but from the beginning we have been fighting rough starting and knocking at WOT. The airflow meter is new and is from a corvette Z06. We have found no vacum leaks. The injectors are 560's, are rebuilt and came with the proper paperwork that they were 100%. I don't know what the latency settings are, but we went over them with Jester from Chrome. I have heard great things about Al from San Diego. Is there some way I could get his help if I drove to San Diego? Could you help me with an introduction? Thanks for the imput, it's appreciated.
You don't need to be a tuner to look at fuel trims, O2 Sensor output, and diagnose a code... That's just part of daily life working on cars. Now if it's already been determined you have a severe rich or lean condition, and it's been determined it's in the tune, (a couple big ifs that I'm not convinced have been answered yet) then a good tuner can fix it.

Almost sounds like your mechanic is washing his hands of it and isn't trying very hard...

You are also dealing with a MAF translator that has the ability to adjust airflow output and compensate for larger injectors. (A piggyback tuning device) you need to make sure it's set up properly also...

I just sent Alan a text with a link to the thread...
 

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SDSU Alumnus
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Thanks for the words and text, Larry!

funfoot - Jeff, right? I believe you are friends with Ray M. (formerly of LA). Correct me if I am wrong, but I thought you ended up going to RRE in Santa Fe Springs for a tune, no? I apologize if I am confusing you with another of Ray's friends, but I presumed it was you since you mentioned an "evo mechanic" heh. Regardless, you guys should make the drive down... he has not visited in ages!

I agree with everything Larry has mentioned and suggested so far and would start with confirming and sharing your MAF-T settings. Even posting a datalog for us would provide greater insight. It sounds like you already have the cable, otherwise, you can record a brief video clip cycling through the LCDBC.
 

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Funfoot
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Discussion Starter #6
ReaMcCoy,

I noticed on my lcdbc that my trims are about 98, 119, 109 and 100 and my front O2 sensor is frozen at .05-.07 and my rear is all over the board. I am running a Z06 MAF-MAF-T. Also, it has been real hot outside and the coolant temp has been below 180 degrees and I have those two cel codes P0125 and P0170.

Thanks much for the imput...


Alan,

Exciting...Let's make this tune happen. We are available any weekend except Aug 10th. Can you do it in one day? I could stay the night at Ray's and we could both come down early in the am? We could do a Sat(the traffic would be better) or even a Thursday. If you need the car for more than one day we could make arrangements. Any suggestions from you as to what I can do or bring to make the tune work smoothly for you would be appreciated.

"92 vr4: Parts were changed about 10,000 miles ago)Chrome ecu, BS Lcdbc, Heads rebuilt by local speed shop, 15 g billet turbos, Irridium plugs gapped at 2.0(one heat range colder), Evo bov, Mac valve, Carbon fiber drive shaft, 560 injectors, new intercoolers, AEM high flow pump(hot wired) and AEM fuel pressure regulator, higher flow muffler, 3sx downpipe, dbest671 rebuilt throttle body, Z06 MAF-MAF-T, New wires and more.

Looking forward to hearing from you,
 

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ReaMcCoy,

I noticed on my lcdbc that my trims are about 98, 119, 109 and 100 and my front O2 sensor is frozen at .05-.07 and my rear is all over the board.
When i had a O2 sensor frozen at low voltage like that, i found the O2 was bad. I replaced it with one from Rock Auto. I posted a thread about it but am at work and can't easily find it right now. Just make sure if you order from there you get the correct one for front/rear as the wire length is different. Note, in my experience this also prevented the ECU from going into closed loop operation.

The O2 sensor voltage will be "all over the board" from 0-1V when the ECU is in closed loop as it is trying to maintain AFR around 14.7. You should see this if you have a wideband. Remember that closed loop only occurs at low load/RPM - the exact cutoff is not known but i have found basically <30% throttle and <3000rpm you should be in closed loop.
 

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ReaMcCoy,

I noticed on my lcdbc that my trims are about 98, 119, 109 and 100 and my front O2 sensor is frozen at .05-.07 and my rear is all over the board.
Short term trim, (FTO2) parked on 100 and not moving means it's in open loop. In closed loop it jumps all around following and correcting for the 02 sensor readings. I'd guess that your front sensor is bad.
 

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Thanks for the words and text, Larry!

funfoot - Jeff, right? I believe you are friends with Ray M. (formerly of LA). Correct me if I am wrong, but I thought you ended up going to RRE in Santa Fe Springs for a tune, no? I apologize if I am confusing you with another of Ray's friends, but I presumed it was you since you mentioned an "evo mechanic" heh. Regardless, you guys should make the drive down... he has not visited in ages!

I agree with everything Larry has mentioned and suggested so far and would start with confirming and sharing your MAF-T settings. Even posting a datalog for us would provide greater insight. It sounds like you already have the cable, otherwise, you can record a brief video clip cycling through the LCDBC.
Hey Alan, I would be more than glad to make it down to your place.
It has been awhile and would be nice to get together killing "Two birds with one stone". I can join Jeff for the tune when he goes. Let us know
convenient days and times for you. Thank you, Ray
PM us!
 

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I just wanted to follow-up here with the actions taken and conclusion in case anyone else comes across this thread during a search.

Jeff, Ray, and I initially met up in October where I performed a series of 20# pressure tests in addition to redoing a few vacuum lines. After addressing about 75% of the leaks, I took Jeff's car for a test drive and verified better/correct boost control albeit "low" boost now instead of high-teens spikes lol. I made some suggestions on a few maintenance items both underhood and on the car for next time. Since then, the remaining leaks were addressed, new knock sensor installed (out of precaution), new NGK-7's @ 0.032", etc. Blackstone UOA was not the greatest, TBH, but we agreed to proceed anyway knowing very well that an overhaul would be an eventuality - seeend it! haha... (switched from 10W-30 to M1 15W-50)

Fast forward to this past weekend, we finally met up again since our schedules aligned while I was in Ontario/Rancho Cucamonga helping Cho with his single turbo Stealth. Apparently, Jeff's VR-4 was having issues passing the sniffer portion of emissions testing even with a gallon of ethanol mixed-in. Mind you, I have not touched the tune yet. Sure enough, trims were pegged and still compensating - go figure.

First order of business was correcting the VE table. After one drive and one flash, feedback was now within 5% - check! I reckon that it will drift with the translator, but it is what it is. I wanted to take the normal approach for making safe power on Cali Piss Pump-91 but quickly realized that the engine was not going to take it. The compromise was more fuel, less timing, and low-mild boost at ~1bar. It probably took 3-4 passes, but I managed a knock-free tune.



"This original owner 1992 3000GT VR-4 with unopened 200k+ miles 2-bolt/cast crank engine made ~320AWHP VD SAE..."

I already advised a "seafoam treatment" to help clean out the likelihood of carbon buildup. Other than that, everything seems to be peachy! woohoo! Fun times...
 
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