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Hey guys I'm going to be as thorough as possible here so this will probably be a long post so bear with me. I am the owner of a glorious 1999 3.5l swapped 3000GT SL. I purchased it not to long ago and it ran and it drove amazing! The only issue is that it burned oil. So it clearly needed valve stem seals. I am by no means new to assembling or disassembling heads, this was no large feat. I also installed a new timing belt and water pump while the engine was out.

Got the engine back in, and everything hooked up. It cranks, and starts for 2 seconds then will immediately die any attempt after the car will just crank and maybe randomly pop. I did my due diligence and inspected both the crank sensor, cam sensor, and both reluctor wheels that pass through them. I attempted again with the same result. I had 2 friends who are actual techs verify my mechanical timing is good to go. I am making compression, I have 12v of ground, and I am getting spark.

Here's where things go off course. The next logical step was to check fuel delivery. In my opinion the easiest way to do this was to unplug the injector harness and try starting the car using starting fluid by bypassing the ECU's and pumps delivery system entirely. Surely enough the car starts every time with starting fluid, but here is the twist. If I plug the injector harness back in and attempt the same test the car will just crank. So I replaced the FPR and while I was in there I was able to confirm that fuel was definitely getting to the rail. Currently I have a couple beliefs. Either it's getting too much fuel (Yes I ensured the cams are in the correct spots), Not enough fuel, or The timing of the fuel delivery itself is off. I am very puzzled as to what could be the issue here. As far as I can hear the injectors seem to be pulsing, but I am going to test that tonight with a 9v battery to see if I can hear at least the front head injectors open and close.

Any insight or pointers are greatly appreciated. I'm leaning towards an ECU failure but I could be completely wrong.
 

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Are the 99 CAS different than 93-98? I was under the impression that all 93+ were the same.
 

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93 NA ATX 3000gt DOHC
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........... I had 2 friends who are actual techs verify my mechanical timing is good to go.........
Does that mean crank was on mark also, or just cams lined up to their marks?

............or The timing of the fuel delivery itself is off..........
The cam position sensor is key to injector timing. Is it the one used while engine was running or has it been replaced?

.......... I'm leaning towards an ECU failure but I could be completely wrong.
1999 ECU’s don’t normally suffer from failed capacitors, but the injector circuit (IIRC) can be damaged by a shorted IAC coil.
 
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Discussion Starter #7
To answer all of your questions, the cam and crank are all on mark yes. Multiple people have verified that besides myself.
I have tried starting the engine both on the cam sensor the car came with and another OEM Mitsubishi cam sensor that's brand new. That yielded the same results.

However it is funny you mention IAC because I was having an IAC issue with the car previous to tear down (It down would die when taken out of gear sometimes because it would not catch idle.)

How would you recommend I go about checking injector circuit?
(additionally thanks for your reply white I've seen you on other crank no start threads and you have great info.)
 

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How would you recommend I go about checking injector circuit?
I don’t know how to check injector circuit without having a test bench for ECU’s, which only some rebuild services have. But there’s a test for IAC to confirm internal coils are OK, if it test OK not likely it could have damaged injector circuit.

Attached is IAC test you can read in step two how to check ohm’s at pins 1-6, yours being a ’99 will have black IAC and ohm’s should be ~ 40 ohm’s.
IAC Control motor.JPG
Click on image to expand
 

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Discussion Starter #9
I will perform this test and get back to you. I have another known good ECU and PTU to attempt as well.

I'll test the IAC first and share my results.
 

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I guess I should add you can test injector firing with node light, which you can usually rent set from some auto parts stores. But since you said you could hear them firing (stethoscope I assume) not likely the node light will show anything different.
 

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I confirmed the IAC is working as Intended what would you recommend next
Maybe try your spare ECU you mentioned having since it would be safe to do so now that you know IAC isn’t shorted. Also node light checks at injectors if you’re not completely sure you could hear clicking of each injector by ear (stethoscope).
 
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By the way if you don’t already know, I think you can just unplug ECU and wires will reach enough that your spare ECU can rest against side of trans hump for testing. At least my ’93 did without me having to unbolt and remove existing ECU, the bolts are not needed for ground.
 
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Discussion Starter #15
By the way if you don’t already know, I think you can just unplug ECU and wires will reach enough that your spare ECU can rest against side of trans hump for testing. At least my ’93 did without me having to unbolt and remove existing ECU, the bolts are not needed for ground.
Well, little bit of an update, looked over the engine more and turned out I had two plug wires swapped, that didn't fix the issue sadly, also tried the known good PTU, and ECU to no avail. Not quite sure what to do next. It will still crank and start then die shortly after. (no modulation of the throttle doesn't keep it alive).
 

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Do you have any way to do datalogging/monitoring? You mentioned you did some fueling tests early on, but did you confirm you are able to sustain fuel pressure? If you pull a front plug after a few start/stalls how does it look?
 

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Do you have any way to do datalogging/monitoring? You mentioned you did some fueling tests early on, but did you confirm you are able to sustain fuel pressure? If you pull a front plug after a few start/stalls how does it look?
Front plugs look fine they just get wet, but they still spark. Also I have a tactrix and evoscan. I'm not sure if the ECU will give me a fuel pressure readout on that, but I could hook my laptop up and see.
 

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Front plugs look fine they just get wet, but they still spark. Also I have a tactrix and evoscan. I'm not sure if the ECU will give me a fuel pressure readout on that, but I could hook my laptop up and see.
That's what i was wondering. If they are getting wet, maybe its too much fuel and not enough? That would also be consistent with the car no longer starting on starting fluid when you plug the injectors back in. How old are the injectors and when were they last tested/cleaned? What fuel pump are you running, and is it hotwired?
 

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Ecu swap did nothing?

Can you confirm that you see the “check engine light” on the dash with the keys in the on position.
 

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Discussion Starter #20
Ecu swap did nothing?

Can you confirm that you see the “check engine light” on the dash with the keys in the on position.
Yeah it does self check when the key is in the on position. Engine light lights up, self checks then shuts off as it should.
 
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