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2G Severe power loss. Please help! Searching 6 months

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bibdrums

Probationary Member
13
0
Apr 29, 2009
Milltown, New_Jersey
1996 Gst spyder A/t, Hallman MBC, MHI big 16g, 3” turbo back exhaust, IPT retorqued converter, IPT shift kit, Autometer boost gauge, 20K on stock rebuild


About 6 months ago I was cruising on the highway doing about 70 when the car had a bad miss-fire and started feeling like it was running on 2 cylinders and sort of chugging. I pulled over and the car idled fine. So I gave it some gas and it sounded normal but was lacking a lot of power. It moved so slowly from a stop that it was hard to pull out into traffic. When I got home I checked for codes and had a p0300.


I have been chasing this problem for 6 months. Yesterday, out of nowhere, the car ran amazing for about an hour. Then, just as suddenly, it started running like crap again. Feels like it’s pulling timing or not getting enough/too much fuel. Also, the exhaust manifold is getting MUCH hotter than ever before. It melted the condenser fan. Builds boost very well though and holds it.


This is what I have checked or replaced:

Fixed ALL boost leaks
Checked timing (like 5 times)
Checked compression (all good)
New knock sensor (was leaking black goo)
Swapped in known good coils
New coolant temp sensor
Swapped in known good ECU
Turbo had play so had it rebuilt
Checked fuel pressure
New FPR
New egr
Salvaged power transistor
New alternator
Ran open exhaust to rule out catalytic converter
New O2 sensor
New exhaust manifold (was cracked and leaking)
New plugs ngk bpr6es gapped properly
New wires
New tps
New crank position sensor
New MAF


When I checked the fuel pressure it was a little high - 43 with the vacuum line connected and 50 disconnected, that’s why I changed the FPR but the new one is showing almost the same so it may be the gauge? Or a clogged return line maybe?


Does anyone have any other ideas on what to check next. I don’t have link, a wideband or anything to log with yet but I am getting link and a wideband in the next month or two. Does anyone have any ideas of stuff I may have missed in the meantime?


Thanks!
 
Last edited:
Did you set the fuel pressure with the line off ?

I’ve had a hot manifold before, which turned out to be a restricted cat. Turn my housing and manifold red. Removed cat and np ever since
 
Thanks for replying.

I don't have an adjustable FPR yet. I ran the car with the downpipe disconnected to rule out the cat. There was no change in how it ran.
 
May not be the problem but check the plug wires. Small cracks in the insulator or plug boot could let the spark arc over & short out. Run the engine at night in the dark and you may be able to see if there is some arcing issues.
 
May not be the problem but check the plug wires. Small cracks in the insulator or plug boot could let the spark arc over & short out. Run the engine at night in the dark and you may be able to see if there is some arcing issues.
Yes, thanks. I knew I would forget stuff. I have been battling this for so long. I changed the wires and plugs (ngk bpr6es). Thanks, any other ideas please keep them coming.
 
Check wiring for anything melted/chewed on, it presents like an electrical or ECU issue.

Have you verified the CAS is functional and stable? Do you have ecmlink so you can post a log?
 
I have not really checked the CAS I will have to look into doing that. I don't have ecmlink, I should be getting it pretty soon.

I found a black wire that had been rubbed through in my harness that I assume was a ground and checked the continuity to ground and there was continuity. I'll have to go through it all better. Thanks!
 
1996 Gst spyder A/t, Hallman MBC, MHI big 16g, 3” turbo back exhaust, IPT retorqued converter, IPT shift kit, Autometer boost gauge, 20K on stock rebuild


About 6 months ago I was cruising on the highway doing about 70 when the car had a bad miss-fire and started feeling like it was running on 2 cylinders and sort of chugging. I pulled over and the car idled fine. So I gave it some gas and it sounded normal but was lacking a lot of power. It moved so slowly from a stop that it was hard to pull out into traffic. When I got home I checked for codes and had a p0300.


I have been chasing this problem for 6 months. Yesterday, out of nowhere, the car ran amazing for about an hour. Then, just as suddenly, it started running like crap again. Feels like it’s pulling timing or not getting enough/too much fuel. Also, the exhaust manifold is getting MUCH hotter than ever before. It melted the condenser fan. Builds boost very well though and holds it.


This is what I have checked or replaced:

Fixed ALL boost leaks
Checked timing (like 5 times)
Checked compression (all good)
New knock sensor (was leaking black goo)
Swapped in known good coils
New coolant temp sensor
Swapped in known good ECU
Turbo had play so had it rebuilt
Checked fuel pressure
New FPR
New egr
Salvaged power transistor
New alternator
Ran open exhaust to rule out catalytic converter
New O2 sensor
New exhaust manifold (was cracked and leaking)
New plugs ngk bpr6es gapped properly
New wires
New tps
New crank position sensor


When I checked the fuel pressure it was a little high - 43 with the vacuum line connected and 50 disconnected, that’s why I changed the FPR but the new one is showing almost the same so it may be the gauge? Or a clogged return line maybe?


Does anyone have any other ideas on what to check next. I don’t have link, a wideband or anything to log with yet but I am getting link and a wideband in the next month or two. Does anyone have any ideas of stuff I may have missed in the meantime?


Thanks!

1996 Gst spyder A/t, Hallman MBC, MHI big 16g, 3” turbo back exhaust, IPT retorqued converter, IPT shift kit, Autometer boost gauge, 20K on stock rebuild


About 6 months ago I was cruising on the highway doing about 70 when the car had a bad miss-fire and started feeling like it was running on 2 cylinders and sort of chugging. I pulled over and the car idled fine. So I gave it some gas and it sounded normal but was lacking a lot of power. It moved so slowly from a stop that it was hard to pull out into traffic. When I got home I checked for codes and had a p0300.


I have been chasing this problem for 6 months. Yesterday, out of nowhere, the car ran amazing for about an hour. Then, just as suddenly, it started running like crap again. Feels like it’s pulling timing or not getting enough/too much fuel. Also, the exhaust manifold is getting MUCH hotter than ever before. It melted the condenser fan. Builds boost very well though and holds it.


This is what I have checked or replaced:

Fixed ALL boost leaks
Checked timing (like 5 times)
Checked compression (all good)
New knock sensor (was leaking black goo)
Swapped in known good coils
New coolant temp sensor
Swapped in known good ECU
Turbo had play so had it rebuilt
Checked fuel pressure
New FPR
New egr
Salvaged power transistor
New alternator
Ran open exhaust to rule out catalytic converter
New O2 sensor
New exhaust manifold (was cracked and leaking)
New plugs ngk bpr6es gapped properly
New wires
New tps
New crank position sensor


When I checked the fuel pressure it was a little high - 43 with the vacuum line connected and 50 disconnected, that’s why I changed the FPR but the new one is showing almost the same so it may be the gauge? Or a clogged return line maybe?


Does anyone have any other ideas on what to check next. I don’t have link, a wideband or anything to log with yet but I am getting link and a wideband in the next month or two. Does anyone have any ideas of stuff I may have missed in the meantime?


Thanks!

Check your MAFS. I similar problem years ago. The pins were contacting properly. Check all of your connection for exposed wires.check the ECU connection pins as well.
 
Check you crank sensor too, I had the same thing happen to my car. car would run and drive great, then the crank sensor would get warm and quit working. It wouldn't get spark, but it would fuel. Does it smell like gas under the hood? and check to see if your plugs are wet! I Couldn't get the car to run again until it cooled down. I switched to a 1G black top and it solved the issue.
 
Thanks guys. Then next two things on my list to swap out are the maf and the cam sensor. First the maf because the cam sensor is tough to get at. I did check all the wires going to the maf and they all have the proper voltages and the ground is good. These are 23 year old parts so changing them definitely can't hurt.

I noticed accidentally, by dropping a ratchet on the maf while it was running, that if I tap the maf while it's running the rpm's go up for a second or two and then fall back down. Not sure if that is a sign of anything.
 
Make sure the plug wires are in the correct order and confirm your O2 sensor is working. Also check the connector on the coil

if the plugs werent on the right coils, the engine wouldnt run at all. in our wasted spark, since 1/4 and 2/3 always fire simultaneously, the only wrong way is coiling 1/2 and 3/4 together. at that point you have totally wrong spark timing.
however, checking the plugs for proper contact is ok and especially check the connectors for the transistor unit and coil pack as they can break over time. been there, a bi*** to track down.
 
Well it wasn't the MAF. I just changed it and its still running awful. I'm gonna start going through the wire harness to look for broken, melted or shorted wires. If anyone has any suggestions on which ones to start with or any good procedures I'd love to hear about it. Thanks again everyone for all your suggestions and help!

Also, I've been searching for ways to test the cam position sensor and I can't really find a definitive way. Can anyone help with that?
 
Sounds like it might have jumped time a tooth or two, that or maybe a clogged catalytic converter.
I checked both of those and they were both good. Maybe the cam position sensor is sending a bad signal to the ECU causing the timing to get wacky. That's the next thing I'm going to swap out. I just took a really good look at it and the wires don't look so good. Definitely looks to be the original so I'm gonna replace it.
 
Finally got link and logged for the first time. Would you guys please take a look and give me some insights. I'm still having the same horrible problem of no power. Thanks!
 

Attachments

  • log.2019.09.20-01.csv
    373.4 KB · Views: 31
Sorry, this is my fist foray into logging and I don't know what an elg log is.
 
Oh I see, it's the actual raw file and not the exported version. This is the one right?
 

Attachments

  • log.2019.09.20-01.elg
    143.9 KB · Views: 91
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