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2G Dsm sounds like a wrx

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zotis777

5+ Year Contributor
41
6
Mar 23, 2018
Oklahoma City, Oklahoma
Hey I’m needing help with my dsm. I have a 98 gsx. I bought it kind of hacked, I’ve done a lot to it so far. Originally I picked it up with some pretty mean boost leak problems. Diy front mount was garbage.



It got a vrsf, 16g installed. Boost leak tested to 25psi. Fixed a couple couplers and a leaking BISS screw. I installed ECMlink. Oil and filter, filled it with fresh gas. New plugs and wires, my front o2 was reading 0.0v all the time and I replaced it. did all the usual stuff trying to freshen the car up.



Well after it sounded like a wrx, it idles fine but with an occasional little skip. Revs fine, but the moment there’s any load on the car it just skips and rubles. No CEL it would be nice if there was it could tell me what cylinder is misfiring. Well I’ve been trying to track that down for a month now. I’m on my 3rd set of plugs and wires, I cleaned the injectors and did filter baskets/injector seals/rail spacers/pintle caps. No luck, every time I take the plugs out they look dry fouled except that the electrode ground is white and charred. I don’t know what that means at all, despite tons of googling on reading plugs nobody’s described dry fouling with a white electrode ground. I’ve searched here and have not found a definitive answer. If the problem is simple and I’m just being a dummy and could’ve found it just by altering my keywords I apologize in advance, though I would welcome the fire just to get this car running top.


Currently no aftermarket monitoring, I’ve been looking at estimated AFRs and the other “estimates” that link can create, I doubt they’re accurate (one of my logs had an estimated 433hp so I know they’re not spot on) but at idle they’re consistently 12:1 area AFRs.



Finally compression tested it and got a solid 135 all across the board, that’s only 2psi above the service limit. That worries me but I don’t think it would cause the problems I’m experiencing. I’m not sure that compression tester was particularly accurate it’s a garage sale special that required some Teflon taping to get it to help pressure and every time I went ahead and tightened a fitting/sealed the tester better it read a little bit higher. Again I don’t think I trust the tester, if 135 is accurate (I hope it’s not) then wouldn’t it be idling and running far worse than what’s described?


I went to test coil pack and power transistor tonight only to find out the hard way that I’ve lent my multimeter to a friend, I will be testing those soon. I’m sorry for the long post but I’m running out of ideas, I’ve tried everything I can think of and I’ve yet to make it at all better or worse. Which seems to me to be pointing to the idea that I’m not getting warmer at all.


I have pictures of the plugs, logs, videos, whatever needed to help track this down. I’m ready to get this thing driving smoothly
 
I think you’re on the right track testing the PTU. I was recently having very similar issues and even felt as though the car had a ‘subaru’ sound to it. Swapped the PTU with a spare I had on hand and it fixed everything.
 
I think you’re on the right track testing the PTU. I was recently having very similar issues and even felt as though the car had a ‘subaru’ sound to it. Swapped the PTU with a spare I had on hand and it fixed everything.


I’m hoping, I wish I could’ve tested it tonight but I will be sometime this week. I’ve found the ohm limits for the coil pack but not yet the PTU. I’m going to try and track those down
 
I’m hoping, I wish I could’ve tested it tonight but I will be sometime this week. I’ve found the ohm limits for the coil pack but not yet the PTU. I’m going to try and track those down
Do me a favor , start the car and let it idle. Pull each plug wire 1 at a time. The idle should change obviously. Imo wrx sounds come from running on 3 cylinders or incorrect timing
 
Do me a favor , start the car and let it idle. Pull each plug wire 1 at a time. The idle should change obviously. Imo wrx sounds come from running on 3 cylinders or incorrect timing


I’ll give that another shot, the idle changed any time I pulled a plug wire. Last time I tried that I was using cheap plug wires and they arc’d Through the boot. When they did the idle would steady out slightly, but if I pulled them all the way out it would dip and sound rough. I’ll get a video of it if it will help.


Just for clarity I’ve since upgraded to some NGK blue wires.
 
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If your settings are right, links AFRestimate should be pretty close.
 
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If your settings are right, links AFRestimate should be pretty close.




Do you know why idle would be around 12:1 if that’s the case? As far as the fuel system it seemed to be working just as youd expect with the narrowband. “Front o2” rises and dives across stoich like the ecu is trying to float around 14.7 but my estimate said 12
 
OK. So your MAFcomp tab looks super messy. I can't see that being right. The curve should be smooth not jumping around like that. Also your "Coolanttemp fuel adjustment" should probably be set back to stock. The MAFcomp tab will help you get your AirFlowPerRev where it should be (0.24 unless you have cams). Once that is set, start working on your fuel trims and see if your AFR estimate gets closer to 14.7 at idle.

Other thoughts, 28 psi on no wideband is foolish.
Your fuel table is a little lean at the higher loads, most recommend 11.0 max for the higher load boxes.
 
OK. So your MAFcomp tab looks super messy. I can't see that being right. The curve should be smooth not jumping around like that. Also your "Coolanttemp fuel adjustment" should probably be set back to stock. The MAFcomp tab will help you get your AirFlowPerRev where it should be (0.24 unless you have cams). Once that is set, start working on your fuel trims and see if your AFR estimate gets closer to 14.7 at idle.

Other thoughts, 28 psi on no wideband is foolish.
Your fuel table is a little lean at the higher loads, most recommend 11.0 max for the higher load boxes.


I didn’t even notice “coolant fuel adjustment” wasn’t stock, I’ve been doing my best to try and set anything I could find back to factory settings (just to get everything functioning correctly and then work from there)


On a side note I have tried the car on the stock ECU and it still sounded like garbage
 
I didn’t even notice “coolant fuel adjustment” wasn’t stock, I’ve been doing my best to try and set anything I could find back to factory settings (just to get everything functioning correctly and then work from there)


On a side note I have tried the car on the stock ECU and it still sounded like garbage
When I first started tuning, my load scale was set to a 2.3l engine and I had no engine how it happened. Weird stuff can happen to these tunes. Didn't even know what a load scale was.
 
When I first started tuning, my load scale was set to a 2.3l engine and I had no engine how it happened. Weird stuff can happen to these tunes. Didn't even know what a load scale was.


I’m definetly still adjusting and getting familiar with link. Ive done a couple cars on hondata and tunerstudios but this is my first real dsm and first time on link.


Doing my best not to be a dipshit noobie and felt like I was buying good parts and doing things right as far as maintenance troubleshooting and upgrading went. This time with this damn misfire I finally threw in the towel and made a thread.


I appreciate the heck out of all the help so far, things have been brought to my attention that would’ve taken me forever to find :banghead:
 
How did it do with the adjustments? New log?


I feel like a donkeys rear for not giving them a shot yet but I don’t get much time to play with my dsm during the week. I’m gonna try them out hopefully tomorrow before work. I have a pretty demanding day job (jet engine mechanic) that eats more of my time than I’d like. However I’ve taken notes of the new settings and will report back with a new log posted hopefully. I appreciate the help though, I’d still be messing with the right stuff and leaving the wrong stuff wrong if I hadn’t posted
 
I’ve found what I believe to be a bad coil pack, primaries reading 1.5/1.2 and secondary reading 16.13/16.31


Those numbers off enough to cause an intermittent or partial misfire like I’m experiencing? Either way i will be purchasing a new coil and still uploading the revisions into ECMlink
 
Alright now I’m idling at 2,000. 1300 with the grounding pin connected. heres a log of that, im gonna start troubleshooting this crazy idle, and setting my TPS correctly
 

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Throttle position can cause odd things, my throttle body was so gummed up AND the cable was way out of adjustment. I had high idle went popped the hood and forced the throttle body closed and bingo idle went completely normal. My throttle percentage would be at like 8% when i was off throttle.. added a spring or two to snap it shut for time being until I rip it apart and clean later.
 
Alright now I’m idling at 2,000. 1300 with the grounding pin connected. heres a log of that, im gonna start troubleshooting this crazy idle, and setting my TPS correctly

So you can verify that the throttle plate closes and opens all the way like Murdertalon suggested. Might help.

What i bet will also work is to log "RawThrottlePos". I noticed in your latest log that it is at 37. With the "Simulate idle switch from TPS" box checked. The ECU is looking for a value below 35 to "close" the idle switch and get the car to idle as you have requested it to (950 RPM). You can tell that the car isn't trying to hit that target idle because your "IdleSw" value is 0. If you uncheck the "simulate idle switch from TPS" it might figure it out onj it's own. If not you need to adjust your TPS.
 
So you can verify that the throttle plate closes and opens all the way like Murdertalon suggested. Might help.

What i bet will also work is to log "RawThrottlePos". I noticed in your latest log that it is at 37. With the "Simulate idle switch from TPS" box checked. The ECU is looking for a value below 35 to "close" the idle switch and get the car to idle as you have requested it to (950 RPM). You can tell that the car isn't trying to hit that target idle because your "IdleSw" value is 0. If you uncheck the "simulate idle switch from TPS" it might figure it out onj it's own. If not you need to adjust your TPS.

I didn’t even notice that box! Man I feel like a noob, I’m going to give that a shot when I get the chance.


I went to adjust the TPS and I could not for the life of me get a wrench on the bottom bolt especially with the engine still hot. That and I zoomed way in on “tps voltage” on the logging screen and was going to use that as opposed to a multimeter. I bumped the TPS sensor when I loosened the top bolt and it immediately dropped from .74v to .53v, idk if it’s just very sensitive, hopefully my TPS isn’t bad too. Before I got to make any real progress it got late and I had to go to work. Tomorrow will be fixing nitpicky stuff well into the night (finally)
 
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