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2G GHS GSX Shop Project- Tuning/Idle Help

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gijoe985

15+ Year Contributor
562
20
Dec 13, 2007
Grandview, Washington
Hello all,

We wanted to start a new thread for our high school shop project that has been sitting for the last half year. You can see our old threads here and here.

We have the car turning on now. We've got our timing correct and we have good compression on all cylinders now. Today when we turned the engine on it ran smoothly, but at 1600rpms. It ran well for a couple minutes, but then began to have some hiccups here and there. Eventually the idle lowered some and the idle became rough and then it just died. We tried restarting it and it idled ok and then again eventually died. Wideband originally showed us right around 14. The last time we ran it it was idling at 15:1.

We did a boost leak test and thought things looked ok. Though the psi gauge we had (attached to air gun) may not have been working well. How long does it take to pressurize the system normally? We were pumping in 50psi for 10 seconds or so and that seemed like overkill. It would hold some pressure, but again, I'm not questioning how well that gauge is reading. Sadly maintenance just came to service our compressor, so we may not have air for a few days. But we didn't hear any leaks when we pressurized it as high as we felt comfortable.

I know that the BISS will need to get adjusted, but I was waiting until it seemed to be running better.

Thoughts?
 
Fuel pressure staying up when it gets warm? I couldn't remember if it had an adjustable fuel regulator on it.
 
Fuel pressure staying up when it gets warm? I couldn't remember if it had an adjustable fuel regulator on it.
It does have an AFPR, I'll have to check that.

I pulled plugs, they look rich. One had some oil around the threads. I'm going to look into that. It appeared from a quick and simple power balance test (via pulling injector harnesses) that the inner cylinders may be making more power than the outer. Perhaps weak/bad coil?

I did another compression test, every cylinder was between 145-150psi.

I also took a short log of it warmed up. I assume I can just load that here and people can check it? This is my first exposure to ECMlink, so I haven't done much with it as of yet. It did lean out in the last couple seconds before it died.
 

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Makes me think the coolant temp sensor is not working, causing it to idle high and rich, cause it thinks it's cold. Then once it warms up, since the sensor isn't working correctly, it just kills fuel and dies.

You did a FIAV delete/bypass right? What is the coolant temp reading in ECM link? Have you verified the throttle plate stop is adjusted correctly and is not hung open a slight amount? When your adjusting the biss screw, how close are you to bottoming it out?

The biss screw video makes me think you still have air leaking somewhere/somehow.
 
We screwed the FIAV in all the way to essentially bypass it. Coolant temp steadily climbs on ECMlink as if it is reading properly. We have set the throttle plate and adjusted it a couple times to be sure. I think the BISS is turned out about 1.5-2 turns.
 
I might suggest making a block-off plate for the FIAV just to eliminate the possibility.

Out or curiosity, what does the airflowperrev show in ecmlink? Sorry I'm on my phone and can't view the log :oops:
 
I'm on my phone too dang it. Will look at the log when I get home but you did good just getting a log posted Joe. It will tell a lot.
 
switched to my tuning laptop to check the log, most of the stuff you have logging looks appropriate. id recommend logging idle switch (iirc that is part of the tps sensor on 2gs), maf, mdp (if possible) and getting the wideband hooked up to log.

biggest thing im seeing is the ISC is a bit high @42, and the O2 doesnt seem to cycle properly (might be that its just a short log), though it also matches the wierd spikes for rpm and AFRest oscillations. makes me think an exhaust leak or boost/vacuum leak still.

ill still stand by doing a full FIAV delete to ensure thats not a possibility for air leaking.
i dont recall, have you check for exhaust leaks? id really check the manifold-to-head, manifold-to-turbo and turbo-to-o2 housing carefully for leaks taht may be causing the extremely lean reading.

keep in mind im about as novice as i gets with ecmlink and tuning :p
 
So, according to the wideband and my spark plugs, I'm running rich. And I thought the F02 was reading rich also.

I can start it up and try to get in another log with more things set later today.
 
Ok, I was able to get a quick test in before the students got here. I think I added the correct values. I just don't see where I can review them.

So this is a log from a cold start all the way until it dies at 190 degrees. I turned out the BISS towards the beginning of the run, hoping to keep it running, and then I also revved the motor up one time (just trying to heat it up a bit faster. )

Let me know your guys' thoughts.
 

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Joe I see one thing that needs addressed. If Brett were on here we would have already heard it...........
Calibrate the TPS. When the car is DEAD at the end of the log, it still shows the TPS at 2%. 3% when it is running at its idle. It is a PITA to get to and I always recommend putting allen head screws back in so you can loosen those hard to get to little bolts that hold the TPS tight. With allen head screws, you can take a short allen wrench and get it in there to loosen them up without taking anything apart. I had to cut about a 1/2" off of a regular allen key so it would fit, but you will thank yourself later. I fired up Link on my work computer (shhhhhh) and I could see that. I don't know if your version allows for STFT and LTFT logging but I log those and they assist me in dialing in idle and cruise tune.
 
Also since you see it is running rich, you can change the global fuel from -46.9 to -48.9 (which is actually the value for 880's) and it will lean it out as it thinks it has a little bigger injector than what it is scaled for. It will lean it out across the board though. Just a thought to try and get her leaner. If it starts to react a bit better, you can tell it that it has 900's (-50 global fuel) and see how she reacts.
Here is what I log, but I like to see A LOT of things when I am trying to dial my stuff in.
 

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@1990TSIAWDTALON I thought the tps was acting up too, and while I haven't checked the second log, if you look at the first, the tps does go fully to 0% and .65v. not perfect on voltage, but the fact that it's reading 0% when "idling" around 1500rpm makes me think it's pretty close, though you're right it technically needs adjusting.

Is it possible the tps is loose, might be causing the sporadic readings?
 
I didn't check the first log, but saw the normal "TPS" thing where it is 1% different between running and off. I suppose the sensor could be loose, yes, it hadn't crossed my mind. I bet Joe will check it though. As I glanced over it, I am on a "company" computer so I have to play some tricks just to run Link, but anyway, I couldn't see a lot of values that I am used to seeing but I believe Joe said the shop car has V2 Link and I have never seen what the difference was between the versions. That is why I suggested maybe playing with the global a little bit to lean her out. If we get to see a WB reading then we all can chime in with more helpful tips.
One more thing I do, from an old tuner, is always start my logs with a full throttle press of the gas pedal when I start the log. Maybe it's just old habits, but it is nice to see that 0-100% swing to begin with.
 
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I wanna say the difference between v2 and v3 was speed density?
From the first log, it looked like the O2 was reading lean to me, bit I'll check the second log and see what it looks like when I get a chance.
Marty your a hardcore dude accessing ecmlink on a company computer haha!

edit: after looking at the second log, its definitely rich. another thing i notice i the TPS is all over the place between the two logs. either the plate isnt closing fully after you hit the throttle, or the TPS is loose. the ISC looks fine in the log.
i agree a wideband is going tell us alot. im still supicious of there being intake or exhaust leaks somewhere, and the FIAV needs to be completely bypassed or replaced with a working unit. after those things are done we should be able to start getting this thing back on track.
 
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Ok, so I have the TPS adjustments enabled in link. Does that not eliminate the need to calibrate it at the TB? I've calibrated one before, but was under the assumption with with link I could just let link do the work.

Also, we are CONTINUALLY having kids leave a door open, or the key on, so the battery is always dying. That said, it wipes my TPS setting as well as the setting for 880s. Which is funny because the chip says that it was tuned for 880s, but it always defaults back to that -46.9 setting. So I adjusted it back to be used for 880s.

I did find a vacuum leak at the MAF because the kids didn't tighten the clamp after we did out last boost check. Which is a bit ironic. But that said, it didn't seem to improve anything.

If these injectors are leaking or not seating correctly, that could account for the rich mixture. Perhaps? Every now and then when cranking it almost acts like it experiences a hydrolock. I'll sometimes have to crank it 3 seconds to get it to start after it has died and then randomly you will hear a strong resistance to cranking, but then it's fine again. My plugs all looked rich, but none were wet.

I'll attach this log, but now I'm not sure if the TPS was recalibrated yet or not. I'll go try to get one more log.
 

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Yeah, I have to hold the pedal down to get it to start (almost like with an older carburetor motor when flooded.)

So here is a log. TPS looks good. Fuel at -48.8. I start with a little throttle, and then slowly let off. Eventually she just dies.
 

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even though you have ecmlink you still want to do a manual adjustment to .63v. using the idle adjustment in link, to paraphrase @GST with PSI , is a band-aide fix and not reliable.

im starting to wonder if the maf is bad, will it run any different, or at all, with the maf unplugged? that doesnt necessarily account for the high idle, but its another test.
 
If you get time, post a new log! We are shooting for 14.7 give or take a few so you are getting it closer. :thumb:
 
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