Studder/pop/hesitate/fail while in boost 1/2 to full throttle

[Firegst]

Ok, So first thing is first I will tell you every mod on the car the symptoms I am having, then what I have tried and or fixed so far. I just bought this car with the symptoms mentioned.

Car is a 1997 gst eclipse, has tdo5h 14b turbo with dnp turbo mani, and external wastegate, has a 2 1/2 down pipe into 2 3/4 exhuast pipe with no cat and or resignator all the way back to a can there is a secondary o2 about 3/4 back in the exhaust tho. Has a Greddy front mount with a Greddy type S BOV, all hard IC piping and a 4 inch filter coming off the MAF.

When driving the car under light to Grandma style driving it is fine, when you use 1/2 to full throttle or 1/4 throttle long enough to build boost the car studders, pops and then hesitates....If you keep your foot in it, it will keep poping and blowing off. In first gear you can almost reach 4k before this happens at WOT. The car is running a 94 ecu with a esm chip and no check engine lights, also have a 97 ecu that I have tried also with no CEL's but car studders faster, pops more drives like poop. The 94 ecu the car likes alot more, than the 97.

I have replaced the FPR solenoid, plugs, wires, test and fixed any boost leaks, waste gate actuator works properly etc....Even tried hooking the factory Boost solenoid back up with stock 97 ecu still drives like shit..I have tried oem spec plugs gap to .032 as well as one step colder plugs.

I have not yet checked timing or fuel pressure, thats on the list for tommorow.

I am wondering if this could be a timing issue? But why would it run worse with the stock ecu rather than the chiped one if its running factory psi via the wastegate?

Also the car runs rich as f**k I have pulled the plugs to find this out, the car doesn't have a wideband nor a a/f gauge which i ordered a day ago.

At first I thought that this was a simple boost leak, but the car doesn't seem to be hitting fuel cut more like ignition cut/shuddering. Then I thought it has to be plugs? NOPE wires? nope...car idles/loops with the 94 ecu but runs better than the 97 which has a better idle than the 94.

I am not getting any compressor surge if that matters, the spark from the wires to a ground source reaches over an inch and I can see the spark in the middle of the day, so I don't think it would be a coil but I have yet to test them. Also I thought maybe the issue could be a bad MAF, but again its not fuel cut, at least it doesn't feel like a brick wall ....also there is no CEL's on either ecu to say its a bad sensor i.e cam, knock, maf, map , etc....Could it be a TPS? also need to check that as well....

Any thoughts and or Ideas of what could be going on here? I would like to get the car running right and any help/advice would be awesome. Again like I said I will test the fuel pressure tommorow, but when I check timing should I run the stock ecu or the chiped one or does it matter? Also if I have a bad FPR would it cause this? And if both the fuel pressure and timing check out where should I go from there...I realize I could probably test every system but I would like to test the most likely ones first.

Sorry I have given you so much info at one time in short little burst, but this is all pretty new to me ( DSM's) so please be patient, and point me in the right direction. Thanks in advance for any help and or suggestions.



UPDATE: The car had a boost leak and a big one at that, when I first did the boost leak test, I had only found two leaks the BOV and BISS, with both of those fixed I still had the same problems. One coupler was hidden behind the bumper support, where I couldn't see, get to or hear. I had no clue it was there...I took the Front bumper off and did a proper boost leak test and found the coupler was blown in half!...I didn't catch this the first time because I had no regulator so I was using constant air flow not allowing the leaks to show.

 

[Dert]

If you have 550cc injectors, that's your answer why are running rich. With no way to tune for them, your ecu has no idea the bigger injectors are in the vehicle, it thinks you have 450's and sprays fuel like there is 450's, but the 550's are infact giving a bigger squirt than the ecu thinks it is. You need link or safc or another type of tuning program to tell the ecu to compensate the bigger injector.
Second, your bov line is not a boost source, it's a vacuum source and needs to be left as its own independent line for the bov to function properly.

 

[Firegst]

If you have 550cc injectors, that's your answer why are running rich. With no way to tune for them, your ecu has no idea the bigger injectors are in the vehicle, it thinks you have 450's and sprays fuel like there is 450's, but the 550's are infact giving a bigger squirt than the ecu thinks it is. You need link or safc or another type of tuning program to tell the ecu to compensate the bigger injector.
Second, your bov line is not a boost source, it's a vacuum source and needs to be left as its own independent line for the bov to function properly.

But the 95 ecu has eprom which I assumed was tuned for the larger injectors, but it still runs rich with either ecu. I understand that the BOV gets the vaccum from the intake manifold after the throttle body and its not a boost source. I need to tap the j pipe with a fitting for a boost source for the wastegate, but what about installing a boost gauge where would that source come from?

The car runs alot better with the 95 eprom ecu that I believe to have be tuned or adjusted somewhat for the mods on the car, which is making me wondering why it would run rich/fall on its face. No CEL's for TPS, or CAS or Knock etc to be responsible for the retard in timing and or ignition cut...also dont understand how fuel pressure could be causing this problem, if I have the 42-45 psi that is oem then why would I been rich? To much fuel pressure? or to lil? If the regulator was bad and had a constant 42-45 psi, I would see the car run like crap at idle or before getting into boos etc, it runs ok at idle and fine before boost so I dont think thats it. IF it were TPS, I would think things would be more random when they happened I.E the ignition cut. But I can be WOT or 1/4 throttle if it builds boost then it cuts out. IF it were the CAS, wouldn't my idle be crap and the same with the rest of the rpm band? Knock sensor would throw CEL, but again maybe I didnt drive long enough....When driving the car and getting into boost it feels like it hesitates, cuts ignition or doesnt ignite then wont go anywhere, that's where the rich problem is coming from, being that when in boost there is no spark to ignite fuel..or maybe I am wrong maybe there is spark but no fuel? would it feel the same? Also do coil packs go out all at once or slowly or can they be intermittent?

 

[delta448]

My thing is if I am running the 95 ecu, have 550cc injectors and 16g how am I still running rich? and or ignition cutting? Do coil packs go out slowly or all at once? I havent looked at the fuel pump to see if there is a re-wire mod but its a quiet pump so I dont think it is aftermarket.

Possible reasons that you are running rich on the 95 ECU:

• The chip may be set for stock injectors and you're running 550's.
• The chip may be set for lower than stock base fuel pressure.
• All the air measured by the MAS is not making it into the cylinders. (boost/vac leaks)
• An injector(s) is stuck open.
• Your return fuel line is pinched.
• Your FPR is not seeing vacuum.
• You have a non-stock fuel pump and are getting FPR overrun.

I really doubt this is your problem, but here's how to test your coils:

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But I can be WOT or 1/4 throttle if it builds boost then it cuts out. ...(snip)... When driving the car and getting into boost it feels like it hesitates, cuts ignition or doesn't ignite then wont go anywhere, that's where the rich problem is coming from, being that when in boost there is no spark to ignite fuel..or maybe I am wrong maybe there is spark but no fuel?

This tells me that there's so much fuel under boost that your plugs are probably completely fouled, that you might be hitting rich knock and that you are probably so rich at tip-in that it won't even ignite. You're probably soaking the whole rotating assembly in gasoline, I hope you change the oil often. I really doubt the ignition system is to blame. How old are the plug wires? Have you checked them at night for spark leak?

Also do coil packs go out all at once or slowly or can they be intermittent?

It's usually all or nothing, but can be intermittent and only occur when the coils are hot. If you're inclined, go ahead and test them. It's a lot easier for you to get a feel for what's really going on since you're experiencing it first hand, if you get a gut feeling, go with it. The rest of us only know what you tell us anyway.

 

[Firegst]

Possible reasons that you are running rich on the 95 ECU:

• The chip may be set for stock injectors and you're running 550's. Dono why, I would think its tuned for the injectors
• The chip may be set for lower than stock base fuel pressure.
  Why would someone do this?
• All the air measured by the MAS is not making it into the cylinders. (boost/vac leaks) checked for leaks and its good.
• An injector(s) is stuck open.
  wouldnt this effect the car at WOT before boost? or make it not want to idle etc
• Your return fuel line is pinched.
  Explain please what this would cause and why?
• Your FPR is not seeing vacuum.
  I will test and double check this
• You have a non-stock fuel pump and are getting FPR overrun.

see below

I really doubt this is your problem, but here's how to test your coils:

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This tells me that there's so much fuel under boost that your plugs are probably completely fouled, that you might be hitting rich knock and that you are probably so rich at tip-in that it won't even ignite. You're probably soaking the whole rotating assembly in gasoline, I hope you change the oil often. I really doubt the ignition system is to blame. How old are the plug wires? Have you checked them at night for spark leak?

I will test spark leak, but they are only 3 days old


It's usually all or nothing, but can be intermittent and only occur when the coils are hot. If you're inclined, go ahead and test them. It's a lot easier for you to get a feel for what's really going on since you're experiencing it first hand, if you get a gut feeling, go with it. The rest of us only know what you tell us anyway.

Thanks for the diagrams I have alldata as well but thank you. The ecu was chiped so I am guessing that it knows the 550's are there...I looked at my fpr it has a vuccum line getting to it but dono if there is any vaccum...ill test that, and the FPR solenoid was replaced as well. If the FPR was getting over ran what exactly does that mean? Its suck open? but the car runs fine unil boost...even WOT until boost..possible the ecu chip shorted out or went bad etc?

 

[GSTurbo1]

Did you try opening your throttle body while you BLT? You may have crack or two in your intake seal.

Your chip did not go bad, you have a leak in your intake. CHECK ALL SEALS, I'm going to garuntee you didn't

 

[delta448]

Thanks for the diagrams I have alldata as well but thank you. The ecu was chiped so I am guessing that it knows the 550's are there...I looked at my fpr it has a vuccum line getting to it but dono if there is any vaccum...ill test that, and the FPR solenoid was replaced as well. If the FPR was getting over ran what exactly does that mean? Its suck open? but the car runs fine unil boost...even WOT until boost..possible the ecu chip shorted out or went bad etc?

The FPS (FPR solenoid) only has one function; to interrupt the vacuum signal to the FPR and thereby increase fuel pressure at start up -only when the engine is already warm-. A warm engine evaporates the port fuel film, so extra fuel is needed to re-establish a constant film evaporation rate, sounds trivial but warm restarts must have been enough of an issue for Mitsu to address it.

FPR overrun occurs when the regulator cannot bypass enough fuel volume back to the tank via the return line and fuel rail pressure rises as a result. That's just one of several reasons that we like to install an aftermarket Adjustable Fuel Pressure Regulator that can flow enough to avoid it.

It's possible the chip is bad, but pretty unliklely. More likely is that it is not coded for the current set up on this car. Most likely is that there is a huge boost leak and that you aren't really pressure testing the intake all the way from the compressor inlet to the intake valves.

 

[Firegst]

The FPS (FPR solenoid) only has one function; to interrupt the vacuum signal to the FPR and thereby increase fuel pressure at start up -only when the engine is already warm-. A warm engine evaporates the port fuel film, so extra fuel is needed to re-establish a constant film evaporation rate, sounds trivial but warm restarts must have been enough of an issue for Mitsu to address it.

FPR overrun occurs when the regulator cannot bypass enough fuel volume back to the tank via the return line and fuel rail pressure rises as a result. That's just one of several reasons that we like to install an aftermarket Adjustable Fuel Pressure Regulator that can flow enough to avoid it.

It's possible the chip is bad, but pretty unliklely. More likely is that it is not coded for the current set up on this car. Most likely is that there is a huge boost leak and that you aren't really pressure testing the intake all the way from the compressor inlet to the intake valves.

I did a BLT from the turbo inlet with 20psi, I found a leak at the BOV and at he idle screw. I did not open the TB tho...I guess When I tap the j pipe tommorow ill be doing another test anyways so I will open the throttle body and test again...Where else should I be putting the pressure and or looking for leaks? I am going to let the car idle while spraying carb cleaner to get an idea then I will leak test again...as far as the FPR, the car does smell of fuel I thought that was because of it running rich, maybe not thinking of the lines being pinched or what have you.

Did you try opening your throttle body while you BLT? You may have crack or two in your intake seal.

Your chip did not go bad, you have a leak in your intake. CHECK ALL SEALS, I'm going to garuntee you didn't

K I will triple check this tomm. Also is it possible for the turbo itself to leak somewhere?

 

[Dert]

You can T a line for a boost gauge into the stock fuel pressure solenoid (FPS) or if you have an adjustable regulator you can T off that. Boost gauge can also be T'd off the "P" line on the throttle body on 2 G's. As stated before, just because you have a 95 EPROM ecu doesn't mean it is chipped for 550's or even proper fuel pressure. Pop it open and see if it even has a modded chip in it. There's a good chance you have stock EPROM ecu with stock chip still in it. Open it and verify it is actually chipped. Just because it EPROM doesn't make it chipped for a tune.

 

[Firegst]

You can T a line for a boost gauge into the stock fuel pressure solenoid (FPS) or if you have an adjustable regulator you can T off that. Boost gauge can also be T'd off the "P" line on the throttle body on 2 G's. As stated before, just because you have a 95 EPROM ecu doesn't mean it is chipped for 550's or even proper fuel pressure. Pop it open and see if it even has a modded chip in it. There's a good chance you have stock EPROM ecu with stock chip still in it. Open it and verify it is actually chipped. Just because it EPROM doesn't make it chipped for a tune.

Not sure what the P line is? And which line off of the solenoid? the line going from solenoid to FPR or From Intake to Solenoid. I have opened the ecu it is chiped with an esmlink chip double stacked..which I believe mean you can use ram/data log?

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[liquidsilver]

Now I've seen everything. That would be V3 if I'm not mistaken...hook up your laptop and set your injectors http://www.ecmtuning.com/wiki/baseinjectordata. Sign up on ECMTuning User Support Forums asap. This problem can be solved in <2 minutes my gut tells me.

I'm nobody special here...but please correct your profile to read "95 ecu with ECMLink V3."

 

[delta448]

Wow.

So I'm guessing you didn't get the ECMLink cable with the car? Otherwise if you had it, you could have easily just gone to the download page with a compatible laptop and fixed 90% of your issues in less than 10 minutes. Contact Tom or Dave and see what you need to do to get set up with the cable to use with your V3 or V3 Lite chip.

 

[Dert]

Not sure what the P line is? And which line off of the solenoid? the line going from solenoid to FPR or From Intake to Solenoid. I have opened the ecu it is chiped with an esmlink chip double stacked..which I believe mean you can use ram/data log?

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On the top of your throttle body there are 3 ports. Its the 1st one (closest to you if your in front of your car)will be a line with a green stripe, should be a "P" stamped on throttle body unless you have emissions delete, then you will have no line and it will probably be capped. Contact Tom or Dave at ECM, get a cable for v3, go to ECM's site, Download software and run a log, you will be able to fix your problem in 10 min or less as its probably not set up for your 550's or a fuel trim issue. As for FPS, you can T off the line from intake to FPS

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[Firegst]

Awesome guys thanks for the replies, links and pictures...I contacted ECM and I am waiting to hear back. I went to the download page and downloaded v3.24.70 for windows I hope this is the correct one. If not please let me know.

Also when I go to the support forums for ecmlink I cannot register, or create a username? Anywhere else I can find some help/info?

 

[2gDSM6bolt]

maybe even check ignition coils

 

[Firegst]

UPDATE: The car had a boost leak and a big one at that, when I first did the boost leak test, I had only found two leaks the BOV and BISS, with both of those fixed I still had the same problems. One coupler was hidden behind the bumper support, where I couldn't see, get to or hear. I had no clue it was there...I took the Front bumper off and did a proper boost leak test and found the coupler was blown in half!...I didn't catch this the first time because I had no regulator so I was using constant air flow not allowing the leaks to show.

I still however have a rev limiter or something very similar at around 5800 6000k, The car runs like a raped ape until then then it will bounce off that rpm as if it is hitting rev limiter.

My question is how and why does this happen? Is it just a ecu thing and thats where the previous owner set it or could a sensor or my plugs/coils etc being doing this?

TO EVERYONE THAT HELPED! THANK YOU SO MUCH I LEARNED QUITE A BIT, I APPRECIATE YOU BEING SO HELPFUL AND RESPECTFUL BEING THAT I AM A NEWB!

COMING FROM THE HONDA GAME, I CAN SAFELY SAY I WILL NEVER GO BACK...NOT JUST BECAUSE THE CARS BUT BECAUSE OF THE PEOPLE. DSMERS ARE SO MUCH MORE RESPECTFUL AND MATURE.

AGAIN THANK YOU ALL!

 

[Dert]

Could be because previous owner has the rev limiter set to that in link. Tom or Dave will be able to help you out with registering on link forums. Once you get your cable you will be able to see exactly what your car is set up like. I suggest watching the video demos and reading a lot on the link wiki so you can get an idea of what's to come once you get your laptop hooked up.

 

[Firegst]

Could be because previous owner has the rev limiter set to that in link. Tom or Dave will be able to help you out with registering on link forums. Once you get your cable you will be able to see exactly what your car is set up like. I suggest watching the video demos and reading a lot on the link wiki so you can get an idea of what's to come once you get your laptop hooked up.

I am still waiting to hear back..does anyone have a direct email to either of the above mentioned people? I would like to explain to them how I acquired the car etc so that they might allow me to use the support forums.

I plan on doing alot of research once I receive and hook up my wideband, and get the cable...Along with about 500+ search inquires and 25+?'s

Thanks again.

 

[Dert]

[email protected] is where I sent emails to thomas, but that was a while ago and I am unaware if it has changed.Tom and Dave are both members on this forum as well, but I can't recall their usernames.

 

[Firegst]

^thanks ill give it a try.