2G Sputtering and fuel cut under wot or partial load

[Popcorn]

Some background i am not a noobie to the boosted world i have a lot of knowledge on bmw as thats what i mainly drive. Ive built a lot of boosted e46 bmw. Anyways.

I recently bought a 1997 gst. My first ever turbo 2g.

car came with a big turbo. Big injectors fpr i installed a 450 walbro and i fixed the vacuum leaks that i could see.
I installed some new sparkplugs and gapped to .023

I put 91 in it and car was idling super rich like maxed out my old style aem guage wich is 11.1. Drove really similar tbh. At partial load would start sputtering at any sort of load almost like it has a limiter placed for 4k. We did rev the car from a stand still and came to realize it has anti lag. Car revs at 4.5k and starts popping and banging all crazy.

We then proceed to drive it until its on empty and fill it up wih e85 and car drives 100x better. Idle is not at like 12.1-12.5 afr which still isnt good but better! But same problem with wot or partial throttle. Sputter!!!! Almost like it has the limiter. Like the antilag sort of. Im wondering if maybe previous owner set up a limiter on it or maybe even set up rolling antilag and i dont know how to drive it properly......... idk. But anything over 3.5-4k afr drops to 17-18afr till car starts sputtering and like lumping all wierd.


I truthfully dont know where to start im super fustrated. I dont know if its possibly symptoms of a bad map sensor?

 

[Popcorn]

1997 GST 5 speed manual
Big turbo
Bigger injectors from what I see. idk size
450 Walbro fuel pump
Aftermarket FPR
Sparkplugs new, gapped to .023

So long story short, we fixed car, got it to start, put 91 in it. Car idles really rich.
It maxed out my old style AEM AFR so lowest it reads is 11.1 and its pegged to that at idle. Upon driving it. Car sputters and doesn't drive to nice. And wouldn't rev to anything past 4k. Kinda like it hit a limiter. We parked car and rev'ed it. To see if maybe it was something else and boom starts rev to 4.5k and come to find out it has launch control. Starts banging and popping.

We then proceed to drive it to empty and put about 5 gallons of e85 and it seemed to like it a lot more. Idled at around 12.1-12.5 AFR which is still rich but better. It drives good too but same issue. After 3.5-4k it starts sputtering! AFR starts going super super lean at partial (half throttle) and its even worse at wot kinda like its trying to do rolling antilag.

AFR vary from 17-18.0 AFR. To the point it reads - - - as in its past the parameter it can read.

I'm wondering if maybe prev owner set up a hard limiter or maybe MAP sensor is bad?

If anyone can help that would be greatly appreciated I'm honestly lost in the deep end. Here are some pics for reference.

Also whats this sensor plugged into? Its a single pin!

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[steve]

I see a MAP sensor on the firewall but it's not connected to the manifold. I don't see a Intake Air Temp (IAT) sensor which you also need to run Speed Density and the car doesn't have a MAF. You don't mention what you're using for an ECU but without anything measuring the Air Flow I'm not surprised is doesn't run right.

That type of connector I usually see on the various noise capacitors. Where does the female end run to?

 

[Popcorn]

I see a MAP sensor on the firewall but it's not connected to the manifold. I don't see a Intake Air Temp (IAT) sensor which you also need to run Speed Density and the car doesn't have a MAF. You don't mention what you're using for an ECU but without anything measuring the Air Flow I'm not surprised is doesn't run right.

That type of connector I usually see on the various noise capacitors. Where does the female end run to?

Hey buddy! So forgot to update but i connected a vacuum like to that sensor and car idles and drives great now! Just again car gets lean under boost till about 5-8psi it goes perfect 11.5 afr


Do you know anything else i can check besides a tune? Ill also update pics of ecu later

 

[1990TSIAWDTALON]

Post a log of the issue happening if you have ECMlink.

 

[Popcorn]

Post a log of the issue happening if you have ECMlink.

Hey bud truthfully im in the deep end with logging these cars ive never done that on a car this old. I do my own personal tuning and logging on my bmw but thats a whole other world. Any advice?


I tried sending pm but i am still to new......

 

[bettfootball]

Do you know if you have ECMlink? Could just pop the ECU out and take a peek. Then I would suggest finding someone to tune it.

 

[Popcorn]

Do you know if you have ECMlink? Could just pop the ECU out and take a peek. Then I would suggest finding someone to tune it.

I shall.be doing this later today after work! Stand by!

 

[Vegas Smith]

Nice car! You can't just switch to e85. Ideally you'd need an ethanol sensor and some way to tune the car. Check out the ecmlink website if you do have ecmlink and it will tell you how to a take a quick log so we can look at the settings.

 

[Popcorn]

Nice car! You can't just switch to e85. Ideally you'd need an ethanol sensor and some way to tune the car. Check out the ecmlink website if you do have ecmlink and it will tell you how to a take a quick log so we can look at the settings.

Thanks bud! And yes i understand you cant just switch over but. Car drives a lot better on e85 than it did on 91....... so i just assumed it was tuned for e85 and not 91 due to the terrible driving conditions on 91....


But yes ill get some pics in about 2 hours and a half.

 

[1990TSIAWDTALON]

I would bet its set up on E.
I'm sure not knocking Vegas, but I did what he said you can't do, but I knew enough about tuning to take a leap of faith and go fill up with E and readjust my stoich on my tune. I made it home and the car drove fine but it did need FINE TUNING after that.
I knew what I had to do though.
Find out if you have a ECMLink chip in your ECU then we can go from there.
Crossing fingers it does have!

 

[Popcorn]

Do i open it up to check inside???

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[steve]

That would be the right case for it to be a 95 EPROM but until you look inside you won't be able to tell if it's had DSMLink installed unless you happen to have received the datalogging cable that goes with. It isn't a 97 ECU case and unlikely to have a 97 ECU board inside it.

 

[Popcorn]

Did i luck out?

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[steve]

Did i luck out?

Yes, now to get you the logging cable.

ECMTuning, Inc.

www.ecmtuning.com

 

[Popcorn]

Yes, now to get you the logging cable.

ECMTuning, Inc.

www.ecmtuning.com

Question. Are these cables married to the board? Kinda like a vq you need the cable that you tuned it with in order for you to upload tune?


Link you provided is the correct one for this one right?


What would happen if i purchase a normal inpa cable. K+dcan and just programmed that. Would that work? What software should i download on my laptop? Just one software or multiple


I use about 4-5 different softwares when tuning my bmw. Hahha.

 

[steve]

Specific to DSMLink not specific vehicles running DSMLink. I doubt an INPA cable will work but I've never tried mine other than on my E90. On that page select a 2G cable. The picture is for the 1G cable. That red circuit board in the EPROM socket is the DSMLink V3 hardware.

You download the client software from their site and you love it compared to INPA.

The 2G V3 cable looks like the one in this kit.

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