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Author Topic: Engine stall - decoupling after high load request  (Read 5375 times)
pitercsg
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« on: September 02, 2023, 12:22:58 PM »

Hi guys. I have a problem with engine stalling - for example: I'm accelerating from 1000rpm to 3000rpm, pushing the pedal to the floor. When i let off the pedal and clutch in - when engine rpm is dropping ,it won"t stop at idle rpm but goes past and stalls. I logged it and i noticed weird maf redings at this situation. They are significantly high - attaching it. When i unplug the MAF, everything is fine, engine maintains idle perfectly. Is that a hardware problem due to intake tract or bad MAF sensor, or can i solve it in software?
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nyet
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« Reply #1 on: September 02, 2023, 01:48:48 PM »

DTCs?
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nyet
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« Reply #2 on: September 02, 2023, 01:51:06 PM »

log clutch switch?
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Please do not ask me for tunes. I'm here to help people make their own.

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BlackT
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« Reply #3 on: September 02, 2023, 01:55:40 PM »

I have same problem, even on two cars one with gt28 other with k04-064.
Like te turbo surge make fake readings to MAF

EDIT: problem ocured after fitting bigger turbos. Both cars was on K04-022 and never have any problems
« Last Edit: September 02, 2023, 02:50:41 PM by BlackT » Logged
pitercsg
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« Reply #4 on: September 02, 2023, 04:05:41 PM »

Thanks guys. Exactly, i have gt2871 installed. So there's no other way to get rid of this? Maybe some dv modification or i don't know... What about running mafless ( which is stupid, but maybe in this case this is the solution)?

Edit: Maybe something needs to be done in MAF pulsation maps, but i don't know what to start with
« Last Edit: September 02, 2023, 05:51:17 PM by pitercsg » Logged
BlackT
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« Reply #5 on: September 03, 2023, 11:52:39 AM »

I didn't find solution so far, I am thinkig about going to blow tru MAF
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prj
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« Reply #6 on: September 04, 2023, 06:01:00 AM »

Really funny how you guys invent reasons and solutions to a problem that is purely your own ignorance.

1. Pressure test.
2. Pressure test.
3. Pressure test.
4. Set TVUB correctly as well as scale MAF correctly if the injectors and/or MAF are not stock.
5. If flywheel is not stock, adjust idle controller.

I hav never ever had any stalling issues that could not be solved by the above and very quickly at that.
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BlackT
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« Reply #7 on: September 04, 2023, 11:46:26 AM »

Really funny how you guys invent reasons and solutions to a problem that is purely your own ignorance.

1. Pressure test.
2. Pressure test.
3. Pressure test.
4. Set TVUB correctly as well as scale MAF correctly if the injectors and/or MAF are not stock.
5. If flywheel is not stock, adjust idle controller.

I hav never ever had any stalling issues that could not be solved by the above and very quickly at that.
If it was yust that easy...
Maf readings go crazy and engine is weted by fuel, no TVUB can help when MAF read(in spikes) 40-50 g/s  at 1000 rpm and TB is at 2-3%
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prj
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« Reply #8 on: September 04, 2023, 12:08:29 PM »

If it was yust that easy...
Maf readings go crazy and engine is weted by fuel, no TVUB can help when MAF read(in spikes) 40-50 g/s  at 1000 rpm and TB is at 2-3%

That's because you have hardware issues with intake.

Apart from the really obvious (boost/vac leak).
Pick one of these:
1. You are completely retarded and are venting bypass to atmosphere, and making pikachu face. "Why it doesn't work???"
2. Your bypass does not open because you removed N249 and friends and it has a way too stiff spring.
3. Your bypass and it's connections are nowhere near big enough for the turbo size you are running.
4. You don't have decent straight pipe before/after MAF.
5. You put the bypass outlet at a 90 degree angle close to the MAF instead of putting it close to the turbo and angling it into the turbo inlet.

Yes, it's THAT simple. Do shit right and this problem does not exist.
The only time I had issues was when the flywheel was like half the original mass, in which case you have to adjust SAWE to have a higher hysteresis for enabling injection, and boom problem solved.
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BlackT
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« Reply #9 on: September 04, 2023, 01:56:19 PM »

As I said if it was yust that simple.
Fitting bigger turbo in A4 chaiss and keep everything as stock is hard yob. Pipes are big and angeled, there is no room for anything. I am now fitting a lot bigger BOV if that doesn't work I will go on blow tru MAF
Of course I have tryed play with springs, with or without N249, in atnosfere or before turbo, and with different BOVs
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Blazius
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« Reply #10 on: September 04, 2023, 02:17:48 PM »

This is age long issue with RS4' mafs and so on specially in the B5 chassis. Yes you can barerly fit an intake with MAF on there. If you do you gonna have quite massive surge , which will need hacks, injection resume way higher , idle PID changes and so on.
Even if the intake is right, the recirc has to be done properly with planning otherwise on recirc you gonna have false readings due to turbulence/surge so yeah.

The golf platform doesnt really have this issue as you got some decent space aswell as the 2.7T either in biturbo or single turbo config.

Better to run SD on the B5 IMO.
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prj
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« Reply #11 on: September 05, 2023, 03:30:53 AM »

I've done many 1.8T with RS4 MAF, not one of them had idle or stalling issues. Some of them built by completely clueless customers, which I was able to fix easily.
I'm sorry, but the problem is you.
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BlackT
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« Reply #12 on: September 05, 2023, 03:47:20 AM »

Okay then I am going to put little more effort to try sort it out
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