2g mas installed. Random stalling. Tuning problems...?

[90 TSI FWD]

Vehicle is a 1991 tsi awd. Main mods are:
Custom intake for 2g mas
Fmic w/ 2.5" ic piping
Rewired Walbro 190
SAFC2
Evo 560cc injectors
Evo3 manifold
Small 16g
Apexi DP and Exhaust
Boost is at 15psi (may be irrelevant because I'm worrying about low throttle)

I just installed a 2G MAS and bpr7es and I'm having trouble keeping it running. The idle is perfect and boosts fine, but when I'm cruising around 1500-2400rpm, the stock boost gauge will jerk to 14 and the car will try to die. Also, when I release the gas it will sometimes try to die as the stock boost gauge jerks up and back down to normal.

The problem is not the wiring or the Mas. I changed to another mas and triple-checked my wiring. No boost leaks.

Could this be due to my safc settings?

800>-18
1400>-14
2000>-6
2800>-4
.. the rest are -4, as well as high throttle

What I did was tune the low fuel trim to 100%. I was looking at other similar threads (there are so many, but none has this jerking problem) on here and dsmtalk, and some people with 550cc injectors have their settings in the positives. Could my setting be Really lean? I understand that all cars are different, but why does mine need to be at -18, whereas others are in the upper positives?

Could a lean mixture cause this jerk on the stock boost gauge? I may try richening up the points tomorrow (don't wanna wake the neighbors).. I wish I was out right now at the big dsm meet, but this problem had to occur.

Thanks in advance

 

[SBR Joe]

Try setting the SAFC at 0% across the board on Low throttle and see if that changes anything. I had similar problems with my 1g with 780's and an evo maf but it was fixed once i got a wbo2 and saw how incredibly wack my low throttle AFR's were, nothing that had to do wth the boost gauge jumpin around though, thats kind of weird....i cant even see what relevance the stock boost gauge would have in the situation. Your % from 800-1400 seen pretty lean. You shouldnt have to take that much fuel out with 560's and an 2g maf. Let me know the results when you zero it out on low thr.

Also do you see any CEL's when this is happening?


Joe

 

[90 TSI FWD]

The random jerking was fixed. For future reference, don't use cheapo wiring connectors.

Try setting the SAFC at 0% across the board on Low throttle and see if that changes anything. I had similar problems with my 1g with 780's and an evo maf but it was fixed once i got a wbo2 and saw how incredibly wack my low throttle AFR's were, nothing that had to do wth the boost gauge jumpin around though, thats kind of weird....i cant even see what relevance the stock boost gauge would have in the situation. Your % from 800-1400 seen pretty lean. You shouldnt have to take that much fuel out with 560's and an 2g maf. Let me know the results when you zero it out on low thr.

Also do you see any CEL's when this is happening?


Joe

No CELs at all.
On the otherhand, I reset my ECU and set the safc to all zeroes. The car smelled really rich and once the trims started to change, they went straight to 81.9% and I had to lean it all the way back to -18 to bring it to 100%.

When I revved the car, the RPMs would drop and the car would stall... even with the safc with all 0s across.

For now, I hacked the 1g MAS to get the car running for school this week. Tuning was SOOO much easier. The settings are around -20 across, rather than -29 with the unhacked MAS. I'd like to put the 2G mas in, but it never worked out right... maybe the 2 Mass Air Sensors I tried were bad...?

 

[90 TSI FWD]

Okay. the hacked MAS is being overrun. I want to put a 2G MAS back in. I am in search for a working unit.

What the heck makes my car so different to tune from other 1G DSMs? It has a 1990 ecu in the 91, but even my friend's settings were positive. Why did I have to lean it out -18 just to get the trims to 100%???

Please lend me some input guys.

 

[90 TSI FWD]

The 2G Mas is back in, but the stalling issue is Still an issue. I'm leading towards the tune, but if I did the revving thing to get the trims at 100, why would it still stall when I rev or go into neutral? Also, it does it when I give it stight boost.. then when I let off the gas around 3.5k rpm, the stock boost gauge will jump (like usual, even on the 1G mas), but it will stay at around "-5" psi.. then once the rpms drop, instead of the stock boost gauge dropping back down to "-7", it will jump to "0" and the car would stall.. any other input?

Did you guys with 1G cars and 2G Mas' have the same problem?

Thanks