Running Terrible, Tuning not helping

[bjc26]

Ok I have gone through just about all the threads here and searched quite a bit but just need some advice on why I can't tune out the problem I am having.. I felt this was more of a tuning problem then a "problem diagnosis" so I posted it here.

Recently my car has been having trouble after startup and occasionally after driving for a while. When depressing the gas the car falls on its face and the rpms drop to <500. This will continue to happen for the first 5 minutes after startup and will occasionally happen when going from cruising to on throttle. According to my datalogger the o2 occasionally drops down to 0.00 or 0.01 volts and stays there, at the same time the FTO2 jumps to 199.99%. The fuel trims are nearly impossible to tune correctly with the safc, as soon as I have LTFT set perfectly to around 100-110% with -2% correction the thing likes to go back to showing a fuel trim of 118.7% and I have to go plus 10 or 15 to knock it down, then it goes to the rich side (82.3%)

I also can't get the mid and high fuel trims lower than 118.7 (which they are both at right now). I made some runs and datalogged and found a knock count upto 10 in some spots... To eliminate this I had to add 20% in some upper rpm ranges which I felt was odd in itself with the 550's and fuel pump upgrades. I have the knock count to 1-3 in fourth gear pulls but still feel that is a lot of fuel to be dumping in....

Any suggestion as to how to get the car running more reliably after startup?? Also maybe someone can explain what the fto2 of 199.9% means.

Thanks in advance....

Here is my setup - 90 talon tsi fwd, walbro 190 - rewired, stock 2gmas, afc, vacuum lines eliminated, joe p mbc, atr 3" catback, vrs 3" downpipe, punishment o2 dump, rre intercooler, buschur uicp, stock bov, 550cc injectors, bpr7's, datalogger, running ~17psi

 

[burldude]

I would have to say check your cam timing and then base timing to eliminate those . With cut out I would say that it could be mass air flow sensor , but cant tell with out the car in front of me . It could also be the ecu ? To many possibillities , we need more info . You need to update your vehicle profile so we have somthing to work with .

 

[bjc26]

I put my current setup right in the post to give you some general ideas, what else do you need to know. Base timing has been checked and is perfect, general maintenance work has been performed on the car. I am leaning towards o2 sensor, which I am waiting to arrive.

When I get the hesitation the FTO2 jumps to 199.9, o2 dives to 0.00 or 0.01V and the timing doesnt change much and I dont see any knock. With the 2g mas I see hz readings around 33 to 37 and in the top end I am approaching 1500 +

Plugs look to be in good condition, not showing extreme rich or lean conditions. What else can I tell you so you can provide some more suggestions?

 

[burldude]

That helps alot , Vehicle profile . I would question my ecu if I where you . The o2 trim hitting 199.9 is not right . From my understanding and messing with my car the highest the o2 trim can register is 167 max. Please research this I am just sharing what I have found with my car .

 

[1LE]

I'd start with O2 sensor, then maybe look into a new FPR.

 

[bjc26]

Thanks for the tips.... The o2 sensor is on the way and I have a feeling that will solve a majority of my problems. The 199.9% FTO2 is definitely showng something major is wrong... THe wierd part is that that reading coincides with when the o2 reads 0 volts. The mid and high fuel trims are still stuck at 118.7% and not moving.

Could the use of the 2gmas have anything to do with the readings? I know the low, mid, and high are meant for 1gmas whereas 2g dataloggers just use a ltft and stft or something similar. Could that be my problem??

Thanks again

 

[steve]

Could the use of the 2gmas have anything to do with the readings? I know the low, mid, and high are meant for 1gmas whereas 2g dataloggers just use a ltft and stft or something similar. Could that be my problem??

While your 2G MAS is going to cause some tuning issues it's not the reason 1G's have three fuel trims and 2G's have short and long term trims. Those are part of how the ECUs work between the 2 generations.

Steve