HELP. My car is dieing.

[ILW84U]

I have been trying to diagnose a problem for the last little while & am getting nowhere. When I step on the gas pedal normally the A/F pegs on rich & the car bogs or stalls. If I am very, very easy on the gas, the car runs fine. I cleaned the MAF & there was no change. I replaced the MAF, no change. I rewired the MAF wires that were extended in the Procharger install, no change. The car was running great until this started at the track a couple of weeks ago. Could this be a TPS issue? I have attached 3 data log files if anyone knows how to read them & help troubleshoot.

I need to get this car back on the road for a track weekend in 2 weeks. Any assistance is appreciated.

 

[ZmanM3]

Sounds like a tune issue. I would make sure that your O2 sensors are connected properly too though. Is it throwing any codes?

 

[ILW84U]

No codes. I have a meth tune & a pump gas tune. When I saw it was going rich I thought maybe the meth was spraying earlier than it should so I switched to the pump gas tune & unplugged the meth system with the same results. I haven't checked the O2's but they looked OK while I was data logging.

 

[bscottie]

make sure you didnt have a hose or piping loose, also check all the connectors

 

[klaw]

I think the TPS sensor was redesigned for 07+. You might want to try a swap out. Also, make sure your fuel rail pressure sensor plug is making good contact. I had a case where the PCM wasn't seeing fuel pressure and was then commanding more fuel. I reseated the plug and everything was good.

Good luck Rick!

 

[klaw]

After reading your post again, and thinking abut it for awhile, your issue sounds alot like my "falling on it's face" issue before the latest tune. Has anything changed with your bypass controller? If you open the throttle too quickly, the car will shed vacuum (it doesn't have much to begin with because of the aggressive cams) and the boost controller will close. Too much boost/air at too low an RPM can result in table pegging in the tune.

Slow throttle tip-in allows RPM to build increasing vaccuum at low throttle angle. On my Whipple setup, I had to go to a very light spring in the bypass which helped - then Eric was able to tune most of the rest of the problem out. I'm assuming that your car drove well after your last tune - until the night at Castrol?

 

[ILW84U]

I haven't changed anything since the tune. First 3 runs at Castrol eveything was fine & then it started acting up. I will try reseating the fuel pressure switch. I'm not sure if it makes any difference since I am running the return style system. Vacuum seem to be normal but I will watch it a little closer.

 

[MesaRec]

From the logs you posted, it looks like your MAF sensor is pegging out early. The PCM sees the voltage (~4.99 volts) from the sensor and response by dumping fuel. That's when the car dies. Not sure what to tell you since you are FI, but sounds like klaw is on to something with the bypass controller.

 

[klaw]

I cross-plotted throttle pedal position versus throttle postion. It seems like there's alot of outlying datapoints. You can see from the plot that the bulk of the data seems to follow a common-sense relationship (linear except at the very low end where the throttle plate is held slighty open at idle). However, there also seems to be "bands" in the data (the dashed lines) where regardless of pedal input, the tps seems to be at 2.5, 15, or 30. I'm no expert on these cars by any stretch but I would intuitively expect a tighter relationship.

In light of the MAF comments and these results, I'm wondering if you have low voltage that's giving your PCM fits. Have you tested your battery and alternator? Apparently, bad alternators can cause all sorts of spurious electrical problems with these cars.

 

[ILW84U]

I never thought of the alternator issue. I agree that they seem to cause wierd electrical problems. Another thing to check I guess. I have sent the data logs to Eric Brooks to take a look at. Hopefully he can shed some light on the subject.

 

[DirtyDogOfTheDesert]

Rick, I just tried to call you.... give me a shout back.