Well i got a dyno tune today. The car ran great on the drive home for the first hour. While driving at 70mph, i tried to pass someone, the trans geared down fine, accelerated fine, then it wouldn't up shift. It stayed in the lower gear until i let off the gas completely. Then as soon as i touch the gas pedal ever so slightly the car gears down instantly and wont up shift again until i let completely off. I exited at the nearest ramp and stopped. accelerating from stop, the car just wouldn't shift right. It actually cut off when turning in to autozone. The code was p0121. Throttle Position Sensor/Switch A Circuit Range/Performance Problem. I purchased a TPS sensor, installed it there then cleared the code. I got back on 95 heading home. Everything seemed fine, i passed 3 or 4 people just like above with no issues. Then the next time i tried to pass the same thing happened. This time no code or check engine light...yet. I called the guy who tuned it, he went back to the shop and did some research on the code and feels what he did couldn't have caused it. Any Ideas anybody? Thanks in advance for the help.

 

Could be an issue with the MAP sensor.
Have you checked for vacuum leaks around the MAP?
Do you have access to a Helm manual or a site like AllData as well as a method of scanning?

-Riggs.

 

I have mitchell on demand 2009 courtesy of bit-torrent THe alldata should be done downloading tonight. Only problem is neither work with windows 7. I'll try to install it under virtual xp.

 

Ok i have mitchell installed and working under virtual xp. damn i love windows 7. If only i felt the same about my tune

i do still have my factory PCM. i think i'll install it and have my mechanic check the KR. It may be to high to get on it like i did after the tune. The tuner said i had 0 kr with the 3.4 pulley after the tune. I had 5 KR with the zzp boxed PCM. It looks like i'm going to have to make another 2hr journey to Durham to get this ironed out. It has to be the tune. right?

 

I don't know that the tune could cause that code to throw.

According to the service manual, that code will set when the MAP sensor is getting a different reading than it should according to what the TPS is set at.

Unless the guy played with your MAP/TPS settings (no reason he should, if those tables are even accessible), then the tune couldn't throw the code.

If you tried switching the TPS, then I would suspect an issue with the MAP.

Alldata will have instructions for checking the P0121 code.
If you have a way to scan (autotap or similar) you can check what your MAP readings should be at certain TPS positions, and see if your MAP is reading incorrectly at some point.

I haven't had any experience with a P0121, but judging by what the books say, I would suspect an issue with the MAP sensor, or a vacuum leak.

-Riggs.

 

I just got back from my local mechanics house. He checked the vacuum lines for me. I did put the factory PCM back in, 0 knock at any rpm. This thing feels like a tank with the factory tune. I cant even tell I've had any mods at all done. Just goes to show that the ZZP boxed PCM isn't that bad. I've been up to 80ish mph already with the factory PCM and no issues yet. I'll keep it in over the weekend and see if it comes back. It's just strange to me that i've never had any sort of drivability issues or MIL's for the time i've had the car (8 months) then all of a sudden its not drivable an hour after the tune. My mechanic feels the same way i do, gotta be the tune. Like i said i'll try my hardest to duplicate the problem with the factory PCM installed. So far, 1st attempt was unsuccessful. Thanks so much for your input riggs. If the problem comes back with the Different PCM, i'll get that MAP checked out.

 

Good luck man, if it is something in the tune then hopefully someone on one of the forums can give you some insight as to what needs to be changed to fix the issue.
Nothing more frustrating than little issues when you install a new mod.

-Riggs.

 

Well it wasn't the tune. It did it again yesterday with the factory PCM. I didn't get the code this time, but got the exact same symptoms. After driving aggressive a few minutes at 80+ MPH, it just goes crazy. If i push on the pedal the slightest after it starts happening, then the car gears down and wont up shift until i let off the gas. no matter how much or how little throttle i give it, it just winds and winds out until 5500ish rpm. It now will do the same thing in low gears and starting from stopped, until i turn the car off for a few minutes then all is well.

 

Had a similar problem with upshifting under hard acceleration - down shifting was erratic - and after all was said and done it turned out to be the catalytic converter coming apart and all the misreading with the PCM and or BCM or TCM - not sure which module was misreading but a new converter solved the problem. I have an '02 with a 3.8 with 55,000 miles and the dealer replaced the converter under an 80,000 mile warranty on the vehicle from the factory for the converter. Hope this helps.

 

I dont think that is my issue. My Downpipe has a flowmaster high flow cat, its only 1 month old.