To all you gurus... Your help would be HIGHLY appreciated.

I just had an APS TT installed by a local authorized APS dealer. I thought I was going to be back in my car by now, but it would seem that the FI gods are not smiling on me. Simply put, my car is F***ed up. Here are the symptoms:

The car starts perfectly and runs under partial throtle very well; however, at WOT, boost will build to between 4-6 psi and then the motor dies... I have not personally seen it, but it sounds like when the stock ECU cuts fuel. The ecu is occasionally throwing a CAS code.

The unichip has a 93 octane base map from GRD on it; the unichip was sent back to them and they retested it and confirmed the map was properly loaded. I believe the unichip was also run in another car and it worked fine. The a/f numbers are within a safe range. The crank angle sensor and the MAF sensor have both been swapped out and the problem remains. I have no ECU reflash.

So the million dollar question: WTF is wrong with my car?

 

If it was installed by an authorized APS dealer, bring it back and make them figure it out.

 

That is why it is good to get it installed at an autherized APS dealer. Now, all you have to do is return it to them and let them figure it out.

 

Yeah, it's an install problem. They fuked it, they fix it.

 

I am not going to jump to the conclusion that there was installer error... these guys know what they are doing and I have yet to talk to anyone who is disappointed with their work. (and trust me, I asked many people before I trusted my car to them) In any case, taking it back is not a problem; it never left the shop. They are working on it right now and have been real good about it... They have spoken to APS and some other APS dealers and still have not confirmed what the problem is.

My point in posting was not to ascribe fault, it was to get some fresh opinions on the problem to speed up the process.

 

Sounds like the CAS wire was done wrong

 

It can't be done wrong by the installer as it is wired in to the harness from APS.

And if the CAS wire was not done right the car would have a hard time starting.

Did you change the clutch or flywheel?

 

I thought the same thing about the CAS wire- it starts up perfectly so that is likely not the problem... though the car is still throwing the CAS code

Yes, I had an RPS flywheel and max street clutch installed at the same time. Could this be causing issues? It seems so disconnected.

My current "best bets" are MAF or TPS issues... thoughts?

 

I know that my APS dealer that installed mine had a problem with a APS TT install on one car. They used mine to look at the CAS wire connection that APS wired, and found the one on the other car wired incorrectly from APS. Since APS will not send a wiring diagram (so you can't copy their system), troubleshooting the system is a nightmare. If you want to talk to the shop I use, PM me and I will send you their name.

 

My shop has an extra harness which they are going to try swapping out... if the one in my car is miswired, hopefully that will solve the problem. I know there were a few reports of miswired harness causing some issues, but if I remember correctly, those cars were throwing an array of codes consistently. Mine is throwing one code (CAS) some of the time.

 

The car is also showing the slip/vdc light... The installer is sure it was installed at the same angle, but is going to check this anyway. We are going to disable the VDC to see if the problem persists. Anyone know how to reset the VDC?

Any other thoughts?

Thanks!

 

It could be a defective or shorted UNICHIP PnP harness. After scanning those codes, I would swap it for another UNICHIP and harness and see if the problem remains.

 

Swapping out the harness is on our list of things to try; my shop has another one and hopefully it was already tried today...

You hit on another strange part of this problem. Before my unichip was sent back to GRD to be reflashed, another unichip was put in my car and it worked fine. However, after reflashing the unichip and trying it (with no success), even the other unichip doesn't work... thus adding to my problems.

 

It's probably the wiring loom. Have them look into replacing it. That should fix the problem.

 

The wiring harness was swapped out with no effect... Please keep the suggestions coming; we are running out of ideas fast.

 

Just a guess though it sounds like the clamp on the mass air flow sensor is not correctly set, if the voltage goes above 4.9 volts the engine will fuel cut for sure. It would also pay to check the crank angle sensor and if you have fitted an aftermarket flywheel this could also upset the CAS signal, a few possibilities for you to check out.

Goerge

 

Could the steering wheel not be correctly aligned? Since he's getting the VDC/SLIP light...just a thought.

 

george, you got PM.

 

I think the guys at my shop spoke to you about this, but if you wouldn't mind, can you explain how the flywheel causes CAS issues? and more importantly, how can you correct the problem? I know we have swapped out at least 2 new CAS's just to see if it would help with no luck. If it helps, I have the RPS flywheel.

Peter mentioned the voltage clamp issue on the other forum. Can you explain how this can be fixed if it is the problem. Can this be easily fixed by any unichip tuner? which, as you know, my shop is...

Thank you very much for your help!

 

Thanks for the idea- We considered that might be the issue so we totaly disabled the VDC system but the problem remianed...

The guys who did my install tell me that because of the splines in the steering shaft hook-up, it is pretty hard to mess up so that also tells me that is likely not the problem... In any case, assuming it is the issue, do you know how to reset the VDC system?