Keep getting P0108 and going into Limp mode on my CTSC!

[Hapa88]

Was hoping someone could help me. I keep getting a P0108 (MAP Sensor High Input) CEL when I go WOT on my 1995. Car recently got a Comptech SC installed and never had this issue before for the first few months. It slowly started rearing it's head and started happening intermittantly, and now it's gotten to the point when it happens almost every time you go WOT. Also it only appears to happen when the car has warmed up (after about 15 min of driving). So the first few WOT runs will be fine, but after 20 minutes it throws a CEL every time you try to go WOT around 4000-5000 RPM.

Car is currently in Tucson, where the altitude is about 2400 feet above sea level (pressure is just over 1 PSI less than sea level)

It's running the stock ECU and stock CTSC electronics (Advanced Control Module (ACM)) It happens when I go WOT and hits Here's a video showing what happens
https://www.facebook.com/headadrian/videos/10105743478529806/

Things I've already done to try to fix it:
1) Took out ACM and sent it back to Nate at CT and had it reflashed. My car does not have an ESM (I think the ACM does the same job). The reflash didn't solve the problem. Do you guys think running an ESM with the ACM would help?
2) Replaced the MAP with another used stock MAP from eBay. This worked!!!.... for about a month but now the problem has come back. I'm wondering if the MAPs either go bad or they're operating right at the limit.
3) I tried a 3 BAR MAP, but I heard that because the car isn't calibrated to run a 3 BAR it wouldn't even run.. I decided to try it anyway and sure enough they were right... It won't even idle with the 3 BAR installed.

So I ask if anyone has any additional ideas on how to proceed to get this fixed?

 

[jwmelvin]

It sure sounds like the ASM is allowing voltage in excess of that representing atmospheric to get to the ECU. I wonder if it has something to do with the altitude or the barometric sensor that is part of the ECU. Can't Nate reduce the MAP clamp voltage slightly to see if that will solve the problem?

 

[Hapa88]

It sure sounds like the ASM is allowing voltage in excess of that representing atmospheric to get to the ECU. I wonder if it has something to do with the altitude or the barometric sensor that is part of the ECU. Can't Nate reduce the MAP clamp voltage slightly to see if that will solve the problem?

I just sent Nate an email with regards to making adjustments in the ACM. I'll see what he says but he's responses are typically extremely slow since he's so busy.

 

[jwmelvin]

Another idea would be to borrow an F/IC if you happen to know someone with one local. That would allow you to adjust the MAP clamp voltage.

 

[docjohn]

Ok I have no real technical ability other than reading stuff on prime.....but does the supercharger have a grounding wire? I remember reading some threads where voltage or electrical issues esp with superchargers was the ground wires were not replaced.....

 

[RYU]

For a brief time I had a grounding wire problem on the igniter ground wire. Everytime I accelerated my car would misfire. Drove me crazy but realized later that when the motor torqued over under wot it was enough to knudge the ground wire out of contact. LOL! Some sand paper at the contact points and a tightening of loose bolts did the trick.

Though FWIW I also think you have a voltage clamp issue. Since you've gone thru 2 MAP sensors, I wonder if the ACM is sending a faulty signal to the sensor and damaging it. Long shot hail mary here. I'd look for a pinched or exposed wire in that circuit. Jason might be on to something with the altitude though. You might ask the CO guys...

 

[RYU]

In all seriousness though... A stand alone would be light years better. I always had random unexplained quirks with the CTSC fueling. It use to hiccup on the dyno after about the 3rd run. Really disconcerting.

 

[docjohn]

awesome.. I was 1/25th on target:tongue:

 

[Hapa88]

Well, I got it at SOS for them to diagnose. Everyone seems in agreement on the Voltage Clamping.
Last thing I did before I handed it over was reclamp the MAP wiring coming out of the ACM to the ECU. I thought it was all good after going through a 4 hour drive over 100 miles to Mount Lemon with no issues. The next day I headed to the SOS open house and WOT onto the freeway and it went into Limp mode....

 

[Hapa88]

Well, SOS said all it needed was a voltage adjustment inside the ACM. The ACM was peaking slightly over the limit, so they adjusted it down. 1 hour of work charged and it should be fine. Had to drive it home in the rain, so I didn't really get to WOT it.

Now I have a transmission, clutch or clutch cylinder issue... Oh and the SRS light started flashing at me on the way home...