Need some help, (nsx experts welcome)

[USAFguy22]

BLUF: TCS & CEL come on when close to redline and engine reverts to safe mode (rich AFR's & lower redline)

I'll try to make this as simple as I can

Symptoms
When accelerating, the TCS & CEL come on at the same time usually between 7500-8000RPM, afterwards the engine reverts back to a really rich fuel mixture and the redline caps around 3000-4000 (can't remember exactly). This doesn't happen every time, and usually occurs in 2nd-3rd gear. I can restart the car and everything is back to normal.

Car Details
1991, 62,000 miles, low boost CTSC (lysholm), headers, BBK, and most of the other common bolt ons. O2 sensors and spark plugs recently replaced.

Codes
CEL 16 - Fuel injection: Not sure how old this code is, but doesn't really make sense. I just replaced the main relay, igniter, fuel filter, and had the OEM injectors rebuilt and flow tested.
TCS 31 - Engine Control Module: I'm guessing this is a different name for the ECU, it's not chipped or anything, only the signal modifier from the CTSC is plugged in.
TCS 34 - Abnormal VREF: Has to do with some kind of reference voltage? Note: the tachometer/speedometer are acting normal.

What I've found so far
Initial symptoms would lead me to believe a bad ABS sensor (wheel speed sensor) however the TCS didn't give me any "4" codes to indicate that. Second guess might be a bad vehicle speed sensor, but that would have accompanying speedometer abnormalities (fluctuating/drops to zero) which I don't have. From the codes I can guess it has something to do with an electrical problem related to the wiring (battery cable, ecu harness, tcs harness, or fuze?) and not so much a faulty sensor. That's really just a guess though.

Thoughts/recommendations appreciated! (Larry where are you )

Edit: i will replug the ecu, tcs and pull the clock fuse and see if I can get any different codes/results.

 

[USAFguy22]

After trying the above I cannot duplicate the problem, it's one of those things that happens when you don't want it to, and doesn't happen when you want it to. I'll try again tomorrow.

 

[tbnsxt]

cel and tcs come on when you have o2 sensor issues maybe you are getting a "lean" reading and it is trying to keep the engine safe. i would investigate your newly replaced o2 sensors.

 

[docjohn]

just a random thought....I've read about some wacky stuff happening to folks with superchargers that have a loose ground wire.

 

[USAFguy22]

just a random thought....I've read about some wacky stuff happening to folks with superchargers that have a loose ground wire.

Hah, yeah I'm one of those guys. Took me a month to figure out that my igniter ground- which had been working fine 6 months after my sc install- all of a sudden went bad.

 

[shawn110975]

what size rims do you have?

 

[bngl3rt]

Hah, yeah I'm one of those guys. Took me a month to figure out that my igniter ground- which had been working fine 6 months after my sc install- all of a sudden went bad.

My car doesn't even have a supercharger but it did at one point and same issue. The wiring on those kits does not seem to be OEM quality as vibration and heat can deteriorate them over time.

 

[USAFguy22]

what size rims do you have?

Well within the tcs limits, 215/35/17, 275/30/18

 

[Larry Bastanza]

I would have to go with a grounding issue. Make sure all grounds are connected firmly and that they are NOT connected to any painted surface. Specifically check the ground located by the output of the ignitor. This wire in the harness has a ground that connects to the SC plate, or the throttle body intake(under the ignitor bolt). If it is under the ignitor bolt, move it to the SC plate for sure.

How long has the CTSC been installed, and has this happened since the install, or is it a new symptom all of a sudden?

I have had two CTSC's with grounding issues and they make little sense, just random weird behavior. I would also not be concerned about the TCS, once you solve this the TCS will go away.

HTH,
LarryB

 

[USAFguy22]

I would have to go with a grounding issue. Make sure all grounds are connected firmly and that they are NOT connected to any painted surface. Specifically check the ground located by the output of the ignitor. This wire in the harness has a ground that connects to the SC plate, or the throttle body intake(under the ignitor bolt). If it is under the ignitor bolt, move it to the SC plate for sure.

How long has the CTSC been installed, and has this happened since the install, or is it a new symptom all of a sudden?

I have had two CTSC's with grounding issues and they make little sense, just random weird behavior. I would also not be concerned about the TCS, once you solve this the TCS will go away.

HTH,
LarryB

Good input as always Larry, I had a problem with that exact ground before and extended it so that it would connect to the raw metal on the throttle body instead. I could try a different location to see if it solves the problem, maybe to a bulkhead or somewhere on the block?

 

[Larry Bastanza]

Good input as always Larry, I had a problem with that exact ground before and extended it so that it would connect to the raw metal on the throttle body instead. I could try a different location to see if it solves the problem, maybe to a bulkhead or somewhere on the block?

Remember the actual throttle body has an intermediate plate, not the best ground, you want that ground on the plate between the blower and the intake manifold to be sure the ground is good.

 

[USAFguy22]

I'll give this a try, so far it hasn't thrown any codes.

 

[LooseNut]

I had a similar situation with my car under hard acceleration. CEL and TCS lights and limited redline. It turned out my tire pressure was way off. My tire gauge had become wildly inaccurate. After resetting the air pressure with a known good tire gauge everything was fine. Unfortunately I found that after checking many other things.

 

[USAFguy22]

I had a similar situation with my car under hard acceleration. CEL and TCS lights and limited redline. It turned out my tire pressure was way off. My tire gauge had become wildly inaccurate. After resetting the air pressure with a known good tire gauge everything was fine. Unfortunately I found that after checking many other things.

Excellent idea, I hadn't checked my pressures yet and I know it's been a long time. This occurred more frequently in the winter and now that it's heating up here it hasn't happened yet. Could very well be a pressure related.