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New to Prime in the Charlotte area

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Hi all! New here (sort of) but not a new owner. I bought my 91 in December of '05 and loved every minute of it. I have used Prime for years, however, to troubleshoot and fix things on the car but have never registered. I'd like to get to know some other owners in the Charlotte (and surrounding, I'm in Gastonia) area as some problems are easier to troubleshoot with some help (swapping out potential failed electronics and such). Currently, I am battling an issue with the engine not going bang in 3 cylinders. I've been troubleshooting with the service manual as well as threads on here with no luck as of yet. I purchased a used ICM for $40 that should be here tomorrow so fingers crossed.


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Hi NSeXy - I am in South Charlotte(Marvin to be exact). There are few NSX owners in the area. You may also want post something on the SouthEast area forum. Welcome and let me know if I can be of any other help.
 
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No unfortunately. It is one on the front bank and two on the rear. I eliminated bad coil packs as a problem by switching know good cylinder firing ones to the ones that weren't firing and the misfire stayed with the same cylinder. Also swapped plugs in the same fashion.
 
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Hi NSeXy - I am in South Charlotte(Marvin to be exact). There are few NSX owners in the area. You may also want post something on the SouthEast area forum. Welcome and let me know if I can be of any other help.

Thank you and I will post something on there as well.
 
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Well - no one else has jumped in so ...
If you have a multi meter (volts/ohms/current)
Remove each coil pack connector.
Ohm each connection on the coil pack to ground in both directions, first red to ground, then black to ground.
Repeat this for the cable going to it.
Make a little table and compare the reading and look for differences between your good and bad cylinders.
A difference in the coil pack readings would indicate an issue with packs or grounding.
If differences are in the cable then the issue may be upstream (into the firing circuit).
Maybe you'll find a hint there.
Good luck.
 
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Well - no one else has jumped in so ...If you have a multi meter (volts/ohms/current)Remove each coil pack connector.Ohm each connection on the coil pack to ground in both directions, first red to ground, then black to ground.Repeat this for the cable going to it.Make a little table and compare the reading and look for differences between your good and bad cylinders.A difference in the coil pack readings would indicate an issue with packs or grounding.If differences are in the cable then the issue may be upstream (into the firing circuit).Maybe you'll find a hint there.Good luck.
By spraying a little carb cleaner in the intake while the car was idling I narrowed down the search, I believe. The missing didn't go away at all so spark seems to be the problem. I did some poking around with the multi meter. All coil harness plugs had the around the same reading in continuity on the constant connection (blk/ylw) with red on connector and black on ground being .072 to .078. I tired to check with the probes reversed but it was all over the place. I never got the meter to settle down to get a close reading. There is continuity all the was from the ECU plug to the ICM and from the ICM to the coil packs on all cylinders. I eliminated bad coil packs by swapping known good ones for known bad one. When checking out the ECU I noticed a bunch of corrosion on the case (pictured below). Any thoughts there? Should I pull the cover off and have a look see on the inside?Top side when mountedhttp://www.nsxprime.com/forum/attachment.php?attachmentid=162684&d=1570807648Bottom when mountedhttp://www.nsxprime.com/forum/attachment.php?attachmentid=162683&d=1570807606
 
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Well - no one else has jumped in so ...If you have a multi meter (volts/ohms/current)Remove each coil pack connector.Ohm each connection on the coil pack to ground in both directions, first red to ground, then black to ground.Repeat this for the cable going to it.Make a little table and compare the reading and look for differences between your good and bad cylinders.A difference in the coil pack readings would indicate an issue with packs or grounding.If differences are in the cable then the issue may be upstream (into the firing circuit).Maybe you'll find a hint there.Good luck.
Thanks for the tip.By spraying a little carb cleaner in the intake while the car was idling I narrowed down the search, I believe. The missing didn't go away at all so spark seems to be the problem. I did some poking around with the multi meter. All coil harness plugs had the around the same reading in continuity on the constant connection (blk/ylw) with red on connector and black on ground being .072 to .078. I tired to check with the probes reversed but it was all over the place. I never got the meter to settle down to get a close reading. There is continuity all the was from the ECU plug to the ICM and from the ICM to the coil packs on all cylinders. I eliminated bad coil packs by swapping known good ones for known bad one. When checking out the ECU I noticed a bunch of corrosion on the case (pictured below). Any thoughts there? Should I pull the cover off and have a look see on the inside?Top side when mountedhttp://www.nsxprime.com/forum/attachment.php?attachmentid=162684&d=1570807648Bottom when mountedhttp://www.nsxprime.com/forum/attachment.php?attachmentid=162683&d=1570807606
 
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By spraying a little carb cleaner in the intake while the car was idling I narrowed down the search, I believe. The missing didn't go away at all so spark seems to be the problem.

I did some poking around with the multi meter. All coil harness plugs had the around the same reading in continuity on the constant connection (blk/ylw) with red on connector and black on ground being .072 to .078. I tired to check with the probes reversed but it was all over the place. I never got the meter to settle down to get a close reading. There is continuity all the way from the ECU plug to the ICM and from the ICM to the coil packs on all cylinders. I eliminated bad coil packs by swapping known good ones for known bad one. When checking out the ECU I noticed a bunch of corrosion on the case. Any thoughts there? Should I pull the cover off and have a look see on the inside?
 
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By spraying a little carb cleaner in the intake while the car was idling I narrowed down the search, I believe. The missing didn't go away at all so spark seems to be the problem.

I did some poking around with the multi meter. All coil harness plugs had the around the same reading in continuity on the constant connection (blk/ylw) with red on connector and black on ground being .072 to .078. I tired to check with the probes reversed but it was all over the place. I never got the meter to settle down to get a close reading. There is continuity all the way from the ECU plug to the ICM and from the ICM to the coil packs on all cylinders. I eliminated bad coil packs by swapping known good ones for known bad one. When checking out the ECU I noticed a bunch of corrosion on the case. Any thoughts there? Should I pull the cover off and have a look see on the inside?

Did you ever figure out your issue?
Did you end up testing the Cylinder Crank Sensor (although that is a lot of effort to get to)? (http://www.nsxprime.com/forum/showthread.php/212095-Crankshaft-position-sensor-question)

Long shot, but did you test your Oxygen Sensors or when's the last time you replaced them?
I had a misfire/stutter issue I resolved by replacing the Oxygen Sensors.
 
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I haven't fully figured it out yet. I did, however, remove the injectors and swapped known misfiring ones and put them where there was no misfire and the misfire followed the injectors. I didn't originally do this because in the beginning of it all the first thing I did was clean the injectors individually, manually. I'm guessing my untrained ear didn't pick up the misfire going away during the carb cleaner test...or at least that's what I am hoping. After the holidays I plan on either getting my injectors ultrasonically cleaned or maybe even buy new ones as they have 220,XXX miles on them. I haven't yet tested the Crank Sensors either.As far as O2 sensors go, I replaced the back one myself about a year ago (or less than 1,000 miles ago) after the CEL light indicated it being bad. My old mechanic replaced one several years ago but I can't remember which one he did. I'm pretty sure it has been less than 15,000 miles back though. Thanks for checking in on me. I probably should have checked the Crank Sensor while I was checking timing but TBH I haven't had a chance to research how to go about doing it. "Old Guy" mentioned that there was a test for it in the repair manual and I'm sure also in the threads of prime.
 
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Did you ever figure out your issue?Did you end up testing the Cylinder Crank Sensor (although that is a lot of effort to get to)? (http://www.nsxprime.com/forum/showthread.php/212095-Crankshaft-position-sensor-question)Long shot, but did you test your Oxygen Sensors or when's the last time you replaced them?I had a misfire/stutter issue I resolved by replacing the Oxygen Sensors.
Yea. I fixed the miss but have other issues now. It turned out to be bad injectors. As a last resort I swapped known missing cylinder injectors for known non-missing ones and the problem followed the injector. I bought some new ones and now all is good. However, now I have a trouble code for the MAP sensor and one for the rear O2 sensor. I put a new O2 sensor on the front a little over a year ago and the rear was replace with the timing belt ~20k miles ago. I have gone through all of the testing procedures in the repair manual on testing the MAP vacuum/wiring and all indications point to replacing the sensor. Any advise on that? Any other testing that could be done that anyone knows of? I would hate to drop $300 on a part to not fix the problem.
 
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Yea. I fixed the miss but have other issues now. It turned out to be bad injectors. As a last resort I swapped known missing cylinder injectors for known non-missing ones and the problem followed the injector. I bought some new ones and now all is good. However, now I have a trouble code for the MAP sensor and one for the rear O2 sensor. I put a new O2 sensor on the front a little over a year ago and the rear was replaced with the timing belt ~20k miles ago.

I have gone through all of the testing procedures in the repair manual on testing the MAP vacuum/wiring and all indications point to replacing the sensor. Any advice on that? Any other testing that could be done that anyone knows of? I would hate to drop $300 on a part to not fix the problem.
 
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Update. I read the CEL codes wrong. They were a code 21 and a code 51 (VTEC Solenoid) and not a 2 and 5 like I thought. I evidently left the F connector unplugged when was checking out ECU wiring. Plugged in and running good with no CEL light at the moment. Thank you for the all of the replies and suggestions.

Unfortunately, before I figured out that I read the codes wrong I already replaced the rear O2. I cut all of the exhaust bolts to get the exhaust out of the way because the sensor was seized. After that I had a ton of room and it came out no sweat with some heat. Since the exhaust was now on the floor I took the opportunity to weld up some stainless test pipes and went back with stainless hardware so no more rusting. In putting everything back together I found an exhaust leak that I've had and never known it. Once under the car you can hear it clearly but with the car on the ground it sounds "normal" until I realized what I was hearing was a leak. The pipe just upstream of the front cat flange is leaking between the flange and the flex pipe. I found some replacement flexes and I can probably reuse the flange. I also found some tiny muffler/resonators on amazon so I'm going to cut those in to the test pipes while I'm at it. Taking the header loose from the head makes me nervous thought. They, too, have not been loosened in almost 30 years.

 
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