Multiple misfire codes

[Timeless1]

Well fellas, here is some good news, timing checked out fine, plugs, coils, ecu, ecm, & all connectors close to or relating to timing belt replacement all checked out ok...& yes tech has been working on NSX's for over 20years, 1 of only 2 techs i use around here.

Turns out to be the main & one of the most common culprit-> Main relay <-, replaced & car started right up.. running very smooth & no more hiccups..
I just recently replaced this on my '91 but it was surprising to see it went out so early on this '00..
Learn something new all the time with these cars...

 

[Ritesh]

Bumping the thread up. I have blinking CEL and TCS light but the car is running fine. Codes P1201, P1202, P1203 and P0300. Hopefully it is something minor.

 

[docjohn]

I'm no expert but I thought a blinking cel is bad....don't drive it till you have it figured out.

 

[angus]

I am still battling this gremlin myself - the funny thing is that it is much much worse in cooler weather - I hardly have it when it's hot out.

the easiest way to make it happen is constant 3K RPM in 5th or 6th.

 

[DDozier]

I am still battling this gremlin myself - the funny thing is that it is much much worse in cooler weather - I hardly have it when it's hot out.

the easiest way to make it happen is constant 3K RPM in 5th or 6th.

I assume you did the Plugs, Coils, and Igniter from your previous post. Did you ever replace the MDU?

I had a very slight mis that I could feel under light load cruse conditions in 5th and 6th gear. I would randomly get misfire codes on all cylinders and a random misfire code, I have never had any other lights come on but the CEL, but I have seen the CEL flash after the light missing starts and is present for a while. I replaced the coil packs and put in a fresh set of plugs and my issue is gone at least for now. My car spends most of its miles on the track now a days so I very rarely spend any time at light cruze conditions, it was not until I spent a few days driving it on the street that I even noticed I had an issue. I have not correlated my issue to temperature but it is curious that yours seems to be temp related. Keep us posted if you get this worked out, I am curious to know how you resolved it in case my issue returns.

Dave

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I'm no expert but I thought a blinking cel is bad....don't drive it till you have it figured out.

Blinking CEL means misfire detected.

Dave

 

[angus]

I assume you did the Plugs, Coils, and Igniter from your previous post. Did you ever replace the MDU?

I had a very slight mis that I could feel under light load cruse conditions in 5th and 6th gear. I would randomly get misfire codes on all cylinders and a random misfire code, I have never had any other lights come on but the CEL, but I have seen the CEL flash after the light missing starts and is present for a while. I replaced the coil packs and put in a fresh set of plugs and my issue is gone at least for now. My car spends most of its miles on the track now a days so I very rarely spend any time at light cruze conditions, it was not until I spent a few days driving it on the street that I even noticed I had an issue. I have not correlated my issue to temperature but it is curious that yours seems to be temp related. Keep us posted if you get this worked out, I am curious to know how you resolved it in case my issue returns.

Dave

Yes, Dave, my car has a new igniter, plugs and coils, twice in fact.

I then swapped the MDU and then swapped the ECU with ones from a running, driving car with no issues. The problem did not change.

It is important to note that my car never has a misfire - only the codes, it'll start flashing the MIL when the engine is running perfectly smooth.

 

[DDozier]

Yes, Dave, my car has a new igniter, plugs and coils, twice in fact.

I then swapped the MDU and then swapped the ECU with ones from a running, driving car with no issues. The problem did not change.

It is important to note that my car never has a misfire - only the codes, it'll start flashing the MIL when the engine is running perfectly smooth.

Mine definitely had a mis you could feel, but only under light loads, run it hard and it never missed. Mine seems to be solved with the coils and plug change. I am wondering if I should not just change the Igniter as a precaution.

Seeing as how you have swapped in known good parts, without knowing exactly how the MDU detects a mis I would be leaning to a wire issue like Valhalla had. Weird though, Keep us posted.

Dave

 

[angus]

I believe the MDU senses the coil impedance to detect misfire, this means that a wire harness issue could very well be the problem, I am going to insect the terminals and measure the resistance of the harness compared to a car without the issue sometime.

You could swap the igniter as it does sound more like an igniter issue if your car has an audible miss.

 

[docjohn]

thanks for that tidbit.:smile: