Running on 5 cylinders!?!?

[speedyizzy]

I've owned my car for 8 years, first day I purchased it, I had it checked out by an NSX mechanic, the owner was not even aware, turns out a coil was bad, so he replaced it. 2 months ago, I had my brakes and shocks done at Niguel Motors, clutch was done about 1 year ago at the same place. Yesterday a friend of mine (a Porsche afficionado) wanted to take the car for a test drive. As soon as he turned on the car and rev the engine, he said "it's missing"! I was like, missing what?!?! He believe it was running on 5 cylinders. I work for a City so I had a City Mechanic turn the car on, he immediately told me the same thing. My ears are not very sensitive and I never noticed the missing power. Even worse, if this is the case, my NSX mechanic never bothered to tell me either.

What is the best course of action? How can I test if one of the cylinders or coils is failing? Any thoughts?

I was planning on replacing all the spark plugs and testing each coil as it has already been 60K miles since they were last replaced.


Thanks.

Israel

 

[NSXCessive]

I've owned my car for 8 years, ... What is the best course of action? How can I test if one of the cylinders or coils is failing? Any thoughts?

I was planning on replacing all the spark plugs and testing each coil as it has already been 60K miles since they were last replaced.


Thanks.

Israel

So you have no CEL or engine codes? Some suggestions you could have another bad coil, fouled injector etc, or even sometimes water leaks by the coil seal causing a misfire I had a similar problem on my old '91? If you suspect low compression get a leak down test done to make sure you have good compression across all cylinders.

 

[speedyizzy]

I don't have a check engine light, I am going to change out the spark plugs today and check all the coils. Any idea what a compression test should run?

Thanks.

Israel

 

[nsxter]

If its truly missing, you would get a cel (mil) light. nsx's run kind of rough up to about 2500 rpm, then smooth out above that. Could this be the problem?

 

[docjohn]

I drove about 140 miles on 5 cylinders and you could'nt miss it.The motor sounds real bad above 60 mph in 5th

 

[speedyizzy]

Yeah, it runs fine upto to 100 mph (its been years since I go faster than that). But then again, I thought the car was fine when I first bought it and it had a bad coil. I am changing out the plugs and testing the coils, I'll go from there.

The car has 190K miles (I'm responsible for 80K of those miles), its time for some TLC. It might be time for the TB/WB/Valve Adjustment job.

 

[EdinKali]

Sounds like someone not familiar with the NSX(Porsche driver and City mechanic). They all feel like that up to about 2500 RPM.

 

[NSXCessive]

I don't have a check engine light, I am going to change out the spark plugs today and check all the coils. Any idea what a compression test should run?

Thanks.

Israel

When I had that wet coil pack problem causing misfire on my car give me a CEL with the exact cyl that was causing the problem, it put the car into limp mode and it ran like crap into 3000rpm bogging out etc. It was very noticeable, sounds like you might be experiencing typical NSX rough idle especially the earlier 3.0L engines under 3000rpm and would disapear after that. As far as I understand the engineers never quite worked the bugs out at idle.

According to the shop manual testing 199psi is 'nominal' and the 'minimum' is 142psi & max variation between ~28psi. Its not unheard of to be around 210-230 during a leak down/compression on a very healthy engine.

 

[Keahistight]

The only way you are going to be able to tell anything is if you have a compression leak down done on the car.

 

[sca037]

Sounds like if you're really experiencing a 'miss', it could be a coilpack / plug....or even an injector.
I would pull 1 plug at a time, inspect it (and re-gap if it's been a few miles).
If any plug looks washed-out (lack of normal light-colored carbon remnant) then it's probably the one not firing properly.
I like to use some fine steel wool to clean the metal contact surface of the coilpacks, then lightly coat them with dielectric grease before reinstalling.
If you've serviced all 6 plugs & packs and they looked fine, it might be a sticky fuel injector.
If they are original, at 190K miles they have served you well
Running some Chevron Techron in a tank might help free it up, but I would look at least into getting them refurbished from a reputable place like WitchHunter Performance ( http://witchhunter.com/ ) and they include new seals as well.

Hope that helps,
Brian

 

[Larry Bastanza]

What year is the car?

 

[speedyizzy]

I replaced all of my spark plugs, furthermore, I tested each of the coils, they all tested out fine. What else can it be? Could it be the igniter? If the car was running on 5 cylinders, what would that feel like? Just a 20% loss in power?

Thanks.

Israel