Rough Idle With Sounds Of Backfire

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14 October 2004
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86
Location
SOUTHERN CALIF.
I have had my 91' NSX since nov. of last year. since purchase i have had a rough idile and faint sounds of backfire at idile :frown:. I then took it to my friend which is a mechanic and he suggested changing the spark plugs. After all it didn't change a thing. Does anyone know what could be wrong? HELP PLEASE!!!!!!
 
Re: Rough Idile With Sounds Of Backfire

Before doingf anythiong else you should have a compression check done. Once you can confirm the engine is sound mechanically (valves, rings, etc) then you can look at other things.

When the plugs were replaced were they looked at for their condition?

HTH,
LarryB
 
Re: Rough Idile With Sounds Of Backfire

PROJECTNSX said:
I have had my 91' NSX since nov. of last year. since purchase i have had a rough idile and faint sounds of backfire at idile :frown:. I then took it to my friend which is a mechanic and he suggested changing the spark plugs. After all it didn't change a thing. Does anyone know what could be wrong? HELP PLEASE!!!!!!

did u clean the TB, check the coil packs?

http://www.danoland.com/nsxgarage/spark_plugs/spark_plug.htm
 
Re: Rough Idile With Sounds Of Backfire

Larry Bastanza said:
Before doingf anythiong else you should have a compression check done. Once you can confirm the engine is sound mechanically (valves, rings, etc) then you can look at other things.

When the plugs were replaced were they looked at for their condition?

HTH,
LarryB

the condition of the plugs looked to be in good shape. the motor runs fine with no power loss (that i can tell). as for cleaning the TB i have not done that yet. i never would have thought the TB would give a backfire. ive been in the market for a supercharger but i dont want to add if the motor has issues. any other suggestions?
 
Re: Rough Idile With Sounds Of Backfire

PROJECTNSX said:
any other suggestions?

Reread LarryB’s post above. As Larry said, a compression test will open the door to a systematic diagnosis. Otherwise, you can spend a lot of time and money replacing and checking things that are just fine. Let us know how the test comes out.

Good luck,

DanO
 
Re: Rough Idile With Sounds Of Backfire

You may also check the exhaust manifold (plus the screws where it is fixed at the engine) for leaks. Any backfires when you release the throttle at neutral?
 
Re: Rough Idile With Sounds Of Backfire

Moisture in the top of the coil packs caused a similar problem for me as well. Check your coils and if they are good, like the rest of the guys suggest do a leak down test.
 
Re: Rough Idile With Sounds Of Backfire

NSX-Racer said:
You may also check the exhaust manifold (plus the screws where it is fixed at the engine) for leaks. Any backfires when you release the throttle at neutral?

No backfires when i release the throttle, that i can hear. car seems to run perfect. im going to get a compression test this weekend and have the results by mon. i will let all know what the results are. :wink:
 
Re: Rough Idile With Sounds Of Backfire

NSX-Racer said:
You may also check the exhaust manifold (plus the screws where it is fixed at the engine) for leaks. Any backfires when you release the throttle at neutral?

No backfires when i release the throttle, that i can hear. car seems to run perfect. im going to get a compression test this weekend and have the results by mon. i will let all know what the results are. :wink:
 
Re: Rough Idile With Sounds Of Backfire

PROJECTNSX said:
No backfires when i release the throttle, that i can hear. car seems to run perfect. im going to get a compression test this weekend and have the results by mon. i will let all know what the results are. :wink:

What you found out with the problems ? My NSX got the same problem right after I drove my NSX during a hard rains.
 
Re: Rough Idile With Sounds Of Backfire

you also might want to try replacing the pcv valve and o2 sensor. i know for fact that the pcv valve causes rough idling. also clean the MAF sensor with carb/choke cleaner or brake cleaner
 
Re: Rough Idile With Sounds Of Backfire

You mentioned "the motor runs fine with no power loss".

Before you drive yourself nuts on this, please note that these cars have a somewhat rough idle (90 degree V-6). I'm also not sure what you mean by "faint" sounds of backfire at idle. Is it possible your car is wholly normal (for an NSX)?

Do you have anyone near you with an NSX that you can listen to, to compare?

Hoping it's perception only, and please note that I'm not trying to be condescending :smile: . . . .
 
had this problem last month

idles fine when cold
idles rough with sounds of backfire when warmed up
hesitation under 3k
feel loss of power

Took it to Ben @ Daisy auto and turned out to be the coil packs in the rear bank... again.. Water get into them and they are ruined.

Don't drive the car during downpour.. don't take it to automated car washes.. stuff a big plastic bag over the rear intake when washing the car.
 
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