Extremely Poor Idle; Looking for Last Resorts
09-25-2018, 02:44 PM
#1
Extremely Poor Idle; Looking for Last Resorts
2002 S2000 with 137,000 miles. I am the third owner, and I do not have much in the way of maintenance history from the previous owners. Car runs great at all times except at idle speeds. I am supposed to take it to its first track day this friday (in 2 days.) An engineering buddy of mine and I were trying to troubleshoot this morning and this is all of what we know so far.
When the engine in cold it idles pretty normally. However, as the engine reaches operating temperature the idle gets very rough. Once completely at operating temperature the engine shakes enough to vibrate all front end body panels and makes one hell of a vibrating, buzzing resonance. (I've tried to include a video of that noise. Video does not show how badly the engine is shaking, but it is.)
Current codes on the car are...
- Cyl. 1 misfire
- Cyl. 2 misfire
- Cyl. 4 misfire
-Random/multiple cyl. misfire
So far we've checked:
- spark plugs,
- coil packs (swapped them out),
- o2 sensors,
- MAP sensor,
- and there are no visible broke vacuum lines.
The spark plugs were changed in May or June of this year at around 132,000 miles. Today when we checked them they had white tips with black on the bases. Looked fairly normal but had a little reason to believe they had been exposed to excessive heat [higher than normal. Jumpy idle around 700-800 RPM, and smooths out around 1100-1300 RPM. During cold idle the engine timing reads 20-30, but during warm idle the engine timing drops down to a reading of 2-3. I performed a compression test this summer where all cylinders read somewhere between 205 and 215.
Other useful info:
- car is believed to run rich
- black tail pipes
- gasoline smell on hard acceleration
- black smoke out exhaust in higher RPMs
Would like to get this figured out in the next two days. [b]ANY SUGGESTIONS/INSIGHT WOULD BE VERY HELPFUL AND APPRECIATED! Thanks. Reach me quicker via text. My name's Ben (865) 771-2800
When the engine in cold it idles pretty normally. However, as the engine reaches operating temperature the idle gets very rough. Once completely at operating temperature the engine shakes enough to vibrate all front end body panels and makes one hell of a vibrating, buzzing resonance. (I've tried to include a video of that noise. Video does not show how badly the engine is shaking, but it is.)
Current codes on the car are...
- Cyl. 1 misfire
- Cyl. 2 misfire
- Cyl. 4 misfire
-Random/multiple cyl. misfire
So far we've checked:
- spark plugs,
- coil packs (swapped them out),
- o2 sensors,
- MAP sensor,
- and there are no visible broke vacuum lines.
The spark plugs were changed in May or June of this year at around 132,000 miles. Today when we checked them they had white tips with black on the bases. Looked fairly normal but had a little reason to believe they had been exposed to excessive heat [higher than normal. Jumpy idle around 700-800 RPM, and smooths out around 1100-1300 RPM. During cold idle the engine timing reads 20-30, but during warm idle the engine timing drops down to a reading of 2-3. I performed a compression test this summer where all cylinders read somewhere between 205 and 215.
Other useful info:
- car is believed to run rich
- black tail pipes
- gasoline smell on hard acceleration
- black smoke out exhaust in higher RPMs
Would like to get this figured out in the next two days. [b]ANY SUGGESTIONS/INSIGHT WOULD BE VERY HELPFUL AND APPRECIATED! Thanks. Reach me quicker via text. My name's Ben (865) 771-2800
Last edited by bpro_r8; 09-25-2018 at 05:42 PM. Reason: Forgot to Tag
09-25-2018, 03:42 PM
#3
Have you checked the fuel injectors?
09-25-2018, 03:45 PM
#4
Registered User
Sounds like coil packs. What did you do to check them?
Should probably do IACV clean, and a new OE MAP wouldn't hurt, but those alone usually wouldn't cause the egregious misfires you're getting.
Once you've replaced everything else, last culprit could be the ECM itself; cross your fingers and hope it doesn't come to that.
Should probably do IACV clean, and a new OE MAP wouldn't hurt, but those alone usually wouldn't cause the egregious misfires you're getting.
Once you've replaced everything else, last culprit could be the ECM itself; cross your fingers and hope it doesn't come to that.
09-25-2018, 04:35 PM
#5
Have you done a compression test on the cylinders?
09-25-2018, 05:43 PM
#7
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09-25-2018, 05:44 PM
#8
Sounds like coil packs. What did you do to check them?
Should probably do IACV clean, and a new OE MAP wouldn't hurt, but those alone usually wouldn't cause the egregious misfires you're getting.
Once you've replaced everything else, last culprit could be the ECM itself; cross your fingers and hope it doesn't come to that.
Should probably do IACV clean, and a new OE MAP wouldn't hurt, but those alone usually wouldn't cause the egregious misfires you're getting.
Once you've replaced everything else, last culprit could be the ECM itself; cross your fingers and hope it doesn't come to that.
