Small idle fluctuations

Mar 1, 2025 | 09:11 AM

PeTaR

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Small idle fluctuations

Idle has small fluctuations as shown in the video. MAF is cleaned and there no obvious vacuum leaks. Engine is freshly rebuild and just done breaking in. Are there any reasons for concern?
Thanks!

Mar 1, 2025 | 08:12 PM

Loki

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Doesn't seem serious. Are the fuel trims at idle near zero and ignition coils/wires/spark plugs fresh?

Mar 2, 2025 | 06:18 AM

PeTaR

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Hi, the LTFT is about 6-7%, STFT is about +-1%. I am not sure about coils, spark plugs are new after rebuilt about 5k miles.It is street ported so does that have some influence?

Mar 2, 2025 | 06:48 AM

Loki

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Sure, could be the porting. You typically want new coils on rebuilt engines because old coils probably contributed to needing a rebuild in the first place.

What was replaced in the rebuild?

Mar 2, 2025 | 06:51 AM

PeTaR

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The housings and seals are replaced, it was side seal failure on front rotor. The housings are changed because they were almost at the end of life because of wear so no fatal damage on them.

Last edited by PeTaR; Mar 2, 2025 at 06:55 AM.