Interesting Relative Compression

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picowight
TwoWaves
TwoWaves
Posts: 91
Joined: Sat Oct 26, 2019 6:45 pm

Interesting Relative Compression

Post by picowight »

Petrol Jag 2001 AJ-V8
Engine hunts at idle and has a nasty noise esp at just below normal idle (during a drop test for example)
The relative compression test on it is interesting
relative compression.png
So either low compression on 1,5,4 and 2 or high compression on 6,3,7,8 - I have not seen the base amperage vary like that. After cyl 1 being easier to turn the crank is going to be going faster so less amps for the next cylinder. The car starts and runs and I had the injectors turned off so it's not bore wash.
One rotation is hard to turn, high peaks high base current, then the next rotation is easy - low peaks low base current. :?:
The cylinders are numbered 1-4 on Bank 1 and 5-8 Bank 2 so it's not varying by bank. Though if 5 was 3 it would be.
I know it's RC so not to read too much into it but it does seem odd. In cylinder and breathing next.
Attachments
20220311-0003 RC current synch on 5 long.psdata
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