Does the sensor I replaced not provide info to ecu for fuelling?...plugs were showing huge running rich and you could smell petrol fumes when cranking from exhaust symtoms of flooding...
P38, 4.0 petrol, 2002, Bosch - no start
- Thread starter Jock85
- Start date
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Does the sensor I replaced not provide info to ecu for fuelling?...plugs were showing huge running rich and you could smell petrol fumes when cranking from exhaust symtoms of flooding...
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- Buckinghamshire, UK. ('95 DT)
Still waiting for a response on that one.
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With my GEMS the CPS gave a signal for spark but did not appear to affect fuelling, but that was in practice, not from looking at Diag
I'll check it out, thanks.
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I bought a Hawkeye Pro about 6 weeks ago and it hasn't given any feedback or codes yet. I've got some spark plugs coming and I'm doing a compression test tomorrow so hopefully be able to rule out more things tomorrow.
Evening all, the spark plugs came today so I was going to replace them and do a compression test at the same time. Putting a battery booster on the car, the first two cylinders closest to O/S/F showed 120psi but the back two on the O/S showed 0psi, literally zero. I thought the tester was playing up so I repeated the first two cylinders again - same result of 120 psi. Back two again showed zero. Scratching my head, I tried a couple on N/S. The back cylinder tested at 90psi the first time, second time 0psi. O/S/F cylinder tested at 120psi. There are no nasty crunches indicating a shafted valve or piston, it just provides no compression at all on some of the cylinders. I've had bad valves on engines before and you still get some compression so I don't even understand how it's possible. Anyone know what I'm missing?
Just to recap - engine just stalled on a drive and wouldn't restart. No mechanical crunching, just like the key had been turned off. Still does run just but simply backfires, won't rev and stalls.
Over to you wizards...
Just to recap - engine just stalled on a drive and wouldn't restart. No mechanical crunching, just like the key had been turned off. Still does run just but simply backfires, won't rev and stalls.
Over to you wizards...
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Seems unlikely. If you tried to start an engine with some cylinders having no compression, then it would turn over very unevenly.
Any chance the tester isn't screwing in properly?
Any chance the tester isn't screwing in properly?
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All plugs out and at full throttle when doing the compression testing.
I always do each cylinder three times.
Pull the fuel pump relay or fuse as well. Easy to say but...
I always do each cylinder three times.
Pull the fuel pump relay or fuse as well. Easy to say but...
He said it does run rough and backfires...hence some cylinders not firing and unburnt fuel igniting in exhaust...
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Popping cats man!!
Marshall8hp
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The only way you will see zero PSI is if the piston has disintegrated. Even a stuck valve will give you some reading at cranking speed assuming your compression tester has a check valve in it, which most have. I doubt very much you have a number of pistons basically missing. Put your thumb over the spark plug hole and have someone hit the key, see what happens.
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Be careful with that
He went back and checked duff readings so after getting same readings assumed guage ok...but did say on one side they changed on second test...would go with @kermit_rr Is guage fitting tight I had to buy a snapon thinwall plug socket for my 101 V8 but normal socket fits RRC V8...90 bloody euros it cost me...
Fubard cats man!!...
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120 psi is very low. So is 0psi. Hard to believe low.
Just to check, all spark plugs removed, battery fully charged, throttle to the floor and then spin engine for maybe 10 seconds? Make sure tester adapter is in nicely, maybe a smear of copper-grease.
Note down all readings and then go back and do again but this time drop a tablespoon of oil down the hole first. Note down all readings again. Listen for chuffing noises. And check coolant for bubbles.
Morning all, thanks for your replies. Having thought about it and with what's been said above, the signs point toward the test/tester as the 0 psi on so many cylinders simply doesn't make sense on an engine that essentially still runs. The thumb trick should confirm if its user error and hopefully it'll lead to one theory or the other and I'll let you know after work tonight. Appreciate it, Ed.
JUKE179r
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Try removing the IAC valve on top of the engine and clean it internally with carb cleaner and an old toothbrush/rag.
Evening all, I don't have any update yet. Weather's been pretty manky up here over the last few days but the old thumb test (cheers Marshall8hp) proves there is definitely compression (like blow your finger away) on the unreadable chambers, I just can't get a read on it yet and, given what others have said, I maybe need to get another compression tester in the first place which is strange as it works fine on other machines. However, if I can get decent readings I'm hoping it eliminates any compression issues as the running problem as it ran so well. Assuming it does, I've got a few leads from here to check out after.
Thanks, Ed
Thanks, Ed
So the confusion continues as I take back what I said about the thumb test blowing your finger off. Basically, the four cylinders closest to the front continue to give a reading of about 120psi and the back four very poor compression near 0psi. Even with greasing the tester o-ring, battery booster, and full throttle. There is an initial pressure from the back four (say less than 60psi) that drops to next to nothing no matter how long you crank it leaving me bewildered. I would have thought had the timing slipped the pressures would be more random than front four 120, back four 0psi but is there a way to quickly check the timing other than removing the timing cover? I assume that other than 1 spark plug and 4 valves nothing else accesses each compression chamber?
brianp38dse
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Sounds like time for a bit of open heart surgery .
