CF Veteran
Good points above.
Surely you found out what was wrong with the original parts while taking everything apart. What was it?
Surely you found out what was wrong with the original parts while taking everything apart. What was it?
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Now:as I understand it:
1) it idles bad and sometimes backfires out the exhaust
2 it's setting an injector code on cylinder 4, but swapping injectors around doesn't move the code. The noid light doesn't show a problem
3) it has NOT set a misfire code, which is interesting.
I have no idea what's wrong with the thing but pretty clearly it occurred after all parts were replaced. Compression is ok, fuel pressure is ok, I really wonder if timing ( ignition or injector) is off on cylinder 4. Put the old distributor AND the old pickup back in and see what happens. There have been a lot of horror stories about replacement distributors having the gear 180 off, who knows what else could be wrong with it.
(Also,btw. You did all this work because of "horrible lifter knock" how did you confirm the noise was actually lifter knock and which cylinder was it?)
I'll put the old dizzy back in and see if that will help, and as for the lifter tick after working on and building Buick Grand National engines for 20 plus years Im pretty proficient at identifying lifter tick/knock even pointed out one on her 2019 SRT Charger that dodge had to fix under warranty Originally Posted by exasemech
From what you have said , before you, for whatever reason, put a cam and an aluminum head on an engine with 340k on it it ran fine with no codes. Only problem was the lifter noise.Now:as I understand it:
1) it idles bad and sometimes backfires out the exhaust
2 it's setting an injector code on cylinder 4, but swapping injectors around doesn't move the code. The noid light doesn't show a problem
3) it has NOT set a misfire code, which is interesting.
I have no idea what's wrong with the thing but pretty clearly it occurred after all parts were replaced. Compression is ok, fuel pressure is ok, I really wonder if timing ( ignition or injector) is off on cylinder 4. Put the old distributor AND the old pickup back in and see what happens. There have been a lot of horror stories about replacement distributors having the gear 180 off, who knows what else could be wrong with it.
(Also,btw. You did all this work because of "horrible lifter knock" how did you confirm the noise was actually lifter knock and which cylinder was it?)
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Surely you found out what was wrong with the original parts while taking everything apart. What was it?
it was bad lifters in two of the cylindersOriginally Posted by TrailerTrash
Good points above.Surely you found out what was wrong with the original parts while taking everything apart. What was it?
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Speaking of which wonder if he solved his issue...
I just did a search, and yep that's one of the ones I read, but he never posted if he got it fixedOriginally Posted by Dave51
Did you do all the stuff in Codak's thread?Speaking of which wonder if he solved his issue...
Also, valves are adjustable (sorta). Is the preload correct?
https://www.cherokeeforum.com/f2/new...stment-213117/
https://www.cherokeeforum.com/f2/new...stment-213117/
Okay, I put the old dizzy back in it runs but seems the same, but now I have a P0500 code after driving it around the block.
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I plugged all vacuum ports to eliminate that cause I haven't checked the crank position sensor yet.Originally Posted by Dave51
OK but vacuum leaks and cam/crank sync were on that list.
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https://www.cherokeeforum.com/f2/new...stment-213117/
I can check them, If they are to tight you would think I wouldn't have the compression that I have.Originally Posted by Dave51
Also, valves are adjustable (sorta). Is the preload correct?https://www.cherokeeforum.com/f2/new...stment-213117/
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1. Use a gauge.Originally Posted by J/D/S
I plugged all vacuum ports to eliminate that cause
2. Check intake manifold for leaks/cracks near #3.
If all the "maybe" reasons for P0204 have been ruled out, even though you inspected wiring IIWM I'd take the cause of P0204
You can do that one of 3 ways:
1. Get a DRBIII tool and analyze (probably can't find one);
2. Get a SnapOn MT2500 or equivalent (very expensive).
3. Get an entry-level oscilloscope (about 150 bucks).
The above screen shows what the normal almost normal waveforms of a Cherokee 4.0 injector look like (one of mine AAMOF). Explanation T/F (if necessasry) but all you really need to do is compare the 6 injector waveforms. If (when) it shows that circuit is bad you can focus on the wiring or the driver (new PCM).
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The injector current falls below a calibrated threshold
and vet that out.The injector current falls below a calibrated threshold
You can do that one of 3 ways:
1. Get a DRBIII tool and analyze (probably can't find one);
2. Get a SnapOn MT2500 or equivalent (very expensive).
3. Get an entry-level oscilloscope (about 150 bucks).
The above screen shows what the normal almost normal waveforms of a Cherokee 4.0 injector look like (one of mine AAMOF). Explanation T/F (if necessasry) but all you really need to do is compare the 6 injector waveforms. If (when) it shows that circuit is bad you can focus on the wiring or the driver (new PCM).
From a ScannerDanner presentation. His injector open hump is more defined. My screenshot might have been my old injectors. Forgot.
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2. Check intake manifold for leaks/cracks near #3.
what am I using the gauge on, the factory vacuum lines? I wouldn't think a vacuum leak would be an issue since i have all the vacuum port in the intake capped off.Originally Posted by Dave51
1. Use a gauge.2. Check intake manifold for leaks/cracks near #3.
I'll give the intake a look, but other then taking it off is there an easier way to check it?
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Spray it with carb cleaner, propane, etc.Originally Posted by J/D/S
I'll give the intake a look, but other then taking it off is there an easier way to check it?