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  #1  
Old September 21st, 2020, 08:30
bigdaddyjlove bigdaddyjlove is offline
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Help with recent engine swap

Hello all

Blew up engine back in March. Due to the current unpleasantness, the build and swap took a little longer than I had planned. The engine has been in the jeep for over a month at this point and it will not run correctly. It will crank and run after some extended cranking. Once running, it idles perfectly. It will NOT rev past 1800. Any attempt to rev causes stumbling, popping etc..

It moves fine in

Spec:
1996 Jeep XJ. AW4 Auto.
4.6L Stroker.
After thorough inspection re-used the crank and cam from the previous engine - Using same combination of parts from previous engine. Only carried over crank and cam. I have only managed to get one CEL code. One stumble and die resulted in an intermittent cam/crank missmatch. Will not repeat the code.

1. late model 258 crank
2. Crane Camshaft that does not seem to be made anymore. Apologies. Don't have the number, but it was their "tourquey" cam from 2008.
3. Stock 258 rods
4. New Sealed Power 802 pistons .030 over
5. Stock '98 head
6. Renix era engine block, bored to match new pistons

What I have done/checked
1. Rechecked cam timing. Verified by second set of eyes.
2. Rechecked ignition timing. Verified by second set of eyes.
3. Swapped ignition coil from running jeep
4. Swapped distributor from running jeep
5. Swapped Crank sensor from running jeep
6. Swapped Cam sensor/ignition pickup from running jeep
7. Swapped Throttle position sensor from running jeep
8. New cap/rotor/wires/plugs.
9. Checked fuel pressure at idle. 48 psi. Need second set of hands. Have not checked while trying to throttle. Will do ASAP
10. Unhooked exhaust at collector to check for plugged cat.

So far nothing seems to make any changes.

I am open to any ideas. I have several other XJs, so some quick swaps can be made

I am stumped, any help is appreciated.
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  #2  
Old September 21st, 2020, 09:18
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

You said you checked the cam timing, by what process? Did you actually degree the cam?
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  #3  
Old September 21st, 2020, 09:28
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

No. I am not that sophisticated. I have pulled valve and timing cover to verify that the timing marks line up and that the intake/exhaust valves are moving as expected.

It honestly "feels" like timing, but I cannot see any obvious issues.
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  #4  
Old September 21st, 2020, 09:35
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

Some of the cams require timing other than "straight up", are you sure it's a fuel injection cam and not one their carb models?
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  #5  
Old September 21st, 2020, 10:00
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

The Cam and Crank have been in 3 separate fuel injected jeeps. I built it for a 98 Wrangler, it lived in a Renix (88) for a couple of years and moved it to this exact jeep several years ago. I have timed this camshaft the same way twice before. Its never given me an issue in a fuel injected jeep.

When the engine failed (Broken Piston) I had the cam and crank checked at the machine shop. Replaced all rods and new pistons and as the block was gouged, decided to use another I had on hand.

Not trying to argue. Just want you to understand what was done. Seen your work before, and I could absolutely use your expertise
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  #6  
Old September 21st, 2020, 10:13
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

Well my next thought would be a vacumm leak but it would be pretty large, have you checked all that? What about the injector firing order?
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  #7  
Old September 21st, 2020, 10:18
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

It also sounds like it might be in "limp" mode, have you put a scanner on it?
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  #8  
Old September 21st, 2020, 10:44
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

Yes sir. Didn't think to mention

Sprayed brake cleaner around all potential vacuum spots, and the idle isn't running up like I would normally expect. No change with spray.

My scanner is basic, but i have only had the one code. I've never had an XJ in limp. Would it show a code?

CEL functions (comes on at start up, then goes out) but does not come on when running, except the one time I mentioned.
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  #9  
Old September 21st, 2020, 10:47
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

I did check injectors. The harness lays out correctly and wouldn't easily fit any other way. Plugs read as too much fuel. I should have mentioned, they are 24 lb ford injectors.
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  #10  
Old September 21st, 2020, 10:49
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

Sorry, its been a month, I'm losing track of everything I've checked.
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  #11  
Old September 21st, 2020, 10:49
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

I don't really know much about your '96 PCM, have you done a compression test? Have you done a leak-down test? My next thought leads to either sensors or a PCM itself.
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  #12  
Old September 21st, 2020, 11:27
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

Trying to run a compression/leak down check later if a buddy can come by. We also are going to check fuel pressure at open throttle. Just need more hands for those.

PCM is a concern a friend of mine raised. Is there a way to check it?

As far as sensors, are there any that are critical to running I haven't swapped?
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  #13  
Old September 21st, 2020, 12:50
RCP Phx RCP Phx is offline
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Re: Help with recent engine swap

Quote:
Originally Posted by bigdaddyjlove View Post
PCM is a concern a friend of mine raised. Is there a way to check it?

As far as sensors, are there any that are critical to running I haven't swapped?
Not that "I" know of other than a "in use" check with really expensive equipment.

All the sensors are fairly critical with some of the cheap auto store ones not performing well. But by your description about the only thing that you could do is "data logging" to look for something "unusual" that the PCM thinks is still w/i it's limits.
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  #14  
Old September 21st, 2020, 12:55
bigdaddyjlove bigdaddyjlove is offline
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Re: Help with recent engine swap

I really appreciate the input. Might need to scout the local yards for a 96 pcm. Be worth the $40. $200 for a new/reman one is a bit steep for a gamble.

Really hate blindly throwing parts at a problem...
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  #15  
Old September 22nd, 2020, 05:05
Evan03 Evan03 is offline
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Help with recent engine swap

Pcm was working when the engine blew up.

Sent from my SM-G960U using Tapatalk
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