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4.0 Renix Head on HO Block - what's my problem?

H

hazeshawn

NAXJA Forum User
Location
Red Lion, PA
I threw a rod in my 1987 Cherokee Leredo at 200k and put in a 1992 block (not sure what it came out of). I used my 87 head, push rods, manifolds, distributer and it runs like utter crap! Timing is in and I put everything back together correctly, but it just wants to run ragged! Any suggestions? Is my cam, rods, rockers the culprit? HELP!:cry:
 
hazeshawn said:
I threw a rod in my 1987 Cherokee Leredo at 200k and put in a 1992 block (not sure what it came out of). I used my 87 head, push rods, manifolds, distributer and it runs like utter crap! Timing is in and I put everything back together correctly, but it just wants to run ragged! Any suggestions? Is my cam, rods, rockers the culprit? HELP!:cry:
Click to expand...
Someone should correct me if I'm wrong but since it's the 92 block I believe you should have the 92 dizzy in there.
 
At the risk of being Captain Obvious, did you use the flexplate/fywheel from the 87 or the 92?
 
The 92 cam should be the same as the RENIX, and it wouldn't make much difference anyhow...

Things I'd check first:
Should be RENIX CPS (works on a different principle)
Should be RENIX flexplate/flywheel (I believe the signal teeth are different.)
Dizzy should be RENIX (the internal sensor is a bit different.)
The absence of the KNOCK sensor should not be a big problem, since it only does something when there is spark knock (most of the time, it's just along for the ride.)

There are some differences on the RENIX sensors vice the ChryCo/OBD/HO, so use RENIX wherever possible (so the ECU can understand what it's being told.) It is possible for the RENIX to run without the SYNC sensor in the distributor working, but it will run like arse, and it's more of a "limp home" than anything else. If you've got the HO dizzy in there, the RENIX system may not understand it.

Check those first, and report back, hm?
 
5-90 said:
The 92 cam should be the same as the RENIX, and it wouldn't make much difference anyhow...

Things I'd check first:
Should be RENIX CPS (works on a different principle)
Should be RENIX flexplate/flywheel (I believe the signal teeth are different.)
Dizzy should be RENIX (the internal sensor is a bit different.)
The absence of the KNOCK sensor should not be a big problem, since it only does something when there is spark knock (most of the time, it's just along for the ride.)

There are some differences on the RENIX sensors vice the ChryCo/OBD/HO, so use RENIX wherever possible (so the ECU can understand what it's being told.) It is possible for the RENIX to run without the SYNC sensor in the distributor working, but it will run like arse, and it's more of a "limp home" than anything else. If you've got the HO dizzy in there, the RENIX system may not understand it.

Check those first, and report back, hm?
Click to expand...

Thanks, I'll check it out!
 
Is there any possibility that I could have put my driveplate on wrong? I know the 87 driveplate looked as though it's slots were uniform the whole way around, wheras the 92 driveplate didn't. I did find that my coil was bad, so I put a new one on, I noticed a slight difference, but it still doesn't want to stay running. It sounds like it's out of time, but everything is on it's correct marks.
 
hazeshawn said:
Is there any possibility that I could have put my driveplate on wrong? I know the 87 driveplate looked as though it's slots were uniform the whole way around, wheras the 92 driveplate didn't. I did find that my coil was bad, so I put a new one on, I noticed a slight difference, but it still doesn't want to stay running. It sounds like it's out of time, but everything is on it's correct marks.
Click to expand...

Shouldn't be - one of the screw holes is a shade "out of round" to "key" the flexplate/flywheel. You probably noticed that trying to get the screw holes to line up when you were under there...
 
hazeshawn said:
Is there any possibility that I could have put my driveplate on wrong? I know the 87 driveplate looked as though it's slots were uniform the whole way around, wheras the 92 driveplate didn't. I did find that my coil was bad, so I put a new one on, I noticed a slight difference, but it still doesn't want to stay running. It sounds like it's out of time, but everything is on it's correct marks.
Click to expand...

:confused: *UPDATE*

I just put a new cap and rotor on, still fires, runs ragged, backfires, stalls, doesn't want to restart for a good 15 minutes at a time. I've been researching and am thinking - bad CPS? It's a possibility that between getting the old engine out and the newer one back in, I may have banged that sensor a bit. The tip on it looks like it has a little chunk taken out of it.
 
hazeshawn said:
:confused: *UPDATE*

I just put a new cap and rotor on, still fires, runs ragged, backfires, stalls, doesn't want to restart for a good 15 minutes at a time. I've been researching and am thinking - bad CPS? It's a possibility that between getting the old engine out and the newer one back in, I may have banged that sensor a bit. The tip on it looks like it has a little chunk taken out of it.
Click to expand...

It's a distinct possibility.

Remember - the RENIX and HO CPS's are different, and work on different principles. Since you have the RENIX control, you must have the RENIX CPS!
 
And did you change to the Renix distributor? I would really do that.
 
hazeshawn said:
Yes, distributor is the 1987 Renix.
Click to expand...


Are you sure you got the distributor in right..........They can be a real bugger to drop it in........in time!

did the new dist have a timing pin.....in the dist......was the eng at top dead center......COMPRESSION STROKE?


Flash
 
:clap: Okay...turns out I chipped the CPS putting the engine back in. Replaced it and it runs great. Has a bit of lope from the H.O. cam, but I can deal with that. Thanks for all the input...everyone!
 
By the way, make sure and mount the ping sensor on the new block. I don't think there is a mounting hole there for it. If you leave the connector unplugged you will fight with erratic timing and crappy performance.
 
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