Transmission problems after engine rebuild.

Hey guys.
I got a 92 Laredo cherokee with a 4.6 stroker.
I pulled the engine. did a quick refresh. then dropped it back in.
The car shifted fine before.
Now it does this really weird thing.
If I drive slow. or gently it does not do it.
Any gas more than 30% makes it happen.
example. driving along getting to 2.5krpms.
It drops to 2k~ like its going to shift
Then almost instantaneously back to 2.7k rpm.
then shifts.
If I give it more gas. It'll continuously fight between going up and down a gear.
But drive it slow and no problems.
Also. At about 55. it shifted down and it almost jogged the transmission.
Ugh... that did not feel good. and i'm scared to blow my transmission.
I have unplugged all sensors and wires. and plugged them all back in again.
Checked all wires on the transmission.
I tipped it down a bit installing . but checked the wires. they never got overloaded. or pulled.
** one thing I would like to note. I tried giving it like 60% gas. (new engine still babying) it roars and goes. so its not fuel cutting.
Bad sensor ?

Ideas ?
Automatic transmissions, to me, work on magic and clearly are not to be understood by the likes of mere mortals.... Ive rebuilt one in a prior car....ugh.....

Also. Wanted to note this in-case its related
When I Originally Rebuilt this engine I found this line disconnected above the transmission. Ill post a pic later and maybe someone can tell me what it is. but it comes off the transmission to a half circle fitting with a bolt hole off it. cant find any replacement parts for it online. I had originally thought it to be a breather line.

But that has since moved positions to a little higher up.
Nothing leaks from it. But Im sure its broken off from somewhere. knowing my luck
(without it hooked up it ran perfect)

Check the transmission TV cable. Try adjusting it. The tube probrably is the breather\vent for the transmission or transfercase

Got it. Will do that today and get back with results.
thanks.

sounds like your TPS is acting up. did you get it wet at any point during the "refresh" ? they have severe allergic reactions to water sometimes. might just be out of adjustment.
a quick search on TPS testing and adjusting will show you some easy troubleshooting.

also, DON'T mess with the TV cable without reading proper adjustment/setting instructions. if you get it wrong it will add to your troubleshooting woes.

Looked up how to adjust it.
Its moved a little now. theres a dirt mark from where it was before.
seems to shift a little better.
but thats not it.

It may be related.
But my new stroker motor is having low idle issues. (but it did this before the refresh)
I feel like its transmission though thats causing the shifting. and the two may not be related.
did'nt get wet.
parts stored nicely.
But a new tps is in the future.

After tv cable adjustment. And toying with some of the plugs. I have it running a little better.
Not perfect but close.
Something is still wrong.
Going to order a new TPS soon.
But she blew a freeze plug......... Ive never seen this happen before. But she actually spit one out. Car temp went up real quick. Lucky I spotted it quickly.
Pulled over. Plug is completely gone.
So cant really get back with more info atm.

I thought I had transmission problems after my rebuild. It was valve float from the incorrect valve springs compression.

1993 Red XJ said:

I thought I had transmission problems after my rebuild. It was valve float from the incorrect valve springs compression.

Click to expand...

this is interesting.
I did get a new head. new valves. the valve tips sit lower on the spring than the stock ones due to smaller keepers.
I dont think this would cause a problem. the valve springs themselves are the taller mopar set. to match the comp cams cam. same ones that came out
I do have a lifter tick, But I believe its unrelated.

What was the compression on the springs? I had 50 on the seat and 210 fully compressed. Should be 90-100 on the seat and 280 to 310 fully compressed according to Comp Cam specs

Mine ran good until I floored it. It would not shift into 3rd gear at WOT. If I drove normal it shifted fine. I also had misfire codes can you see any misfires? Look at your tach does it jump slightly.

Currently a freeze plug blew off the block. So im replacing all of them.
So cant really mess with her.
I topped off the transmission fluid.
wiggled some connectors no the transmission and engine before the last drive.

At 60% throttle and higher it just shifts.
its only from 30-60% throttle it wont.

Narrowing it down. my real thought is tps or cps right now

Grounds , tv cable , and maybe swap the tps . Check tranny fluid level.

So. Been tinkering with her for a little bit now.
Put a new TPS in. its better now. but that wasn't my issue.
Have adjusted Tv Cable. no change. maybe shifted better but its still not the issue.
I need to get a video up soon. of what it does.



Shifts fine it you drive it easy. No problems at all there.
Hit the gas while rolling at 35 to try to get it to downshift. and it just fights.
Up a gear
down a gear
up
down
like its not sure what to do.

but sometimes. hit the gas and she goes perfect.

its really intermittent but the one thing Ive found. Gas slowly works great. Any quick changes cause the bucking.
When rolling to a stop. it'll idle at 200 for a split second before going back to its idle speeds
Im going to replace my crank position sensor. with my spare. see if that changes anything.



what else controls shifting ?


My low idle/hunting idle issue Im convinced is another issue altogether.
Im leaning towards a fluctuating fuel pressure or timing (I cut a hole in the distributor cap and lined it up. cylinder 1 tdc. lined the cap up a fraction past the node. but the cam does change the timing.)
I cleaned the iacv. it was gunked up soo bad. Going to replace that soon.

Just stumped.
Other issues.
Wont start unless hold gas to 700rpm. otherwise idles at 100 and dies almost instantly.
after 1min of engine running. idles at 500-800 fluctuating randomly. sometimes it will idle great for 30 seconds then go back to stumbles/misfires/ just hunting idle.


Grounds are a very good idea. Im gonna throw a 4Ga. ground on the block and attach to the frame just in case. As well as a new dist cap and wires.

Any other ideas on this one guys ?
Its most likely two issues.
Because Ive had this low idle issue.
The shifting this is new since the engine rebuild.

I had the shifting fight up and down when trying to go up a hill especially. Hit the gas to accelerate up the hill and it fight shifting drop down for a few seconds then shift back up.
What fixed it was adjusting the the kick down cable at the throttle. It several attempts for it to settle at the right place.

I think this was done already.

Oh I had another problem about the time I readjusted the cable. Family had used the jeep to move a few thing that wouldn't fit in their car, the said it felt like it had no power in gear. I replaced the TPS and brake switch (brake switch is actually 3 switches in one) , and it went back to normal although it never did fail outright for me. I figure one of those switches failed causing the torque converter to disengage while being driven.

Driven 10k since then and no problems.

But I'm not sure any of this is related to your issue.

It feels like the TQ is disengaging while driving.
the more I drive it. the more I get what its trying to do.
When hitting the gas harder. It wants to downshift.
But it wants to downshift way to early.
then as its downshifting. it shifts up.
then back down.
If you continue to hit the gas it will bounce. up down up down.
It certainly doesn't feel good...

it seems electrical... its too intermittent to not be.


Ill toy some more with the tv cable.
Convinced its one of a few things...

prior to the rebuild. my rear reverse lights stopped working.
I know the nss controls this.
Does it control shifting at all ?

I Have the day off tomorrow So ill put some time into it and see what I can come up with.

If the TQ is disengaging only a couple of sensors that control it, TPS and brake switch for sure. Of course the transmission ecu .
Or a failure inside the transmission. I'm not sure how the TQ is engaged.

Far as I know the nss will affect starting and reverse lights but I don't think it could cause this. Then it's got to be gummed somewhat if reverse lights went out.

Id definitely try to adjust the kick down cable again.

i am in renix TPS hell and it has effected my shifting, altho right now i thi nk it is stable and shifting fine again.a great deal of mine was grounds being bad and other grounds being dirty. not sure of yours is a renix or early non HO engine era. locating and cleaning all your grounds might be a good thing to do.

Its the early H.O era.
Not sure which transmission it is. but its auto. (was replaced 10 years ago by P.O with receipts from shop.)
242 xfer case.

Going to check everything I can today.
Ill hold off on the nss for now if all it does is lights. (I got a rear facing led bar for that)

replaced tps.
brake light switch seems to be fine. both lights work perfect.

so what else does that leave that controls when the transmission shifts up.
The more I think about it. It has no problems shifting down. Its only up.


I bought A 5 4ga wire grounding kit. Ill see if that makes a difference.