engine/tranny playing up after ZF rebuild

[Randell]

I had my ZF 4HP22 rebuilt in november, and it has been perfect since then (apart from whining when it's hot, sounds like the non-filtran filter problem). However the other night i turned right at the lights with the car in 1, revved to about 5000, then shifted up through 2,3 and into D. The power didn't seem all there, and after that the transmission started acting odd, bucking about a bit and giving me rough downshifts.

the next morning I started it up, let it warm and then put it into reverse, and the revs spiked up to 1500, then settled around 550, the whole car shuddering. I lifted my foot off the brake and it surged backwards! I hit a curb, put it into drive and the revs spiked again, then it started shuddering and fighting to move off under brakes.

I had it towed to the shop it was rebuilt at, the guy said it had an oil leak which they fixed, but the strangeness is still there... he said it was because the engine was out of tune and the torque from putting it into gear was causing the problems (it is well overdue for a service). I drove it back to work and it had smoothed out a little by the time i got there (the rev spike was gone, but the low revs and hard shifts hadn't).

Has anyone experienced this? I'd just like to see if someone out there can tell me if it's an engine or transmission problem, so I can take it to the right person and get back to normal driving!

Thanks

[Randell]

after some more driving... there is absolutely NO power between idle and about 2600rpm, the throttle feels like a soggy sponge, then suddenly it all rushes in and goes all the way to shift point without a problem, also shifting smooth.

downshifts are really abrupt, 4th to 3rd is stuttery, 3rd to 2nd and 2nd to 1st are abrupt and harsh... upshifts are smooth under full-throttle, but under light throttle it feels like it's shifting twice rapidly, and it feels like something is grabbing the car is pulling it back

also, it seems to be building torque when im stopped, causing the car to move quite rapidly when i let go of the brake, but then it will suddenly lose momentum and just roll silently. the engine is FINE in park or neutral, revs smooth and normal, all fluids are fine, no odd noises or smells. idle in park or neutral is normal (~700), in reverse or drive hovers around 550 and is rough as hell

if anyone has any idea what could be causing this, please let me know... even if it's just an idea... i am totally stumped, i've looked through the bently for the last hour and googled a hundred times but come back with nothing :( i've also disconnected the battery for 30 mins in the hope it might reset something buggered in the software, but no change

[632 Regal]

well... give Kirt Kohller a call and see what he tells you, then after that you will have a better idea what to do or whats going on with it. At this time it could be anything from a clogged filter, leaky filter pickup allowing air in to the wrong fluid causing problems or the computers.

Kirt Kohller:
(800)624-3876 ext 5735
or direct at (616)748-5735

[tim]

Sounds like it could be a fluid level problem. Why not do a filter service, and refill it properly with the right fluid, and see what happens? It's been hot there, and it's easy to cause the shifter seals to leak if the case was overfilled at the rebuild. That's the diy part.

Other than that, it could be a valve body or solenoid issue. Kirt K. is the right guy. He could send you a rebuilt VB for your core. I forget but it's like $300-400.

I'd also get the codes read, in case you have an error code that hasn't forced "trans prog" yet.

-tim

[Kalevera]

Randell:

Koala Motorsport installed a ZF remanufactured 4hp-22 in my car about two weeks ago. After a day of driving (esp after putting it into manual mode), I noticed that the car would shudder if I accelerated slowly to about ~ 35/40mph at around 1500 revs. At first, it was barely noticeable - came off as a lack of power.

~ 2 days after having the reman put in, I was coming to a stop at a red light after doing about 60 on a country road. The tach started jumping and the engine started to stall out. I had to keep my foot on the gas and brakes to keep it alive. I was *really* freaked out, and Brett's shop was conveniently about 5 min away, so I headed over there (hoping the car wouldn't die along the way). I had to stop at one other light before I made it there, and, although it came to a complete stop with no fuss, it made a loud "BANG" while idling at the light, which to me sounded like the exhaust manifold falling off.

My car's diagnostics are messed up - something's wrong with the bus and no computer can communicate with OBD. So Brett and I took it out for a spin. It did it once, as before, at around 1500 rpm...but it was too short of a period of time to diagnose anything.

Brett suggests that it is pendulum shifting (or perhaps, but unlikely, crossfire), probably related to a messed up tranny computer, and perhaps the reason why the car lost reverse (by remachining it's F clutch basket) to begin with. I didn't own the car when it last had reverse, so I don't know.

The next day (a week ago), I drove the car ~ 500 miles. Brett told me to just drive it, see what happens, so we can better diagnose it. He also mentioned that, if it happens in E mode, I can just flip it into manual mode and it should stop trying to switch gears. I noticed that the shift between 3 and 4/OD was a bit rougher, but there was no pendulum shifting until I got off the highway near my house. Then, going at about 25mph (same characteristics - no fancy driving, no punching of the throttle), it happened again. I punched the throttle for a second and it went away.

Since then, it hasn't occured, although the car has been sitting due to brake and cooling system problems.

Best, Whit

[Randell]

thanks for the input guys

632 regal: being in australia I don't think i'll bother kirt with my problems, but thanks for the suggestion... you guys have it a bit easier over there, seems to be a few good experts around

tim: i've just had the transmission rebuilt 2 months ago, i assumed that included work to the valve body also... i don't really feel like plunging more money into it, it's got a 2 year warranty and the shop gives me top priority when i take it back, which is nice to see! i might give the filter a thought though, and i'll suggest it to the transmission shop. i suspect they've put a non-filtran filter in, and i've no idea what fluid they've used.

lowell: your problems seem similar to mine, but not quite the same.. my idle is rough but it never seems to threaten to stall, if i put my foot on the brake and give it a tiny bit of throttle to bring the revs up, it's almost impossible to keep the car still! it feels like there's just too much torque going through at idle, which would probably explain the rough downshifts... perhaps this is a torque converter issue? also something that was part of the rebuild..

i'm not experiencing pendulum shifting either, just rough, stuttery downshifts and strange partial-throttle upshifts... full throttle is fine.. also, the idle is better after the car has been driven (ie warm), but if i coast at slow speeds (20km/h) it will eventually jolt a few times like if you lifted the clutch in a manual... also, every time i lift the throttle, regardless of speed, it feels like something grabs the car and it kinda lurches for a split second..

i'll take it in to my mechanic this week and ask him to give it a quick look-over and tell me if it could be engine related, and if not ... straight back to the transmission shop!

[Kalevera]

Randell:

Yes, I noted, as well, that our cars have slightly different problems. I guess I failed to mention that the solution to my problem seems to be in upgrading the transmission computer's firmware. The torque converter sounds like the thing to check out first, though.

The jolting, under the same conditions in my car, was diagnosed as pendulum shifting (that didn't seem like the case to me when it happened, either), so that's why I mentioned it. But, it sounds like you've got your plan all figured out ;)

best, whit