5s-fe auto transmission slipping?

[jdmccright]

Okay everyone, I just completed a timing belt change along with the water pump and the front seals. Everything went smoothly though I did notice that the TDC marks between the cam and crank aren't exactly spot on. With the crank set at 0-degrees, the little hole in the cam sprocket is just to the left of the matchmark detent on the head by ~1/16-1/8" and it looks like if I adjusted the cam another notch forward on the belt it would overshoot the mark to the right. Anyhow, this is all foreground info but might be relevant.

For some time now my car has had a strange acceleration pattern. It would feel like a stepped acceleration where the speed would increase, then hesitate, then continue, at about 1 second intervals. It is most noticeable under light acceleration and lower rpms. I would not lose speed during the hesitation, just would not accelerate. The tranny fluid has about 10k miles on it and is full when hot. It isn't bright red like new, more of a very pale pink but isn't burned. Dabbed onto a white paper towel it appears clear and colorless whereas new fluid would have a clear, pale pink color. Typical for aged fluid I believe.

Now, after the timing belt change, the issue is more pronounced. The car appears to not want to accelerate when the engine rpms are in the 1750-2250 range. Lighter acceleration will be decent, and acceleration above that is good and strong. But in that range there is a lull where the car feels sluggish and exhibits the stepped accel symptom.

Further, when the car is in O/D in that rpm range (abt 50 mph) and the torque converter (TC) locks up, I can feel a very slight bucking. Just below that speed ~40 mph, the TC will disengage but still be in O/D at abt 2000 rpm and the bucking symptom disappears. Any thoughts?

[somick]

Dead spots on acceleration is a symptom of a bad TPS. Have you looked into it?

Another thought. Since you played with timing belt, did you chech your timing?

Sam

[Brian R.]

Is it possible you damaged the crank timing sprocket (for the CPS) during your timing belt change?

[jdmccright]

I made very sure that I kept the timing aligned between the two and at zero, but I'll admit to not dbl checking it with a timing light after I buttoned it all up...it was 12:30am then & I was beat.

When I press the accelerator, the car seems to respond until it hits that rpm band. Off the line, I get better response if I keep the rpms below that range. If I press it down more, the rpms rise into that problem range and it becomes sluggish. If I give it full throttle at stand still, the rpms rise quickly into that range and it is sluggish though that rpm band then accelerates quickly above it. But in your defense, the same happens no matter what gear I am in...pointing away from the tranny.

I also ought to have mentioned that the car sat for a few days with the battery disconnected since the alternator was pulled, but I don't think this is a "learning" type of transmission, is it?

As far as I can read, on 5s-fe engines, the ECM gets the camshaft and crankshaft position signals from the distributor (the NE and G coils), not from a CPS. But I handled the crank timing sprocket with care. Good thought though.

I can double-check my findings, but that is what is happening as far as I can describe. I will check the timing and the TPS through the dashboard pigtail and follow-up.

[Brian R.]

Originally Posted by jdmccright

As far as I can read, on 5s-fe engines, the ECM gets the camshaft and crankshaft position signals from the distributor (the NE and G coils), not from a CPS.

You're right. Your '92 doesn't have a CPS. '96 and later (OBDII) have them. Sorry for the misinformation.

[Brian R.]

Intermittent hesitation may be your plug wires or coil. (Coil again?) Check the resistance of the plug wires as you bend them and twist them somewhat and see if they are fragile that way. Coil resistance may not tell the whole story. If you can't find anything wrong, you might try the coil as a last resort, even if it tests good.

Sounds like an intermittent ignition short or open circuit to me. Maybe also check for bad/loose connections or damaged primary or signal wires in the ignition circuit.

[jdmccright]

OMG, another 4 hours late at night in the garage, but the problem (at least the sluggish part) was incorrect timing alignment. See, the manuals always state to mark the timing belt IF YOU'RE GOING TO REUSE IT. They never state that if you are going to replace it, you should TRANSFER THE MARKS TO THE NEW BELT!

When I checked the timing, it was actually firing after TDC...whoa! Then I remembered back when installing the new belt that there was some slack in the front part of the belt (from the camshaft sprocket down to the crankshaft sprocket). When the crankshaft was turned, the belt tightened up, but then set the camshaft timing BEHIND the crankshaft.

I already stated that getting both to line up EXACTLY at the 0-deg marks was futile for some reason...I farted around for 1-1/2 hours rotating, realigning, checking, nudging, rechecking, but could never get them exactly on the zeros. So, I set the crankshaft slightly before 0-deg when the cam was at zero.

Another 1-1/2 hours was spent trying to break loose a distributor that had never been moved in 16 years...without success. But I did remove the cap & rotor and cleaned those up and checked the coil...it was a bit high but acceptable. Any ideas on how to get it freed?

Got it back together at 2:30am and fired it up, idle was better and higher right away. At idle and no terminal jumper it was running 700rpm and ~8-deg BTDC (the mark in between the 10- and 5-deg marks on the timing cover). With jumper, the engine kicks up to ~1000 rpms for a few secs, then idles down again, but lower ~650 rpm. Timing then was ~5-deg BDTC. Still firing late per the manual and hood label (should be 10-deg BDTC), but the pep is back at least. Will correct the timing when I can free up the distributor.

The acceleration issues remain, albeit greatly subdued and harder to feel. Still a lull around 2000 rpms, and a slight bucking in O/D and lock up when cruising. Will keep everyone posted. Any further advice or info is greatly appreciated!