Engine stumbling between 1500-2k rpm under load

[Hooyah]

Alright...I have a new/old issue with my 97 lesabre (automatic). It stumbles when under load. It got better after I serviced my transmission but is now back. car has 166,000 miles on it.

Simptoms
-when driving up hill or hitting the gas slightly harder than normal between 1500-2000 rpm it will begin to stumble rather badly and fluctuate between 1400-2000 rpm. Up and down. If I let off the gas and push it again it will go away for 3 sec and then start again.

-engine does not want to go much over 2k rpm but will rev all the way at free idle.

-it did happen a few times from a stop but not as bad and rarely. mostly happens between 40-60 mph. Im going to test drive the car more and in different gears.

-no codes

-pieces of thrust washer in transmission pan.


Repairs I have done
-Replaced MAP sensor
-Replaced plugs (NGK)
-replaced wires
-replaced TPS sensor from bone yard
-replaced fuel regulator (it did get better after this, undrivable before I fixed this)
-replaced fuel filter
-Tested bleed down on fuel system and it was in spec with engine off. Can't remember if I tested when idling but the idle is good.
-Entire head gasket job. It took two weeks on my off days, thoroughly cleaned and reassambled each piece. I did replace the head bolts too. I know I didn't do anything wrong because the issue is no better or worce after. (maybe slightly better)
-I dropped the pan on tranny and did fluid change (noticed that there was a leak where the dip stick meets the pan but only when filling tranny)
-replaced chewed tranny mount


I suspect
-weak or intermittent fuel pump?
-sensor on transmission???
-ignition coils or modual?
-egr valve -(Tested and made no difference)-
-plugged cat?


Amy help would be great. I have been working on this car for 3 months now and I just want it fixed. I didnt even include the myriad of other things I fixed!

[Tech II]

Think we debated this before, as to whether it was an engine or transmission problem.....you need something like a Tech II scanner on the vehicle during a road test....when it happens, you want to look at misfire data and also tranmission slippage data, to determine which is at fault...

[Hooyah]

I was going to buy a good scan tool anyways so I guess not is a good time. Any good suggestions? Willing to spend up to $300 on it.

I was getting a misfire code before I did the head gasket job. Found the lower manifold gasket was leaking.

[Hooyah]

Just went out to road test and it DID NOT do this in drive 1 and 2, it revved up to the red line fine. It only happens in drive 3 and over drive. I guess this means it is transmission related?

Also in 3 and o it won't go above 2200 rpm without a big fight.

Edit: I just read a post that was exactly like my problem and it turned out to be tcc regulator valve.

Edit: Looks like it could be three things now, TCC clutch is worn out, valve body is worn out, or tcc solenoid is bad. Anyone know how to test these?

[Hooyah]

Another road test. I unplugged the tcc solenoid (i think that is the one on the front of the tranny) and drove it a few miles. It was very sluggish to get rolling but the problem did NOT happen. However I got 8 tranny codes when I got back to the house. I'm very sure I have to drop the tranny now, I just want to pin down exactly which part is causing this.

[HotZ28]

You should eliminate the coils, as well as a plugged cat as the culprit, before condemning the trans.

[Hooyah]

Im taking it in the morning to my buddies shop and hooking it up to the pro scanner. You are right, I should get them out of the way i supose. I went ahead and ordered the tcc solenoid because it is cheap and not that hard to put in.

I'll report back in the am.

[maxwedge]

tcc solenoid is not an easy job, the side cover on the trans must come off, look into that before doing the job.

[Hooyah]

Well got dang! I took it to the shop and as usual it did nothing wrong. Poked around for a few minutes and then decided to leave the shop scanner on while I took it on a quick drive. The damn thing was misfiring in cylinder 4! and slightly on 1. Changed out the coil pack and the problem is gone......That was a way simple job that took forever but I'm very happy that it's done!!!!!!!!!!!

It was not thowing a code and I had already switched coil packs several times but oh well.

Now the last thing I have to fix is the horn. Horns are good but wont make a sound. Relay is good but not clicking. 60 amp fuse is good too...

Anyways, thanks a ton for the help everyone!!