Transmission skipping or 'fall-out' ?

My 99 Suburban 1500 has 155k miles on it. At 145k, I had the transmission fluid purged - thought I was doing the right thing.

Anyway - it 'skips' now. To try to explain better - it feels almost like you went over a few bumps in the road. Then it goes away for 10 - 20 secs. At first I thought it may be the OD Converter cycle lock up - but it does it in 3rd and OD. You can feel it at 55 when you level the gas off and are cruising. It does appear at lower speeds...45, etc It also
ocurrs at high speeds, but you really have to 'feel' for it at the higher speeds.

Last - it almost feels like a 'stumble' from the engine, but I think it is indeed the transmisison.

Last last - a few weeks ago - I heard a noise in the transmission - it was heard on a cool (40 degrees) early morning startup and lasted about 4 blocks of driving. I heard it the next day for a short period and then never again. It was like a whining/grining gear noise.

thanks

GMCMudBogger - where are you? :-)

My 99 Suburban 1500 has 155k miles on it. At 145k, I had the transmission fluid purged - thought I was doing the right thing.

Anyway - it 'skips' now. To try to explain better - it feels almost like you went over a few bumps in the road. Then it goes away for 10 - 20 secs. At first I thought it may be the OD Converter cycle lock up - but it does it in 3rd and OD. You can feel it at 55 when you level the gas off and are cruising. It does appear at lower speeds...45, etc It also
ocurrs at high speeds, but you really have to 'feel' for it at the higher speeds.

Last - it almost feels like a 'stumble' from the engine, but I think it is indeed the transmisison.

Last last - a few weeks ago - I heard a noise in the transmission - it was heard on a cool (40 degrees) early morning startup and lasted about 4 blocks of driving. I heard it the next day for a short period and then never again. It was like a whining/grining gear noise.

thanks

I have a similar problem with my 2002. It shutters at low speed and when going up hill. I also recently had my tansmission fluid changed. Any ideas?

I have a similar problem with my 2002. It shutters at low speed and when going up hill. I also recently had my tansmission fluid changed. Any ideas?

My 97 Does The Same at 50+ Mph ,Tranny Shop Said It was Lockup Torque Conv ,Replace or just deal with??(it feels like bumps in the road)

Tonight I will be checking the tranny while driving using a computer type monitoring device. A friend has it and will be able to monitor the actions of the transmission and actually seee what is happening while we are driving. I just spoke with him and he feels pretty sure it is the Lock Up switch anyway... ??? will get back

I'm thinking it's a lock-up problem, also. Also, your transmission can engage the torque converter clutch in 3rd or 4th..

I had a '94 that done that and the '02 I have now has done that. I was told it likely was the tc lock up thing. Put 2 cans of Lucas in the '94, fixed it. Flushed the trany in the '02, added the additive the quick lube had to go with the flush and a can of Lucas and it stopped the vibrations.
What I was told to do: when it does it keep your foot on the gas and tap the brake pedal enough to light up the brake lights and see if it stops. As soon as you hit the brake it kicks out the tc lockup or stops it from trying to lockup.

I will try the brake test.....

Results from last nights Test....

From what I understand, the transmission itself is fine. The computer he hooked up said that I have TCC (converter) slippage (which he thought might most likely be the result of a damaged stator. ) The TCC is cycling way too much. He said that possibly the 3-2 shift soleniod could be sticking and could be the result of the backflush I did this summer - knocking a bunch of crap loose and plugging the solenoid.

His guidance is to change the filter (which I will do this weekend) and then a new converter if that does not work. But he wants to do another diagnostic test after the filter change to make sure the 3-2 solenoid is operating the way that it suppose to........if not........then the soleniod should probably be replaced before the converter.

Hmm, the stator and the torque converter clutch are 2 seperate components in the converter. A bad stator would reduce low end torque multiplication, but has nothing to do with the TCC. I've also had this problem, but updated PWM and TCC solenoids fixed the problem. A faulty 3-2 shift solenoid would prevent 3-2 downshifts, but shouldn't affect TCC apply. There are a few things that cause converter clutch slippage... Low fluid pressure, worn clutch friction material, and a faulty TCC solenoid . It's fairly easy to get to. After removing the transmission side cover(drivers side), it's located on the lowest left-hand side of the valvebody.

Also, I've heard of this problem being fixed by changing the plugs, wires and coil, even if they all test/look fine..

Thanks d3....... If my memory serves me right, the test indicated that the TCC switch was working as it should. He did say that he did not know why there were no pressure readings - possiibly from that part of the test unit not functioning? I appreciate the input and will get back

OK - replaced:
A. ATF filter
B. 2 Solenoids (1-2 and 2-3 shift) on rear of valvebody
C. 1 switch (TCC) on front right side of valvebody.

I took it for a drive last night. The traffic preventing me from 'cruising' at a set speed for a long period to really get a good test. I think I still feel the same issue occurring - but I just need to drive it again to confirm.

I did tests on the old switched that I removed and they appeared to be operating fine - well - at least they 'clicked' into and on/off mode when 12v was applied. - Is that any kind of worthwhile test?

We will retest with the ODB mobil computer unit this coming week and I will give status.

I've misdiagnosed a dodge ram transmission thinking it wasn't the solenoid, but it turned out even though it tested ok, it was bad. But the scanner will be a sure way to tell. If the transmission still acts up, you may want to think about changing your plugs and wires..

Could be something as simple as the wrong ATF fluid. The Dodges will act funny if you put regular DexronIII in them if I remember correctly. Dad's Caravan did the same thing. Almost like you were running over something til someone told him to use only Mopar ATF. I hear the new ATF+4 is good for the Fords although Mopar makes the stuff.

OK - replaced:
A. ATF filter
B. 2 Solenoids (1-2 and 2-3 shift) on rear of valvebody
C. 1 switch (TCC) on front right side of valvebody.

I took it for a drive last night. The traffic preventing me from 'cruising' at a set speed for a long period to really get a good test. I think I still feel the same issue occurring - but I just need to drive it again to confirm.

I did tests on the old switched that I removed and they appeared to be operating fine - well - at least they 'clicked' into and on/off mode when 12v was applied. - Is that any kind of worthwhile test?

We will retest with the ODB mobil computer unit this coming week and I will give status.

Hello, I am having this exact problem with a 99 5.7 van. I also had my fluid changed. It started at 105,000 for me. I do not see any more posts after you performed the work above. Did this solve the problem? Which item do you think fixed it. Any help would be greatly appreciated.

All is still the same.... :( I plan on a Converter next - as it is $110 +- at Autozone. Also - I may try to go by Aamco Transmissions and see if they will diagnose/give advise for a fee... Chevrolet wanted $300 and to tear into it at minimum.

All is still the same.... :( I plan on a Converter next - as it is $110 +- at Autozone. Also - I may try to go by Aamco Transmissions and see if they will diagnose/give advise for a fee... Chevrolet wanted $300 and to tear into it at minimum.

Thanks a million for the update. I find it amazing that Chevrolet has no help or insight. I have been working this problem for a year. I am not even sure if it is a transmission or engine problem. My vehicle does not have the problem when the engine is running cold. It has to warm up and run about 12-15 miles. This seems to indicate that it could be a closed loop situation. Possibly something causing the computer to run in limp mode. (or cold/thick fluid?) So far I have done complete tune with wires, fuel filters and motorvac (combustion chamber cleaning) The problem started as jerking during "light throttle at the top of hills" only and has progressed to "a miss, or shake, at very light throttle" over 15,000 miles. I bought a obd program for my laptop, but so far have not seen a smoking gun.

Hello, I am having this exact problem with a 99 5.7 van. I also had my fluid changed. It started at 105,000 for me. I do not see any more posts after you performed the work above. Did this solve the problem? Which item do you think fixed it. Any help would be greatly appreciated. After reading this stuff and I'm not a tranny expert, it is starting to sound like to me the Torque converter. I have a 91 Nissan V6 and under a load in 1st gear, it shutters pretty bad, but i deal with it. I also had a 90 Mazda van V6 and I think it takes the same tranny the Nissan did. Same thing. At 179K I had the Mazda tranny rebuilt and they rebuilt the torque converter. Well long story short, they had to go back in and replace the converter.

As for feeling some rumbling leveling out on the hiway, don't discount your engine doing some of the mischief. That TPS can make the throttle twitch and make the tranny act a little crazy. I noticed that in my '00 Camry. Feels like it sort of jumps in and out of converter lock. I now don't think it's the tranny doing it, but the engine giving it some weird feedback. Just my 2cents.

My 97 Does The Same at 50+ Mph ,Tranny Shop Said It was Lockup Torque Conv ,Replace or just deal with??(it feels like bumps in the road)

See if the following has any relevance to your situation:

CHUGGLE-SURGE ON TCC APPLY - NO DTC'S - 5.7L 4L60E (http://168.144.127.175/Suburban/TSB%2077-71-53.pdf)

See if the following has any relevance to your situation:

CHUGGLE-SURGE ON TCC APPLY - NO DTC'S - 5.7L 4L60E (http://168.144.127.175/Suburban/TSB%2077-71-53.pdf)

Very interesting. Thanks for the info. This sounds like what my van is doing, but my van is a 99. Every bit of information helps. It does it when I am on the highway doing 65 mph. It does it at the same places in the road every day on my commute. This forum has been a great help. I will pass on any helpful information I find.

you can try putting a higher friction fluid in there instead of the Dex/Merc 3 fluid. use a atf +4 or mercon V fluid. its the same stuff, wont damage your transmission, but itll add a bit more friction to the fluid so the clutches dont slip as easily. i know on F series trucks the TCC likes to slip when the trans fluid gets some mileage on it and a flush with mercon V takes care of the problem easily. its worth a shot and cheaper and easier than putting in a torque converter.

ECM - I checked out the bulletin and that appears to be for pre 97's... I asssume (I know - don't snicker :) ) that that should have been applied to mine - as it is a 1999.

In the tests we ran, there was no indication of a engine issue, although I recall what one post noted that wires. etc can create this issue.

I will follow up when I replace the Tourqe converter......

you can try putting a higher friction fluid in there instead of the Dex/Merc 3 fluid. use a atf +4 or mercon V fluid. its the same stuff, wont damage your transmission, but itll add a bit more friction to the fluid so the clutches dont slip as easily. i know on F series trucks the TCC likes to slip when the trans fluid gets some mileage on it and a flush with mercon V takes care of the problem easily. its worth a shot and cheaper and easier than putting in a torque converter.

I am going to try this. A common denominator has been transmission fluid changes. One person did say they used an additive that worked. (I don't like additives much) The additive probably thickened the fluid. Am I correct in thinking that these transmissions shift electronically, which means the lockup torque converter can not be unplugged for testing purposes?

you can unplug the solenoid but its kind of a pain. we used one type of additive at the shop but i dont know what it was. said it had parafins in it, which is a wax, and i dont know if i would use it in my vehicle. but as far as the fluids go its a pretty good idea and it might buy you some time ;)

OK - latest update. I have been lazy - I had another car to drive - so the Sub has just been sitting. I did buy the Torque COnverter , front tranny seal and rear engine seal . Today a friend was to come over and do teh Converter for me - but he got tied up.

Since I am ina hold pattern, I heard Aamco gave free External Diagnosis w/a computer. I went and they checked the tranny - said all is fine with the tranny. hmmm. I would assume that if a customer is there and says he has problems, I am sure they would not want to turn away business - so I feel good to hear the diagnosis. He offered to say that it could be an engine issue.

So I stopped by Chevrolet for a check - they want me to come back Monday so a technician can drive with me while watching with a computer. Thyat will cost $80. will keep all posted.

I returned the parts I was going to install on the tranny. As mentioned - Amoco felt it was an engine related issue. Chevrolet said the same (most likely). The Chevy transmission guy went for a 20 minute ride with me. He drove and indeed felt it. His assessment was to replace the plugs/wires, etc. first. BTW - he did that at no charge ! Way cool.

I did the wires and plugs. Previously I installed Delco wires ($100+-) and new plugs and cap about a year or so ago. I repurchased new ones but went with Borg Warner Cap, Wires and AC Plugs. When I took the cap off - I was stunned to see each contact post heavily corroded and was igniting a bit off center to each post. The wires fit a bit looser at the cap than the AC wires, but they were only like $50+-). BTW - they were exchanged as the Delco had lifetime warranty.

The car idles much better. The 'tranny' stumble I had been eager to get rid of is ...'mostly' gone. Sometimes I wonder if my mind is playing games on me - sometimes I feel a slight stumble - othertimes - I am thinking - its all gone. The more I drive it the better I feel the situation is resolved properly.

Either way - the wire/plugs and cap were indeed the best first solution (rather than the solenoids). I have been driving the car now for a few weeks and I hardly think about the issue anymore.

If someone tries this and it does not work and they want to replace the solenoids like I did - if you are on a budget - give me a shout - for a decent minimal offer - I will send the solenoids - as they had no affect on my issues and I do believe they are still good).

Remember Amoco did a free test - Chevrolet was really cool too. Both used test equipment - and even for $70 test fee - at Chevy - that would have been worth it. Chevy noted that the transmission appeared to be shifting at all appropirate points correctly. Thanks to all for the help - hope this closing comments assists someone else. - Good luck