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1994 Fleetwood 60" Stretch; '07 Avalanche, '95 Nighthawk
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Discussion Starter #1
I think my TCC solenoid is failing, but I want to get opinions on it before I rule out other possibilities.

First, there are no codes set - history or current.

I was driving along on Saturday at about 45 MPH, with steady throttle I began climbing a hill and the car began 'jerking'. It felt like it was switching between 3rd and 4th gear, but after some experimentation I'm pretty sure it's the torque converter locking and unlocking. It only happens above 35 MPH and only in 4th gear. If I drop it to 3rd the 'jerking' stops. If I let off the throttle (thus letting the converter lock) it stops. If I give it some more gas (thus unlocking the converter) it stops, too.

I read the TSB and it seems to address a situation where the TCC soleniod has stuck shut, thus locking the converter as soon as the fluid path permits (4th gear?) causing harsh up and down shifts. Mine is acting like it's failing, not stuck.

Could this behavior be anything else? I'm thinking not, but you never know.

If it is the soleniod I'm going to limp it along until spring. It's getting too cold to take the engine/trans out of it.

Jim
 

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Sounds more like you have a secondary ignition problem to me.
Sometimes you get what's called a "fishbite" sensation in 4th gear when going uphill.
You likely have "carbon track" on the sides of a couple of spark plugs.
This is the formation of a string of carbon growing down the side of your spark plug from misfire events. At a certain time in this process under heavy load it becomes easier for the spark to jump out of the side of the plug and run down to the metal base of the plug than it is for it to jump the gap in the cylinder due to the high pressures.
If this is the case you might be able to duplicate the miss by "brake torquing" the motor. Meaning hold the brake really hard and give it the gas.
Usually on TCC problems you'll see a code set long before you feel anything.
When this condition starts, hold it to make it happen worse, if you are lucky it will set a misfire code to tell you what cylinder to start looking at.
However you probalby just need to replace the spark plugs and plug wires anyway. A word of caution, if you replace just the plug you will have the same problem a couple months from now as the carbon grows on the boot too, and just causes a new carbon track to grow on the new plug.

HTH
 

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1994 Fleetwood 60" Stretch; '07 Avalanche, '95 Nighthawk
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Discussion Starter #3
ewill3rd said:
Sounds more like you have a secondary ignition problem to me.
Sometimes you get what's called a "fishbite" sensation in 4th gear when going uphill.
You likely have "carbon track" on the sides of a couple of spark plugs.
This is the formation of a string of carbon growing down the side of your spark plug from misfire events. At a certain time in this process under heavy load it becomes easier for the spark to jump out of the side of the plug and run down to the metal base of the plug than it is for it to jump the gap in the cylinder due to the high pressures.
If this is the case you might be able to duplicate the miss by "brake torquing" the motor. Meaning hold the brake really hard and give it the gas.
Usually on TCC problems you'll see a code set long before you feel anything.
When this condition starts, hold it to make it happen worse, if you are lucky it will set a misfire code to tell you what cylinder to start looking at.
However you probalby just need to replace the spark plugs and plug wires anyway. A word of caution, if you replace just the plug you will have the same problem a couple months from now as the carbon grows on the boot too, and just causes a new carbon track to grow on the new plug.
HTH
I hope you're right! The plugs are about a year old and the coil pack on the left bank is new (there are no wires - it's an '01, I should've mentioned that). The plugs were auto parts store variety Bosch and not from the dealer. I can definitely hold it and make it worse - I'll see if I can get it to throw a code.

Thanks!

Jim
 

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White Diamond '03 DHS (with DTS floor shift)
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Your symptoms sound much like mine on a '97 Deville after the fuel rail recall. I also thought the worst. After much diagnosing and discussion here, I did exactly what ewill3rd said and set a P0300 code after inducing a misfire and holding the RPM at about 2000 RPM. A new set of wires cured the problem, though that obviously can't help you, but the carbon tracking sure sounds logical.
 

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I am allergic to bosch plugs. In my experience GM cars just don't run right with them. I have fixed everything from no starts to check engine lights just by putting Delco plugs back into a GM car and tossing the Bosch's out the window.
I know they make good product but for some reason they just won't burn right in a GM engine. You might have had carbon track on one when you put the boschs in and not noticed it.
If you did the work yourself you might just take the plugs out and inspect them one at a time... of course it's easier if you can narrow it down to one cylinder.
 

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1994 Fleetwood 60" Stretch; '07 Avalanche, '95 Nighthawk
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Discussion Starter #6
It sure feels like the TC locking and unlocking. But I don't have a lot of experience with these Cadillacs. I really hope you guys are right. The research here does point to a PO741 or PO742 code before any physical problems. I have the physical problem but no codes so maybe it is a misfire. It has a random miss at idle, too, but nothing severe enough that the PCM has detected it.

Thanks!

Jim
 

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1994 Fleetwood 60" Stretch; '07 Avalanche, '95 Nighthawk
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Discussion Starter #7
ewill3rd said:
If you did the work yourself you might just take the plugs out and inspect them one at a time... of course it's easier if you can narrow it down to one cylinder.
I did the work myself. I replaced the plugs because they were carbon fouled and the car was running really rough. Plus the car had been underwater so I figured new plugs couldn't hurt. The plugs I took out weren't Delcos either. Might've been NGKs. Anyway, the car still ran rough (had a P0300 code too) and it turned out to be the coil pack on the left side. Once I replaced that it ran great and has been fine for about a year.

I'll let you know if I can get it to throw a code. On my way out to lunch now.

Jim
 

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1989 Fleetwood FWD / 2000 ETC / 2000 STS / 2006 STS V-8 1SF RWD
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Hello...

Generally, does a TCC lock up based on speed or gear?
What happens if you drive in "3" ?
Would this prevent the TCC from locking up?

It is my experience that:
-the solenoid must function to signal the TCC to lock-up;
-an inoperative TCC is independent of the solenoid
(the solenoid can send the signal to lock-up but a faulty TCC will not lock up.)

I've had a TCC problem in my 1989 Fleetwood for years-
...no harm- it just runs @200 RPMs faster/2% lower MPGs.

I know you'll trace the problem.
Post back when you do.
 

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1994 Fleetwood 60" Stretch; '07 Avalanche, '95 Nighthawk
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3,963 Posts
Discussion Starter #9
ElDawgg 2G said:
Hello...
Generally, does a TCC lock up based on speed or gear?
What happens if you drive in "3" ?
Would this prevent the TCC from locking up?
It is my experience that:
-the solenoid must function to signal the TCC to lock-up;
-an inoperative TCC is independent of the solenoid
(the solenoid can send the signal to lock-up but a faulty TCC will not lock up.)
I've had a TCC problem in my 1989 Fleetwood for years-
...no harm- it just runs @200 RPMs faster/2% lower MPGs.
I know you'll trace the problem.
Post back when you do.
On my GN, the fluid path to the TC is only available from 2nd gear on but the ECM will only call for lockup in 3rd or 4th (unlike the Caddy this can be changed with a chip change). Also in the GN the ECM will only call for TC lockup if you're moving faster than 35 MPH, below a certain TPS value and if you're off the brakes. I assume that similar algorithms apply to the Caddy, but I'm going to check out the manual tonight.

The Caddy has been doing this since Saturday, and it did it again on the way to work this morning. But of course when I wanted to try to get it to throw a code (lunch time today and on the way home from work) it behaved just fine. No problems whatsoever.

Next time it does it I'll try to get it to throw a code.

Thanks all for the replies.

Jim
 
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