Transmission Surging

[Calabrio]

I just installed a new (rebuilt) transmission and torque converter into the '93 Mark VIII. All is not right though and I can't quite determine what the problem is. To further complicate this, it's difficult to explain the symptoms.

1993 Lincoln Mark VIII. When I'm driving at low RPMs under load, I can hear and sometimes feel, the RPMs surging up and down. Sort of rythmically lunging. The problem will stop if I accelerate, and if I touch the brake the surging will stop and the RPMs and tone will steady at the higher RPM (until I change my speed).

When I say low RPMs under load, I mean if I'm driving at a steady speed under the lightest acceleration. So, if I'm doing 45 mph, with just a little bit of gas, the car might go into this surging tone. Of even if I'm holding 70mphs and just lightly apply gas it might happen as well.

It's not linked to any specific speed. And it's not remedied by turning the overdrive off.

My hunch is that it has something to do with the torque converter not locking up properly. Might this be a defective torque converter clutch solenoid?

Engine, prior to installation, was trouble free and not generating any codes. During the installation, the pinhole in the EGR tube became more pronounced, and upon test drive resulted in a CHECK ENGINE LIGHT.

Transmission is full of Mobile One Synthetic, Mercon V compatible.
Brand new Motorcraft IAC valve was installed as well.

 

[torquemonkey]

From what you had described, it sounds like I had the same issue. Just for giggles, where on the dipstick is the tranny fluid? I had mine overfilled by a shop and after some highway driving, I would feel the same kind of rythmic surge. After a few miles down the road the O.D. light repeatedly flashed on and off. I pulled over and found the fluid way high on the dipstick. I took out almost a pint and a half to get it at the "Hot" mark. After that it was fine. No more surgeing.
While the tranny was cold the level looked correct, it was only after it was good and hot did it show high on the dipstick. It happend to me once before when I topped off the tranny (overfilled it), I filled it to the "hot" marker on a "warm tranny", I drove it around for @5 min. Appearently not enough time to get it up to temp as later on in the day, the O.D. light started flashing.
So, yours might be just a little (to) high, IMHO.

 

[Calabrio]

Unfortunately, this is a different situation. I'm not experiencing any flashing O.D. light and my fluid level is good. It's a brand new installation so all the levels are good.

Surges under light load, it feels like the torque converter is locking and unlocking. The symptoms persists regardless whether the car is locked in 2nd, in D, or if the O.D. is on or off.

Just a little while ago, the car slipped into neutral while I was driving.

If it's anything, I'm hoping that it's just the MLPS. That's easy enough to swap. But I'm still not totally confident that is the problem. The transmission is new, the torque converter is new. However, the MLPS was from the original transmission.

 

[98LSC32V]

Try taking out your chip to see if it's messing with your torque converter lockup schedule. If that doesn't work then it's either your MLPS, TCC solenoid or you have a vacuum leak somewhere.

 

[Calabrio]

Where are the vacum lines that affect the transmission located? I haven't found any leaking lines so far.

I'll pull the superchip and see if that helps.

 

[Calabrio]

Pulled the Superchip. So far, I haven't noticed any real difference.

I can't find any vacuum leaks, but is there anywhere in particular I should be looking?

 

[Calabrio]

If I had pin holes in my air intake (after the filter before the engine) due to bad body work when modifying it and cutting out the air silencer, might that be the problem?

Unfortunately, I don't know if the problem existed prior to the modification.

 

[Brozly]

If there after the MAF sensor, I would think they could be a factor...

 

[Calabrio]

I'll test for leaks in the morning. It's unlikely, but possible.
I'll go the soapy water route.

 

[Calabrio]

I think I found the problem....

It's looks like I have a leak in the t-splitter on the back of the engine, I think it's part of the PCV system. Anyone know what the part number of that splitter is, otherwise I'll be down at the parts department at the dealer trying to match it up on Monday.

 

[Calabrio]

Replaced the EGR tube.
Replace the t-split rubber piece on the PCV system.

After all, this problem doesn't feel like it's a transmission problem. After a little thought, it now seems like an ignition problem. It feels like a miss?

To repeat the symptoms:

1993 Lincoln Mark VIII. When I'm driving at low RPMs under load, I can hear and sometimes feel, the RPMs surging up and down. Sort of rythmically lunging. The problem will stop if I accelerate, and if I touch the brake the surging will stop and the RPMs and tone will steady at the higher RPM due to it's downshifting (until I accelerate into the next gear).

When I say low RPMs under load, I mean if I'm driving at a steady speed under the lightest acceleration. So, if I'm doing 45 mph, with just a little bit of gas, the car might go into this surging tone. Of even if I'm holding 70mphs and just lightly apply gas it might happen as well.

It's not linked to any specific speed. And it's not remedied by turning the overdrive off.

What do you think?
Replace the ignition coils?
A fuel injection problem?

Any ideas or tests you can think of.

 

[segxr7]

Do a tune-up first. The turbo on my old Thunderbird would cook the plug wires about every 10k miles.. I always knew when it was time to change them because it'd lose power and feel like I was running over rumble strips at low RPM under load. Sounds pretty similar to what you're experiencing.