92 Park Avenue tranny issues.

05-06-2006, 05:50 PM
Hi there. This is my first time posting to this forum. I've been researching it for a while now, but haven't found anything specific for the problem I'm having. So here goes...

I have a 92 Park Avenue with 215,000 miles on it. For the most part it runs and drives great. The problem I'm having though is that if I try to make the car downshift to pass someone the engine just lugs down and it won't downshift. If I feather the accelerator a bit it'll go ahead and downshift and act fine until I try to make it downshift again. However If I use the Cruise Control switch to speed up, it'll downshift without a problem.

I've recently (within the last week) replaced the modulator, and there's no change. I'm led to believe that it may be the throttle position sensor because when it's in park and I floor the pedal the motor revs up a little and then chokes. but if I only do 3/4 throttle it' won't choke. Would this cause my problem with downshifting?

Also another problem I have is that every now and then the transmission will slam into gear from Park to Drive. It's done it cold and warmed up. What would cause this?

Thanks in advance -- Ryan

05-06-2006, 05:57 PM
oh yeah, there also seems to be plenty of vacuum to the modulator.

05-06-2006, 07:46 PM
Not much you can do about the slamming to drive issue, unless your fluid need changing.

But you might want to check your fuel filter as well for the chugging. They're cheap and easy to replace, I always start with the cheap stuff first :) If you'd rather check the fuel filter as opposed to replace it, remove it and put your mouth on one end of it, ideally, the direction of flow of gas, and blow, not inhale, but blow. If it blows easily, IE no resistance, then its fine, if theres no/little air movement, time for replacement. As cheap as they are, the taste of gas isnt worth the trouble to me

05-06-2006, 08:15 PM
Fuel pump could be getting weak after 14 years, do a fuel pressure test under load.

05-06-2006, 09:12 PM
The PCM does depend on feedback voltage from the TPS in order to determine whether or not to engage the shift solenoid. Check the voltage on the TPS blue wire, at various throttle openings. It should range from .5 @ idle to 4.0+ volts @ WOT. If you are not getting the WOT voltage to the PCM, the PCM does not know that you are @ WOT and therefore will not tell the shift solenoid to engage. By the way, the TPS white wire should be a 5.0 volt reference and the black wire will be ground.

As far as the transmission slamming into gear when selecting drive, that would be due to an internal lip seal leak causing low line pressure to the clutch pack when you first shift to drive. You would have to rebuild the tranny to replace the seals. One thing you might try before shifting to drive would be putting the shifter into reverse or 1st gear, until you feel either gear engage, then shift to drive. By selecting either 1st of reverse, the trans goes to full line pressure on that clutch pack and also throughout the trans.

05-07-2006, 05:14 AM
Thanks for the help. I'll check those things out in the morning or Monday.

As for it slamming into gear; we have to back out of our driveway, so we've already had in reverse before putting it into drive. It only does it every now and then. When it does do it, it takes a few seconds before it'll engage, when it does it slams hard. The only other time i've had a transmission slam into gear like that was when the engine was revved too high while shifting. But in this case, engine is idling. It doesn't matter whether it's cold start, or after we've driven a while and it's warmed up. It's happened in either situation. As far a rebuild, how much do those run on the average?

PS. I've only had it slam into gear twice (once warmed up, once cold start) and that was last week after I replaced the modulator. My wife said that it's done it to her four or five times over the last two months. Hope that clears it up some more. Thanks again.

05-07-2006, 06:30 AM
A complete rebuild would range from $1200 to $2600 depending on the area you are located and the shops desired profit margin & overhead. Most shops will give you a cost estimate based on the low figure in the range and will add the famous line, "it really depends on what is wrong" phrase! You can rest assure that the final invoice will always reflect the top of the range they quoted!! Walk away from those guys and never look back! Any reputable and honest trans shop will give a firm price quote for a rebuild without any "it depends on" added.

You could also have something as simple as a shift valve or solenoid sticking in the valve body and most shops should be able to find that with a scan and pressure test. I would do that first, but do as you would do with your with your personal medical decisions, get a second and third opinion! The "slamming into gear" will play havoc with trans and motor mounts. You could already have a broken left front left trans mount. You need to check that also.

05-07-2006, 01:55 PM
Ok, thanks. I'll start calling around tomorrow. With 215000 miles I'll probably feel better with a complete rebuild anyway. Hopefully it'll last me for the 300 mile round trip I have to make on tuesday. Thanks again.

05-11-2006, 07:24 PM
Check the Vacuum with a Vac Gauge. The piston may not be releasing on the new modulator. It must be out when you put the car into gear. The reason it did not do it with the old one was the spring in the modulator was broke. I ran into the same problem while working on my tranny.

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