Monte downshifts at highway cruising speed

[Psych0matt]

A little backstory: When I bought the car about a year and a half ago it had a similar issue, I would get up to speed (65-70) and it would drop in to overdrive for a bit, and then kick back down to third and stay the rest of the trip. Around september last year I replaced the FPR, and that solved a lot of issues, including this. Around the end of december I noticed some raw fuel smell when it gets warmed up and then idles (stoplights, parking lots, whatever). It's been going on ever since, but I've always maintained around 22mpg and have had no other issues, aside from it sometimes not starting right away if I don't let the fuel pump prime, basically meaning I have a pressure leak somewhere, I figure in an injector o ring probably. Today it starts doing the downshift thing again, get up to speed, it drops into overdrive and sits around 2500rpm for a few minutes, and then a downshift where I sit around 3500rpms. So, do I assume my fpr is on the way out again, or would something else cause this issue? No SES lights or anything...

[RobertISaar]

not necessarily FPR related, seems like a valvebody issue, which seems to effect the 94-95 3.4 cars..... a lot. if i had to guess, i would say the PCM is detecting too much slip after a while and then disables 4th gear and TCC operation. if you shut the car off at speed and turn it back on after a few seconds and it works in 4th gear w/TCC for a while before repeating, that is almost certainly what is happening. what causes the TCC slippage appears to almost always be a valvebody issue.

[l67ss]

Didnt know the pcm in car was fancy enough to sense tranny slippage till i blew a front seal a couple weeks ago, fixed the seal and scanned it, sure enough it showed a dtc for tranny slippage.

not necessarily FPR related, seems like a valvebody issue, which seems to effect the 94-95 3.4 cars..... a lot. if i had to guess, i would say the PCM is detecting too much slip after a while and then disables 4th gear and TCC operation. if you shut the car off at speed and turn it back on after a few seconds and it works in 4th gear w/TCC for a while before repeating, that is almost certainly what is happening. what causes the TCC slippage appears to almost always be a valvebody issue.

[Psych0matt]

So basically live with it? I guess if thats the case it just seems weird that it was doing it 100% of the time, fixed something, did it 0% of the time for over a year, and now it's doing it again.

 

I wonder if I could disable that (with a chip of course)

[RobertISaar]

Didnt know the pcm in car was fancy enough to sense tranny slippage till i blew a front seal a couple weeks ago, fixed the seal and scanned it, sure enough it showed a dtc for tranny slippage.

 

if the model in question uses a TCC PWM solenoid, the ECM watched for it. depending on the model, they came in as early as 1991 for the 4T60E.

 

So basically live with it? I guess if thats the case it just seems weird that it was doing it 100% of the time, fixed something, did it 0% of the time for over a year, and now it's doing it again.

 

I wonder if I could disable that (with a chip of course)

 

it could be disabled, but then you run the risk of if it does start slipping much more than normally allowed, the TCC material will wear out fast, so you'll end up with no TCC and a whole bunch of material stuck in the filter.

 

if it bothered you enough, driving in 3rd gear shouldn't cause this issue and still allow for TCC operation.