Recaro T/A

Recently rebuilt 200C on a 1982 T/A with Crossfire motor.

Question: At constant speeds around 35 mph with light pedal pressure, the converter lock-up feature oscillates (comes on with noticeable rpm drop and then off, with rpm increase). There was no lock-up before I had the transmission rebuilt because at some point in the past, the wire to the unit was cut. (I've owned the car since May and have been restoring it.) My sense is that the lock-up feature should not be that sensitive (ie, constantly switch on-off in this speed range). Would appreciate any thoughts on whether this is normal or, if not, how to correct.

Thanks!

8Mike9

Not sure if TV pressure affects it or not, but...would be prudent to adjust the TV cable asap to ensure

Da Spudro

Had that issue with my 92Z. It kept kicking the TCC on around 35 and with a little throttle would kick it off. I believe this is the normal function at least according to my trans shop locally. It annoyed the snot out of me, so I reprogrammed my computer and set the TCC to lock up at 55 when in over drive, and to never lock up if in drive. It was a massive improvement and made drivability much more pleasant.

Something of note though is my TCC has been kicking off and on again between 60-75 mph randomly. No ryhme or reason, a friend told me there is some kind of solenoid that may be bad. I don't really know anything about automatics so i'm taking his word on it. I mention it only because if my TCC locking up at 35 wasn't normal (i adjusted the TV cable numerous times and had the line pressure adjusted a few times) then whatever ails my car might be ailing yours as well

jmd

iTrader: (4)

Most ECM controlled lockup is functional based on:
the ECM seeing a value from the temp sensor of at least "engine is warmed up"
the ECM seeing the TPS as "stable within a certain range"
the ECM not seeing a TPS signal that would indicate WOT
the ECM seeing a certain speed value or greater.

Ideally and when new, there shouldn't be a "hunting" between locked up and not. And each of those isn't necessarily going to set a check engine code.

So if you were to drive the car with a scanner, you could see if those items are doing what they should. Or perhaps, the TPS is a jumpy value, or the VSS value is wavering, or the temp signal to the ECM is jumping around.

Recaro T/A

Thanks all - very helpful. My inexperience with the electronics on these cars will probably show through with the following questions, but here goes:

What type of scanner should I use and where should it be plugged into the car to access TPS values, VSS value, and the temp signal to the ECM? Is it the port where the check engine light codes are accessed or would it be at the ECM?

Also, Da Spudro, how can I go about reprogramming the computer to change lock-up to a higher speed? Like you, I find the oscillating lock-up at lower speeds less than desirable.

Thanks again!

jmd

iTrader: (4)

While you can use a sharp-end volt meter test lead to pierce wiring at the TPS and monitor the values it puts out, reading the ECM with a scanner will be better from a diagnostic standpoint. But...

OBD-II has been 100% implemented for over 15 years and is a standard (versus each manufacturer using a different data stream, under-dash connector, etc. Plus, the OBD-I capable scanners can be hit-or miss in compatibility. A friend bought one; it would scan an early 90s S10 but not an 87 LG4. So buying a used one on eBay and hoping it works with your early 80s car could be a really big crapshoot.

I don't think Autozone lets you borrow one; just scan for codes. So post in the TBI forum on here to see if anyone has had luck with a certain scanner. Check with anyone local you know who might have wrenched in the 80s and has their tools still.

There's very very little support of changing the chip / tune for the cross-fire cars, so I wouldn't count on it being worth your while to change the speed. Besides that, upping the speed costs you mileage unnecessarily. Beyond that, the car didn't do it new, so fixing the problem instead of masking it in the preferred way to go.

Da Spudro

I can't say definitively about if it is supposed to do this or if it did or didn't do it when new. Never owned one new and truethfuly I hate automatics. I had never owned one prior to my vert and had no intention to buy another, but I have done business with this shop for over 15 years and they've never given me a reason to doubt them. They claim mine functioned normal before I reprogrammed it. The guy I had reprogram it is an electronics and circuits expert and has been able to fix problems no one else could come close on. He tells me there's no harm in adjusting the tcc programming, and I'll believe him (he's an avid hot rodder and has a few drag cars under his belt).

That being said if originality is what your looking for I would agree with checking everything mentioned above just to make sure. However everything you need to reprogram your computer can be found on moates.net. the knowledge is a bit more tricky. My buddy has a few things that made this painless:
First was an older computer with a memcal reader. He first took a backup of my existing bin file on my chip. Looked up the chip program and info on one of his corvette sites for the tpi vettes. He then uploaded this file to his laptop and connected his laptop to what he called an ostrich. This was basically a black box that connected to the laptop and had a chip type plug on the other side which would be plugged into the computer. He had some kind of software that allowed him to read the bin file and alter settings on the laptop. He then sent this to the ostrich which acted like my chip in the car. We drove around and did some varying style of driving to tune out the car. He would make the changes real time on the laptop and reupload them to the ostrich. Instantaneously the car behaved with the changes. This is how we tested the tcc lock up and even made a custom chip for my daughter when she gets old enough that resets the speed limiter to 55mph. Once he had the tune set we went back to his shop, and he took the changes to the bin file checked for obvious errors and then uploaded it to the computer with the memcal reader. He then took one of the new chips I bought off moates.net and flashed the chip. Insert into the moates.net adapter and put into the computer, its ran great ever since. No regrets.

Now the caveat I should mention is that if this does long term damage to my trans I'm not worried about it on my car. I bought my car because finding a clean lowish mile vert is getting harder and harder to do. I didn't want the automatic but was afraid I wouldn't find a cleaner car for the same price. So I took the auto with the expectation of converting to a 6 speed later. If mine burns out as is implied above, no worries for me just time to get the swap done. Do what you feel is safe and in your interests. I don't mean to insult any of the guys one here with real knowledge by saying their wrong, but likewise i am not going to dismiss what I've told by guys I have done business with for a long time or am friends with who have had their own experiences.