Penglii's 1989 TGP

[GOT2B GM]

IIRC its just the 3 screws and then its just clips...but let someone else confirm that, its been a few yrs since I've had my TGP dashpad off.

[Penglii]

IIRC its just the 3 screws and then its just clips...but let someone else confirm that, its been a few yrs since I've had my TGP dashpad off.

Well that is even what the factory service manual says... so I bet I'm just being too careful... but since the illustrations are so vague about dash pad removal there is a good chance I got the wrong screw. But there is an equally good chance that the dashpad has never been removed, causing the clips to be stubborn.

[Addicted To Boost]

It is just the two screws above your gauge cluster and the hex screw above the little access hole in your glove box. Once all three of those are out, pull up on the part of the dashpad closest to you, then pull the dashpad toward you and it will pop out.

[Garrett Powered]

remove the glove box. its easy enough. and then grab a flashlight and look. its hard to see unless you really get under there.

[Penglii]

It is just the two screws above your gauge cluster and the hex screw above the little access hole in your glove box. Once all three of those are out, pull up on the part of the dashpad closest to you, then pull the dashpad toward you and it will pop out.

Thanks! I'm amazed though that they don't make that accessable via the access hole... amazed but not remotely surprised.

remove the glove box. its easy enough. and then grab a flashlight and look. its hard to see unless you really get under there.

Yeah I was wondering if it would come to that
It does seem very easy... but thanks to the heat+humidity I've been left with a mere 5 minute window of opportunity to work on my car these past few days. I like to imagine that if I had more time at my disposal that I'd have figured it out on the first try. But that is what the internet is for...

[Penglii]

Changed the oxygen sensor and the IAC and did an idle relearn with the Tech1.
Confirmed in the process that the tach is off (high) by like 400 rpm, but actual idle is a good speed. And more consistant now.

No more progress on taking apart the dash, hopefully tomorrow.

[Penglii]

Update: Found the third screw... holy crap is it in an annoying place. Wised up and used a telescoping mirror, made me feel like a dentist or something. It took a T10 Torx driver.

Although the new HUD does not seem to work at all... maybe its not plugged in all the way.
I'll find out before I go to work tomorrow.

Idle is a lot better with the new O2 Senor and IAC. Oil pressure gauge still sucks. It has occasional fits of not being pegged so maybe it has only mostly failed.
I really need a rebuilt xover... Hopefully I will be ordering one in early June.

UPDATE: Re-connected the plug and now the HUD works like a charm! It's quite nice to have an accurate speed reference again. My speedo is 7 MPH high at 45 MPH.

[Penglii]

Got the new X-over installed this past weekend... major PITA but worth every single bit of effort. Major improvement.

So now on to the next order of business:
After the new crossover and an idle relearn, things are just almost perfect.
The idle is still rough sometimes though, but this might be an easy fix.

The rough idle goes hand in hand with the oil pressure gauge spazzing.
I assume the pressure sender unit is bad, because the gauge is pegged most of the time... but sometimes during idle it will start working and drop down to a reading right around 35. This seems to trigger a voltage drop, which drops the revs and roughens up the idle.
Sometimes the oil pressure needle stays 'working' the whole time I'm in idle, and other times it pegs itself again. As soon as it pegs the revs go back up and the idle smooths back out.
Getting back on (or even tapping) the throttle will also re-peg the oil pressure needle.

This can all probably be fixed by replacing the busted Oil Pressure Sender and replacing the crappy Bosch 02 sensor with a better one... but it would be way cool if someone could explain why the oil sensor sometimes tries to work and why it screws with the idle in the process.

[Twenty]

Sounds like you're making good progress.
Glad to see another TGP being fixed.

[Penglii]

So I noticed that there was no check valve on the vac line to the trans modulator.
I got a new check valve now but I'm not entirely sure how it goes on.
I'd think the most obvious way would be the two small diameter ends connect to the vac line... with the larger, cone shaped end left open. Is that correct?
Or does the large end connect to the TB end of the vac line... and one of the small ends connect to the trans modulator.
I'm having difficulties imagining which way the pressure waves would all want to go...

Any ideas?

[mfewtrail]

That's correct.

Here's an image for future reference(it's hosted in the "how do I" section on the other board by the way - you can also find an engine vaccum line routing diagram there as well)

[Penglii]

Sweetness, thanks! I searched for that pic but I did not find it.
Maybe now the clunk in reverse will be less.

[Penglii]

With the trans modulator check valve in place it is really no surprise that all the upshifts and downshifts are significantly smoother.

Shifting into reverse is still excessively bone-jarringly firm... but it does seem slightly better than before.

[mfewtrail]

With the trans modulator check valve in place it is really no surprise that all the upshifts and downshifts are significantly smoother.

Shifting into reverse is still excessively bone-jarringly firm... but it does seem slightly better than before.

Check your trans mount and all other mounts on the car. If they're getting worn, the trans will have firm shift into reverse or drive usually. This is especially true if you park on an inclined driveway. If your driveway is on an incline, set the parking brake before moving the gear selector to park. This will take the load off the trans/parking pawl making shifts from park to reverse or foward much easier.

EDIT: If your parking brake is inoperative, see this: http://web.archive.org/web/200710232...om/index2.html

[Penglii]

Go figure... the same day that I order a new turbo oil return line is the same day that the existing one goes south.
So the upside is that the amount of smoke I am blowing is not large... no bigtime mosquito fogging or anything.
If I had known, I would have considered expedited shipping. LOL