G/box: 850 Auto: Late shift - Vacuum Leak?

[Oly.850]

Gents,

I changed out my starter on Saturday to a rebuilt Bosch unit and disturbed my vacuum tree, flame trap, throttle position sensor, intake boot, and various vacuum lines at / near the idle air sensor in the process. Thought I had it all together correctly, but obviously not as the car is now idling around 1150 RPM instead of ~850 and the most annoying thing is it's shifting late in all gears and rarely shifts into 4th gear (D) at all which is killing my gas mileage I'm sure.

Question is: Are the two things really realted? Vacuum leak = late shift?

Your comments are of course welcome.

Thomas

[charlotte001]

Only thing I can think of is you have either knocked one of the vacuum pipes that go to the bottom of the airbox or you have connected a pipe that should go to the tree on the manifold and youv'e connected it to the airbox [little box with a plug]

[Oly.850]

Thanks. It sure acts like it has a vacuum leak, occasionally throwing P0133 codes, and hunting while idling, but I just can't find it. Dug all through the stuff around the idle air controller tonight and didn't find anything yet.

Any suggestions would be great, AND if somone can explain the mechanism for an auto trans to shift at a higher than usual RPM because of a vacuum leak, it would be fantastic.

[Oly.850]

I had a long look at it last night, can't find a vacuum leak to save me, but I'll look again this weekend. The car WILL shift into 4th gear if I drive it very carefully and accellerate very slowly from 40mph, or pop the throttle and immediately release it. Odd. Irritating on the freeway.

My thoughts:

Poorly adjusted throttle cable?
Poorly adjusted throttle body link?
Bad throttle position sensor?
Disconnected transmission speed sensor?
Huge vacuum leak?

Seems like the sensor possibilites would be throwing a code, which they're not. Seems to behave better when it's warm.

Any thoughts would be a help. I thought I was smart, but my opinion of my mechanical prowess has dimmed somewhat in the last 48 hours.

[charlotte001]

to replace the starter i assume you had to remove the inlet manifold ? did you get a new gasket if thats the case ? If so check to see if you completely removed all the old gasket when I did the PCV the first time I found i'd left a tiny bit of old gasket on that caused a very similar problem

[Oly.850]

Acutually I didn't, the removal steps I saw online and in the Haynes manual called for removing the intake manifold and the cooling fan, but I did neither and just removed the following:

Throttle position sensor
Vacuum tree
Throttle cable and roller
Idle Air controller
Intake boot
Flame Trap / PVC

After that, just unbolted the starter and it came right out of the right side of the engine compartment towards the battery. I know I've hosed something up, so I just need to go back through it and find the leak. I'm wondering about the throttle cable though, on a 20v, does the cable go on the inner track or the outer track, seems like it could fit both.

Thanks for all the comments!

[liuleichan]

Originally Posted by Oly.850

TAND if somone can explain the mechanism for an auto trans to shift at a higher than usual RPM because of a vacuum leak, it would be fantastic.

Things involved in transmission shift points:-

throttle position
engine revs
engine load
mode selector
road speed (I think...)

to a certain degree:-

ATF temperature

maybe coolant temperature is an input?

[Oly.850]

Gents,

Found the vacuum leak on the vertical rubber hose coming up off the idle air controller towards the black plastic vacuum tree on the intake manifold. My brother and I took the throttle / idle air controller cover off and sprayed some starting fluid about with the engine running (yes, it's really safe, right?) and found the air leak almost immediately. The hose had been installed without a clamp (probably by me a couple of years ago) and it had hardened enough to allow air to slip by. Fixed the shifting and idle problems immediately. Drives like a dream. Thanks for all of the suggestions and help!