Old Post: http://www.bonnevilleclub.com/forum/...ic.php?t=55684

This is my topic from around 6 months ago, on what might by a 6k shift (doubtful but maybe), my high overdrive RPM'*, and my high idle. I just reread the whole post, and these are the idea'* we came up with:
1. Tach is off 400+
or
2. TC is slipping big time

I am hoping to get a scan tool for my birthday in a few days, and should be able to check the actual shift and trans slippage. Is there anything else I need to check with or without a scan tool. I am interested to see if my trans is really slipping. I cant get over 22 MPG when I baby the car in mostly highway driving (60-70). (could my o2 seneor cause the bad MPG?) Hopefully the scantool will give me some answers. Again though, is there anything else I should check?

-Andrew

400+ rpms, while possible is a lot. I've verified my tach to be off about 150rpm.

As for knowing what is happening before getting the scan tool, my suggestion would be to get a free estimate from a trans shop and ensure you act like you are aiming to probably have it rebuilt.

well, i went and got a scan tool today. Then came some expensive news. I never get a TCC lock up. It goes into OD, but it never engages. What are the causes of this? Is there anything externally of the trans that can do this?

Update and Question: When setting in Park, the computer is calling for an idle that ranges inbetween 685 and 765 RPM. The tach reads around 1,000 to 1,100. Could something be keeping the RPM'* up, or is the tach really off?

It is possible for the tach to be off by that much. FWIW, my GP STE idles at ~650 when fully warmed up, my tach shows just about dead on 1000rpms at this point. On cold idle my tach reads 1600 or so and the car is idling at no more than 1200. At my 5800rpm shifts my tach reads 6800ish, the higher the rpms go the more it is off.

Anyways, with a scantool you can verify if your tach is off, read the rpm reading off the scantool and compare it to your tach and that will tell you how far off it is.

i couldnt find that on my scan tool. it only had what the PCM was calling for.

really, what scan tool were you using? It should also have an actual rpm reading.

Aren't you using the CP9110? Engine RPM'* are on it.

CP9145...only one available around here