Help with tps adjustment

[FoxBuddy]

Follow the idle set procedure:

With the engine at full op temp (which means driven for 10+ miles), disconnect the IAC.
Use the throttle stop screw to set idle speed to 750.
Recommend the iAC, wait for it to settle to normal idle speed - 900-1000 RPM.
Stop engine.
Set TPS to less than 0.900 at closed throttle, and check to be sure it goes greater than 4.50 VDC at wide open position.
Put tools away.

Open beer.

Alright another question for something that appears simple or I am overlooking.

Do you disconnect/reconnect the IAC while the engine is running?

Last night I disconnected it with the engine off (after warming it up good) and set the idle with the timing light tach at around 750. I reconnected it while the car was running and it surged up to ~2500-2800. I waited a number of minutes but it only seemed to settle down to around 1200.

I tried it again by reconnecting the IAC with the engine off but the idle still never dropped as low as you mentioned above.

Thanks for any further insight.

(I never made it as far as getting to the TPS adjustment)

[MikeFleming]

Do you disconnect/reconnect the IAC while the engine is running?

Shouldn't mater as it won't hurt th EEC or the IAC solenoid. When you connect with it on, the EEC is still commanding to raise idle speed by the max possible amount - since it been unable to do that while it was disconnected. It can take a few minutes.

If you switch off the engine, reconnect iAC, then start again, the EEC determines desired idle speed from the ECT sensor at startup time - there is absolutely no memory of the previous run cycle IAC speed setting. It doesn't use the high idle if the engine is warm except for the initial few seconds of no-pedal startup.

Last night I disconnected it with the engine off (after warming it up good) and set the idle with the timing light tach at around 750. I reconnected it while the car was running and it surged up to ~2500-2800.

Expected. See above.

(I never made it as far as getting to the TPS adjustment)

Yes, you must finish the whole procedure - you stopped before you were done.

As your punishment, you are banned (until your next post). Let that be a lesson to you!

[FoxBuddy]

I never updated this with the end of the story.

Finished. Once I figured out what to do, where to do it and how, it was easy. The screws for the TPS aren't the easiest to get at though!



One thing I noted is that the Alan Slocum book has slightly different numbers for the TPS closed throttle setting than what has been suggested here. Is there anything to that? The car seems to be running great regardless; thanks for the help!

[MikeFleming]

The screws for the TPS aren't the easiest to get at though!

I use a #1 Phillips that's about 5" overall long - fits perfectly.

One thing I noted is that the Alan Slocum book has slightly different numbers for the TPS closed throttle setting than what has been suggested here. Is there anything to that?

Most of Alan's book is dedicated/based on the EECs in the Merkur. The values I use are for the PE EEC, which is SVO-specific.