AFM question

[mikeoc1]

I am trying to track down a 1300rpm idle issue. TPS is good, ICS is good. My AFM is showing 1950'ish on the ohms at about
62 degrees (f). That is under the 2000 to 3000 for 68 degrees (f) the TSRM states. But, the TSRM doesnt list the AFM as a cause for a high idle in the troublshooting. So I am about to pull and check the cold start injector. Is the AFM out of spec enough to need replaced? Can the AFM cause a high idle. No codes.

edit: cold start switch and injector checked out ok.

 

[AJ'S 88NA]

Checked timing?

Also check for pirate air.

 

[jetjock]

Pirate fuel would a better bet along with checking for an open throttle plate or excessive bypass air. Timing is a good call though.

 

[mikeoc1]

Throttle plate is fully closed and thoroughly clean. It has the bosch bypass valve upgrade so I will check it out closely tommorow. I have a stock one I can put on if needed. I read in some other threads about air in the coolant system can cause the water temp sensor or cold start switch to keep it idling high. Seems unlikely that it would stay ideling high after full engine warm up.

 

[3p141592654]

Bypass valve will not affect idle speed.

Pinch or otherwise block the ISC air hose and it should stall. If it doesn't, suspect pirate air or a leaky throttle plate.

 

[jetjock]

I meant throttle bypass air. Since the CBV is upstream of the throttle plate it can't be a factor. If the throttle plate is fully closed the only metered air paths are through the ISCV, an opened TB bypass screw (if you have one), and the PCV system.

Assuming the ISCV is working the coolant sensor can be eliminated as a possibility by simply unplugging it.

Your test of the AFM was invalid.

Edit: Beaten by 3p. I wish the pirate air = high idle on L Type EFI myth would die though...

 

[mikeoc1]

blocked off the ISC hose and it did not stall. Timing rechecked and is good. Although the lever on TB is againts the screw, If I put alot of pressure on the throttle the plate closes a little more and it will idle down to normal. Is there an adjustment on the TB? What is the bypass screw and how do I know if i have one?

 

[jake8790]

There is an adjustment screw on the throttle body that faces the front of the car. It's inside the aluminum on the top right of the first throttle body. My car idled at 1100 and that was the problem.

 

[jetjock]

...Throttle plate is fully closed and thoroughly clean. ..

...Although the lever on TB is against the screw, If I put alot of pressure on the throttle the plate closes a little more and it will idle down to normal...

 

[mikeoc1]

My TB doesnt have that peice like the one in the photo, thanks for showing. I thought my throttle plate was closed in earlier post because I checked that the lever was fully seated againts the stop screw, it was, fully seated. I was wrong assuming that meant the plate was fully closed.

 

[jetjock]

Yeah, just because the screw is on the stop doesn't mean the plate is fully closed.

To set everything up right:

1) Disconnect the throttle linkage (pop the rod off the ball end at the TB).

2) Back the stop screw off until there's space between it and the stop. Verify the throtte plate is *fully* closed. Retighten the screw until it just touches then 1/2 turn more.

2) Set the TPS per the TSRM

3) Set the dashpot per the TSRM.

4) Reconnect the throttle linkage. If the screw comes off the stop adjust/fix the linkage.