helped my friend replace his intake gaskets on his 86. car starts right up, no leaks, is idling at 1400rpm. i pull tan wire to set timing to 6 deg
gos down to normal 700rpm. I do IAC procedure and it idles at 1200rpm with tan wire connected, still 700 disconnected. am i correct in thinking i dont have a vacuum leak somewhere due to the fact it idles fine tan wire off? not sure if its adding too much timing somehow when wire is connected effecting idle? we also replaced the egr, could that be a problem? again kind of confused because car idles great with tan wire off

chris

 

What happens to the idle when the engine warms up?

When the engine is cold the IAC function will work independent of idle advance.

 

1400 seems high.Let it warm up and go into closed loop and see what the idle is. My 84 goes into closed loop @170 temp degrees.Mine idles @900 cold 600 warm.

 

idle never changes when it warms up, took out iac to clean it, seems
frozen, I should be able to spin the pintle by hand shouldnt I?

 

Sounds like a vacuum leak. You should turn the engine off when unhooking the wire to put it in timing mode. If anything double check all the hoses & grounds, also unhook the battery for a while.

 

I agree. I'd do a smoke test to be certain it's not a leak. Replacing the intake gaskets requires touching every vacuum line and they get very brittle. It's easy to get a crack in them and not know it. I recently did an intake swap and replaced every vacuum line.

 

im figuring not a vacuum leak because idle is perfect without tan wire connected 700rpm, at base timing of 6deg. connect wire, computer adds timing and gos to 1200rpm. of course not sure. trying a new IAC tomorrow,

 

What was the idle before the intake job?

 

Is that the procedure listed in the FSM? I hate that procedure because it will ASSUME everything is within spec. If everything is within spec and no issues, it will work. OTOH, if anything is out of spec or the chip has been altered, all bets are off. Kinda why I never use that procedure.

You say you timed it. Did you check that the timing is right AND the harmonic balancer is not walking on you? If it walks, NFW you will get the timing right. I would run a white paint strip to make sure it doesn't move.

How did you get the idle speed? The tach is not really good. Mine was 300 over at least. I have no idea why but the F-body tach was always on. I have an inductive timing light that tells RPM and after getting the tach and speedo calibrated, it now matches the timing light.

As others have mentioned, do you have a leak somewhere? Even if all your hoses are right, the booster might leak. You can try plugging all the vacuum lines one by one but that is tedious and doesn't tell if there are leaks in the intake.

You say you cleaned the IAC. Did you just spray brake cleaner on the IAC? I wouldn't try pulling or pushing it. Best you can do is spray brake cleaner on the pintle and gently wipe it off. Still that doesn't really cover a cleaning. A through cleaning would have you take the TB off, take the cover plate off, take the IAC housing off and spraying all the passages with brake cleaner. Reassembly is with fresh gaskets. The gaskets are paper ones so toss them after use just like condoms.

I would borrow a scanner that can give you data and NOT a code reader. Those are glorified paper clips. From there you can see what the command idle is. So in my car, whatever you do that is within the ECM adjustment range, it will try to achieve 900 RPM because that is what the program wants. With the scanner, I will get the engine to final operating temp and closed loop, shut everything but the motor off and see what the IAC counts are. Ideally you want about 30 counts give or take. So, if it is higher, it means the ECM calls for more air so you turn the adjustment screw in to open up the butterflies. If it is less, the reverse. This is very important. IF you get 0 counts and turn the screw out till it cannot close it anymore, you have an air leak. With the scanner, you can see what the ECM sees for an coolant temp and intake air temp. With an infra red thermometer, hit the coolant temp sensor and see if it is roughly the same as the ECM data. If not the CTS needs to go. See if the intake air temp is roughly the same as ambient. Should be.

 

as a quick update new IAC fixed problem, in theory it was a vacuum
leak because that what the IAC does, a controlled vacuum leak. anyway car run perfect now.