Throttle body/Maxbore question

Kristi with a K · Sep 12, 2022

Dirty Pool said: ↑

I'm a little lost with the "checking by voltage" thing.
As far as the harness vs ECM. The harness should be conveying anything it sees at the ECM. You should be using the same ground point you used at the ECM when checking at the harness end. Delicate microprocessor systems sometimes have an "in house" ground point so signals referenced to ground have a uniform comparison point. Never the less at some point closer to the battery all grounds are connected together or "bonded" as they say.

I would be setting the throttle stop by eye/feel then verify the idle TPS is in range and hope for the best but it sounds like it already is. IIRC the TPS signal can be read with a reader/scanner, ignition on/engine off and should change as you open and close the throttle by manipulating the bell crank at the TB.

I would also be looking at why the idle is 1K, should be around 750 in neutral/AC off. Might try giving this a shot. Assuming no vacuum leaks, engine running and warmed up, back off the stop screw exactly one turn (so it can easily be returned to it's current spot) and see if the idle speed drops. If it does there may be too much air getting by the plate and the IAC can't deal with it. If that's the case it will be a balancing act to get idle speed and TPS in range.
Click to expand...

& I have been at the idle thing for over a year. I figured out some stuff. Fuel pressure sensor, a leaking injector, intake manifold pitting wasn't happy with the gaskets I used, exhaust manifold crossover gaskets, maxbore, hmmmm...., there may be more. Everything I've done has then sent me elsewhere still with the high idle. I found a suspicious hose, the larger vacuum for the TPS. I thought aha! Changed it & the idle actually went up a little....

YotaBro · Sep 28, 2023

Kristi with a K[OP] said: ↑

& I have been at the idle thing for over a year. I figured out some stuff. Fuel pressure sensor, a leaking injector, intake manifold pitting wasn't happy with the gaskets I used, exhaust manifold crossover gaskets, maxbore, hmmmm...., there may be more. Everything I've done has then sent me elsewhere still with the high idle. I found a suspicious hose, the larger vacuum for the TPS. I thought aha! Changed it & the idle actually went up a little....
Click to expand...

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Throttle body/Maxbore question

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Throttle body/Maxbore question

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