*SOLVED* - Blacktop 20V High Idle

[70XIN]

Excellent. Thanks Ant, that gives me quite a few things to check on tomorrow. Will report back here once i (hopefully) have some good news

[70XIN]

Okay. So i have checked and replaced all the vacuum lines, checked for vacuum leaks everywhere, and now have a new O2 sensor.

I have adjusted the mixture screws almost all the way in, the revs are down to 1600 (i will get the throttles balanced when this problem is fixed). Also, the vacuum based "throttle opener" is not touching or affecting the throttles at idle, so we can rule that out.

Are the throttles themselves supposed to suck in any air at idle? If i cover one of the throttles with my hand, the idle drops by a few hundred revs, and it sucks hard enough to almost hurt my hand.

Any thoughts? Anybody have any suggestions?

[Anthony]

the throttle should come to rest against that dashpot (the vacuum based throttle opener). If theyre not, there might be an obstruction in the linkage somewhere.

[slide86]

sounds like the throttles are definitely staying cracked open causing your problem.

it there enough slack in the cable? ie its not seized and not actually allowing the throttles to return to full close?

[biggo]

Ilde/closed throttle is where engines make the most vaccume.

I actually gave up trying to get my old BT to idle lower, i think in the end i disconncted the thingo under the dashpot and restricted the little breather thingo in #1 in the pic



usually idled at about 1200rpm

[70XIN]

Okay lovers,

I have adjusted the throttles to the factory manual specs, checked the water and intake temp sensors, checked the TPS resistances, all is good. Car now idles at 1400rpm

With the ISCV unplugged, the car idles PERFECTLY at 850rpm. Does this mean it's rooted? Or just that the ECU is telling the ISCV to idle high (possibly due to faulty sensor/s and or wiring)?

I'm going to buy one of those diagnostic tools so i can check all the error codes

[biggo]

Why not leave the iscv unpluged?

[70XIN]

Car has a shit attack and goes into limp mode or something

[Anthony]

Id say the ecu is knocking the idle effort up due to unconnected load inputs. See above ^^^ Find your AC1 wire. ground it, watch the idle drop...

You wont get any codes out of a scanner other than the same light blinking ones btw. These motors are one generation too early for that.

[70XIN]

*Solved!!* - Thermostat must've been stuck. Replaced it, idles beautifully at 800/900 rpm Cheers for all the help guys!