My car won't idle smooth unless my headlights are on. I set warm idle at 800rpms. I can't set idle without the IACV plugged in, so i skipped that step in the Helms manual. I pulled off the intake, and the 7oclock hole was still sucking in air. I screwed in the white screw this past summer, and it hasn't backed out. Is it the FITV or something else?

 

It affects quite much. After years the spring inside the FITV becomes "lazy" and the whole valve is not acting properly. There are some tricks to make it work, but I decided to replace it.

 

the FITV only allows more air flow when the engine is cold. If its warm and you still have surging idle, then you have a different issue.

 

That's the thing, i don't have any of the classic symptoms i.e. bouncing, surging idle. My car drives great when the headlights are on, according to my test tach, it sets at 790-800 which is dead on. but if the headlights are off, it takes a long while before the car will idle. even then, it's not smooth. I can't set the idle without the IAC plugged in so I can't set base idle. The FITV should be shut and not allowing air once the car is warmed up, so if air is sucking in the hole, then it's bad and has to be replaced correct. I've backed the screw in all the way, so if it still has vacuum then I'm **** out of luck. Correct?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">the FITV only allows more air flow when the engine is cold. If its warm and you still have surging idle, then you have a different issue.</TD></TR></TABLE>

that is not entirely true, although unlikely the white wax screw can back out so much that it will create a vacum leak at all engine temps. i have seen this happen. I have also seen this happen after turning the screw in and it back out several months later, so dont rule that out.

the iac valve is adding enough fuel at that engine load but not at normal load. see if this also occurs with your rear defogger on also. This is normally a sign of a bad iac valve. another way you can check thes components is to remove them from the manifold. tape off the ports with duck tape and see how the car idles. if it idles better with the iac valve off than wiht it on then rep[lace the iac valve. the car shoud idle perfect with it off as long as it is not at really high elvation or abnormal humidity. but keep the iac valve hooked up even when you take it off to keep it communicating with the ecm.

also if it is a usdm motor tape off the fast start valve also.

good luck

 

I'll check the the white screw to see if it backed out. The IACV crapped out on me this summer so I've already replaced it. I've checked voltage on the IACV, and according to Helms, it's good. The car won't idle without the IACV, so I assume it's good. According to Helms, the IACV bumps up idle when the defroster, Headlights, wipers, Power steering are on as well as a couple of other things. That goes back to what I was saying earlier, if I increase electrical load, the car idles great but under no load conditions, it idles like crap unless I have driven for a long trip i.e. 30 mins +. According to the all the research or rather searching onthis board, I have replaced everything except the FITV. The main relay was bad when I was doing the swap because the fuel pump wouldn't get power. Then the IACV went bad this past summer. I don't have a Starting Air Valve. I replaced all the hoses when I did the swap, doubled check the vacuum routing cause it was all f---ked up after the swap. I'll take/welcome/appreciate all suggestions, I'll do, test, and replaced any and everything but this idle is driving me nuts. I hate stalling randomly at stops, not the coolest thing in the world.

 

what year motor? what year car? What do you mean by crappy idle. describe more. and is it stock?

 

I had something very similar but it actully turned out to be bent valves. Try a compression test.

 

92 lude with h22a swap. According to my test tach, the idle holds steady at 800 rpms when the car is under load i.e. headlights are on. if the headlights are off, idle stumbles at 400-500 rpms then jumps quickly to 1000 then stalls out. but if headlights are on, smooth as can be. another thing, if i drive for a long time i.e. 30+mins, i don't have idle issues at all.

p.s. i don't think it's anything seriously mechanical because the car drives great.