Hey guys, I need some advise and help. I've been tracking down a vacuum leak and think I might have found it. Here's what it's doing.

The car runs great, but the throttle response wasn't good and while driving the car, when I go to stop, it idles around 1,100 rpm. If I goose it before I stop, it'll idle around 700 rpm. It's a 383 stroker TPI with 10:2.1 compression. I've lubed the throttle body shaft, made sure the blades were closing all the way, which they are, and sprayed WD-40 on all of the vacuum lines, hoping to find a leak, and nothing. The spring is fine on the throttle body also.

A friend recommended disconnecting the EGR valve and see what happens. I disconnected the black wire from the EGR valve (not solenoid) and the vacuum line, and the throttle response was awesome all of a sudden, but it still has the high idle problem.

My question is, should I replace the EGR valve? Or, since I don't have it hooked up to a vacuum source anymore, and disconnected the electrical wire, without having the check engine light coming on after 50 miles of highway driving, take the EGR valve off, clean it and make sure the valve closes, then put it back on?

Or, could it be something else?

Thanks in advance.

 

Sounds like the choke isn't pulling off all the way and it's hanging JUST SLIGHTLY on the fast idle cam that kicks in when the choke is on. This is REAL common with QJet carbs that use an electrically heated choke.

Not uncommon for the car to get more responsive at part throttle with the EGR disonnected on older motors. It won't make any difference at WOT, though. This is one of the reasons people used to rip off the EGR valve back in the old days- made the motor feel more responsive.

Fix the high idle problem first and then deal with the EGR if you want.

 

Damon, I appreciate the reply, but I have a TPI and not a Quadrajet.

Anyway, I changed the EGR on Sunday, and still have the same problem. Idles high until you goose it to kick it down.

I've tried both ways, having it hooked up and disconnecting it, and still the same problem persists. Could the EGR soloniod be bad?

Could anyone shed some light on this situation for me?

 

Felo,

It still sounds like you have either a throttle body problem or vacuum leak (or both).

When the idle "hangs up", get out at a convenient place, open the hood, and try to manually return the throttle by hand without opening it - in other words, force it against its stop. If the idle returns to normal, you may have a worn TB, throttle shaft, binding linkage, etc. If not, you may have a vacuum leak from an unusual source, like the EGR, brake booster, PCV hanging up, etc.

Incidentally, the black wire from the EGR valve is the lead for the diagnostic temperature sensor on the base of the EGR valve. Disconnecting it will not affect the position of the valve at all.

An idle vacuum test could be helpful if you have a vacuum gauge. I noticed that none of your replacements or tests included replacing teh PCV valve. When you do, use ONLY an AC part, since aftermarket parts can be poorly calibrated, and have caused high idle and lean problems for me as well.

 

Thanks a million Vader, I'll try the PCV. I've overlooked it in the past because I didn't think it was that important.

I'll try messing with the throttle again, it's been awhile since I've done it. It's been an ongoing battle. I think last time I was having a problem, it was because I took it all apart and forgot to lube the shaft (no sick comments please). After I lubed it, the throttle didn't stick as bad, but still does. I just spayed the hell out of it last night with PB Blaster, and a couple of weeks ago with Heavy Duty Silicone. So I hope it's the PCV. Is there any way to test those?

 

Vader,
I changed the PCV and no change, but after changing it, I messed with the throttle linkage and noticed it was loose. So I tried to tighten it, and it broke. I didn't even lean on it, but it must have been weak enough to snap the throttle shaft.

Do you know if anyone has replacement throttle shafts?

Are they all universal, because I have an Accel 1,000 cfm?

Plus, how do they come apart? I tried taking it out last night and the collar, between the linkage and throttle body, wont come off. There's a nut between the tb and collar, but I can't loosen it with the collar on it.

Thanks

 

Ahh, the good-old hanging throttle shaft/plates. I have no idea where you can get a replacement shaft. Maybe Accel? Maybe they could warrant the TB and replace it for you?