DupermanDave

I adjusted my TPS as per the 4crawler instructions. I had the typical idle surge. Everything has been fine up until today. Today, the idle surge came back every few minutes. It never did it every time I hit the brakes, but about half of the time.

So my question is, can a TPS go out of adjustment?

Also, my idle has risen from 800 RPMS to about 1100 RPMS, so I tightened the idle air screw all the way and the idle went to 800 and the idle surge stopped. What's the cause of this?

abecedarian

If the TPS is adjusted properly, it won't drift out of adjustment unless it's bad.
I'm sure you have... but you've checked idle air valve / auxillary air valve under the throttle body?.... don't limit it to just the valve... if there are water passages to the valve, make sure they are clean and clear of gunk so that coolant can flow around the valve.

DupermanDave

I haven't, but I may check that on Tuesday. Thanks for the advice.

Does the entire coolant system need drained for this? Or just from the valve?

DupermanDave

Ugh!!! I was researching info on how to remove the IAC. Do I need to remove the throttle body to get it off? I'd like to avoid doing this, as all the work will be done in a parking garage (very cold and dark.)

-edit-
been searching more. if injector wires are crossed...say cylinder 1 and 2's connectors were switched...will that cause a bad idle and power loss on acceleration? Wouldnt it be impossible to time the engine if the injector wires were switched around?

DupermanDave

*bump* is it easy enough to take off the IAC without removing the intake manifold? I want to get started on it tomorrow and hopefully finish tomorrow. Weather is supposed to be nice, so this may be the only chance I get for a while.

Can I just drain the coolant and spray some carb cleaner in both inlets/outlets for coolant?

DupermanDave

Ok, so today I just took apart the throttle body and cleaned the IAC valve. It was very clean, but cleaned it with carb cleaner anyway. No change in my idle

I have the idle adjust screw all the way in and now and it idles at 1100 RPMS. what's the deal? What can I check next? It's still surging at idle.

DupermanDave

come on guys, I'm getting frustrated. I just tried to adjust the tps to no avail. I couldnt even get the lower screw loose, even with the right angle screwdriver. I can't push on the head enough to get a good grip and get it loose. I just took off the intake manifold yesterday and do not want to do it again. The only reason I'm having to adjust the TPS now again is because i have a high idle and surging. Everything was fine until I took the intake manifold off. Any tips for getting it loose?

i'm about to get something without any sensors at all and swap it in. I don't care if it's a go kart engine. I'm sick of sensors failing.

Junkers88

Dave I had a similar issue on the 86 22re. The idle would surge when I hit the brakes and it would sometimes spike. I couldn't time it or get it to adjust, and STAY adjusted.

After all the TPS/AFM/blah blah blah it turned out that the intake gasket between the head and the down tubes from the intake plenum was busted around the number 4 intake hole. I found this out when I ran Seafoam through the motor and noticed liquid leaking out. You might be able to start the motor and spray carb cleaner or something around the intake surfaces and see if that's the issue.

In my case I was pissed since it turned out that a 3.15$ gasket caused weeks of headache and I didn't find it until after replacing everything else I could think of.

Hope it helps.

DupermanDave

hrrm. When I removed the throttle body from the intake manifold, I did notice my gasket broke by the bolt hole. It didn't break near the intake holes. I believe it was like this when I put the gasket on 6 months ago. It is a possibility. I went outside with a propane torch I borrowed and sprayed around that area and all other vacuum lines. Couldnt get the idle to drop. I used water and sprayed the area too. Nothing. Used some wd-40 around that gasket and the vacuum lines. Still nothing.

I also noticed that if I press and pump the brake pedal, the idle surges upward. I got a video of it. (in HD )

[YOUTUBE]http://www.youtube.com/watch?v=mSfdxBMiXGM[/YOUTUBE]

Junkers88

Before I actually found the leak I sprayed water/WD40/Carb cleaner etc around all the vac lines and anywhere I could get to that had a gasket. No change in idle or anything. Dude it was strange. Believe me when I tell you that the damn busted gasket was killing me. 10mpg, CEL codes for O2/TPS/AFM/ crazy idle, timing off and impossible to set.......... I almost sold it.

If nothing else go down and grab a gasket set and put it in. Since you said on of the gaskets is already a little messed up it might not be a bad idea to redo them.

Understand that I don't want you to do extra work just because I hinted at it. I'm just trying to get this fixed for you so you'll stop cluttering up the forum.

DupermanDave

I'm going to use some high temperature RTV gasket maker to fix it. I'll be doing it this sunday. I really don't want to have the throttle body off and not replace the TPS, but I guess I'll have to. I can always readjust the TPS while it's off. I dread draining the coolant again :-( that was an awful mess last time. You think I can replace the gasket with RTV without removing any coolant lines?

What causes the idle to surge as the brake pedal is pumped?

Junkers88

Dude get a gasket set, don't use RTV. Besides the fact that RTV is a mess to work with what you need to realize is that the factory gaskets last for hundreds of thousands of miles.

In listening to your video I either hear you pumping the brakes like a mad man or I hear a miss in the motor. If it's a miss then it stems from the brakes using vaccum to actuate. If it is indeed a vac caused miss then you have an open source somewhere. You've already checked all the vac lines yes? How is the big line going to the brake booster? How about the inline valve in that brake booster line? For that matter how is the booster.

Vac leaks are one of the hardest things to trace on these rigs due to the large number of lines available.

When you push the brake pedal is there indeed a miss? As far as I know if you push the brake pedal and vaccum (spelling?) drops, and it's a small leak, the motor will ramp up to compensate. Especially if it's a post afm/tps-pre-combustion chamber leak. What happens is the leak introduces un-metered air into the system (the afm doesn't know where it comes from, the tps doesn't know either but the O2 sensor knows it's there and increases the fuel mixture via the ecu to compensate) thus more fuel..... ergo higher idle.

Damn I wish you lived near me I'd have you drop that thing off and give you my truck for the weekend and let me chase this issue for you.

DupermanDave

That sound is me pumping the brakes like mad. My foot and leg were tired from experimenting with the pedal. By experimenting, I mean I removed the vacuum line going to the brake booster. I inspected the line and booster. The line is good, no cracks in it and no leaks. The clamps are nice and tight.

I was kind of anxious to use RTV. I used it on a water bypass gasket for the first time on sunday and it worked nicely. I may pick up a backup from the dealer, though, just in case I lose my nerve while doing the repair on sunday (if the weather is nice)

-edit-

looks like my time frame to get everything purchased will be tight. I get paid tomorrow, money won't be in the bank until saturday (if even by then.) I'll have to get the gasket at an autozone. Dealer won't be open on sunday and I work all day saturday. Only autozone will be open. Are the gaskets from autozone any good? I know they cary felpro gaskets, but don't know how comparable they are to dealer's.

Junkers88

The gasket set I got from NAPA was a Felpro set, had everything I needed and so far the truck hasn't had any issues, 15,000+ miles so far.


If your time frame is that tight then wait. Man there is no sense in rushing anything. Do some more looking. I don't want you to tear into the motor just on what I've written, I want you to be sure.

If nothing else grab a can of Seafoam and run it thruough the motor as per the instructions. It might reveal a leak like it did for me. It will also clean everything out for you so any build ups will be gone.

Good luck little brother.

DupermanDave

I'd still feel safer removing the gasket from the list of possibilities. I tore up my back really bad removing it on tuesday. So I might hold off. But I have confidence that I can remove everything fast and easily next time. I just dread the coolant. Iiiick.

I still think I want to give the RTV a try. The previous owner had used it for most of the gaskets and it seemed fine. It did look like a mess when pulling it all off, but it was easy to peel off and clean.