Bad Idle has me stumped

[Flyin Ryan]

Re: Bad Idle has me stumped

I don't remember that much at all really.. about anything but I do remember Ed Hess havinga simular problem. It wasn't til he went to rebuild his motor that he fould the cause. I believe it was the lower intake was loose or something like that. I would search for his post when you get time.

 

[Dr.Evil]

Re: Bad Idle has me stumped

Another weekend gone and its still not right. I did find my timing to be 8* advanced. I thought for sure that was it. Wrong!

I bought a heavy duty ground cable (will a battery cable work or does it have to be strap-like?) and will give that a try.

I have pressurized the system by blocking off the intake inlet and sent 15psi into the system via the brake booster line w/ my air compressor. I found one leak at the throttle body shaft. Not much I can do about that.

Also, it seems to have really bad boost control. I broke my controller and replaced it with a brand new OEM unit, and that didn't help. It will go stright up to 15, then drop down to 8-10, then creep back up to 15, then drop again. Maybe the two problems are related...?

Any other ideas?

I am about to sell some stuff and just rebuild the damn thing.

 

[Dr.Evil]

Re: Bad Idle has me stumped

Well I swapped on a new BBK throttle body (i know, I know.) and now the intake system is super tight, no leaks anywhere. I thought that would do it....wrong!

I picked up a used MSD 6A box, maybe that will help?

I will also try the ground strap tomorrow. If both of those fail, what next?

 

[bizkit]

Re: Bad Idle has me stumped

Yesterday and today I also noticed this problem on mine, and only when the engine is warm. When cold it idles beautifully. I have no new ideas other than what you have tried but I'm searching for an answer also.

 

[Dr.Evil]

Re: Bad Idle has me stumped

Yesterday and today I also noticed this problem on mine, and only when the engine is warm. When cold it idles beautifully. I have no new ideas other than what you have tried but I'm searching for an answer also.

PLEASE let me know when you find it! :tup:

 

[Flyin Ryan]

Re: Bad Idle has me stumped

After resolving the leakage issue in your tb, did you try possibly resetting the computer by pulling the ecm "b" fuse? I think it's "b" for a few then let it re-learn ?

 

[tyson__91]

Re: Bad Idle has me stumped

Mines kinda doing the same found the problem yet. MSD box help.

 

[Mad Mike]

Re: Bad Idle has me stumped

Swap the ECM with a known good one. Have you checked FP? Leak down test? Are the injectors you put in the correct ones?

 

[SY2455]

Re: Bad Idle has me stumped

Try putting on a stock coil, On my truck I can't use the MSD coil with the MSD 6A as it would burn holes in the dist cap and pitt the rotor real bad.

 

[RSpengler]

Re: Bad Idle has me stumped

Check and adjust your valve lash... After your engine warms up, it might shrink down the clearance and cause an unseated valve...
-Rob

 

[mrweelr]

Re: Bad Idle has me stumped

I'd replace the IAC, ECM, distributor, check compression, and look for vacuum leaks. My Sy purrs like a kitten now. Even with solid motor mounts, I can barely feel the motor running. Something is not right. Also check your voltage at the alternator, battery, ECM, fuse panel, etc.

 

[sy2675]

Re: Bad Idle has me stumped

Im not sure that this will be any help at all but here i go. My truck started having an idle/cold start issue and it kept getting worse. Truck was running real rich, replaced lots of parts, plugs, wires, cap rotor, o2 sens, thought inj was stuck had them cleaned, did vac leak test, everything seemed cool but the truck wouldnt idle and was a dog under 1500 rpms. The prob ended up being a small tear in the diaphram inside the FPR. The fuel pump was making plenty of pressure but under vac was sucking gas straight out of the top of the FPR into the intake( and everywhere the vac hoses went). Put an older FPR i had laying around on and the truck was back to new just like that. I found a post on here that mentioned the poss of this problem after hours of reading and wrenching. With the truck off, pressurize the fuel system by addeing a pos source the lead at the back of the intake/firewall. Do this with the vac line off of the FRP. If fuel comes out, you have a problem. Some are rebuildable. I am going to look for the kit to rebuild mine now. Anyone have any ideas where to look. Its a billet FPR but no name brand on it anywhere. Hopefully this reply helps someone, or at least narrows downn your search.

 

[Crimson93Ty]

Re: Bad Idle has me stumped

This'll take some time but it's free. Take out the cat conv. and see if the problem resolves. If it does, the converter may be partially clogged or flow restricted. The method of checking that is in the Helms won't always work.
When done, run a datamaster file of it and put it up. You can use a datamaster to save a lot of money.

 

[bezerk]

Re: Bad Idle has me stumped

have you tried disconnecting the o2 sensor, so it goes into open loop?

 

[wantingasy]

Re: Bad Idle has me stumped

Did you ever solve this problem? I'm thinking the alternator is going bad as mine is doing the same thing. I have a tune up kit on the way, so hopefully that helps.

 

[syclonekid43]

Re: Bad Idle has me stumped

mine runs the same. there times where i put it in gear or turn the a/c on and the truck stalls. i just did a tune up on mine,high flow cat,new fuel pump,AFPR and inj. last year. nothing changed

 

[wantingasy]

Re: Bad Idle has me stumped

I'm going to buy a volt meter because I know there is something going on with my electrical system. I'll lock my doors or push the window lever/switch down when the window is already down and it will like make my truck bog down bad. I can just watch the volts drop on my apexi turbo timer. I'm almost 100% its the alternator, but can't be sure until I get a volt meter...