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I think a set of plugs would be a good place to start, they are probably fouled. At least it may get it to idle right and then you can work your way from there. Since it starts right back up it is probably something minor.

 

I had similar idle issues which I traced back to a bad IAC, bad TPS and finally a bad module in my brand new distributor. Try swapping the module out with another just to be sure and check your base timing with the ESC unplugged. I installed one I found on the floor of a garage and have had no more idle issues.
Take your IAC out and clean it up if you haven't already and check your grounds. I swapped the main battery to engine ground from a wimpy little 6ga to a 4/0 cable (I build marine electrical systems, always have a ton of heavy cable left over) and that solved a ton of issues as well.

 

ok ill try those things out thanks


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ill try this weekend thanks



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will do thanks



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good info here, I appreciate it, thanks.



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The IAC is your best bet with a rough idle, or it was mine at least. I just cleaned it after getting tired of below-500 idling and frequent stalling, and now its at 650 and idles smoothly. Checking and cleaning the MAF is also a good idea, if you're able.

 

how did you clean it ?


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1st Put in new plugs
2nd do a fuel psi check again
3rd OHM your injs if they are stock gray/silver rodchester units.
4th check for strong or weak spark.
Sounds like you may have more than 1 problem going on which happens sometimes.

A factory service manual is a good friend to have.

 

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I forgot about EGR. sometimes it can stick open and cause problems.

 

Basically you can go about it one of two ways. I chose the full cleaning route, taking the throttle body off and cleaning it out, unscrewing the IAC valve (the black unscrew-able thing jutting out from the left side of the throttle body, with a wire attached to it) and cleaning it with throttle body cleaner and a rag, and cleaning the area it screws in to with the same. I'm almost certain you can't compress or move the little spring and pin thing, those move electronically or something, so just try to clean the carbon junk off as thoroughly as possible, maybe blowing some air into the little spring area to get gunk out. If you can't or don't want to remove the throttle body, you can unplug the IAC, unscrew it with a crescent wrench or something like it, and just clean it off that way. Put it back in, plug it in, and see if you can feel any difference. Also, when I first tried starting my car (after cleaning the IAC), it took two tries but now runs fine and starts perfectly every time, so don't freak out like I did haha. Hope this helps!

 

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My rough idle issues were caused by the vac hoses going to the charcoal canister from the tb and from the charcoal to the little plastic valve that connects to the fuel tank vent. $2 fix if that's it. Just change them to get that out of the way.

 

Backfire is a dead giveaway, change your ignition module inside the distributor.
Bad module will cause all sorts of wacky issues like plug fouling, bad idle, harsh acceleration and backfire.

 

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ok ill try that out, thanks


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Pull the module out & take it to a parts store, most of them can check it to see if it is bad. Ask to watch, I took a known good module in to a local store and asked if they would check it for me. They came back saying it was completely dead. If they won't let you watch them then I wouldn't take their word. If you know someone in a parts store then you shouldn't have any worries. It sounds as if yours really is acting up so having it checked is a good idea.

 

I have heard that before but not on my car so I did not have to track it down. But it should not be the vent that goes to the canister as it does not have a dip tube. I THINK the return line is not a dip tube but it may be.

Just talking through the issue...
To get a bubbling sound you will have to get a vaper going into the tank that dips below the fuel level. None of the fuel system is under pressure of the cylinders so the only way you can get vapor going into the tank, I would think, is from a fuel line getting too hot (like too close to the exhaust manifold) and causing it to vaporize and build up pressure. Since you have a FPR holding pressure on one line (and may not dip), and a check valve on the feed line, I might suspect the check valve on the feed side might be leaking back. Measure your line temps near the exhaust while watching fuel pressure. Again, this is just a starting point as I have never dealt with this.

 

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sounds to me like you are chasing more than one problem. Really hard to separate out problems from the descriptions you are giving. Can you post a video? Can you start over with what is happening in one post, with history, mileage on engine, any maintenance done recently and especially just before this started.

Compression test? Could the timing chain have jumped?

Double check your plug wires. Especially 6 and 8 to make sure they did not get mixed up since they are hard to see due to A/C. Did you change cap and rotor and did you use a good brand? Did you time the dist correctly? Do you have a good ground to your engine, all grounds looking good? Is the engine and wire harness factory untouched or modded and cut up? Are all emissions equipment still hooked up?

Does rough at idle mean a hard vibrating type rough or is it swinging rpms up and down

 

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From my post #11, have you done #3 yet??

 

On this post did you check connections, wire voltages, etc? Other than replacing knock sensor. Check prom to see if it is seated? Change prom? Need to get that code 43 to go away and it seems that it will if everything here is done and checked.

http://www.chevythunder.com/esc_map_code_43.htm

 

You've definitely got a lot of gremlins. In regards to plug wire length start with the longest at the front and work your way back, best advice I can give. Check your firing order and double check your base timing and a timing chain inspection would be a good idea too. And don't ignore the electrical suggestions, when you hit 20+ years plastic connectors and thin molex pins are usually done in no matter the outward appearance of the car.

 

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