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Funky idle issues?

aychdee

aychdee

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'91 tbi K5 350 stock, 700/241
Went wheelin' yesterday and about 3 hours into it, it started idling rough and no power what so ever, hit the gas and it souded like I had the rev limiter set to 900rpm. Check engine light was on (haven't scanned it yet) Shut it off and restarted it and it idled and ran fine no CEL, then about a 1/2 hour later same thing but without the CEL:crazy:. Tank is inside the truck and when it starts to idle rough I don't hear the pump change pitch at all ( blew 2 fuel pumps because of crap in the tank so I listen very carefully to that now)
Put it on the trailer and when i got home (2 hours later) started it up and ran fine.
Any ideas on where to start looking. Not sure if any codes will be there when I scan it.
Tanks for the help in advance
 
If the cel came on, the code(s) will be set in the ECM memory and remain as long as the ECM has not been reset.
Check the codes and post them up it wil be easier to help diagnose your problem.
 
Will do, didn't know if it was something obvious that jumped right out at ya that I was overlooking
 
Alright, jumped A and B and it flashed a 43 code and a 44 code. Low voltage at EST and O2 lean (o2 lean I believe can be caused by an EST problem, correct?)
 
Code 43 is usually knock sensor related. Low voltage or loss of knock sensor siginal to the ECM from the ESC will cause the ECM to retard timing as much as 20 degrees. Wich may be part of the poor performance.
I dont know if the 44 is related to the timing being retarded. I think not. Check the fuel system (fuel filter) if running lean. EGR may be open when it should be closed.
Vaccum leak.
 
Did you ever get this fixed? I'm having similar problems but not intermittant. It was running great one day then all of a sudden it wouldn't idle for beans and would backfire out the throttlebody when you hit the gas. I looked at it and the driver's side injector wasn't spraying, it would stop/drip/spray/etc....

Swapped a whole new injector pod and injectors on there and they both spray now but am having the idle issue. It seems like something is causing the timing to be off or something. If you hold partial throttle(1/8,1/4,etc.) it acts similar to a rev limiter?!

I went to check the codes like I have before but with AB jumped the SEL will flash one initial time then go out?!

I've visually checked the wiring underhood and pulled the battery connections off for a while thinking it would fix it from before when the injector was jacked up. I also checked the knock sensor underneath.


Any help would be appreciated. I really wanna get wheelin':(
 
Well now it won't even idle at all for some reason. It will start and die right away unless I try to feather it to keep it running. I pulled the line off right after the fuel filter and it spewed fuel with the key on so no trouble there. Has to be something electrical I would guess. The damn thing wont gimme any codes though. I am gonna have my brother in law tow it down here to my house so I can work on it. Kinda a pain to try and get up there an hour and a half away to look at it on the weekends.:mad:
 
BlackBourbon,

Did you get your idle problem fixed? I am having a similar problem with my '93 350tbi. It runs better when it's warm out then it does when it's cold out. Once I get it started it idles like crap whether the engine is cold or warm. It seems to depend on the weather outside.

Thanks,
Rick
 
rick88blaze said:
BlackBourbon,

Did you get your idle problem fixed? I am having a similar problem with my '93 350tbi. It runs better when it's warm out then it does when it's cold out. Once I get it started it idles like crap whether the engine is cold or warm. It seems to depend on the weather outside.

Thanks,
Rick
Click to expand...


yeah, mine turned out to be a faulty ECM. swapped a new one in there and it's been running great for about a month or so now. more info in my thread.
 
I figured mine out too. But mine was too much fuel. I swapped in a fuel pump for a '90 Iroc and the regulator wasn't letting enough fuel back to the tank and it was loading up. I haven't swapped the pump out yet but I cut the spring in the regulator to allow it to open up more. I am planning on swapping a stock fuel pump back in over Thanksgiving weekend and replacing the spring in my regulator then too.

I upgraded the pump after doing a rv cam swap last spring. I realized the reason it ran fine for the first few months was because my fuel filter was clogged. After I changed the filter is when I started having problems at idle.

Rick
 
Ok, changing my fuel pump helped. But my main problem was the new IAC I installed back in September. The damn plunger came loose and was closing off almost all the air coming in at idle. Mines running like a champ now.

Rick
 
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