Any help would be appreciated. I have fought rough idle and occasional engine cutting out for some time. Problem seems to come and go. Computer has been scanned, only code ever coming out is O2 sensor, which I had replaced. Truck is tuned up (plugs, wires, cap, rotor, fuel filter, fuel pump). I only run premium fuel and run injector cleanor at least once a month. Right now the truck idles rough and will cut out and back fire through the intake at highway speeds. Check engine light comes on after cruising at highway speed, but always resets when ignition turns off. This has gone on for the last six years. No mechanic can find anything wrong. Could this be an issue with the EGR solenoid? I am pretty much lost. I have 170k miles and would really like to see 200k. but if this keeps up I'll be looking for a different ride. Thanks for any help....

 

Replace the vacuum lines, clean the EGR, check for other vacuum leaks. Run some seafoam thru it as well.

 

I've seen seafoam, but am not familiar with the best way to use it. Can you elaborate?

 

I had a similar problem with my '91 4.3L like 3 years ago. It would crank over, but would run very nasty. Black smoke, backfiring,and choking out through the F.I. I changed Distributor, plugs,sparkplugs,ignition module,pick-up coil,AC Delco 02 sensor, and fuel pump. After like 3 weeks since the problem had started I was finally able to take it to my dad's friend's house which has a diagnostic scanner. We changed the T.P.S. and that's all she wrote. I know your truck isn't giving any trouble codes, but just try it. My problems were identical to yours except that my computer was actually smart enough to tell me the problem.

 

wow...6 years with it running like that? my cutty had a problem running like that. running really rough and backfiring through the intake...and had a bad knock too. come to find out it was a bad rocker arm on the exhaust side of cylinder 6. does it knock at all? with it backfiring through the intake, there may be a possible leak in the intake or exhaust manifold gaskets. how long have you been running premium fuel in it, since you bought it or since it started this problem? was the temp sensor ever changed? the temp sensor has A LOT to do with how the vehicle runs.

 

If my memory serves me correctly, I changed the throttle position sensor about a year and a half ago when the truck was having one of these episodes. I didn't notice any great change, the problem just seemed to go away after a couple of weeks.

It hasn't been running like this for six years, just the idiot light has been going on and off for six years. I've heard some say it could be a MAP sensor, but I am kinda tired of buying new sensors for 40 bucks a pop and not seeing any results. Would be nice if the computer would speak.

 

Alright, like a year before my Blazer went crazy like that, the check engine light turned on, but truck ran okay (not perfect) but okay. I actually took it to the same guy that scanned my Blazer this last time. The T.P.S. was changed out and the C.E. light turned off. Meaning that the first time the T.P.S. went was nothing like the second time it went. I don't know what to tell you anymore, I think i'm fustrated for you[:@] (that face looks more like constipation), lol. It's been six years, don't give up!!! Find out what's wrong with her, then post it!!!!!

 

I think I'm going to replace the EGR control solenoid. I'm getting vaccum from the manifold to the solenoid, but no vaccum from the solenoid. Picked one up today, but it was the wrong application. Will try again tomorrow. Also I think I'll pull the plugs and check the gaps. Anyone ever experiment with narrowing the gaps below the 0.045" factory spec?

 

Did some work tonight, here's the skinny:

Replaced the EGR control solenoid and seafoamed the throttle body and fuel tank. No more cutting out and backfiring and so far the idiot light has not come back on. Will post again if more issues arise. Thanks for your help.

 

Glad to hear that!! Does this mean you're keepin her?