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1989 s10 4.3 TBI rough idle and surging

Old 05-25-2013, 03:06 PM
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Smile Idle too fast. Rough at start up.

My 1989 S10 Blazer 4.3L V6 was idling too fast and rough at start up. While driving, I could take my foot off the gas and it would cruise at 30mph. It has 345,000 miles. Tried everything. Mass air sensor, idle speed sensor. Took throttle body off cleaned it very well. No change. No vacuum lines broken or cracked. Was advised to replace intake manifold gasket and check distributor. Replaced distributor and intake gasket. One intake bolt was broken, gasket in bad shape, distributor pretty worn out. That did it! Runs just fine now!
Old 06-27-2013, 06:52 PM
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Default Old thread but making progress.

Sorry to bring back an old subject, but I finely got around to working on my poor old Blazer again and I am trying to bring it back to life again after almost 2 years of sitting.

A few days ago I rebuilt the Throttle Body as one of the posters had suggested, and today I went to the auto part store and got a new battery. While I was there the person helping me put it in noticed that I had a Spark Plug Wire loose.

Well I put that back on and it is running alot better after the above fixes but it still has a inconsistent idle and alittle rough. So I bought a new Cap and Roto. I will try to put it on tomorrow when I get off work and post again as to the results.

In the mean time are there any other suggestions?

Thanks again for all the help.
Old 06-28-2013, 12:03 AM
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Possibly check out the TPS (throttle position sensor) or the IAC valve
Old 06-28-2013, 04:05 PM
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I replaced those as part of the troubleshooting process before but I don't think I adjusted them. I read that the TPS is not adjustable on this year, is that true? How would I adjust the IAC?

Also I replaced the Distributor cap at it didn't help, I also ran a rod through the CAT as it had been sitting for a while and I wasn't sure if it might have been clogged...

It runs fair now, but the idle is still inconsistent and wants to bog out. Also there are strong exhaust fumes which doesn't seem normal.
Old 08-28-2013, 06:55 PM
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get a pack of vacuum caps and cap the line going from the EGR control solenoid to the EGR...and also at the TB that goes to the EGR control solenoid....see what that does.
Old 12-21-2017, 04:20 PM
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Default 1991 S10 Blazer missing/surging

I finally figured my blazer out.....I've read these threads about the 4.3 TBI surges and missing at idle and i have done what everyone else has done. I replace EGR plugs and wires this and that and i found out that after cleaning my new egr, i noticed my egr port on the intake was complete clogged. I cleaned it out and even with a timing adjustment needed, HUGE difference. I am missing a motor mount on the drivers side and i still cant feel it run. I hope this helps anyone out there
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