help!! 4.3 drivability problems

1998 4.3w 4wd s10 187k miles it runs great on a 80 degree day, but when it starts to get a little cold outside it runs like "s"!!!. It's finally gotten to the point where it can't be driven. It's almost like the catylitic converter is stopped up but it's not getting red hot , and if you turn the engine off and back on again it will run for a few more miles and lose power again. any and all help is greatly appreciated.

have you tried a tune up yet?

tune up? if this were the case it wouldn't straighten out by simply turning key off and back on again as i stated in my original thread

tune up? if this were the case it wouldn't straighten out by simply turning key off and back on again as i stated in my original thread

Not true... Tuneup consists of plugs/wires/pcv/02 sensors/cap/rotor Any of these things when cold can cause issues... Lets assume for the moment that one of the traces in your cap is bad, when it expands full contact is made, when it contracts the metal seperates enough to cause you issues...

Now, I'm not saying it's definatly the problem, but it's a place to start... If you haven't replaced the 02 sensors within the last 70k I would replace them. Clean the MAF, and do a full tune up...

replaced tune up parts, removed and cleaned under upper air plenum, most problems are gone except the engine does ok closed to 1/4 throttle opening anything above 1/4 throttle the engine misfires and won't rev?

sounds like a tps to me give it a try it is cheap

fuel filter MAY be causeing a bit of your problem too..ever changed it?

Also check your egr tube... could be a bit clogged. Have you checked your coil? If you have a weak coil this can cause similar issues. (try a new one, if it doesn't help, simply return it)

If none of that helps, I would look into the injectors...

Im having a similiar problem. My 98 4.3 fullsize has a misfire when its cold, mainly when it rains, so Im guessing it has something to do with moisture. After the car is run for quite some time it stops misfiring. When it rains its also a shaky start, and once before didnt start at all after 3 strait days of rain. Ive replaced fuel injectors and done a COMPLETE tune-up, even the MAF. Does anyone have any ideas?????

cgdiaz: id check the connectors for the distributor, injector harness and pcm for moisture inside the connector. theyre weatherpack connectors which means they have a rubber seal to keep moisture out. any moisture, especially in the pcm connector, can cause major problems.

gg: ive had funky things like a crappy cap cause all sorts of problems. it sounds like it wasnt doing the same thing before right? most major parts stores dont give you a lot of guff on bad parts. if you have your old stuff as testers (cap/rotor type stuff not plugs or o2 sensor) try swappin out and see if it makes any difference.

the catilitic converters for the 98 s 10's are on recall, you nailed it on the head in your post, your cat is junk

cgdiaz: id check the connectors for the distributor, injector harness and pcm for moisture inside the connector. theyre weatherpack connectors which means they have a rubber seal to keep moisture out. any moisture, especially in the pcm connector, can cause major problems.

gg: ive had funky things like a crappy cap cause all sorts of problems. it sounds like it wasnt doing the same thing before right? most major parts stores dont give you a lot of guff on bad parts. if you have your old stuff as testers (cap/rotor type stuff not plugs or o2 sensor) try swappin out and see if it makes any difference.



Hey thnx for the advice, Ill give the connections a check for moisture, and see if thats whats going on. Appreciate your time. Keep you posted.