Has anyone actually eliminated the miss or surgethat occurs from 17,1800rpm to 2300 rpm? I have been chasing a light miss for several weeks now. Here is the stats. 2001 Jimmy, 4.3, 5 speed, 63,000 miles, 5 speed, 3.42 gears, 31in tires, and 4x4. I have changed fuel filter,new K-N drop in filter, several cleanings of MAF,plugs, with AC delco, cap, rotor, icm, sea foamed and fuel injection cleaner and both forward o2 sensors.. Still slight missFriday im installing Magnaflow catalytic converter and Dynomax mufflerand the cleaning of egr.I will post results. Quick question, can a throttle position sensor be a culprit as this the rpm that i am sure most 4.3 engines operate most in. Sorry for the long post, but i searched the forum for hours and no one ever posts that the problematic miss or stumble is gone.

 

Not had this happen on a 4.3 lt but found this on a 3.3 (also a GM motor) turned out to be a bad IAC and TPS combo that was causing this. Just a thought

Good luck

 

Is your miss happening while stopped during rev's or while driving down the road???


I had a slight miss during driving (highway speeds) and no ck. eng. lites.Pressure tested the cooling system and found a small leak in intake gasket.

 

An out of adj TPS can cause that problem, My friend had that problem in his 91 chevy van he replaced the switch wala problem gone......

 

Yeah, its while driving, gonna get a cooling system flush anyways, so i will get a pressure test also.Tps, is also an avenue worthy of exploration after the pressure test, coolant flush.

 

Well, after the instalation of new Magnaflow catalytic converter, Dynomax muffler, warrantied icm, new tps, 20 dollar jug of GM fuel additive, still the miss lurks slightly.Great bottom end till 1900rpm,weak up till 2600-2800, then strong again. I searched and found a thread about aftermarket cap and rotor possibly being the culprit, as well aftermarket icm as opposed to GM, any thoughts?

 

I am having the same trouble when I drive my chevy Blazer LS 2000 4x4 when I come from a stop I accelerate and between 20-30 mph I loose power like Im flooding the vehicle I dont know realy then if I give it gass and the rps go up ut starts to run fine again like it didnt alomst kill itself..

 

There is another possibility, which I almost hate to suggest, that the valves may be sticking in the guides in the cylinder heads. I have seen a few of these over the years where almost all electrical and fuel related items were replaced without resolving the missfire. The cylinder heads were removed, sent to a machine shop, had the guides replaced and there were no futher missfires.

 

I am having kind of the same problem, I have replaced the catalytic converter, distributer, cap and rotor. I have changed plugs, and wires. My 02 Blazer cuts out on me when I am idleing, and will start, but acts like it is flooding when I hit the gas, when it cools down, it starts right up and goes on. What to do?

 

Well, i put onnew GMcap, rotor. Distributor is nice and tight without play side to side.Tested fuel pressure,57-58 at an idle, taped it to hood and drove , near 65 at wide open throttle, hard to read guage and no fluctuation at the stumble rpms. One other thing is i seemed to have lost my strong bottom end now. This 4.3 is nearly making meconsidering taking up drinking again. Looking like i am gonna pony up and put it on a scope!