miss in 3.8 ltr, 2000 impala

I would check the ignition system mainly plugs and wires. wires will test good but can break down under a load.If this has been helpful an accept would be appreciated or if you need more info let me know. Thank you Bill

Hello Bill , they checked the wires & plugs and they all functioned fine , and it only seems to happen when going up a grade , but if you give it a little throttle the chugging goes away, thanks Terry

do you always keep tank full or at least 3/4 full?

No Bill , she runs it down to about a quarter of a tank or less and refuels at different gas stations, add dry gas now and then , even tried higher octane gas, and add injector cleaner every other tank. Terry

check fuel pressure ( and I assume it will be okay with new pump and all) how long since last plug wire change (in miles and time)?

pressure was fine , replaced plugs and wires about 20,000 miles ago at 172,000 . Terry, signing off for the evening.

when this occurs there are no codes set? does it sound/feel like misfire or just bog down. if latter suspect egr valve.

No codes set. It is more like a miss as it will keep jerking until you give it some throttle, or let off , it does it every time you are going up an incline with cruise or without. Terry

check the egr valve for carbon build up and also check wires visually if after market they don't always fit as well and chaffe.look for "hot" spots on wires. Let me know.

Hello Bill, you got me wondering if one of the wires was bad so I bought new platinum plugs and a new set of wires and installed them yesterday, was that fun, anyway no change in the miss, still very prevelant, and what is the egr valve ? thanks terry

egr valve is exahaust gas regeneration valve.Fancy name for what basically does is, at higher rpms under little load, puts some of the exhaust back into the intake to reburn.It helps reduce pollutants cause your burning twice and also helps combustion in some applications. If the valve sticks its will cause hesitation under load if sticks at idle will cause rough idle or stall.the valve should be located by throttle body with a tube going to exhaust. remove and check for carbon build up. Gm also had a service bulletin with little hunks of carbon breaking free and getting stuck. there is a stainless steel screen you can purchase to put in front of valve to prevent it from entering. (available at advance for sure or any other major parts store should be able to get. Also would ohm out coil packs to verify okay.

Bill, had the wife stop in and they checked the egr valve and it was clean and looked ok. Could I have a problem with the injectors even though we have put several bottles of cleaner through them and nothing shows up on the computer. Also my wife said the car may have been struck by lightning before the chugging started, could it have affected the computer without it showing up on an analizer. Terry

If injector pulse is okay the only other way to check well is to remove and watch them spray. has anyone actually had on the scan tool monitoring the live data when the problem occurrs?

one mechanic hooked a small one up and drove it down the road and said it was the fuel pump as it was only at 40# so we replaced the intank fuel pump, but it didn't help. could the lightning which my wife said struck the car have done anything to the computer ? Terry

It could affect computer or any other electronic component. Did they retest fuel pressure after pump?

No they did not check the pressure again. terry

I apologize for not returning your answer sooner had some tech difficulties here. If he suspected low pressure it should be rechecked to verify pump took care of problem.

Hello Bill, we had it rechecked by another shop and it is fine.   Terry