snic68

Hello all

You all have been a great help in everything!! Great forums

My new issue is my 5.7 350 TBI is stalling/ chugging at highway speeds and started having a rough Idle. it wants to stall when I slow down for traffic and chugs a bit on the idle. I just replaced plugs and wires and filters about 2 months ago. I am not having any tempature issues. any ideas where to start?

I have been told fuel filter, fuel pumps/ and sensors. I am not getting any engine lights besides when it actually stalls. I was hoping I would not have to make 10 trips to the parts store and throw parts at it till it runs agian.

Thanks in advance

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2002 Avalanche Z71

BowtiePowerhouse

was it a gradual change? something that started happening after u ran it very low on gas perhaps? when was the last time u swapped the fuel filter?

snic68

It has happend twice in a week. the first time I had just filled up and was trucking down the highway and it started to chug for about 3 minutes than ran fine. yesterday again i had just filled up the previous night and was trucking down the road and it started after about 10 minutes but this time it chugged and stalled many times. I work 24 hours so on my way home this am it ran like a champ. engine was rebuilt 2 years ago and they did not chane the fuel filter from what I can gather since I know the previous owner the filter has not been changed in over 6 years maybe closer to 10. I am going to check the plugs and wires today and maybe a new dist cap and for sure the fuel filter. I may even change the ERG valve ( if that is what it is called)

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2002 Avalanche Z71

BowtiePowerhouse

because of how cheap fuel filters are, definitely get one. 6-10 years if i read that right, i wouldnt be at all suprised that even if this wasnt the problem u notice an improvement in performance when this is swapped. might see some sludge come out of it when u disconnect it. when u say chug, do u mean like it was missing a pair of cylinders? or just a cylinder? u might have lots of deposits on the terminals inside the rotor. get to auto zone, they will scan your truck for error codes free. with that u can stamp out sensors etc. does your exhaust smell normal? if your fuel checks out and your spark is good, is the auto choke in the snorkle sticking and starving your truck of air? if you are sure of the fuel, sure of the air, and sure of the spark, then it might be restricted exhaust probably in the cat. if u have any more detail it would help alot.

snic68

Thanks for the replies guys.

I put in a new fuel filter and ERG or ERV I can never remember what it is for sure. I also had to get a diagnostic done. Because it still ran like crap after that. My map sensor was bad so it is fixed and it wants to stall on take off now at about 1500 rpms. as long as I am giving it a steady amount of fuel it works great. The mechanic guy thinks it may be a TPS (throttle position sensor) but we ran out of time to work on it so will jump back in after the weekend.

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2002 Avalanche Z71

snic68

OK so here it is. the first day I brought it back to the mechanic and it stalled a block from the place and I was lucky to coast in and park it. They replaced the distibuter and got it running and called to tell me it was fixed so I went down and got it payed the $260 and drove it around the area to make sure it was working- as soon as it warmed up it started hesitating on take of then would take off like a bat out of hell. the engine light came on and I drove it back to the station. it also ran like there was no power. they hooked it up again to the machine and changed the sensor that connects to the ERG/V and a sensor that told the engine how to run that connected near the starter- when they put it up on the rack the sensor was hanging out. the last owner had stuck it in its place and tried to silicone it in. so o replaced that also and drove it home that night and it worked fine- but it still felt as if it was lacking power. the next morning I started it up and drove 10 feet and it died and would only start if it was floored and on 1 cylinder made it back to my drive way. called the auto place they came and towed it and found out the distibuter they put in was bad and put another new one in and today is the first day I have driven it and so far so good. anyone know of a reason why a engine would fry a distubter or do you all think it was just a fluke bad part and I should quit being afraid to drive?

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2002 Avalanche Z71

Rs051802

Have you replaced the idle air control valve? That is the tub looking thing behind the TBI on the intake. This sounds like an IAC issue to me. I have a 95 and have had the same issues with it stalling, trying to die when idling. I replaced my IAC and its good to go.

texasboy05

check ur intake. probably a vacuum leak somewhere