Guys i bought a 1996 gmc jimmy,it has the 4.3 in it.When idling it is not smooth up and down kinda rough,going down the road it runs perfect also the gas mileage is bad like 210 miles to a full tank.I have also noticed that when you put it to the floor it will black smoke out of the tailpipe like a diesel any ideas will be great thanks chris
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rough idle/poor gas mileage
- Thread starter BIGCHRIS
- Start date
barks507
New member
I would start with the basics. Clean throttle body, IAC, MAF sensor and run Sea Foam through it.
If none of that works, time for new plugs, wires etc.
If none of that works, time for new plugs, wires etc.
I would start with the basics. Clean throttle body, IAC, MAF sensor and run Sea Foam through it.
If none of that works, time for new plugs, wires etc.
Thanks,seafoam and throttle body done,not sure what the iac and maf are thanks
barks507
New member
IAC is a small valve located on the back of the throttle body. Just spray some cleaner into the hole for it or, take it off and clean it.
MAF is Mass Airflow Sensor located in the air intake line. Should see electrical connector for it between air filter location and throttle body. These are very delicate so don't bang it around or touch it. Just clean and let it dry before putting back on.
Did you see any improvements with what you did?
MAF is Mass Airflow Sensor located in the air intake line. Should see electrical connector for it between air filter location and throttle body. These are very delicate so don't bang it around or touch it. Just clean and let it dry before putting back on.
Did you see any improvements with what you did?
barks507
New member
As far as gas mileage. Not the best vehicles for that. I usually get around 350-400 km's. That would be 220-245 miles roughly.
jrobb913
New member
you guys are lucky for gas mileage, i had a 1999 gmc jimmy sl 2 door 4x4 and i was getting 200 kms to a tank city(125 miles) and about 370 kms highway(230 miles)...but i traded that vehicle yesterday for 3 toyotas, ones a parts truck, ones a strictly mud truck and ones just a regular truck to drive around, made it about 400 kms on 5/8's of a tank so the gas mileage will help me out greatly. now i just have to get better at drving standard haha
79MKII
New member
I had a similar problem and it turned out to be an EGR valve. I was able to remove it and clean it. My mileage was down to 9mpg highway and it would barely idle. My check engine light would always come on with that problem though...is your light on?
I had a similar problem and it turned out to be an EGR valve. I was able to remove it and clean it. My mileage was down to 9mpg highway and it would barely idle. My check engine light would always come on with that problem though...is your light on?[/QUOT]
Tried cleaning it first,didnt seem to help thanks