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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Chevy
Satisfied Customers: 3223
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles A6 - Electrical / Electronic systems A7 Heating / Air Conditioning systems
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I have a 94 s10 with a 4.3 it has started bucking at highway

Customer Question

I have a 94 s10 with a 4.3 it has started bucking at highway speeds after driving it about 60 or 70 miles other than that drives fine
Submitted: 10 months ago.
Category: Chevy
Expert:  Chad Farhat replied 10 months ago.

Hi, I'm Chad ,Welcome To JustAnswer, I'm reviewing your question and I will be posting a reply ASAP

Customer: replied 10 months ago.
Ok
Expert:  Chad Farhat replied 10 months ago.

how about fuel pump ?

what is the mileage on it ?

spark plugs replaced or checked ?

vacuum leak check around the intake ?

Customer: replied 10 months ago.
I changed the fuel pump plugs cap rotor and wires also told had distributer module checked
Expert:  Chad Farhat replied 10 months ago.

does it have the Original exhaust and catalytic converter ?

ok what is the mileage ?

have you done a compression test ?

have you pull egr valve and port been checked and cleaned , the vacuum line on top of it ?

Customer: replied 10 months ago.
Has good compression haven't checked egr valve has only 103000 on it
Expert:  Chad Farhat replied 10 months ago.

how bad would you say the bucking and doest it smooth out if you give it more gas or it bucks down more

Customer: replied 10 months ago.
Smooths out when give gas
Expert:  Chad Farhat replied 10 months ago.

good quality wires used and were routed correctly nothing touching a hot spot on engine ?

Customer: replied 10 months ago.
lifetime warranty on the wires all put back in original holders
Expert:  Chad Farhat replied 10 months ago.

un hook the exhaust from manifold down take catalytic out of the loop and drive it with out and go to 60 70 does the bucking go away ?, i know it will be loud

Customer: replied 10 months ago.
Doesn't start bucking until I have driven it about 60 or 70 miles
Customer: replied 10 months ago.
Just wondering if you are still there
Expert:  Chad Farhat replied 10 months ago.

yes , i m

i mean after 60 70 miles ,something heating up

Customer: replied 10 months ago.
That's what I'm thinking but no codes
Expert:  Chad Farhat replied 10 months ago.

I know sometimes it want thru a code

Expert:  Chad Farhat replied 10 months ago.

1, the coil, injector, pick up coil in distributor etc .

Expert:  Chad Farhat replied 10 months ago.

60 70 miles is a good distance ?

do you use consist fuel grade in it or what ever you see at gas station ?

Customer: replied 10 months ago.
Use the same gas have changed coil already
Expert:  Chad Farhat replied 10 months ago.

not much to go on , distributor pick up , but i will be guessing

Customer: replied 10 months ago.
Haven't changed that still has the original distributer in it
Expert:  Chad Farhat replied 10 months ago.

something like this i will hook up a lab scope to it and test oxygen sensor , tps sensor etc ...and let it run and record it , i can spend hours on it .

but a distributor will fail on extreme temperature

Customer: replied 10 months ago.
Ok that's the only thing I haven't change will try that thanks
Expert:  Chad Farhat replied 10 months ago.

sorry this one is a little tough , wish had a better answer

Let me know if you need anything else on it ,if you are good , Please Kindly rate me.

Hope I was helpful to you &

A Positive Rating is Much Appreciated

This Post Will Stay Open for You To Come back and Ask me Any Follow Up Question You May have on this issue , even after you rate me

Thank You

Chad Farhat
ASE Certified Technician

Customer: replied 10 months ago.
Will do thankd
Expert:  Chad Farhat replied 10 months ago.

you welcome

let me know what happens if that fix it