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94 4.0 bogging under throttle

5K views 7 replies 3 participants last post by  badinten 
#1 ·
My 94 seems to idle fine but when I give it throttle it bogs really bad. It started out as an occasional issue and has gotten progressively worse. So I pulled the expensive NGK plugs and put in some cheap autolite plugs as that seems to be whats recommended and the NGKs were black.... REALLY black! Could it be the coil is bad or would it be more of a fuel issue?
 
#2 ·
I would suspect fuel issue. A possibility is a leak in the exhaust, if the o2 sees more air than it should it will tell the computer to put in more fuel than the motor needs. Also you can borrow a fuel pressure gauge at some auto stores and take a reading KOEO [key on engine off] and then KOER [key on engine running]. Should be at ~40 psi for both.

Richard
 
#4 ·
It's not the same as a carb. The sensors tell the computer info, if the info isn't right the computer does the wrong thing. Using a higher heat range plug won't fix the problem and will eventually screw up the cat as too much unburnt fuel will be going out the exhaust.
 
#5 ·
Do you have a code reader? That would help narrow down the problem. You can buy a cheap one for under $50.00 nowadays.

Richard
 
#7 ·
There are code readers for obd1 as well. Also you can use a VOM at the connecter under the hood. Unfortunately I don't know the procedure. The auto parts store should have a obd1 reader.

Richard
 
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