1994 Buick Century poor performance

WMGWIZARD

MEMBER
1994 BUICK CENTURY
6 CYL
FWD
AUTOMATIC
71,000 MILES

Cleaned engine and did oil change. Test drove car and ran fine. Daughter drove to school and home ok. Went for a drive a few hours later and about ten miles out car began to misfire and would not make power. Checked plugs and wires and all other connections seem clean and dry.
Any suggestions?
How would I check for bad coil pack?
How would I check for bad injector?

Thanks

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

How would I check for bad coil pack?
How would I check for bad injector?

You check their resistances with an ohmmeter-other cause below

Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

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Monday, November 9th, 2009 AT 7:05 PM

WMGWIZARD

MEMBER
2 POSTS

Thanks for the quick response.

I am a fairly accomplished mechanic, but certainly no master.

I understand checking the resistance of a coil but what values should I have?

This car has a DIS ignition system, how can I check the coil driver board?

The injectors are really inconvenient to get to since they are under the manifold. Any other way to check them or a plug in the wiring harness to work from without having to remove the manifold?

I would also add that the problem got progressively worse. My daughter called said she is broke down, car is not running right, shaking, no power. When I got to her about 20 minutes later it ran ok but not right. Swapped cars with her and proceeded to drive home. The closer to home I got the worse it ran, no power, heavy misfire. Wouldnt accelerate without full throttle.

Thanks

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Monday, November 9th, 2009 AT 7:33 PM