: 5.0 skip... Out of luck?

Faded Crest
04-18-08, 08:31 AM
Hello bretheren,

Bought a 1991 Brougham D'Elegance from an old geyser who did nothing but drive and change the oil. At 119,950 miles, the spark plugs were ORIGINAL, as were the AC Delco Cap/Rotor and numbered Packard Bell spark plug wires... Have a look at one of the spark plugs. Burned down from .035 to .055.


The car had a little bit of a rough idle, so I naturally figured that a tune up would fix it, no go...

So I drove 100 miles into the country with some Lucas Injector cleaner and 93 Octane in it, giving it a WOT whenever possible, no change, not even any black or brown coming out of the tailpipe.

Then someone in the Brougham/RWD thread suggested it may be an EGR valve, so I replaced that, no change.

Obviously, I am worried that I may be looking at a burnt valve. I didn't figure in that kind of work when I bought it, so I am looking for wisdom...

Could it be anything else? Basically, it is a very slight, but consistent miss. There is a small exhaust leak toward the front, probably on top of the catalytic converter, or where it connects. The miss is only noticeable when just rolling to a stop. You can feel a pulsating flutter. But on the road, she screams! One of the strongest TBI 5.0's I have driven (I've had 3).

If it is a burn valve, dare I drizzle some water down the throttlebody in an effort to break it up?

Thoughts, anyone?

Faded Crest
04-18-08, 09:01 AM
In case the link doesn't work, here is a picture of that spark plug...


Here's a picture of the car...


04-23-08, 05:07 PM
Go back to the basics. Run a compression test first. Then hook a vacuum gauge to it and report back what you get.

Faded Crest
04-23-08, 09:37 PM
Problem solved... It was either the MAP sensor or a vaccuum line in that area. I replaced it, secured the hoses in the area, and now it runs PERFECT!

04-23-08, 10:58 PM