Mechanics

BUICK CENTURY COMPRESSION PROBLEM

1998 Buick Century

Hi All,

The other day my '98 Century, which has always run just fine, just suddenly started running very rough: I was in a dept. Store parking lot with the engine idling and the heater running while I waited for my daughter to run in. After about 5-10 minutes the idle characteristic went from smooth as you please, just like always, to suddenly running very rough - almost like it's severely out of time or missing badly - and would only stay running if I constantly feathered the throttle. The key word here is "suddenly: " It just turned on a dime. There were no accompanying events or noises; nothing crunched or squealed, no grinding, etc. I had to have it towed home because, though it "runs" after a fashion, any attempt to put it in gear would immediately result in a stall. Oddly, when I connected my OBD-II reader it returned "NO CODES."

Again, it will start and run for a moment after several turns of the starter, but without constant throttle attention it will die immediately, and even then I can't keep it alive for more than a moment. Ahy help would be appreciated, thanx.
Avatar
Guest
February 20, 2013.



I would start by checking fuel pressure you can rent a gauge at auto zone.

Saturntech9
Feb 20, 2013.
Any way to check that w/out a gauge? I'm 40 miles from the nearest, well, anywhere! And, would insufficient fuel pressure cause the kind of gripe I'm seeing? Not to question you, but it seems badly out of time. Any enlightenment would be appreciated as I would like to understand the problem. Meanwhile I will try to track down a fuel pressure gauge.

Tiny
Gregghull
Feb 20, 2013.
There is no way to check actual fuel pressure without a gauge. Yes low fuel pressure will make the engine run very badly. You also check compression to see if the compression is low from it possibly jumping time?But again you need a compression tester to check that. You have to elimate the basics first fuel compression you know it has spark it starts. Your code reader doesn't read live engine data does it?Alsoauto zone rents compression testers also. Do you have a multi meter to do some testing?

Saturntech9
Feb 21, 2013.
I have a compression gauge, several DMMs (including inductive p/u ammeter) and hand tools aplenty. I also have a better than working knowledge of automobiles as I used to build and race (drag) years ago. The problem nowadays is that EVERYTHING is solid state and there's about a zillion sensors that I'm completely unfamiliar with. When I was doing this kind of thing we were still using Mallory distributers with mechanical points and condenser (for instance.) I'll check for low-comp/jumped belt too and get back to you. Honesty it hadn't occured to me cuz cars didn't have damn belts when I was doing this; it was chains, and they DON'T jump (stretch maybe) and all us racers swapped even those out for Pete Jackson "cheater" gears. So yeah, I'm on that.

As far as the triumvirate of "starting" goes - spark, fuel, compression - I assumed that I had the basics locked cuz, as you said, it does start and run (after a fashion). But as you say, fuel pressure can be an issue with f/i engines, yeah? What I meant by "is there a way to test that without a gauge" was more looking for a rule-of-thumb kinda thing, like "if you pull the injector and it's spraying a cloud of fuel 3 feet in diameter, you're probably ok."

As far as my reader goes, no live data: it's one of theose little cheapy U-480s so it only retrieves stored codes, clears "check engine" light, etc, and it's giving me a NO CODES readout. Seems like one of the zillion monitored sensors would have registered something, yeah?

I'll get back to you. And thanx. : -)

Tiny
Gregghull
Feb 21, 2013.
Sounds good keep me posted.

Saturntech9
Feb 22, 2013.