Opinions Needed Please
Thread Starter
Le Mans Master
Joined: Jan 2003
Posts: 8,602
Likes: 48
From: Napa California
Opinions Needed Please
I have a 1988 coupe 4+3.
Last weekend, after some spirited driving by my wife, it began running very ruff at low RPM.
It will not idle smooth. It idles like it has a lopey cam. It is not smooth driving at low RPMs. At about 2400 RPMs it smooths out and feels as if it has normal power and accleration.
Timeing is right on 6 deg BTC with ecm disconnected.
I hooked the induction of my timeing light to each plug wire and it seems as if spark is traveling down each wire.
I unhooked the battery to clear any codes and then drove it hard to normal operating temp with a few WOT.
I checked for codes and there are none.
Where do I go from here? Could it be plugs and wires.
What has me baffled is that it happened suddenly last week and that it runs good above 2400 RPMs.
Any advise is appreciated.
Thanks.
Last weekend, after some spirited driving by my wife, it began running very ruff at low RPM.
It will not idle smooth. It idles like it has a lopey cam. It is not smooth driving at low RPMs. At about 2400 RPMs it smooths out and feels as if it has normal power and accleration.
Timeing is right on 6 deg BTC with ecm disconnected.
I hooked the induction of my timeing light to each plug wire and it seems as if spark is traveling down each wire.
I unhooked the battery to clear any codes and then drove it hard to normal operating temp with a few WOT.
I checked for codes and there are none.
Where do I go from here? Could it be plugs and wires.
What has me baffled is that it happened suddenly last week and that it runs good above 2400 RPMs.
Any advise is appreciated.
Thanks.
Race Director
Joined: Sep 2004
Posts: 13,793
Likes: 0
From: St. Peters MO Sometimes you have to prove yourself by doing alot of killing or alot of dying...
My first inclination is the ignition system. Double check to be sure you are getting a good spark and not a weak one. I'd also check the fuel delivery system. Maybe start at the filter or check the pressure. It has been my experience that a fuel pump is either good or bad with no real indication that it is ready to take a dump... so I wouldn't be too worried there, but injectors , bad pressure, or clogged filter can cuase the symptoms listed above.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
With drivabilty problems ONLY below 2400 rpms, *I* would rule out the fuel pump and the ignition, with the possible exception of a spark plug wire that may have come loose under the "spirited driving". Both of those systems become MORE highly stressed as the rpms go up, and wouldn't likely clear up as the speed is increased. Your symptoms would have me looking for vacuum leaks. Also, I would check the TB and IAC for newly dislodged carbon particles, blocking something up.
RACE ON!!!
RACE ON!!!
