Marcus, don't be discouraged. My TR6 has a similar problem. And I'm
pulling my HAIR out tring to figure this fricken thing out! ARRRGGG!
My misfiring history....(some of you are already familiar with this...)
The car runs great under load or at high revs. But let it idle down,
and it will stumble. It doesn't die, but it... well, it misfires.
This is a bad thing because the car won't pass emissions here in
colorado as the TR fails the HC test. (unburnt fuel down the pipe!)
The car has a mild street cam in it. I'm thinking the only way to get
this thing through emissions is to loosen up the valve tolerances.
This isn't my idea of a good thing, as I want the car to run right all
the time.
My first hunch was that the distributor had a loose shaft (thanks to
net.wisdom here on the list). SO I bought the Crane electronic
ignition module to alleviate this problem. Car ran just the same.
Actually the car started up and ran GREAT the first time. I was
amazed. After shutting it down, cleaning up, etc, the car began to
run the way it always did. I'm still tring to figure out why it ran
so fantastic for that moment. So I know that it can be done!
I thought maybe the distributor springs where a bit weak and perhaps
the timing was bouncing a bit. Maybe the weights seated properly and
it idled great that one time. Yeah, that must be the problem. So I
ordered new springs from TRF. I put the new springs in this weekend,
and they were stronger than the old springs. At first, I thought the
car was running better again. But after the drive in this morning, I
think I've found that the car is behaving as always. Misfire at idle.
I also decided to make sure that darn valve cover was sealed nice and
tight. You know when the sucker is leaking air, the car won't run
right. Try pulling the oil cap off and seeing what happens. The TR
runs REALLY bad if I do that. I figured maybe there are other leaks
in the cover that need some attention. So I used some silicon to seal
the three studs that poke through the top of the cover. The cover is
sealed with NO oil leaks whatsoever, and still, misfire at idle.
I can't find any air leaks. (that doesn't mean their aren't any, but
I can't find any!) If it does have a leak somewhere, it's not really
bad. I'm dubious on how well the vacuum retard is working. You know,
I pull the hose and nothing really happens. So, I'm going to take a
trip to the autoparts store and run a single vacuum hose instead of
the stock plastic hose with 47,000,000 connectors on it. Screw the
concours, I want a smooth idle!! :-) I've tried adjusting the timing
by hand/ear, and still I can't find that sweet spot.
I do notice that my contact breaker plate inside the distributor is
able to move up/down if I push on it with my finger. This will change
the timing a bit, but the thing is under tension and I wouldn't think
that it would be a problem. But then again. Do they all do this? Is
there a circlip that fastens these two plates together or do they just
slide together?
Anyway, I'm at a loss, and starting to through money at the car to see
if it helps. The coil been replaced with a lucas sports coil, the
plugs look like textbook plugs of a fine running engine. (remember it
runs great on the road) I've tried gapping the plugs at .025 and .030
(to try and get a bigger spark with the sports coil) but that did
nothing. It has new plug wires too. The cap and rotor are good.
I've attempted to check ground connections, and I believe they are
good, but I'm open to suggestions on other things to check. I feel
this is a timing/ignition problem, or an air leak somewhere.
Any ideas, suggestions, or stress relieving aids are welcome.
TTFN,
-Scotty
|