Ignition

84CAB · 04-10-2005, 06:11 AM

I'm stumped... A few weeks ago I replaced my dist. cap and rotor, immediately I developed a rough idle and a stumble upon slight acceleration. Didn't notice much of a miss at WOT acceleration. Assumed it was the plug wires so I replaced those as well. Problem still existed. Took it to a local shop that specialized in older cars. They said the new Clewett wires were bad and replaced them...no fix. Then we tried another new rotor ...no fix. Next they tried swapping out the DME, gas cap, and checked for intake leaks, still not fixed. I brought the car home for the weekend and have checked all electrical connections and everything looks fine. The Reference Mark Sensor and head temp. sensor were replaced a few years ago. I'm thinking the problem must be in the distributor just because this all started with replacing the cap and rotor...SUGGESTIONS??

stlrj · 04-10-2005, 06:32 AM

Only thing you missed were the plugs. Why not give them a shot?

84CAB · 04-10-2005, 06:34 AM

forgot...replaced plugs as well.

stlrj · 04-10-2005, 06:47 AM

Is it possible the new cap had an invisible crack?

Can you hear something like a snapping sound that a spark makes?

How about running the engine in the dark?

Gunter · Gunter's Garage

Recheck the ignition wires for correct firing order on the cap side and the plug side. Is it possible that the rotor was not correctly seated on the distributor shaft and did some damage?

84CAB · 04-10-2005, 07:00 AM

the plug wires are on correctly, replaced the new cap with another new one, haven't tried running it in the dark...no snapping sound. Might be possible the rotor damaged the distibutor, is there any way to check? What exactly is done when they rebuild a distributor?

Hladun · 04-10-2005, 07:03 AM

84CAB, I just put some Clewetts in, did the shop say what was wrong with the Clewetts? I did put up a post that I was getting arcing from the HT coil lead to the primary terminals.

84CAB · 04-10-2005, 07:28 AM

Quote:

I just put some Clewetts in, did the shop say what was wrong with the Clewetts?

they didn't say. I just blacked out my garage and checked for sparks.. there were none visible..

stlrj · 04-10-2005, 07:46 AM

So before your replaced the cap and rotor it was fine. Then why not put the old cap and rotor back on as a process of elimination?

84CAB · 04-10-2005, 07:51 AM

threw it away... trash pick-up was the same day

normally i keep stuff like this forever "just in case I should need it" but in an effort to keep down on clutter i have been tossing a lot of stuff.

Hladun · 08:15 AM

It's hard to get the plug wires onto the plugs, you might have a cylinder not properly connected. No. 6 is hard and I found I had to turn the connector with the lead going up before it snapped on. You might also have broken a plug insulator getting the leads on.

Check your timing also (but changing leads shouldn't affect that).

Has anyone used the old fashion oscilloscope that gives the voltage plot for each cylinder? I don't know if it will work with the CDI system. This is a very good tool for isolating a bad cylinder. You can also try the old test of pulling a lead at the distributor, but I found that pulling a cylinder had little noticeable affect on engine RPM.

Gunter · Gunter's Garage

Good point, make sure the Beru connectors are seated properly on the plugs; it fooled me a couple times.

84CAB · 04-10-2005, 08:32 AM

Quote:

Has anyone used the old fashion oscilloscope that gives the voltage plot for each cylinder? I don't know if it will work with the CDI system. This is a very good tool for isolating a bad cylinder. You can also try the old test of pulling a lead at the distributor, but I found that pulling a cylinder had little noticeable affect on engine RPM

not sure. The wire connections have been checked several times.

84CAB · 04-10-2005, 08:40 AM

if i mark the distributor position - remove, inspect, clean and reinstall will the timing have to be re-set?

RoninLB · 04-10-2005, 08:50 AM

fwiw.. sometimes I'll use a water spray bottle to provoke a spark in a dark garage.

84CAB · 04-25-2005, 10:05 AM

UPDATE- Car has been at local P-Car shop for the last few weeks. The 1st mechanic replaced and checked several things (rotor,dist. cap, plugs all for the 2nd time.) He swapped out the DME, distributor ,checked for air leaks and several sensors, etc, etc, etc. Finally he said he taught the fuel injectors were dirty and just for me to drive it with a fuel cleaner in it. Still didn't work. I took the car to another shop and they have gone over everything as well. Now they say cyl. 6 is loading up with oil and they recommend a valve job. I find this hard to believe since it has used no oil in the 3,000 miles since I bought the car AND it does not smoke. Thoughts? I have used both shops in the past and they seem knowledgeable and have a good reputation for being honest...

84CAB · 04-25-2005, 12:24 PM

anyone?

TerryH · TerryH's Garage

Have someone hold the throttle at 2k and remove one plug wire at a time. Try to isolate the problem to one cylinder. Might help to kneel on a rubber matt. This is how I discovered a clogged injector after many hours chasing electrical gremlins because I washed my motor.

911pcars · 04-25-2005, 12:44 PM

I don't have a solution for the engine problems, but I'd recommend finding a shop that can diagnose. When they say "swap", does that mean they temporarily install a known working DME box rather than selling you a new one? If so, they're more like parts replacers rather than knowledgeable techs.

Sherwood

84CAB · 04-25-2005, 12:49 PM

yes- the parts that were swapped out were with other known working units, including fuel injectors. They did not charge for any labor at all, or parts, because they put my original parts back on after eliminating it as the culprit. Of course they will charge $$$ if it comes to a valve job.