Troubleshooting

[roca]

I have a 1980 tr-7 that has an intermittent problem. It runs perfect for 20-30 miles then runs so rough that it is virtually undrivable( car barely moves when you hit the accelerator) I have ruled out the plugs , ignition wires, cap, rotor and ignition module. I also replaced the diaphrams in the ZS carbs which were worn but not cracked.
Possibilities?

Rich

 

[KLUTZ]

Welcome.
Do you still, by chance, have a Catalytic converter on the car? If so, perhaps it is pluged up?
What happens when you let it sit for a while and how long before you can drive it the 20 to 30 miles again? One hour, five hours, one day?
Let us know, it will be helpful.

Paul

 

[ObiRichKanobi]

Do you have the Lucas or Delco ignition? If the Delco, it may be the ignition module going out, probably due to heat. I've had a very similar situation...and swapping out the module fixed it.

See this thread Ignition Problem? for a complete rundown. I know it ends with the OEM plugs fixed it, but in reality the problem still was there until I swapped out the module. If you need one, they are readily available at your local Delco distributor part #D1906.

 

[roca]

The problem happens usually after I have driven 3 to 4 times
a total of 25-30 miles. The problem usully occurs within 1/4 mile of driving after the car has been sitting overnight. Sometimes it clears quickly othertimes it lingers.

 

[roca]

I ruled out the delco ignition module per thr initial post as
I tested it at the local autozone. I am wondering about other
components of the electronic ignition? At this point I can't really drive any distance as I would need a tow .

 

[dklawson]

The focus seems to be on ignition. However, next time it starts acting up, is there any possibility you can check the level of fuel in the carbs?

 

[Geo Hahn]

[ QUOTE ]
I ruled out the delco ignition module per thr initial post as I tested it at the local autozone...

[/ QUOTE ]

And how hot was the unit when they tested it?

 

[ObiRichKanobi]

Could also be the coil internally shorting out. Sounds like this is going to be one of those pesky gremlins that you'll either end up replacing each ignition part until it's fixed or get a positive diagnosis when it's happening.

Autozone tests ignition modules? Didn't know that. How do they test them and do they have to be on the car? Since I have about 3 or 4 laying around (bought some used, along with spare coils), should see if any of them are good.

 

[roca]

I took the ignition module into the store. They simply attach a cable from their machine to the connectors on the module and run the test several times until it gets hot. Pass/Fail is indicated by green /red led's. I was hoping that was the problem but it least I saved $30 on the part. This was in
So Portland Maine (USA) I am wondering if I should test the capacitor. It looks old.

Rich