View Full Version : Poor running advice?

10-02-2006, 09:52 AM
I'm looking for some help in sorting out the poor running of my 6. The car sputters and misses when accelerating under load. Most noticable at low rpm's. Car will actually shudder and may even backfire. What's more the backfire seems to be coming from the front of the car not the tailpipe. Car has a new fuel pump and coil and really hasn't run right since. Carbs were rebuilt 2 years ago however the car ran great between then and now. Only other thing I can say is it is revving high at warm idle (1200) and at cold choke it may go up to (2000).

10-02-2006, 10:46 AM
Are any of the spark plug or coil wires cracked or loose?

What is your timing set at? With a timing light at curb idle 900 RPM and the advance/retard line disconnected and plugged, it should be at 12BTDC.

Are the points clean (not burned) and gapped correctly?

Is the rotor center connector properly attached, not loose in any way? These have been reported as coming loose and causing misfires.

Are there any cracks in the cap or excessive carbon or corrosion on the terminals inside the cap or in the wire towers on the outside?

Any vacuum lines disconnected or cracked? Are all wires on the plugs tightly connected?

Are any of the plugs fouled black or oily?

Just for starters...........

10-02-2006, 11:24 AM
Thanks Paul.
Just put on new plug wires. No change.
Car has lumenition EI. Timing shouldn't change once set, should it?
I will check the inside of the rotor cap. I know its pretty dusty in there.


10-02-2006, 02:08 PM
It's been a while since the valves were adjusted in this car. Could that be it?

10-02-2006, 02:13 PM
Timing shouldn't change, but sometimes things work loose, like distributor hold down clamps, so check it. The valves would probably have to sound like a machine gun before they would affect it that much, so if they're really loud, you may have a possibility there.

Also, things wear out. How many miles since the last tune-up? How many miles are on the car?

Did you check the oil in your dashpots recently?

Did this just happen or has it been growing on you over a period of time?

10-02-2006, 02:27 PM
Valves aren't too noisy. Car has new plugs/wires.
Don't know about the timing. I was under the impression that with EI you didn't need to worry about it because it wouldn't change from the time it was originally set. Oil is correct in dashpots.
Car has 32K showing (can't verify). Problem seemed to appear one day, but not a day that I'd done anything.

10-04-2006, 06:44 PM

What year TR6

10-04-2006, 07:08 PM
This sounds like a lean condition, pull #1 & #6 sparkplug to confirm by color which carb is lean. Perhaps a sticky float??
MD(mad dog)

10-04-2006, 09:14 PM
Check the diaphragms in the carbs for holes. As mentioned before, check for bad vaccuum lines. The elbows are prone to deterioration.

10-04-2006, 11:24 PM
The high idle can be from leaking accelerator shafts. The seals can be leaking and drawing in air around the shaft and leaning out the mixture. That will cause a high idle when the car is warm. My TR3 has that problem. How to check is to take a can of brake and parts cleaner or carb cleaner and spray around the shafts. If the RPM changes, there's your problem. Renew the shafts and seals. Missing and lack of power can also be that the carbs are to lean or need balanced. This will happen when trying to start out from a stop and there is not enough fuel to create the Torque need to over come the weight of the vehicle.

10-11-2006, 08:24 AM
Its common for the advance assembly to rust up in the distributor. Check to make sure that you are getting advance as rpms increase, or your timing will essentially be fixed, resulting in a serious loss of power and poor running as you described!

10-11-2006, 09:24 AM
I had the same symptoms on my TR4. The short verson is that it was running way to cold due to a poorly installed thermostat. One thing I did that you could do is to pull the choke just before this heavey acceleration and see if the problem goes away. In my case it did go away. This was the red herring that had me running down the mixture road then down the timing road. A lot of trouble for nothing. I just installed a 195 degree thermostate and all was great after that.