MikeTCarter

Hi

I started my SC one morning and there was a single BANG. Ever since then the car has had a lumpy idle, especially when cold. This makes it difficult to check the oil level because it wants to stall as soon as I remove the oil filler cap.

In every other respect the car runs well. It is just at idle that the problem presents itself.

I would be graetful for any ideas. I did hear that sometimes the vacuum pipes pop off but they all seem to be in order.

Many thanks

Oldtee

You went lean. Probably an air leak. Maybe something cheap. Check for a rotting or loose hose behind the popes hat. Is the vaccum hose to the distributor OK? You can use a water spry at the injectors to see if one of the seal went kaput. A propane torch used carefully is a good tool. So is a smoke test (ie puttng smoke into the injection system and watching for leaks.) Welcome to the SC CiS fan club!

Auto_Werks 3.6

Does your car have the pop off valve upgrade for the airbox? If not, your worst case senario is a cracked airbox.. I hope not for your sake!
Good luck!

emac

Mike
The first thing I would check is that you have a pop off valve in your air box. If not there is a good chance you cracked the box. Once warm I would check the mixture, sounds like you could be lean.


Ernie 81 SC

bargamon

My 74 with 78' sc engine blew the pop off valve (hey, it popped off!) and since we could not find the leak, and the old box was once repaired, we are replacing it. The seals to the manifold are leaking oil so we just keep going deeper and deeper.

I figure the engine is down, and its all a part we might as well just slap the new one on it.

Im learning we don't "Fix" these cars we "improve" them. The new box and valve will help and going forward not make it so darn "delicate".

Im learning so much!!!!

MikeTCarter

Hi thanks for the replies folks. I dont have a pop off valve, but will soon. Can I ask for clarification::: What is the Popes Hat and what is the Air Box? I am guessing this is not just the plastic air filter holder.


Thanks again

Peter Zimmermann

The filter "holder" is the cover (held on with two rubber straps). The airbox is what those straps attach to, the large plastic housing that is easy to see after you lift off the filter and cover. I've never heard the term "Pope's Hat", but I assume it's the dome at the very top that is black rubber and connects the throttle body to the sensor plate housing. That can come loose or split open, both will cause a lean condition. A cracked airbox also can cause a lean condition. I think that you should at least have a P-car shop take a look...

Oldtee

"I've never heard the term "Pope's Hat", but I assume it's the dome at the very top that is black rubber and connects the throttle body to the sensor plate housing."

Yup, thats it.

X2 Porsche mechanic.

Propane torch works. Use a rubber hose over the nozzle and tape the air holes. It works, and you can direct the rubber hose to very specific areas.