just put on a GHL and now it hesitates and pops on deceleration

[Dignan]

Hey Guys,
I gust replaced a pre 73 exhaust with a GHL duel in/out. It sound MEAN AS HELL but i have a hesitation isue now as well as a poppoing under deacceleration it sounds like a turbo car after nailing the gas and then letting off it snarls and pops at me.. and ideas as to what the probems may be i'll live wth the sound of popping . but NOT the hestiation!
thanks!! for any insight I have a 78SC with SSI's if you were wondering.

[dean]

I would make sure the fuel mixture is in spec.

[Doug Zielke]

Richen the mixture.

[Dignan]

well that two of you saying hte same thing.. is there a way to do this the true D,I,Yer way by simply doing it till you can hit a happy result .. if where do I find the screw or what have you to begin this task?

Thanks for the fast replies... i am looking forward to tending to this issue in the morning! then going out and testing my tinkering.. hahaha and have some sweet six sounds with the NEW exhaust!

[Dignan]

where would I do the adjustment for the mixture.? stupid question I am sure but you guiys help cut to the chase with fast answers and save me a bunch of sorting thru books..

[dd74]

I'm sure you checked this out - but you might want to make sure the gaskets are okay at the flanges where the muffler meets the heat exchangers. On my muffler, a Bursch, there are small puffs of air coming from this area on the right-side HE, which my mechanic believes to be the source of my own backfiring. He suggests double gaskets between the flanges. Hopefully this will take care of the problem. IMO, the backfiring on deacceleration is nice at first, but wears thin after a while.

If this doesn't work, richening the mixture is my next step.

Good luck!

[Steve W]

Sounds like backfiring due to extreme lean condition. Betcha your car is running way lean at idle now. With a condition like that, you will backfire in your intake manifolds too, potentially blowing out your expensive airbox. Hope you installed a pop off valve.

[Vipergrün]

The fuel adjustment is done by turning mixture adjusment screw which is hidden in a hole just to the left of the fuel distributor at the 9:00 position per the following link.

http://www.pelicanparts.com/911/911_Parts/1978-83/1-7.JPG

See the hole under part #14? That's it. Part #14 originally plugged the hole, and may be still, if so, remove it. A lot of them have been removed already. You'll need to use either a long 3mm hex wrench, or purchase the special tool used to adjust the mixture. Takes a bit to get the wrench in the hole and properly inserted into the screw the first time you do it. Be gentle.


Be careful when making the adjustment, don't push down on the tool when it's in the hole and don't rev the motor with the tool in there either. Also, it does not take much of a turn to make a difference, like 1/8 -1/4 turn. Clockwise is rich, counter- clockwise is lean. typically go to lean, then richen back to where you want it. Should probably have a shop check your emissions so you know where you ok with that mixture. For what you are doing should be fine. I'd go about 1/8 turn lean , then 1/4 rich, which is a 1/8 adjustment net to rich. Also, since the car is running at this time, BE AWARE OF THE FAN AND BELTS!

Hope that makes sense.

cheers
-Brad
80SC

[Dignan]

Thanks guys!! I'll get to this in the morning!!! you have all been a great help! I be cautious of al the noted hazards

Thanks!

[Wayne 962]

A picture of this is in 101 Projects in the CIS section...

-Wayne