Violent Jerking while driving at low rpms.

[Anthony zane]

1980 engine. The car starts just fine. It sounds very smooth and idles nicely. However when driving on the street, it really struggles in the low rpm's.

For some time I thought the car was simply going to slow to be in the specific gear, but my father drove the car and said that this problem isn't due to that and was not there before. The car runs great at the higher rpm's and is powerful and smooth. The issue occurs on flat ground and on an incline when the car is under load. I believe the violent jerking occurs in all gears, although very rough while in second.

I have thought about the possibilities of a bad fuel filter, fuel pump, dirty injectors, or possibly a vacuum leak.

I have also considered the possibility of a bad fuel to air ratio, however, the car was recently tuned.

Any suggestions and help would be appreciated.

Cheers!

Anthony

[Joe Bob]

Could be any of that but I would suggest taking it back to the wrench and blaming it all on him......

[Anthony zane]

Well, here's the thing, it was tuned when taken in for a smog test, and was running fine for a while after. The issue only developed recently, so I'm inclined not to think it had to do with the mechanic.

[Justin@Athens]

Does the car attempt to stall out? Im guessing vacuum leak with the info you have given. Change the fuel filter if you don't know when it was done last.

[Anthony zane]

Yes it was attempting to stall. I'm leaning towards vacuum leak as well.

[86911cab]

Intake to head leak

[DRACO A5OG]

Use a cigar and find the vacuum leak/leaks

[JohnJL]

Came here to see if Ronnie is around...this thread title is Ronnie-bait.

[john walker's workshop]

Helps to state what year it is....

[roblav]

Agree we need to know what year / model the car is. All my old Solex and S cam cars had to run above 2700 RPM around town or they'd buck.

[john walker's workshop]

Yeah, like how long is this rope?

[Tippy]

Originally Posted by john walker's workshop

Helps to state what year it is....

Oh, not all 911's are the same?!?!

[javadog]

A three second investiation leads me to conclude that he's probably talking about his '78 911SC.

My first suggestion would involve checking the CIS system and related issues. That's assuming that he's not trying to spin the engine at too low a speed in a particular gear.

It's also always worth having a look at the distributor, as these seldom seem to be serviced by most people.

JR

[Tippy]

Originally Posted by javadog

A three second investiation leads me to conclude that he's probably talking about his '78 911SC.

JR

You must be referring to his sig.?

If that is the case, when you use PP on a smartphone, the mobile theme does not show sigs., as I assume you are aware.

[mhackney]

Tippy, the OP doesn't have a signature but he does have a Garage that shows a 78 911 SC. You might not see this in the mobile view either. It's always best to explicitly state the model and year of your car in the first post for help!

[javadog]

Originally Posted by Tippy

You must be referring to his sig.?

If that is the case, when you use PP on a smartphone, the mobile theme does not show sigs., as I assume you are aware.

No, I wasn't looking at his signature, which doesn't list anything. I looked in his "garage" which can be accessed on a smart phone.

Not that I use my smart phone for perusing the internet... Being a (somewhat) older fart, I have not been surgically attached to my precious personal device and so I still use a computer of one sort or another to peruse the internet. I keep the phone around, in case I should get a phone call.

Not that it matters in this case...

JR

[911 Rod]

How is it in the rain?
I'd check the distributor as already mentioned.

[Tippy]

Originally Posted by javadog

No, I wasn't looking at his signature, which doesn't list anything. I looked in his "garage" which can be accessed on a smart phone.

Not that I use my smart phone for perusing the internet... Being a (somewhat) older fart, I have not been surgically attached to my precious personal device and so I still use a computer of one sort or another to peruse the internet. I keep the phone around, in case I should get a phone call.

Not that it matters in this case...

JR

Right on, didn't think of that. To me, it's a simple courtesy to list vehicle and mods if any.

Beings you have "java" in your title, I figured you knew that already. HEHHEH

I use the Internet on my phone 100%. So easy and convenient.

[javadog]

Originally Posted by Tippy

Beings you have "java" in your title, I figured you knew that already.

Wrong again, Kemosabe. The java in my user ID has nothing to do with Java, as it relates to computers....

Back to the original topic, one other thing to look at would be the specific things done when it was recently "tuned."

JR

[Bob Kontak]

Originally Posted by 86911cab

Intake to head leak

How do you know this because the only time my car ever bucked was when #4 runner at head was sucking wind.

Get the carb./brake cleaner out and find it.