Chas

Hello all. I seem to be having an acceleration problem with my '83 911SC Targa. The car pulls like a racehorse from 1k - ~3.5k, but then falls flat on its face. It does continue to accelerate through redline, but the power is maybe 1/4 of what it is down low. Culprits come to mind like spark plugs, fuel pump, fuel filter, etc. I took the car to a well known mechanic in my area for an oil and spark plug change. When I got the car back, the wrench told me that he attempted to remove the plugs, but couldn't - and did not want to attempt it. Great.

Another (probably related) issue, is that the car runs pretty horribly the first few minutes of a cold start. The car starts up and idles fine (maybe a tad high), but then about 30 seconds in, it stumbles trying to keep itself alive, and I have to lightly blip the throttle to encourage it to build revs high enough to pull away from a stop. This issue goes away after a few minutes of driving (however, the no power up high issue does not).

So I suppose I am going to have to heat cycle + PB Blaster the plugs over and over again until I get them loose. It seems to me that at least one of the plugs is quickly failing. There is a chance that this will solve the no-power-up-high issue as well...but I'm not as optimistic.

Has anyone had this type of issue before? Any comments on what I can check to help figure this one out?

Thanks a bunch in advance!

theiceman

Well sounds like you need a new mechanic for starters, We are constantly reading about " well respected" and " top notch " mechanics that just don't fix the cars. .. anyways ..
First things first I gues .. as it always been this way ? when did it start ? have you comapred it to other SC's so oyu know what to expect. ?

Also did your mechanic check the fuel mixture and set your co ?

it could be just so many things at this point but there a few things you can check , most will require tools without swappping parts.
You need to check your system and control pressure therfore checking your fuel pump and WUR for the cold start issue. Then you need to check for escaping spark through your plug leads .. run it at night and see, then get a timing ,ight and check for the advance , there is a great thread on pelican about checking advance and cleaning gummed up distributors that are causing advance issues ...
Also when was the last time the valve clearances were checked .. your car will be down on power if this is off, also it could even be actual cam timing. So much to check , but i would certainly start with getting those plugs out .. i don't know how you are going to 'heatcycle " a plug more than being in an engine head though ..
Sounds like you may have to drop the engine to do it properly.. it is pretty akward in there and dropping the engine may be the least painfull ( and expensive ) way of doing it ..

nikkoa

Do you notice any change in different gears?

TroyN

Sounds to me like insufficient fuel up top. How did this start, did you change anything? Insufficient fuel could be things like fuel filter, fuel distributor, fuel pump, incorrectly adjusted air meter plate (my locknut had fallen off and the plate was out of adjustment and the car exhibited symptoms like you describe), vacuum leak (unmetered air will lean you out), injectors, gunked up gas tank, etc. I would bet vacuum leak but of course impossible to tell from here!

Daniel Dudley

Still have a cat ? They can clog. The fuel filter post was also a likely culprit.

Daniel Dudley

Is this car parked a lot ? Has it been sitting ? Did this just happen over night ?

kallberg

Did the "wrench" forget to put the spark plug wire back on one of the cylinders after he attempted to remove plugs?

Chas

Well, I consider my mechanic smart for not putting himself at liability and just cranking down on the spark plugs trying to get them loose. This condition started quite a while ago...I can't remember exactly when. I do remember that I didn't do any work on the car, and nothing changed that cause this condition to emerge. And while I haven't compared my car to others', it's very obvious that something is up with the car. I remember very well how the car used to pull throughout its powerband.

It's the same in all gears.

I highly suspect the same. I think I'll go in order of easiest to hardest, and replace the plugs, then fuel pump, then fuel filter, then get into the more involved stuff.

Didn't even consider the cat, or anything exhaust related. I'll look in to that. While I do remember this issue happening all of the sudden...it was very slight at first (and not persistent), and has gradually gotten worse and worse.

Haha good call...yeah I looked at the plug wires...they all were put back on the plugs.


Thank you all for your input...this forum has some very smart and insightful members.

ron mcatee

You need to get the plugs replaced first, then see what it does in terms of performance. always do the obvious and easiest first.