Need some basic help re: maintenance

[Rob Gold]

I haven't driven my 83 911sc much lately. Took it out the other day, and the engine is running very rough above 3k rpm. If I do not finesse the accelerator, the engine will die at idle. I am a novice , but the car feels like it is loaded up, and that is why it is missing. Is there any truth to the theory that if I drive it hard it will clean up the plugs?

I was reading in the forum that I should change the plugs or at least remove them to check their condition. When I started to remove the plugs, I realized that because the car has ac, access to one side is difficult. Is there a recommended method to remove the plugs? Which items in the engine should be removed if any to get to the plugs?

Thanks again

Rob

[Zeke]

I had a '77 (CIS like yours) in the body shop for a couple months years ago. Starting and driving a few feet at a time did foul the car up good. A long drive helped a lot. But, you may have issues beyond some fouled plugs. Best to at least look at one on the side you can get to before going the full monte on a tune up.

[ramonesfreak]

i believe the answer is yes, but you may not have to drive it hard...just drive it for a long drive. when i got my car, the owner had not driven it for 9 months. when i test drove it, he had no plates on it so i had to test drive it in the neighborhood....which i dont advise. during the test drive, it stalled a few times...i thought it was weird but the owner didnt seem to be bothered by it..anyway, i bought it then and there...when i picked it up and drove it home...every time i got below 15 mph it would stall. the 30 minute ride home it stalled at every light...and everytime i was stopped. my heart sank as i had zero knowledge of the internals of these, or any cars. well i started to freak out but thought about it and decided to go get a full tank of gas and go back out for a drive. it was about 8pm and i drove till midnight back and forth on the highway at regular speeds.

after that first night, all i had to do was turn the idle up a bit and its been perfectly smooth ever since, about 11K miles - one year.

give it a try before you start taking things apart. if that doesnt work, the experts here will help you trouble shoot and advise you which gauges you should get etc... :-0

[oneblueyedog]

Running a bottle of Techron when your tank goes below a quarter tank and then driving it as long as you can stand it might help. Maybe a repeat couple of times. Cheap to try. Worked for me on numerous times. Might be a bad tank of gas too.

Best!

[dshepp806]

Originally Posted by oneblueyedog

Running a bottle of Techron when your tank goes below a quarter tank and then driving it as long as you can stand it might help. Maybe a repeat couple of times. Cheap to try. Worked for me on numerous times. Might be a bad tank of gas too.

Best!

Can you get the comp out of the way so as to access the plugs on that side? I'd change ALL of the plugs out (as a starting point).

After the Techron, do get that oil changed......

Best,

[Rob Gold]

Thanks for all your advice. I think I will get the techron, and drive it because the car was not running badly the last time I put it away. I don't know if this means anything, but when I looked at the distributor cap to make sure everything was on tight, I noticed a vacuum line that had popped off below. Would that cause the car to miss even after I made sure it was securely back on?

again , thanks to everyone for their help. This forum is the most enjoyable read on the net.

[ramonesfreak]

im not sure what you mean by "miss"...you mean misfire? are you sure you are describing the symptom correctly? you described rough idle and what i assume is having to keep giving it gas at idle in order to keep it from stalling. i dont think that is a "miss". i dont think the hose is your problem. i think letting the car sit was the problem and youve got some dirty injectors. put whatever bottle of fuel injector cleaner in there, fill it up, get the engine up to temp and rev it a bit for 50 miles or so. i bet it clears up - especially since the car was running fine before you stopped driving it for a period of time

putting the hose back on should correct whatever symptom that was created by having it off. but again, i dont think thats your problem, especially since you indicate you put the hose back on

[Rob Gold]

Installed a new fuel filter last night. Interestingly, the low rpm idle improved immediately, I can start the car without using the gas pedal and it idles without dying. I thought I had the problem solved until I took the car out and it still is running rough and without power at rpms above 3K. I still have less than 1/2 a tank of gas treated with techron. Could the techron be affecting the performance?

when I take the car to redline, it feels like it is misfiring , but not stalling or backfiring. As always, your help is appreciated

[tshih]

The fuel distributor and other components of the CIS FI system are very prone to rust caused by ethanol fuel these days. I have a 1974 914 which was running fine but exhibited bad symptoms like yours after it sat for 5 months. The best running cars are those used daily and have fresh fuel cycled through these systems. Unfortunately these older FI are most vulnerable to todays' water attracting fuels.

[Pazuzu]

Clogged cat? Does it cough and buck above 3K? Can you even get it to 6K, or does it fight enough that you can't even get it that high?

[Rob Gold]

it does not cough or buck it climbs right up to 6k, but you can feel hesitation, it simply does not drive like it used to. I would almost describe it like a stutter

[beasty]

check your dme relay. its under the driver side seat, it could be overworked.

[Rob Gold]

what is the dme relay, and how can I tell if it is defective?

Thanks

[gtc]

No DME relay on SCs... it's the relay for the ECU and whatnot on the Carreras.

[gtc]

Did you check inside the distributor cap to make sure all the contacts are in good shape?
It still sounds like a fuel problem to me, though. In my opinion, Techron is a good preventative maintenance treatment, but it won't work miracles on seriously varnished injectors. If you get through your half tank of gas and fresh fuel doesn't make it better, I would try testing the injectors for good flow and spray pattern. I'm not sure how to go about that on a CIS car, but it would basically mean pulling them one by one and having them squirt into a jar, while noting how they flow and mist the fuel. There is a good shop here in Washington that will clean and check injectors for a reasonable price -> WitchHunter

[dshepp806]

When did you last change out the dist. cap, rotor, plugs?

Best,

Doyle

[Por_sha911]

How long did the car sit? How old is the gas? If its been a long time, you may just need to fill the tank and drive the sucker.

[Head416]

Originally Posted by Rob Gold

I don't know if this means anything, but when I looked at the distributor cap to make sure everything was on tight, I noticed a vacuum line that had popped off below. Would that cause the car to miss even after I made sure it was securely back on?

Hazy memory . . . is this the vacuum advance?
(Not that it's the problem, just curious.)