Irregular idle every now and again.

[bennkishh]

1981 Porsche 924 Weissach. Stock 2 litre, 5 speed. Sometimes my idle sits pretty at like 800 rpm, but sometimes it literally feels like its idling at aprox. 4 rpm's. I would say its a 70% 30% split between the two, with the latter being the 30%. As of now I'm uncomfortable driving the car as it sometimes cuts out. I know my battery is garbage, but I'm not sure if that's the problem with this. Thanks for insight mates

[Dave Colangelo]

I would say do a basic tune up, fresh air filter, oil filter and oil, fuel filter, spark plugs, distributor cap and rotor. If that does not take care of it then look into more serious options. I have found that those small things can get gunked up and cause serious issues for such simple and inexpensive parts.

If the battery is shot I would replace that as well and have your alternator checked then replace it if need be. One or both of these items could be contributing to the issue.

If that is not the cause then I would start looking into sensors, timing belt tension, or other more serious mechanical issues.

Regards
Dave

[bennkishh]

Originally Posted by Dave Colangelo

I would say do a basic tune up, fresh air filter, oil filter and oil, fuel filter, spark plugs, distributor cap and rotor. If that does not take care of it then look into more serious options. I have found that those small things can get gunked up and cause serious issues for such simple and inexpensive parts.

If the battery is shot I would replace that as well and have your alternator checked then replace it if need be. One or both of these items could be contributing to the issue.

If that is not the cause then I would start looking into sensors, timing belt tension, or other more serious mechanical issues.

Regards
Dave

Thanks a million Dave, looks like I know what I'm doing this weekend!

[Jrboulder]

In addition to Dave's suggestions:
Do the injector O-rings as they perish and cause vacuum leaks.

Clean the grounds because that's just good practice.

Run a bottle of fuel system cleaner.

[Gawernator]

^^^ I recommend the silver STP "full system" clean or whatever. I use one before every oil change in my 944 and it cleans stuff up well.

[Dave Colangelo]

+12345254 for cleaning grounds. I completely forgot about that, my first 924S had such bad grounds the wipers would come on when various other things were turned on. Also if you have the original vacuum lines in your car consider replacing them. Like all rubber lines they deteriorate over time. You can get a good length of hose for cheap, some new metal T joints to replace the plastic ones and have at it.

Injector O-rings are also a good idea. Remember to release the pressure in the system before removing the fuel rail.

Regards
Dave

[Jrboulder]

You don't need to depressurize anything o get the injectors out on a 924. It has CIS like the 911's 74-83. There is only one O-ring per injector and all you need to do is pull up on the banjo bolt. Don't pull on the braided fuel line going to the injector. The injectors are between the throttle body and the valve cover.

[Dave Colangelo]

Ahhh my mistake I was thinking 944, I stand corrected.

Regards
Dave

[bennkishh]

New battery helped it out a bit. Need to get a different one as the hood doesn't close properly with this taller one Still going to order the whole tune up kit off of the website. It's super inexpensive for what it includes, so I might as well do it. Timing belt will also be done within a week.