Tune Up, Spark Plugs, Idle things

Marcone · 12-29-2007, 09:36 AM

Ok.. i took a day off work today.. watched as many episodes of Dexter as i could... now its tune up time.

I have the S2 to tune today.

I know it needs Spark Plugs
What ones are recommended?

Im having a slight rough time with its idle.. every once and a while it seems to give one out of sequence 'lump' ... i dont know what mis firing feels like but i hear everyone talk about it all the time.... so could some one give a pointer on that?

lastly ... every once and a while it searches for its idle between 1k and 800 rpm .. im assuming this is all related. So i am going to start with plugs. i have a new DME relay to put in, and maybe some WD40 in the idle controller(is that recommended?)

Can some one point out something else i should get to?

Thanks everyone in advance!!!
the porsche tuner is closed today and I would be relying on Canadian tire if you werent around.. and well.. just thanks!!! haha

hpservertech · 12-29-2007, 01:11 PM

For the idle hunt, check your vacuum connections. You might have either a cracked hose or one that isn't connected.

Marcone · 12-29-2007, 01:22 PM

Even with that little bit .. its only going up and down a couple of hundred rpm once and a while ..

Razorback1980 · Razorback1980's Garage

Idle hunt is usually vacuum issues but it can be the idle control valve as well as a few other things. Use the factory recommended plugs as most say there are no others out there that are better. New DME relay isn't a bad thing to change periodically although I don't think it will help it run any better. I keep a spare one in the glove box in case mine goes bad and the car won't start, but I don't periodically change it. Maybe I should. Other than the plugs the plug wires and distributor cap may be issues. I also change my O2 sensor periodically but most don't.

Marcone · 12-29-2007, 09:35 PM

Thanks.. i changed the DME relay because it hesitated one day and died.. that was a symptom of my other one going. its been a few weeks without trouble...so i just put a new one in.. and am gonna use the "decent" one i took out as the backup to get me out of a tight spot one day..

New NGK plugs in .. they are direct replacements for the bosh ones that are recommended.. and i heard theyre better.

My turbo is f'd but i posted that over on the other side.

The idle issue didnt go away completely..but was aided.. the startup was quicker too.. old plugs looked tired but not in a bad way. Reminds me .. the valve cover does look a little tired too.. time to have her polished

hahaha

Ill keep hunting for the culprit. it may be the wires.. as its only periodically that it shudders a little at idle.

what vacuum lines should i look at first?

Thanks

Marcone

Razorback1980 · Razorback1980's Garage

There is no way to tell which one it is. Often times it's actually the connectors over the lines themselves. The hard part is some of them are under the intake and hard to see. Also take the J boot off and look for cracks in it along with the tube that runs back to the oil/air separator. One person suggested that you spray connections with WD 40 while it's running and if the idle changes, then there is the leak. I've never tried that, but it sounds like it would work if you don't mind that stuff all over your engine. I just change mine periodically.

gtroth · 12-30-2007, 07:51 AM

It kind of sounds like it is bouncing back and forth between cold idle set point (~1050rpm) and normal (~850rpm). So you might check the temperture sensors (NTC I & II).

But I too would start looking at vacuum leaks. The usual way is to spray suspect leaks with carb cleaner (or even an unlit propane torch) and watch for an idle surge as it gets sucked into the leak, but the ISV compensates for that pretty well unless you disconnect it. Try smoke (have a cigar).

hpservertech · 12-30-2007, 08:02 AM

I would just replace all the vacuum wires & connectors. Lindsey has a kit that is cheap and easy to do.

Marcone · 12-30-2007, 02:16 PM

Thanks guys... Upon reading this i failed to mention a problem that i assumed would be unrelated.

The fans only turn on for about 30 seconds and shut off and back on then off.. when the car is off.. normally my others stay on for a little bit and then stop completely.. i was told that it was a temp sensor.
Where are these?

and Really... there is a kit with all the lines i need? awesome!

As far as the rest of the tune up goes.. im into vacuum lines and this temp sensor now..

i had the thing pressure tested and it read around 200 ish but one was at 180.. should i do the head gasket too?

Thanks for the aide!

Marcone

Tidybuoy · 12-30-2007, 04:40 PM

Marcone,

With regards to the vacuum lines, I had the identical symptoms as you - a very small surge from about 800 to 950 (just enough to make the engine vibrate a little).

Regarding the kit mentioned above, it may not have "all" the lines as there are many. I did mine over a 6 month period and with each change to new lines, my surge problem improved.

Some lines, you won't be able to see cracks (i.e., cloth covered) but if your car still has the factory, non-adjustable, hose clamps - you can assume they are old and need changing. The cloth lines go to the charcoal cannister under the driver side fender.

There are also small hard-plastic lines. I did not notice any improvement when I changed mine out but I noticed that the little rubber connectors were loose. So I ordered those (I think there are 9 u-shaped and 3 y-shaped). This made a big difference when I changed those. You may also want to change the large hose that goes to the brake booster.

My last project which I am planning to do in a few weeks will be to change the hoses under the manifold that go to the oil-seperator and idle control. I will also clean my idle control with carb cleaner.

Anyway, my hunting idle has gone from 800>950 to 900>950 and that little bit has helped a lot. I also changed my 02 sensor but that made no difference as my old one must have still been good.

Lastly, if and when you change the hoses under the manifold, you will have to remove the manifold to do that (so order manifold gaskets). When I do mine, I am also planning on cleaning my ground points that are under there as these can get coroded and really can only be reached with the manifold off (at least with my fat hands). I've also heard it's a good idea to replace the nut and washer on the engine ground point with new hardware (cheap and better than just cleaning).

Vern

Razorback1980 · Razorback1980's Garage

I like Vern's advice. I too found the rubber connectors were a problem on mine and I replaced them all.

The temperature sensor for the fans is not related to the running of the car. The fan temp sensor is on the radiator under the top radiator hose if I remember correctly. The temperature sensor for the computer is on the engine.

John_AZ · 12-31-2007, 05:28 AM

Marcone asked as well, "... maybe some WD40 in the idle controller(is that recommended?)"
I don't know if it's recommended but I have read some listers do it. The hoses are real stiff and subject to cracking by the ICV. It is something to fix later like Tidyboy said. Get new ICV rubber mounts at Pelican for $4.50 each because yours will crack.

I'd like to know the best source for the rubber "U" and "T" vacuum fittings.

Happy New Year to all,

John_AZ
1988 924S to Show
1987 924S to Go
1998 Cherokee to Tow

Marcone · 12-31-2007, 06:08 AM

Wow..thanks for the huge help.. this will be a good post to look back at when working.. thank you!

I appreciate all the info.. ill get started in the new year..

Happy new year to all! and ill let you all know what goes down once i get the stuff ordered and installed!

Marcone

Luis de Prat · 12-31-2007, 08:22 AM

From reading this thread it's not clear to me whether the responses are referring to a 944S2 or a 944 Turbo.

At any rate, there are a lot more vacuum connections to check on a Turbo than an S2. What you describe sounds ISV related and, as others have suggested, I would try pulling it out and rinsing it with WD-40 or some solvent.

If this is a 951, then you definitely have a lot of vacuum lines to check, including a blue plastic check valve towards the back of the intake manifold that may be loose or disconnected. When this valve broke on my 951 I got a loud hissing sound from the back of the engine and the car would not boost.

Happy New Year to you as well!

Tidybuoy · 12-31-2007, 09:30 AM

Quote:

Originally Posted by John_AZ

I'd like to know the best source for the rubber "U" and "T" vacuum fittings.

I got mine at http://www.944online.com/home.html

They're not cheap (about $8 bucks each for the Y's and $4 for the U's). They also sell the hard plastic lines by the yard. My hard plastic lines were not in too bad of shape but they were brittle.

Vern

p.s. my vacuum situation was for a n/a 944.