SteveG

FYI: 944: You probably know, but you mentioned a limited tool supply: A generally useful tool for removing "C" clips that hold elect connectors in place is a dental pic. Actually it needs to be a little stronger, mechanical pics are avail thru Harbor, Home Depot has a set of 3 various curvature, for 8-9 bucks. I'm sure Porsche has their own tool at several times the cost. If you were doing a lot of electr, it might be worth it, anybody have info on that, John?

John Speake

Hi SteveG,
I don't know of a Bosch tool, but I expect they do have one, being thorough, methodical people !

I don't usually have a probelm to disconnect the Bosch connectors, rocking them side to side, lengthwise usually unclips one end, and then the other. The 6 way MAF connectors are a little harder, but the come unplugged reasonably easily.

Porsche have a long handled 2 pin Bosch connector tool in the Tools Catalogue, It's intended for the idle stabiliser connector on the S4 and later 32v which is tricky to reach. This tool does not have a spring release function, just relies on rocking and pulling.

Jeff928S4

**Update**

I managed to simply pull the connector off of the MAF by hand. I thought "ohhhh - maybe this was my problem". It wasn't.

With the MAF unplugged, I started the car up and noticed right away that it was "crisper" (no hesitation when giving gas and no looping of idle/gas input)....but, it would not hold idle at all. Foot off gas resulted in an immediate stall. The smell of gas was very noticable also. I don't know if this is "limp home" mode, but it sure a heck would be hard to limp anywhere the way it was running and smelling.

After I plugged it back in, I didn't notice my looping idle was less "loppy", but it may be a placebo effect of the unplugging and plugging back in. I think what John said about it needing to be a gross MAF failure before you will see any difference is what is causing my inability to diagnose this. Perhaps my MAF isn't totally gone yet, but I do suspest it's on it's way out. I will try to get it tested properly or go the donor route to finally know the truth.

A second possibility....could a bad Fuel Pressure Regulator be giving me this up and down surging feeling? Wouldn't a bad FPR effect the car at all RPM's though? Mine is only bad under 3000 rpm. Over 3000 and the car runs almost perfectly.

John Speake

78km is a low mileage for MAF ageing to be an issue, but it depends on the usage the car has had. If lots of shortish >10km journeys, then, yes it could be aged.

There are several other possiblities as well. Although it runs OK at higher rpm, is the fuel consumption higher than you would expect ?

Bill Ball

Normally a looping idle would be the idle stabilizer, but your oscillations are too wide, I believe. Still, it would be worth putting a few 10-15 second blasts of WD40 or another solvent/lube into the vacuum line that feeds it, letting it soak, start the car, repeat. The vacuum tube that feeds the stabilizer is the large one that runs along the driver side of the intake near the throttle plate. It is the one that comes off the Y-connection and disappears under the intake (the other arm goes to the brake booster).

Jeff928S4

I'm not sure how to gauge the fuel consumption exactly. Basically, if I put in 10 litres of gas, I get 100 klms showing on the "remaining distance" display on the dash and that disappears quite quickly. It does seem to go through a lot o' gas in comparison to the 944 I had. Almost double, it seems. It doesn't seem to burn gas hardly at all on the highway or if I drive very conservatively.

The car is now used primarily for short trips. My drive to work takes 3 minutes...then it sits till I drive the 3 minues home again. I take it to the store, but those are usually short trips also. The PO pretty much did the same thing...just used it for short trips back and forth to work and the odd weekend trip. I talked with him and the said the car only had a problem with jumping spark, due to aging plug wires when he sold it to my uncle. The car had sat on a lot on and off for about 3-4 years prior to me buying it. It had rougly 800 klms put on it in a 3-year period.

Does that info help at all?

Jeff928S4

I've done this trick a few times. Didn't seem to effect the car too much. I do know that the injectors are quite dirty and have run a few bottles of cleaner through the system also. I don't see dirty injectors having the effect I'm getting.

Sometimes the car idles at 1200 - sometimes at 600. But always it won't stay steady. It wasn't too bad, then I cleaned up the battery really good (lots of white powder on posts) and it seems to have multiplied the problem. Before the battery clean-up, the loop was not noticable while giving the car gas...only when off throttle and it seemed to go up and down, but with the feeling that gas was being applied at all times........little gas.......more gas...little gas....more gas. After the clean-up, you can now feel the loop when applying gas under 3000 rpm - like the car is driving on pavement, then in sand, and back to pavement. Now when off-throttle, it more of a gas on........gas totally off......gas on, etc. feeling.

Bill Ball

Well, O2 sensor and failing LH brain would be on the list, but before you go replacing the car a part at a time, there was someone else with a similar problem posted here a few months ago. Let me do a search.

But in the meantime, certainly the MAF is a possibility. The best thing to do would be to appeal here for a Scotian that might be in your area with an 87-91 car with who you could swap parts. It's simple to swap the LH brain and MAF. Generally you swap the suspected bad one into the good car, as the bad car MAY have an electrical fault that is taking out the parts.

Jeff928S4

Thanks Bill....

I do have a "Scotian" (funny) near by. Garth S has helped me with his knowledge and kindness in the recent past on a timing belt retension. We are currently setting a time to do the MAF swap. That will be one bird down hopefully and I can go from there. I was doing all this self-MAF testing to save possible trip, but then I remembered, "Hey, you drive a 928....trips are a good thing".