Mongo

Just came out of the garage doing the WD40 test on the 928 to see if the ISV is bad or not. The car had a very erratic idle today where the RPM speed varied between, well....stalling and 700 RPM. I ran the car for about 2 minutes to get the ISV to open and the WD40 to lubricate it. I shut it off after and am leaving it to penetrate over night.

However, if this doesn't solve my problem? Is this pointing to an MAF? My car has had difficulties starting warm for a while and you have to depress the accelerator a little bit to get it to fire when warm starting.

Rich9928p

Check out the idle switch. There are many past posts on which connector pin to plug onto and how to check that it provides ground. This is the first thing to check.

Warm it up, unplug the MAF and see if it runs better. If you can tell that it does run better with the MAF unplugged, your MAF is probably going bad. This is a very "gross" test. If you don't get a change try swapping with a known good MAF and see if the problem goes away. If no change, look elsewhere. Vacuum leaks are high on the list of problems. Clogged injectors, leaking fuel pressure regulator, etc.

If no change, then the idle speed regulator is probably going bad. If that doesn't cure it, the LH fuel injection controller manages idle speed regulation. If all the other possible causes are verified not to be the problem, I'd suspect a failing LH controller.

Mongo

yeek, well I don't like paying for a brain that's worth it's weight in gold; the unplugging idea sounds like a really good one Rich. I will let the WD40 soak tonight; when I leave for work tomorrow I'll see what happens and if it worked. If not, next up is the MAF troubleshooting.

goldknight

very similar to my 88's problem. I have tested the Temp 2 and its good. When i unpluged the maf it ran about the same. Hope you have better luck there then i did. I did find 2 plugs not firing but have not found out why as yet.

Mongo

Looks like the ISV check out on the WD40 test. Injecting WD40 did not change the idle. I don't have an MAF to swap with someone since my buddy Bill is out of town. I know that the MAF has never been replaced on this car. It has about 125,000 miles on it.....again this is definitely something I wouldn't mind doing. Hey Jim, expect to get my gift of a core and some cash in exchange for your healthy rebuilt MAF sensors when these holidays are over

Now back to dealing with my 944 and trying to get that car running on the road again

Mongo

oh BTW, where's the Temp II Sensor located? Might as well change that too!

goldknight

the Temp II sit in the water bridge just below the cross brace. It has a hard pulg on it just like the injectors. its grey on my 88.

Mongo

pic?

SteveG

oops

SteveG

http://members.rennlist.com/v1uhoh/underthe.htm

This is not an '86, but it is generic.

You're so damn helpless, must not have the manuals either.

Merry Xmas.

Mongo

Thumpity-thump-thump…thumpity-thump-thump…look at Frosty go..



I have them, I just don't use them because my 928 doesn't usually beg me to open them up every week to help it

But in this case, I'll go blow the dust off of my CD

Merry Christmas to you Steve. I hope you don't have the problems I do at the moment with cars....both of them

Mongo

Hey guys it definitely has to be the MAF. I took it out for a drive this morning and the car idled at 400 and almost stalled!

After coming home from the post office, I pulled into the garage and the idle was about 700 still varying +/- 200. When I put it in park it shot up to 900. Can you say MAF now??? or is this a fuel delivery issue? The car starts right up perfectly fine when cold!

jetrainor

Those symptoms are exactly like my 87....what cured it was new hoses and idle stabilizer under the intake....Consider what's called a 'valley service' and i bet your problems are solved. Not cheap though but my car started first touch ever since.

87 euro auto

the flyin' scotsman

Not necessarily.............I had my MAF replaced spring 2005 with a rebuilt recalibrated unit from our good friend in England, John Speake. Sometimes, not all, my car behaves like yours, after the MAF swap..........idle unstable, almost stalling to high idle to normal. I have also done the WD40 trick to the ISV and not much difference intially but has got better in that the car's idle is less unstable. I also installed a new O2 sensor with the X.

The only other symptom I have is poor economy but this may be because I love the way the exhaust note screams with the X and RMB. I'm thinking its the ISV and related hoses or the brain. Given both are original my brain is going to John for recondition and I may remove the intake for the ISV surgery when winter really sets.

Talk w/ JDS he gives great advice.

Brett928S2

The only other symptom I have is poor economy but this may be because I love the way the exhaust note screams with the X and RMB.

Hi Scotsman

Regarding the above quote,,,I am having an X-PIPE installed in January to go WITH my RMB.....

Every one I have spoken to says it will BE TOO LOUD ,,,,quotes like,,,"it will sound like ARMEGEDDON" or "like a FORMULA 1 car on STEROIDS"

As you have done it ...can you tell me what YOURS sounds like ?

Mine will have an X-PIPE at front...the 2 small resonators in middle (no cats as in UK) AND THE RMB at back....but I like LOUD


All the best Brett

928 S2 AUTO V8 4.7 LTR 1986 IRIS METALLIC BLUE WITH PROMAX CHIPS, RMB, KICKDOWN SWITCH.