When things get really odd and everything else seems to check out.....it points to LH....plain and simple

Okay your in Quartz Hills which is just outside of Lancaster......there has to be someone close that could lend you an LH for testing......which works best by removing your ??? LH and plugging it into the otherwise well running 928 for testing.....

 

I've suggested you swap your LH into another 87-95 928 2 or 3 times now. Brian just suggested it again. You can check sensors, as you have, till the cows come home, but you won't be able to diagnose a failing LH.

 

Well, perhaps it is the LH but I see nothing wrong with testing the other components as they can cause similar symptoms. Some here state that the LH goes out as often as you need an oil change and others that state that the LH rarely ever goes out.

I may send the MAF and LH to perhaps 928srus for diagnosis.
But diagnosing a problem is half the fun.
thanks for the input.

 

I wasn't criticizing your sensor testing. I think you've done it. You should test the LH. Yes, after 20 years, LH failures are very common, but don't expect it to fail like a yearly oil change. Mine failed a few years back, but I don't expect the replacement to fail for a very long time. Here's what John Speake has to say:

"These ECUs have a poor reliability history. This is almost entirely due to failure of the “tile” – a Thick Film hybrid circuit exclusive to Bosch. JDSPorsche has developed a re-engineered replacement for this vital component."
http://www.jdsporsche.com/23fiecu.html

 

I only witnessed one LH failure and when it went it did the clickity clickity of the injectors. It was plain as day. The car would not run at all. But that's not to say that yours has failed int he same manner.

A faulty TPS could provided similar rough running, but if you hear the click, it's probably good. But best to ohm it to be sure.

If there is a 87+ 928 nearby, you should buy a bottle of wine and sweet talk the owner into letting you swap the LH for a difinitive test. (Sending to Roger would also work - but doesn't include the wine!)

 

Looks like I'll be back in Cali this weekend, and I have a known-ggod car with a known-good LH, and a known-good source (or three...) for repair. If you haven't come to a conclusion by the time I filter through the gotta-do-this-first-before-you-do-anything-else list, I may be able to test yours in my car in Glendale or some point in between. Don't know if the PCA breakfast is this Saturday in your area, for instance.

Pull the LH brain loose and take it to someone local who has a S4+. You can plug yours into their car and know in a few minutes whether you are chasing a failed-brain problem. A couple screws hold the pass side junk tray in, and the bracket with the brains on it comes off with a couple Allen-head screws. You can bring the whole thing or unbolt the inner (closer to the fender wall there) box and just bring that. PM me if you can't find a closer volunteer.

 

Andrew: That's the classic failure. When mine failed, the car would start but it would not run above a very rough idle.

 

Dr Bob, I sent you a PM, thanks

 

Here's a vid of that LH I saw fail. We put it in my car as it was a know good runner.

http://members.rennlist.com/andrewmolson/Failed-LH.WMV

 

Looks like we'll be testing his components in my car today or tomorrow. Short of sending a test brain to try in his car, this is the definitive test method I think. This will be the second test-and-try for me in the last month or so. We can't blame winter storage here for under- or over-voltage issues. Must be something in the air.

News later after the testing.

 

Hmmm. The jar the old one came from said abby-something. I'll call it 'disturbed'.

Same symptoms plugged in to my car, plus it took a bit to clear out the 'extra' fuel once I put the connector back on mine.

 

Thanks again Dr Bob for your assistance . Beautiful home.

Bad LH. Now time to find me a replacement as the car is up for sale shortly-I am looking for a nice GT to boost. I suppose I am glad it went out now before a sale vs after as I would not feel comfortable with selling a car with a bad ECU in it.

 

Lee, it was a pleasure meeting you and your son last evening. Glad you were able to find the place. I need to go sit in on a few city council meetings and get some action on our little 'road closed' problem I guess.

Give Rich Andrade a call and get your controller on the way for repair. It's about as fast as the UPS driver will carry it, and you'll be on your way.


On your GT quest for the supercharger project--

I thought about this a little after you mentioned it last night. If I was looking for a car to boost, the GT would not be at the top of my list. First and foremost, I wouldn't like to see a good GT 'cut up' into a supercharged hot-rod when it's a pretty good hot-rod example out of the box. Next reasons are more practical. The high GT compression is exactly what you don't want in a blower car. The quicker gears are a waste with all the extra torque, unless you own a tire store and a refinery. The manual trans is wonderful and fun, except for the clutch and maybe the shifting part. Look at threads here that discuss the significantly upgraded clutch requirements, and the quests for replacement input shaft$ that are NLA.

My thinking: My quest for a blower candidate would be a '87 or '88 S4, or maybe an '89+ with a 2.20 final drive swap from the earlier car. LSD a plus. I'd accept a manual, but in this situation might actually prefer an auto. The auto is a real simple final drive swap compared with the manual, since the pinion bolts on. I might send the gearbox to one of the better rebuilders to beef it up some, especiallly if you are going with one of Tim's stage-III monster setups.

Conclusion: You may have the ideal candidate car sitting in your garage right now.


JMHO, YMMV, etc.