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FINALLY, I have my '86 951 up and drivable after nearly 4 year restoration. Tomorrow I'm off to the alignment shop after a total suspension rebuild, including adjustable M30 front struts, 17" Cup one wheels and rebuilt steering. One issue that's puzzling me is that It takes forever for the car to start. It's got fresh 93 octane fuel, all new fuel system components throughout, and just did a pressure and leak-down test per Clarks Garage parameters. All is good and within prescribed limits. One lifter rattles for a bit (after sitting for a couple of weeks) and then pumps up but outside that, I'm stumped. The idle speed is 1,000 RPM, AFR is 14.7 and the engine runs strong. The AFM is working properly, all new vacuum system, replaced intercooler, ignition system, belts, rollers and front engine seals.
What are the 1st things I did was replace the DME relay with a known good one. Then did a fuel system test. All fuel system components are new. Since I replaced the speed sensor early on because it was chewed up (missing shim on the sensor) and reset clearances at that time I've discounted that as the issue. Also because the engine seems to run normal, once it's started. Am I missing something here?
I'll follow this myself since I recently finished a normal top end rebuild on my '89 S2 and it also doesn't start as easily as my 928 S3. which cranks once or twice (on a bad day) and starts right up after and intake refresh a few years ago. I know the 928 pretty well but I'm still learning the 944. No idea why mine has such a sluggish start either.
Doesn’t mean your 86 isn’t also notched, many prior years were notched by owners or their mechs when they changed the clutch, it was common practice at one time until it was found to cause laboured starting.
Mine's notched (it wasn't originally and it's an '89) but it's shielded, at least it has an aluminum tube that covers the reference sensor, which I've been told is the shield.
Maybe I'll try using some aluminum HVAC tape to put a piece of copper mesh EMI shielding over the slot.
I haven't looked down in there recently, but strangely enough, when I was trying to find TDC in the little window and below the bell housing, I noticed that the flywheel teeth were not showing up where they usually are (offset away from where they should be) and the flywheel didn't have the OT markings on it. This makes me believe that someone has replaced the flywheel at some point with an after market one, possibly a lightweight one. I'm suspecting that if that's the case and the flywheel teeth are just offset enough that they don't expose enough material for the passage under the sensor, I may be getting a weaker signal. My original sensor was gouged up by the flywheel and the small figure eight shim that should have been installed with it was missing.
view of flywheel from bottom
9 times out of 10 laboured starting is sensor related. Seeing as you’ve had previous issues with them, that might not be fullt resolved, I’d start afresh there and wyit, if you find your housing is notched and you don’t have the shielding, fit that also as per the tech bulletin.
As I reflect back I'm 90 pct convinced that my bellhousing isn't notched. That being said, I haven't really run the car in a long time. WhiIe I did rebuild the entire fuel system, the fuel and additive I had in the tank probably wasn't sufficient for a good running engine. Last week I added 6 gallons of 93 octane fuel to the a nearly empty tank. Now that I've driven the car a couple of miles around the neighborhood and cycled the good fuel through the injectors, after sitting 24 hours it started right up, idled smooth and ran great. So, unless it is a fluke, I'm compelled to believe this may have been a crappy fuel issue. I'll know in a few days after it sits for a while. If so, my thanks to you all for your continued support.
It looks like the sensor in your picture is shielded, but it would be nice to have that confirmed. My understanding is the aluminum casing surrounding it is the shield but maybe not? It does look pretty chewed up though. Have you thought about replacing it?
That pic is the old sensor which I replaced. I was right about the old gas being the issue. it runs and starts right up after a full tank of 93 octane. Finished the wheel alignment today and it drives really good. Now onto a cooling matter.....Separate posting for that
07-24-2018, 04:15 PM
'86 turbo starting problems
