Please check your speed sensor or crank sensor.We did a complete intake job last july and never did replace this sensor.Well the car ran awesome and a few days ago the idle went from 750rpm to around 500rpm at idle during a stop and stalled.I was dumb founded,shee i should have stick with a new car again thinking.I called Roger and 928intl-this part does not go bad often,but check -well i bought one and i needed to install quick.I started to unscrew the old one it looks good all around until i took it out everything from the connector to the boot of the old sensor fell apart.I say look can be deceiving,and i installed a new one today.The car ran like it supposed to and pulls hard.Please check this sensor if your car had replaced everything,but thought this part could not cause your car to stalled or idle a little rough, and it can cause a fluctuation in rpm.This is one of the many problem in our aging beast.

 

I disagree and think the the crank sensor is NOT a very common problem area.

Knock sensors are another story

actually you said unscrewed the sensor, maybe your talking about the knock sensor? If a crank sensor doesn't work i would think the car wouldnt run at all? Knock sensors are notorious for crumbling up, crank sensors.... uh not so much. Was it one of the knock sensors, there is a small allen screw holding the crank sensor in, but once the screw is out its often times a PITA to remove the sensor because of the o-ring in it. You didnt mention any swear words so maybe you have your parts mixed up?

 

The crank sensoer is a good thing to replace, when you get easy access such as when doing an intake/fuel hose replacement. The nightmare scenario is if the connector body of the crank sensor breaks, when you're twisting off the sensor. I suggest applying penetrating oil and letting the car set overnight before removing the sensor. There are good reasons for making a clean sweep and refurbishing/replacing all likely suspects when doing an intake job: The more you find youtself removing harness connectors in the future, the closer you are to a harness job. Finish and button up the top end job all at once.

 

I have had two cars reported to me in the last couple of months that ran fine when the engine was cold/cool but cut out when the engine was hot.

One car would cut out if the engine was worked hard and then wouldn't restart for 5 minutes or more.

The other car could be left idling and shortly after it came up the normal temperature it would cut out, and wouldn't start until it was left to cool off.

In both cases the flywheel speed sensor was the cause of the problem.

 

I just replaced my crank sensor when I did my intake R&R/fuel line replacement job. The connector to the harness crumbled and broke (see pic). New part not cheap$$$. I'll rebuild and sell cheap the old one if anyone wants it. It worked fine prior to pulling out, and except for the connector, looked ok.

 

This was a problem on my car ! It took months to figure out that this was my problem and the connector just fell apart when I touched it !

So I agree

 

I stand corrected

I wouldn't think a car would run or start if the crank sensor was faulty. Good to know

Good post by the OP. Check your crank position sensors

 

The material used on the sensor side for all of the three-pin connectors crumbles after 10-15 years. Knock sensors, Hall sensor, speed/crank/impulse sensor. (Although, the knock sensors used on 91+ seem to use a different material.)

I am curious. Was the speed sensor harness connector in the retaining bracket when you decided to remove it? Or had it been removed from the bracket previously?

That is the by-the-book failure mode. Vibration, noise or heat-induced transient (or not-so-transient) errors do happen. The good news with the speed sensor is that even the bizarre failure modes at least (seem to) result in the motor simply stopping. Similar issues with the Hall sensor can be very, very vexing as they do not seem to result in a simple timing retard as The Book suggests.

 

I just replaced my Hall sensor on my '90, the connector was fragmented and only the metal pins were holding the connection together. It took a good 5 minutes of picking out crumbly fragments of plastic to get the old male connector remnants out of the harness connector. I didn't replace the crank position sensor when I did the intake, I don't recall disconnecting it, or I probably would have shattered it too.....

 

My crank sensor connector was in the same condition in my 90GT. Only 73K miles. I've been trying to track down an idle problem & removed my intake for the 3rd time. I had not checked this sensor before & sure enough, the connector crumbled. This sensor, however, was working according to Theo's diagnostic tool. I am replacing it anyway & got a screamin' deal on Ebay: http://cgi.ebay.com/ebaymotors/ws/eB...MEWN:IT&ih=005 $19.95 + shipping. You may want to keep an eye on this vendor if you need one.

On a side note, I discovered the problem with the idle in my car. The plastic pipe that sticks out the top of the oil filler neck was broken off inside the neck. This pipe is attached to a rubber hose that runs to the bottom of the intake & caused a slight vacuum leak that has caused me great grief. I fixed it for now with some black RTV- hopfully it stays fixed.

Brian

90GT Guards Red/Lt Grey Sport Seats, Ott X, Bilstein/Eibachs

 

I have replaced them as a standard item on all my 928s, along with a whole list of other sensors and ignition components...

To each his own but I personally hate chasing down little gremlins that could have been avoided because of these sensors.

 

Wow $19.95 that was way cheap. I thought I was one of the cheapest at $154.28.

 

Yeah. $19.95 is fell-off-a-truck cheap.

 

I can't believe that price. Roger had the cheapest at $154. I am not sure I would trust a $20 part that is supposed to replace an oem part that costs many many times more. The thought of breaking down somewhere, getting a tow (with all of the bad things that can happen with that) diagnosong the problem, tearing off the intake and the fuel lines again, keeps me from trusting deals that are simply just too good...my .02 anyway

 

also, upon closer inspection in that ebay listing, the crank sensor lists for $99.99 (altho it looks like the win bid was $19.99), and to my eye, it looks refurbished and not new. The plastic housing is not slick and shiny like the new one I just bought, but crinkled like the one I just removed. I know the add says "new condition", but that picture tells a different story....