gricec

My car is in the shop at the moment due to a hesitation issue which has progressed to a no start issue.

They guy at the shop is a german guy and is pretty knowledgeable about BMWS and VWs. He says he has worked on Porsches before. I know he has had a 928 in there.

Well he thinks my nostart issue is down to the speed ref sensors. As he says that they are providing an intermittent signal. The funny thing is though, I replaced these about 3 months ago with the cheap ones from Paragon . part # 0.261.210.003. My old ones didnt fail exactly they just required tapping from time to time. The mechanic says that I should not have used these sensors ans should have used the proper ones. which are twice as expensive.

My ? is though would the speed and ref sensors cause hesitation if they were bad? Also has anyone else had a similar experience with this part? When my old ones started going, there was no hesitation, it just would not start without me tapping them.

MAGK944

I got mine from RockAuto, less than $50 a piece, genuine Bosch #0261231006, I think they were listed for an 80's Ford Escort. Have them fitted to two 944's with no issues.

Are you sure they were fitted (gapped) correctly when you had them replaced?

nickg

so does being a german make him any better a mechanic than anyone else?

gricec

Well tbh I replaced them so I may not have gapped them correctly. I thought that you only did that if you actually replaced the bracket.

So these sensors can produce a hesitation. The strange thing my tach is bouncing so I thought that means that they are good. I just dont want to buy a new set of sensors when the problem is something else.

As for the german part, probably not, but he certainly looks the part. He does do a lot of work on older BMWs. He also did a good job with my clutch.

PorscheDoc

how about the harness to the DME and not the sensors themselves.

PorscheDoc

Oh and i have used dozens of 325e sensors (the cheaper one than the porsche) and have never had an issue. Not to say the sensor can't fail prematurely in general, but it isn't because it shouldn't be in the car. The only difference was the length of the wire.

gricec

Thats a good idea.

3 months does seem a little bit too premature for a failure.

Weston

Yup, that's my suspicion as well. My car seems to have an issue with the reference sensor intermittently losing its connection due to the wiring harness (new sensors and I tried two different DME's). Here's what I've found...

The reference sensor is the one towards the front of the engine (furthest from the firewall). If it is disconnected, the car will not start and the tach will not bounce while cranking. However, if it is disconnected after it is already running, it will not die and the tach will still work. I wouldn't say that it will run right without it, but it will at least idle and rev up.

The speed sensor is the one closest to the firewall. If it is disconnected, the car will not start and the tach will not bounce while cranking, and it will immediately die if the engine was already running.


So, if you have a intermittent no-start problem related to these two sensors, but the car does not die once you get it started, I would suspect the reference sensor and its wiring, rather than the speed sensor. And when you have new sensors, that really points to the wiring, which is a common problem on these old cars, or perhaps the DME. But if you end up replacing one harness, I'd just do both and be done with it. In fact, if I had to do it all over again, I'd replace the wiring harnesses for these sensors before anything else.

gricec

well my initial problem was alot of hesitation on a cold start. Which at first went away when it got warm. At that point it started every time, but when i gave it gas it would stall.

Now it wont start at all and the tach is bouncing. The odd thing though was when I changed out the DME relay with a brand new one, the tach stopped bouncing. I guess it was just a bad one

It is also definatley getting fuel.

Charlie

Have you tried a different DME. I also had a problem where my car was running rough and then became a no-run (it would only start for a second or two) and it was due to a hose on the bottom side of the intake manifold creating a big vacuum leak. This hose could not be seen from the top of the motor.

CurtP

That's listed as a knock sensor.

Luis de Prat

This is what you need to double check, I think. The 0.8mm gap may be off.

There's a fellow in the forum from Canada (Sebastian?) who went through all the trouble of replacing the sensors AND the harness only to find he was still having an intermittent non-start issue.

PeteL

FWIW, the Paragon ones work fine for me.

MAGK944

My bad, looking at the wrong invoice, they are Bosch part #0261210003

Mine came from here: http://cgi.ebay.com/ebaymotors/Porsc...QQcmdZViewItem $70 each

gricec

Well I changed out the new sensors with my old ones(that need to be tapped) and it ran!! for all of 2 secs. So maybe these sensors went bad quick, got some more on the way along with a fuel filter. See what happens then. Fingers crossed.