Any special considerations for replacing the DME relay? - Page 2

Timmay! · 10-09-2011, 09:02 AM

Mono,
sounds like the relay is ok.

John_AZ,
That tip for using the BMW flywheel sensors is a good one. Saves $. Good on you. I had forgotten about that because we have so many used spares.

Solreaver ???
The 924S has the DME relay in same exact position as an early 944.
I doubt Joe average 944 owner has a noid? I'd check for spark at the end of the line- at the spark plug. Remove a plug and set it on top of the engine so that it can ground out and show a spark. That will verify your reference sensor, coil, distributor cap and rotor, plug wire,etc are all good and in one fell swoop.

monomoy4 · 10-09-2011, 06:16 PM

Quote:

Originally Posted by John_AZ

A sensor from a 1988 BMW 535i will work in place of the OEM Porsche 944 reference sensor--thus interchange and is cheaper.

The wire is longer and Porsche prefers the longer wire to prevent kinking of the wire in a TSB.

Do a search for others that will work on the forums.

I prefer to use sensors with the silver can at the bottom instead of an all plastic sensor. A little more protection for the sensor.

Pelican has both.

GL
John

Ah got it - figured that may be what you meant - thanks for the advice. I'll be sure to keep that in mind

monomoy4 · 10-09-2011, 06:29 PM

Quote:

Originally Posted by SolReaver

Sorry Monomoy, I never could keep the whole tach thing bouncing stuff straight.

OK, soo...the fuel pump energizes., we don't know if we have signal and we don't know if we have spark...Great.

yea, check for spark. Yaknow an industrious little fellow would have checked spark by now.

If you have a "noid" now would be a good time to use it.

Please don't ask me what a "noid" is...I would just loose faith in you.

With the ignition on check for voltage at the hot side of the coil.

Sensor connectors are taken apart very carefully and yes, they stink. Be aware the plastic that they are made out of has become brittle with age and if you are not uber careful it will all shatter.

When you have the connectors apart measure the resistance of the Sensors as Clarks recommends.

If you have spark...try a shot of starting fluid and see if she kicks.

Getting bored here....

Good advice - much appreciated. Heh, yeah Heard of the noid but haven't used it. I did pick up an ignition tester this afternoon. in the learning stages here regarding diagnostics...

84 944 oneowner · 84 944 oneowner's Garage

oh man i feel your pain and just fixed mine 944, Post one of mant problems, maybe not. Turns out my tach isnt even working, Replace both sensors speed and ref sensors, without both working you will get a no start 100%. hope it helps.

monomoy4 · 10-09-2011, 06:38 PM

Quote:

Originally Posted by CatsEyes

If it does indeed turn out to be the sensors (did you test the connectors yet, by the way?) I'd recommend reading up here before doing the change. It's not so hard, but a bit fussy.

Especially note the advice to cover up the small hole at the top of the clutch bellhousing where you look for engine TDC. Or just stuff a cloth in the opening. I forgot and had my heart in my mouth for a good couple of hours before I finally located the speed sensor bolt, hiding out of sight a few inches away...

Haven't tested the connectors, yet. I'm not sure what I was doing wrong, but I couldnt get the connectors to separate... I'll try again tomorrow night when I can work on the car again.

And thanks on note re covering the hole - yeah, I recall that advice and was sure remember!

monomoy4 · 10-09-2011, 06:53 PM

Quote:

Originally Posted by Timmay!

Mono,
sounds like the relay is ok.

John_AZ,
That tip for using the BMW flywheel sensors is a good one. Saves $. Good on you. I had forgotten about that because we have so many used spares.

Solreaver ???
The 924S has the DME relay in same exact position as an early 944.
I doubt Joe average 944 owner has a noid? I'd check for spark at the end of the line- at the spark plug. Remove a plug and set it on top of the engine so that it can ground out and show a spark. That will verify your reference sensor, coil, distributor cap and rotor, plug wire,etc are all good and in one fell swoop.

Awesome Timmay - thanks. Yeah - I think that ignition tester i bought yesterday will do what you're saying. I got the one that clamps on the plug with an adjustable gap. As you mention, this test was suggested by the guy who's worked on the car before. I can't work on this thing until tomorrow after work. DME i ordered will also arrive should I Need it. Tomorrow - Will be checking for spark, hopefully also be checking sensors if I can just get the connectors to separate...

All --Much appreciated help!!

CatsEyes · 10-10-2011, 07:35 PM

Quote:

Originally Posted by monomoy4

Tomorrow - Will be checking for spark, hopefully also be checking sensors if I can just get the connectors to separate...

Not sure I follow you. I meant the electrical connectors, which are connected only with a gentle push and one of those little metal clips, like an over-sized staple. Shouldn't be any trouble at all. A flat-head screwdriver should get the clips off.

You test the sensors at the connectors with a multimeter, as described at Clarks Garage:

http://www.clarks-garage.com/pdf-manual/ign-02.pdf

monomoy4 · 10-11-2011, 06:53 AM

Quote:

Originally Posted by CatsEyes

Not sure I follow you. I meant the electrical connectors, which are connected only with a gentle push and one of those little metal clips, like an over-sized staple. Shouldn't be any trouble at all. A flat-head screwdriver should get the clips off.

You test the sensors at the connectors with a multimeter, as described at Clarks Garage:

http://www.clarks-garage.com/pdf-manual/ign-02.pdf

Ah, okay - I figured those clips had something to do with pulling apart the connectors, but quite honestly, I've already thrown a ton of money into the car and was afraid I'd mess something up further. I'm glad to hear it's not a big deal.

When I test with the multimeter, should ignition key be turned to on? engine cranking?

monomoy4 · 10-17-2011, 08:33 PM

Just a quick update, anyone still listening? - Haven't had much time to work on this lately.

1) Tested for spark - none at any of the 4 wires (recall, there is fuel, though...or at least, pump is working...pump, filter, and injectors were recently replaced)

2) Also tested DME relay - replaced with new one that I had ordered as a spare...no change...replaced original after cleaning metal connections - the relay connectors seemed a bit - darkened?? with an odd burnt smell...not sure if this mattered since the new relay didn't work either.

3) Disconnected the speed and reference connectors...in great condition, physically. Tested terminals with multi-meter...With ignition turned on and using Clark's specs ("Sensor Resistance Checks"), it appears the the BG sensor (reference) was reading 1024 ohms on 25-26 terminals and a >1 M reading on 25-78 terminals. The DG sensor (speed) did not show response on the multimeter...at least not in the way I saw with the reference sensor.

Have not tested ignition coil. plug wires were not replaced with recent change of plugs, cap/rotor. The wires appear to be in okay condition and were not recommended for replacement by the mechanic. Recall, also, that there is no jump on TACH on crank.

SolReaver · 10-18-2011, 05:40 AM

Just noid if you can hear me...
Is there anyone on the home page?

No spark! boo hoo!
DG not showing response on the multi meter? like open field? Short?

Yea, if it is out of spec...looking like the sensor. unless power isn't getting to the coil or a dozen other things. Oh well.

I DID ask about power to the positive side of the coil and if you had tried a noid we could know if the injectors were firing..... BTW a Bosh noid is like 5 bucks off of fleabay. buy a couple and give them as stocking suffers to your Porsche friends along with spare DME's .

Hmmm...welll if the DG is out of spec...you know what to do. Hit it with penetrating oil to loosen hings up and get to it when you have a chance.

Timmay! · 10-18-2011, 07:47 AM

Mono,
I'm still listening..........busy, but listening.
Swap out that sensor with a used one.
Remember both sensors are the same part. Make sure they are connected right at the wiring harness tho. If the connectors break, make a bridle for them with zip ties.
Get together with other 944/924S owners in your area to pool parts/resources.
Keep working on it.

These are cool old cars.......

monomoy4 · 10-18-2011, 06:19 PM

Quote:

Originally Posted by SolReaver

Just noid if you can hear me...

I DID ask about power to the positive side of the coil and if you had tried a noid we could know if the injectors were firing..... .

Okay, okay - geesh, I'll buy a noid. I know I need one anyway... What do you think about the universal ones?...or should I focus on one that fits the 944 engine specifically?

monomoy4 · 10-18-2011, 06:24 PM

Quote:

Originally Posted by Timmay!

Mono,

Swap out that sensor with a used one.
Remember both sensors are the same part. Make sure they are connected right at the wiring harness tho.

Thanks Timmay! I'll take yours and SolReavers advice and get on that as soon as possible. I agree, this is a great old car...I hate seeing it sit in my garage unused.

Timmay! · 10-19-2011, 06:27 AM

The only noid I have is one that fits into the injectors plug of the wiring harness. About the size of a quarter.

michael944s900s · 10-19-2011, 06:32 AM

put ur or have sumone finger on the relay if it clicks at key entry n start its bad if it clicks once its good

michael944s900s · 10-19-2011, 06:34 AM

Quote:

Originally Posted by monomoy4

My 924S cranks and cranks but won't turn over. The fuel pump/filter are new and work. Plugs are new but I'm checking spark this evening regardless. There's no jump or movement of the the TACH on crank - People seem to point to crank position and speed sensor failures here.

However, would there be TACH movement if the DME is bad?? Seeing how removing the sensors seems like a very difficult job b/c there doesn't seem to be any room to work with tools, I figured maybe I'd try the "easier" job of replacing the DME instead and hope the sensors are actually fine.

Sorry for the long lead up, but I'm assuming I need to unscrew the lower fuse holder (1-9) to get to the #2 fuel pump relay? or is there some trick to getting to it without having to unscrew a bunch of stuff. It just seems like such a hassle to remove that relay, given the tight space and awkward position I have to get into to reach the relays.

DME Relais 944.615.227.00

Clark's Garage Shop Manual Index

Timmay! · 10-19-2011, 11:08 AM

MONO,
My noid says OTC 7602 GM PFI. The spacing of the contacts matches a 944 injector plug.

michael944s900s · 10-19-2011, 12:19 PM

did u check the ignition switch

monomoy4 · 10-22-2011, 08:43 PM

Coil good, have not checked ignition switch

Recap....dme relay/fuse good, fuel filter/pump good, injectors good, have fuel, have spark, reference sensor good, speed sensor appears to be bad

Just got 2 sensors in mail yesterday, and I'm ready to replace the speed sensor which seems to be the bad one according to my multimeter check....but even with a socket 10" extension, I can't reach the retaining bolt...let alone get my arm/hand down in the space to effectively guide the removal/replacement of the sensor. the sensors are located so close to the firewall and under other engine components that I'm unsure how I could access the retaining bolt without removing a whole lot of stuff to get to it. what gives? is there some unique difference between the 944 and 924S engine compartment design that makes this replacement more difficult on the 924S side? Aside from disconnecting the connector, what needs to be done to get this sensor out??

monomoy4 · 10-22-2011, 08:43 PM

Quote:

Originally Posted by Timmay!

MONO,
My noid says OTC 7602 GM PFI. The spacing of the contacts matches a 944 injector plug.

Thanks Timmay! appreciate the info