944 wont start.. please help!

Gonçalo · 03-27-2014, 12:27 PM

Hello,i have a 944 84 and the engine cranks but it will not start, i get no spark and no fuel , already did a dme jumping but stills the same..no spark and no fuel..the tach does not bounce also..any help would be appreciated

schibsted · 03-27-2014, 01:11 PM

Quote:

Originally Posted by Gonçalo

Hello,i have a 944 84 and the engine cranks but it will not start, i get no spark and no fuel , already did a dme jumping but stills the same..no spark and no fuel..the tach does not bounce also..any help would be appreciated

Hi! I'm pretty sure this related to the speed/reference sensors. Atleast on a late 944 if they don't work, the DME does not know the engine is spinning(cranking) so all your doing is turning it over and over. The DME uses these sensors to determine spark timing, injectors and i'm guessing fuel pump activation.

More about this here: Speed and Reference Sensors - Checking, Replacement, and Adjustment

I'd do a test of them to see if they're the problem

markivtruck · 03-27-2014, 09:47 PM

check speed and reference sensors at the rear of engine they have a black connector plug one on top of the other. they are very brittle with age [ heat bakes them ] carefully disconnect each plug do not mix them up. there is a spring wire around each plug that fits in a groove carefully remove that clip with a tiny screwdriver put rags below wiring plugs in case you drop a clip first. once plug disconnected take a ohmmeter and check resistance between terminals on harness that goes to sensor [ 3 pins ] should read between 800 to 1100 ohms check between center and outer pins if no reading sensor is defective check both sensors. both sensors are the same part. bmw has same sensors but cables are longer but they are cheaper thru world pac parts but you have to have an account with them. good luck

Gonçalo · 12:37 PM

i checked them, both read about 950/1010 ohms..

the car has been sitting for about 6-7 years also...

schibsted · 12:43 PM

Quote:

Originally Posted by Gonçalo

i checked them, both read about 950/1010 ohms..

Hmmm, Have you measured all terminals like it says in this link?

Speed and Reference Sensors - Checking, Replacement, and Adjustment

should give you four readings, the two you have done looks okay, but you're looking to get ~1M ohm from the other tests
If that looks okay too, it might be the DME. Can't really think of anything else that will cause all these problems at once :/

EDIT: You could also test your fuel pump by feeding 12v manually and see if it runs, i believe it's easy accessible by the fuel tank somewhere. This is just to be sure it's not the coil/fuel pump that's the problem

Gonçalo · 01:02 PM

I dont understand this multi-meter very well.. when i check the middle pins with the left ones(8-27 and 25-26) reading is ok. but with the pins 8 -23 and 25-78 reading is 1 .. even when im not checking anything it reads "1" ..
sooo is that ok? x)
im using this one : http://i01.i.aliimg.com/photo/v1/249297723/GS_CE_Approval_DT830B_Digital_multimeter.jpg

schibsted · 01:06 PM

Quote:

Originally Posted by Gonçalo

I dont understand this multi-meter very well.. when i check the middle pins with the left ones(8-27 and 25-26) reading is ok. but with the pins 8 -23 and 25-78 reading is 1 .. even when im not checking anything it reads "1" ..
sooo is that ok? x)

You need to adjust the scale of the multimeter

it will not show more than the current setting. IE if 2k ohm is chosen, then the highest it will show is 2000, if more, it defaults to 0 or 1 in your case i guess. turn the selector to 2M ohm (2000k) and see what that gives you when you test

Gonçalo · 03-30-2014, 01:12 PM

25-26 reads 000
25-78 reads 1

same with the other sensor

schibsted · 03-30-2014, 01:16 PM

Quote:

Originally Posted by Gonçalo

25-26 reads 000
25-78 reads 1

same with the other sensor

hmm okay, that might be the problem then.. try touching the multimeter leads (one hand on each) and see if you get a reading of some sort. I got 1300(K) (1,3M ohm) which makes me think both your sensors are shot because the 1 might indicate there is no connection.

Gonçalo · 03-30-2014, 01:17 PM

which scale?

schibsted · 03-30-2014, 01:18 PM

Quote:

Originally Posted by Gonçalo

which scale?

2000k scale. Just to see if you get any reading other than "1" with the multimeter on this range

Gonçalo · 03-30-2014, 01:21 PM

i got values around 1000..

schibsted · 03-30-2014, 01:24 PM

Quote:

Originally Posted by Gonçalo

i got values around 1000..

Then i think both your sensors are shot. If you are absolutely sure you tested the right terminals (25 - 78) + (8 - 23). You can also test these with the 200k range, but i don't think it will give you anything else.

Gonçalo · 03-30-2014, 01:31 PM

ohh..my english is not that good ,im from portugal

so with "shot" you mean they are.. some kind of dead?
they look very wet and dirty btw.. maybe a good clean would solve the problem?

schibsted · 03-30-2014, 01:36 PM

Quote:

Originally Posted by Gonçalo

ohh..my english is not that good ,im from portugal

so with "shot" you mean they are.. some kind of dead?
they look very wet and dirty btw.. maybe a good clean would solve the problem?

By shot i mean dead yes

You could try cleaning them. I'm not too familiar with these types of sensors so i don't know if that might help, but no harm in trying! If you still cant get any reading other than "1" from the failed terminals, then replace both sensors.

Gonçalo · 03-30-2014, 01:41 PM

hmm okay..
ill see what i can do this week ,
any progress i will post here

Thank you very much

schibsted · 03-30-2014, 02:20 PM

No problem. Good luck!

Gonçalo · 03-31-2014, 12:04 PM

Quote:

Originally Posted by schibsted

No problem. Good luck!

maybe theres nothing wrong with the sensors..

https://answers.yahoo.com/question/index?qid=20090502091338AAEtanA

schibsted · 12:49 PM

Quote:

Originally Posted by Gonçalo

maybe theres nothing wrong with the sensors..

https://answers.yahoo.com/question/index?qid=20090502091338AAEtanA

I'm not sure what you are thinking here, but the 1 you get when you measured the terminals is either infinite resistance, 1k ohm or more than 2M ohm, either way they are wrong from the specs which in this case should be somewhere over 1M ohm (>1000k)

Edit: I can measure the resistance in the sensors in a 82 car i have on wednesday, should give you clearer answers

Gonçalo · 03-31-2014, 01:07 PM

Quote:

Originally Posted by schibsted

I'm not sure what you are thinking here, but the 1 you get when you measured the terminals is either infinite resistance, 1k ohm or more than 2M ohm, either way they are wrong from the specs which in this case should be somewhere over 1M ohm (>1000k)

Edit: I can measure the resistance in the sensors in a 82 car i have on wednesday, should give you clearer answers

thank you