944 Turbo Headache odd...No spark

[Sweeney2255]

Please help fellow club member before I have a brain meltdown.

I have a 944 Silver rose that I purchased from the estate of my best friend who passed away last year.

I purchased it as a project so was fully prepped for headaches!

Basically I knew there was a no start issue, he was told after putting power to the coil that it was the keyswitch.

Basically its had a new key switch, and and with the swich off the back of the barrel, it produces a small spark when coming off the crank position on the return to pos 1. Cranking it produces no spark, and only occasional near fire up when returning.

The rev counter flicks up when turning, to 2 k revs then returns.

I have replaced the DME relay, it was clicking but now isnt, but the battery has dropped to about 9.5v

I have tested the crank sensors and both seem to be working fine, one producing large waves, and the other sensor small peaks, we have also tried a new sensor in both positions.

There seems to be a ground on one plug to the air flow but cannot find a live to it with the ignition on.

In my haste I have taken out what looks to be a slightly aftermarket alarm, (hopefully correctly!) and still
there is no difference.

The coil has been tested as ok, and also the coil i believe has power but no spark coming from it.

Due to the history of my friend having the car, I am keen to get sorted and not keep banging my head for answers.
As an auto electrician has spent 2 hrs scratching his head today, and im losing my marbles fast!??

 

[Waylander]

I would offer a few suggestions but I'm no 944 expert
I think they have an ignition amp KLR module but it does kinda sound like a duf Motronic computer

I would get a 944 specialist involved as internet diagnosis is a bad hobby
If you give up your rough location there might be a member that knows these cars. Inside out close by

 

[Sweeney2255]

Thanks, I am in Norwich.

 

[bmnelsc]

http://arnnworx.com/download/DME_KLR_Test_Plan.pdf
this is where you should start... the dme testplan is always the protocol of choice - otherwise you are just guessing and potentially throwing parts at it for no return.

 

[Frenchy]

Check out the distributor cap especially the King lead post a small amount of corrosion in there which happens really buggers them up, ask me how I know !

Send the ecu to Augment Automotive and they will put it on their test rig to fault find / repair if it is faulty.

It will be something simple I will bet.

 

[Waylander]

Thanks Bruce, told you I was a 944 novice, 968’s I’m fine with

 

[Sweeney2255]

Thanks, have checked king lead, if i try and start it 20 or so times it will occasionally catch the spark and run, albeit sounding like on 2 cyls??
I have since removed alarm ao hope i havent made it worse ????

 

[peanut]

If the engine starts and runs albeit for a few seconds on 2 cylinders then its highly unlikely that there is any issue with the ECU or reference and speed sensor otherwise the engine wouldn't start at all.

Likewise for the same reason the removal of the alarm does not appear to have compromised the electrical and ignition system otherwise the engine would be very unlikely to fire at all.

if the engine hasn't run for some time there is a strong likeihood that the injectors will be sticky and not operating .
If you haven't access to a local specialist to clean and test the flow rate and pattern of the injectors there is a quick and dirty way you can get them working again. Once they are working they should self-clean as they are designed to do.

I use a 9v PP3 battery with a couple of flying leads . Disconnect the 4x electrical connectors of the injectors ,(don't forget to remove the wire retaining clips first) and use the PP3 battery leads to briefly flash the terminals of the injectors with the PP3 leads 10-20 times until you can clearly hear the injector solenoids clicking as the the injector coils pulse the solenoids. For this test ,battery polarity of the injector terminals is not important as they are isolated from the ECU and electrical system. Make sure that you do not hold the battery leads on continuouslybut rather stroke them across the injector terminals quickly .

You may be unaware that the ECU will not ground the DME relay until it sees an engine cranking speed of at least 200 rpm . (Count the engine rpm over 10 seconds whilst cranking and multiply by x6 ) If the battery does not have a good charge you will be wasting your time trying to start the car. Tip ..Use a battery booster or jump leads if you need to .

Remember the golden rules Never change more than one thing at a time . Mark original positions when adjusting or disturbing settings or components s that you can return back to original .

The first test I would try is a good squirt of Easystart in the inlet manifold. This is a very useful diagnostic test. If the engine fires and runs for a few seconds then that will confirm that there is little wrong with the ECU, and electrical / ignition system components and you should concentrate initial attention on the fuel delivery system.

 

[Sweeney2255]

Thanks for that, it just seems like something is telling the car to fire at the wrong time, if you imaging over 2 weeks 50 efforts of starting and only twice it managed to fire, but only by chance of catching the moment of the single spark, but it should
spark when its cranking ???????

 

[peanut]

I have replaced the DME relay, it was clicking but now isnt, but the battery has dropped to about 9.5v

The coil has been tested as ok, and also the coil i believe has power but no spark coming from it.
!??

you say that it should spark when cranking why ? .... unless the engine cranks at above 200rpm speed it will never fire . The ECU is programmed not to ground the injectors and ignition system to prevent a fire in the event of an accident hence the critical 200+rpm.

On late models the ignition spark is produced by an ignitor unit on the inner wing which is pulsed by the ECU . If the ECU doesn't see 200+rpm it won't pulse the ignition . Make sure your battery is fully charged and the engine is turning over at 200+ rpm

If you ask for help and advice as a novice from owners like myself that have decades of experience with these cars and then ignore their advice what is the point ? ..................Sorry but I'm a bit grumpy today

 

[Sweeney2255]

Understood and appreciated ?? I shall fully charge the batt and connect booster to see the spinning.
I wasnt aware of the igniter unit on the inner wing, anyidea what side?
I shall report back tommorow, and dont be grumpy! You are v helpful, and its appreciated ??

 

[peanut]

what year is your model ? I am not familiar with the Silver Rose edition.
If its the same ignition system as the S2 then the igniter is on the NS inner wing but all you need to do is follow the HT lead from the coil to see what is at the end of it . I'd better refresh my memory and check the schematic. its probably going to look like this https://www.ebay.co.uk/itm/162987786397

Have you got a workshop manual ?

 

[Sweeney2255]

Hi yes I have looked for one of these, but cannot find anywhere, its motronic with another KRW ecu. I think this has the energiser you are talking of inside it possibly. Mine is an early 88 car.

 

[944Scott]

I'm in Norwich also, I cant say I have much of an idea what the problem is but if you want a second pair of eyes to come over and look at it then just give me a shout.

 

[peanut]

..

 

[Sweeney2255]

Cheers Scott, Im going to get the KrW and ECU tested to check these are ok. Shall let you know how it goes.

 

[Sweeney2255]

Just a coil at the end of the lead, no little igniter box on the wing. Also its not on the wiring diagram either.

 

[peanut]

sorry ignore my comments about the igniter amplifier I didn't notice that yours is a Turbo version and has a different ignition to the NA models ...wasn't paying attention.

However sending items away at random is going to get very expensive very quickly. The usual way to fix a hard start non running car is to troubleshoot to diagnose the problem first .

Everything about the fuel and ignition system is controlled by the ECU but the ECU is dependent on all the various sensors supplying the correct information.
If the 2x relays inside the DME relay are not functioning correctly ...you will never get a spark .The ECU will not produce a spark or activate the fuel pump.

You should fit a 3x wire bypass in place of the DME relay when testing to eliminate the DME relays being a possible issue. Its straightforward to do there is a guide on the Clarkes Garage website and Pelican Parts . Its basically 3x pieces of wire joined together with spade connectors on the ends .

The bypass provides a permanent power supply to various pins on the the ECU as well as the fuel pump, injectors,etc. When fitted you should immediately hear the fuel pump running continuously so theres a useful test straightaway. If the car doesn't start and run with the bypass in place then that test will eliminate a lot of possible sources and help with diagnosing the problem

When fitting the bypass you should fit a spade connector to terminals 87 and 87b then lastly fit the 3rd spade connector to terminal 30 which is constantly live so be careful.
Terminal 30 is a constant 12v+ live feed to the ignition switch and terminal 30 of the DME relay base . If you do not have 12+v on terminal 30 at the base of the DME relay then nothing will work . You should check that terminal 30 is live with the ignition switch off .

 

[Sweeney2255]

Cheers peanut... Understood. I have tried the 3 wire thing and pump runs but no start ??

 

[peanut]

thats good ......at least you can eliminate the pump and fuse .

the reason i advise sticking to the 3x wire bypass instead of the DME relay is because it guarantees you should be getting power supplies to the relevant pins on the ECU and all of your various sensors are powered and the injectors also .

if you continue to use a DME relay during testing you can never be certain if one of the 2x DME relays are playing up or one of the DME relay grounds are absent etc . The 3x wire bypass makes testing easier because it bypasses both the relays