1984 Gold Porsche 944 Lux - AFM replaced

[Verysleepyboy]

17 hours ago, captain_cal said:

I have a set of cookies sat around doing nothing, but I'm in deepest darkest Cornwall.

Also I always thought all 944s were Motronic, and also mine was a fucker for idling when cold but I understand there's an idle control valve somewhere, which I never bothered to investigate as I lived at the bottom of a big hill and after a minute of climbing it was fine,

The cookies came off of this, a Feb 85 car in Kalahari Beige:

This is my current victim, looks like there is a secret society of transaxle perverts crawling out of the woodwork around here.

Your beige beauty looks very simialr to mine - but with the original "targa" roof, as opposed to the (in period) Halfords tin opener sunshine roof.

Send me some details of the Cookie cutters please (sizes/ condition/ offfset etc.), can always arrange shipping or a road trip if necessary

[Verysleepyboy]

Well - one week in and already my first FTP in the Porsche 😥

Took it out for a local drive yesterday afternoon to see a mate, and on the way back along the A5, I heard a loudish backfire and then nothing as the engine decided to cut out on me. Luckily I had just enough momentum to roll off onto a side road away from the main traffic.

Under the bonnet, nothing immediately obvious, but it wasn't for restarting, not even a cough.

I had almost no tools on me so diagnostics wasn't really an option so it was out with the recovery phone number and a Truckofshame ride back to my local mechanic (who had rightfully gone home by this point)

Initial thoughts are either fuel pump relay (weak spot on 924/944) or an ignition system failure - but won't be able to do much to check until the weekend.

Not a great start to the ownership experience........

[Dick Cheeseburger]

10 minutes ago, Verysleepyboy said:

Well - one week in and already my first FTP in the Porsche 😥

Took it out for a local drive yesterday afternoon to see a mate, and on the way back along the A5, I heard a loudish backfire and then nothing as the engine decided to cut out on me. Luckily I had just enough momentum to roll off onto a side road away from the main traffic.

Under the bonnet, nothing immediately obvious, but it wasn't for restarting, not even a cough.

I had almost no tools on me so diagnostics wasn't really an option so it was out with the recovery phone number and a Truckofshame ride back to my local mechanic (who had rightfully gone home by this point)

Initial thoughts are either fuel pump relay (weak spot on 924/944) or an ignition system failure - but won't be able to do much to check until the weekend.

Not a great start to the ownership experience........

It still looks fit on the transporter though, so almost a positive!

[Verysleepyboy]

19 minutes ago, Dick Cheeseburger said:

It still looks fit on the transporter though, so almost a positive!

Indeed it does - need to take all the (albeit small) wins at the moment!

[petermcpete]

Always worth having a spare fuel pump relay in the glovebox for these, or even a paperclip to jump the pins will do. Last FTP I had in mine last year was the fuel pump fuse had a crap connection to the holder - annoyingly only realised once I'd been recovered home, as it looked fine visually!

[Verysleepyboy]

It's all a learning curve, but yes a spare (tested good ) relay is on the list of must haves in the glove box!!

[Verysleepyboy]

Interestingly, the car started up fine yesterday morning (lumpy cold idle), warmed up to a nice smooth run but then after about 10 minutes went really lumpy and cut out.

No time to do much diagnostics yet but new fuel pump relay now ordered as first thought - or at least to have a spare.

[N Dentressangle]

Try running it until it cuts out. Then squirt some brake cleaner in the intake and see if it starts again. If it does, you know it's a fuel problem.

[Verysleepyboy]

24 minutes ago, N Dentressangle said:

Try running it until it cuts out. Then squirt some brake cleaner in the intake and see if it starts again. If it does, you know it's a fuel problem.

That's broadly the plan, just need to get some time on it!!!

Should then give me a clue if its ignition or fuel

[Zelandeth]

5 hours ago, Verysleepyboy said:

Interestingly, the car started up fine yesterday morning (lumpy cold idle), warmed up to a nice smooth run but then after about 10 minutes went really lumpy and cut out.

No time to do much diagnostics yet but new fuel pump relay now ordered as first thought - or at least to have a spare.

Has the rotor arm recently been changed?

I had very similar behaviour on a Saab 900 where it turned out that Intermotor had the wrong rotor listed.  It worked fine for about a week, then one day I spluttered to a halt at the side of the road - it behaving all the world like fuel starvation.  

It would run fine for ~10 mins from cold after that before starting to cut out under load, and eventually stalling altogether.

I was chasing this for WEEKS before I found the old rotor floating around the boot and just tried it to see if anything changed...and it just worked.

I still had a spark when it died - it just wasn't strong enough.  So it managed fine when it was cold and the mixture was rich - but as soon as is started to lean off as the engine warmed up, it wasn't then strong enough to ignite the mixture.

Not saying that's the problem here, but wouldn't surprise me if a lot of the ignition system are the same or similar, so if you've got a spare floating around it might be worth trying!

[dome]

On 03/04/2025 at 12:26, Verysleepyboy said:

Thank you - let me know what you have please

Hope the car is going well for you? 

I found the boss with a wheel attached. To be honest the boss itself is cheap, you can get them for £13 on eBay! If you want it with this wheel attached you can have them both for £40 posted. Drop me a pm if you're interested 

[petermcpete]

7 minutes ago, dome said:

Hope the car is going well for you? 

I found the boss with a wheel attached. To be honest the boss itself is cheap, you can get them for £13 on eBay! If you want it with this wheel attached you can have them both for £40 posted. Drop me a pm if you're int

If @Verysleepyboy doesn't want it, I would happily take it off your hands for my 924S 👍

[dome]

26 minutes ago, petermcpete said:

If @Verysleepyboy doesn't want it, I would happily take it off your hands for my 924S 👍

I'll keep that in mind if he doesn't but check it fits, from memory this is MK1 Golf small spline. I know it'll fit early 944s and my 2.0 924, not sure about your S though?

[Verysleepyboy]

On 04/04/2025 at 14:04, Zelandeth said:

Has the rotor arm recently been changed?

I had very similar behaviour on a Saab 900 where it turned out that Intermotor had the wrong rotor listed.  It worked fine for about a week, then one day I spluttered to a halt at the side of the road - it behaving all the world like fuel starvation.  

It would run fine for ~10 mins from cold after that before starting to cut out under load, and eventually stalling altogether.

I was chasing this for WEEKS before I found the old rotor floating around the boot and just tried it to see if anything changed...and it just worked.

I still had a spark when it died - it just wasn't strong enough.  So it managed fine when it was cold and the mixture was rich - but as soon as is started to lean off as the engine warmed up, it wasn't then strong enough to ignite the mixture.

Not saying that's the problem here, but wouldn't surprise me if a lot of the ignition system are the same or similar, so if you've got a spare floating around it might be worth trying!

Not sure - a full service of ignition parts will be on the cards though. No tell tale "spares" of this kind in the boot though.

Where do you recommend currently for decent parts - don't fancy playing the GSF /  ECP parts roulette?

[Verysleepyboy]

On 11/04/2025 at 09:53, dome said:

Hope the car is going well for you? 

I found the boss with a wheel attached. To be honest the boss itself is cheap, you can get them for £13 on eBay! If you want it with this wheel attached you can have them both for £40 posted. Drop me a pm if you're interested 

Yes please!!! DM me your details and I'll get some £££ sent over

[Verysleepyboy]

Small update on the FTP!!

After being recovered to my friendly local garage we had a loom and diagnosed no fuel pump operating hence no go.

First port of call was to replaced the DME relay - so a genuine OEM one was ordered and fitted (previous one looked almost brand new OEM) but made no difference.

Next step was to check the crank potions sensors (two of them) and found the connector broken on one of them and barely hanging on - they were the next parts to be ordered. Had to get (decent) pattern parts rather than genuine this time.

 

Would the old sensor come out without a fight? Of course not!!! Seized in solid!!

That then necessitated removing the mounting bracket - tucked right at the back of the engine bay against the bulk head with little chance of getting an Allen key socket in. Lots of swearing and cut hands later - the bracket is off - but the front sensor is still solid in place.

Destruction, drift and hammers required to remove and its finally free (the back sensor came out easily btw). Cleaned the hole and managed to finally refit it all (with a  little copper slip on the new sensor body).

Would it then start???

No, of course not, fuel pump still not kicking into life.

(New sensors and refitted bracket down the back there - pic doesn't do it justice just how awkward it is!)

So back to the fuse / relay box - being an early car, this is unhelpfully tucked up into the passenger footwell as opposed to easily accessed in the engine bay.

Here is where I discover that the fuse for the fuel pump has been bypassed some how (still need to investigate further) and the wiring the the pump relay base has been butchered badly including a corroded electricians terminal block inline.

This got removed and swapped out temporarily for a Wago connector and then I spotted the small brown wire spade connector (ground wire on the ignition key circuit) hanging out the back of the relay base - refitted this and tried again - SUCCESS!!!!!!

(see the lovely bodges to the DME relay wiring and the small brown earth at the back that appears to be the source of the FTP)

Finally got the car home now - need to sort of the wiring bodges and there is a massive stutter on acceleration, think it is now the AFM that needs attention but it is definitely a step further forward!!!!

AFM module that is next on the hit list to resolve the stuttering on acceleration - any tips on how to set these up would be gratefully appreciated!!

 

[Zelandeth]

33 minutes ago, Verysleepyboy said:

Not sure - a full service of ignition parts will be on the cards though. No tell tale "spares" of this kind in the boot though.

Where do you recommend currently for decent parts - don't fancy playing the GSF /  ECP parts roulette?

Look up the Bosch part numbers involved and get those, even if you have to resort to finding NOS in eBay was my take on it eventually.  My logic was that if Intermotor were using the wrong template, who knows who else is.  We also found the same problem on six Cylinder's Trevi - there was a huge difference between the correct Bosch part and all of the supposedly compatible alternatives we tried (about a millimetre of length and half the value of the series resistor as I recall).  Which resulted in this nonsense when we were trying to find one!

Two on the left are correct (old/new), the rest all were different brands which supposedly would work but didn't. One of them from memory didn't even fit on the distributor shaft.

[Stinkwheel]

The dodgy crank sensor wiring is a big red flag to me. I've had issues with similar older bosch injection/ignition systems where the crank sensors would be fine when cold but as the engine and in turn, the sensor warms up they throw weird resistance readings back and the car wont run. Always fine when cold, give up or get worse when heated slowly.

So i think you have fitted 2 new ones, so hopefully avoid the issue. But maybe if the mechanic still has the old ones then test with meter on resistance and apply some heat, see what happens to the readings

I always think its nice to know which item was really causing the problem so you can not have to worry about it anymore, especially when more than one thing has been done to try and solv the issue

[Verysleepyboy]

6 minutes ago, Stinkwheel said:

The dodgy crank sensor wiring is a big red flag to me. I've had issues with similar older bosch injection/ignition systems where the crank sensors would be fine when cold but as the engine and in turn, the sensor warms up they throw weird resistance readings back and the car wont run. Always fine when cold, give up or get worse when heated slowly.

So i think you have fitted 2 new ones, so hopefully avoid the issue. But maybe if the mechanic still has the old ones then test with meter on resistance and apply some heat, see what happens to the readings

The front one with the broken plug I had to butcher to get out, however I still have the original back sensor - I'll make up a test rig for it when I get a chance.

[AltheJazzman]

Ahh 944 starting issues! Been there. I never did work out which intermittent fault I had with my 944 before I sold it. Sometimes it wouldn't start and I would do a combination of: unplug and replug both the crank sensors, unplug and replug the AFM connector, bypass the fuel pump relay, clean the fuel pump fuse and connectors with sandpaper, replace the fuel pump fuse, and unplug and replug the ECU connector (DME in Porsche parlance) under the steering column. I even tried bleeding out a supposed air lock in the fuel rail a couple of times which always resulted in a lovely shower of super unleaded over the headlight.

If you do need to make an FPR bypass jumper, you need a 3-way jumper cable, not a simple 2-way bridge like the Jetronic cars. This is indeed Motronic. How to make an FPR bypass jumper: https://www.clarks-garage.com/shop-manual/fuel-05.htm

The best resource for DIY 944 repairs is Clarks Garage. The website design alone is a nostalgia trip. https://www.clarks-garage.com/

[inconsistant]

Try Frazerpart for spares and service stuff

https://frazerpart.com

If you can’t find what you need on the site give Max a call, I’ve always found him really helpful.

Porsche dealerships or  ‘OPCs’ are, surprisingly, a really good source for parts too, and usually more reasonable than a lot of the resellers and eBay listings. 

[Verysleepyboy]

On 25/04/2025 at 14:56, AltheJazzman said:

Ahh 944 starting issues! Been there. I never did work out which intermittent fault I had with my 944 before I sold it. Sometimes it wouldn't start and I would do a combination of: unplug and replug both the crank sensors, unplug and replug the AFM connector, bypass the fuel pump relay, clean the fuel pump fuse and connectors with sandpaper, replace the fuel pump fuse, and unplug and replug the ECU connector (DME in Porsche parlance) under the steering column. I even tried bleeding out a supposed air lock in the fuel rail a couple of times which always resulted in a lovely shower of super unleaded over the headlight.

If you do need to make an FPR bypass jumper, you need a 3-way jumper cable, not a simple 2-way bridge like the Jetronic cars. This is indeed Motronic. How to make an FPR bypass jumper: https://www.clarks-garage.com/shop-manual/fuel-05.htm

The best resource for DIY 944 repairs is Clarks Garage. The website design alone is a nostalgia trip. https://www.clarks-garage.com/

Already lost a few hours on that website - between that one and Pelican Parts, there is a huge amounf o online info on keeping these old cars going. Lucky really, as the HBOL for this model is ridiculously expensive for what you get!!!

[Verysleepyboy]

On 25/04/2025 at 21:28, inconsistant said:

Try Frazerpart for spares and service stuff

https://frazerpart.com

If you can’t find what you need on the site give Max a call, I’ve always found him really helpful.

Porsche dealerships or  ‘OPCs’ are, surprisingly, a really good source for parts too, and usually more reasonable than a lot of the resellers and eBay listings. 

Yep - found them already - will be ordering a load of service ignition parts from them in due course. Interestingly, it appears the 944 distributor cap (4cyl) is a part shared with both the Porsche 928 (V8) and the Bentley Turbo R / Rolls Royce  Corniche (V8)

[Verysleepyboy]

Minor update - struggling to get time on this car at the moment.

I had identified that the AFM on the car was a weak point,  the PO had warned me that he had to tweak it occasionally (often?) to get it to run right, so I thought it worthy of further research and investigation.

It appears there are two variants of it on the 944 - "early" and "late with the crossover around the time mine was made - outwardly almost identical, but the signal coming back operates in a different way back to the DME (read: early Porsche ECU)

The really helpful Clarks Garage website describes the difference and how to test them: https://www.clarks-garage.com/shop-manual/elect-22.htm

Obviously in my haste, I had already purchased a (known ok)replacement second hand AFM prior to reading this and of course, I had purchased a late one which was no good to me on an early setup unless I sourced and replaced the DME with a late one.

So back to eBay and I managed to track down an early AFM at a price too good to refuse (£30 ish) thinking that at least I have a decent core that could be refurbished if necessary whilst keeping the car mobile. Found a service to do this at about £325 if I needed to.

First thing thought was to check out the original installed AFM - however a bit of electrical contact cleaner to wipe away some of the oil residue soon revealed a major issue in so far as a big chunk of the copper track was missing from the unit where the wiper arm runs - might explain some (a lot) of the idle issues and poor running?

 

So time to break out the replacement albeit untested unit! Now most people would have followed the procedure to make up a test lead and prove it all works fine - but as I said, time is not something I have a lot of, and the original AFM clearly has issues so I just went ahead and opened it up, saw the track was in better condition so decided to fit it and see what happens!

Not too tricky to do - opening  the air box up revealed an almost perfect new filter, had one jubilee clip on the air hose snap (cable tie fix for now until I order a replacement)  and the "new" AFM went in nice and easy. Car then started first time (once I had remembered to plug it in) and settled down to a much better idle than normal. A quick drive around the block revealed better throttle response and generally an improvement so far!! I'd take that as a win so far!!!

Cover back on, check everything was tight and all good - now onto the next issues, including the pop up headlights no longer popping up!!!

[bezzabsa]

Brings back memories of the time i was offered 2 924's for £250 **WEEP**

one had been used as spares for the other but was still a runner, main car was more primer than paint but the interior and engine were mint...

Guy needed cash asap so I offered £250....he agreed, but then next day sold them to someone else for £100 😮  he couldn't wait the extra day..

spares car was scrapped for IIRC £50 and he sold the runner for £850 .. To this day I still think about that day when I see a Gold 924 out in the wild

 

[Verysleepyboy]

On 09/05/2025 at 15:29, bezzabsa said:

Brings back memories of the time i was offered 2 924's for £250 **WEEP**

one had been used as spares for the other but was still a runner, main car was more primer than paint but the interior and engine were mint...

Guy needed cash asap so I offered £250....he agreed, but then next day sold them to someone else for £100 😮  he couldn't wait the extra day..

spares car was scrapped for IIRC £50 and he sold the runner for £850 .. To this day I still think about that day when I see a Gold 924 out in the wild

 

What a shame - but that’s life!!!

[AltheJazzman]

Those AFM's are also notorious for wearing out the track in the same area, so you can bend the arm to retrack the arm on a different, unworn part of the copper track. I've never seen one with a piece of track completely missing though. That wouldn't help!

[MiniMinorMk3]

I'm thinking of getting another 924 or 944. I had a 2.0 924 followed by a 2.7 944 about 20 years ago. The 924 was black with a Pasha interior and cross spoke wheels.

The 944 was in doom blue with a linen logo cloth interior. 

Here's the 944