Help with sporadic probem

phil21turbo · **Posted:** Sat Oct 05, 2013 9:48 pm

Hi All.

Looking for some advise on the below 944t problem. Have changed DME relay, and issue still persists..

Cruising at 80 on motorway in 5th. Have maintained same throttle position for 10 odd miles. Upon acceleration the car has a little splutter as if the fuel is not getting through. Lift off throttle and back on gas and she is ok.

Same journey but this time on a country road doing variable speeds, gears etc. Car suddenly loses momentum. SPlutters a little, and when I give more gas the spluttering gets worse. roll to a stand still and engine just about ticks over. if you give it any gas car tries to cut out and revs hunt a little. Turn car off leave for 20 seconds and problem is still there. Leave for around 2 mins and can drive off normally.

Tonight it did this 3 or 4 times. The last time it happenned I carried on with my journey for approx 20 miles no issues whatsoever ?

My guesses are fuel regulator, but wanted to see if anyone has experienced anything similar on their turbo so I have a possible head start on what to look for.

Many Thanks

tr7v8 · **Posted:** Sat Oct 05, 2013 10:09 pm

Could be AFM, Air Flow Meter?

EDDIE · **Posted:** Sat Oct 05, 2013 10:14 pm

sticking/dirty ICV ?
I had similar with my S2 .Only happened when hot.
Nick

phil21turbo · **Posted:** Sat Oct 05, 2013 10:29 pm

tr7v8 wrote:

Could be AFM, Air Flow Meter?

That was something I was thinking too... Are these testable, or even repairable ? thanks

phil21turbo · **Posted:** Sat Oct 05, 2013 10:31 pm

EDDIE wrote:

sticking/dirty ICV ?
I had similar with my S2 .Only happened when hot.
Nick

I will take a look, and give it a good blast/clean. thanks

lindsayhbrown · **Posted:** Sun Oct 06, 2013 10:21 am

Is there a cylinder head temp sensor on these ?

EDDIE · **Posted:** Sun Oct 06, 2013 10:38 am

is there an inlet manifold air temp sensor ? there is on my S2 - I found it the other day,didn't know there was one , right at base of the manifold.

Nick

scam75 · **Posted:** Sun Oct 06, 2013 11:56 am

I had this problem too. It was the AFM. When it happened I took the multi plug off and sprayed wd40 on the connectors and when reconnected it seemed to work ok for a bit. When I scrapped the AFM and installed a MAF the problem never ever returned.

Stuart

Porker · **Posted:** Sun Oct 06, 2013 5:26 pm

Weirdly my 87 944 Turbo started doing exactly the same thing yesterday!

You're buzzing along merrily and then you move the throttle and it seems to gag and loses power then picks up again.

I was assuming the AFM was the cause. Mine has obviously been messed with. I shall try the multi plug WD40 trick - thanks.

Is the move to a more modern MAF (heated wire in the air intake?) a wel documented mod? The AFM on an L-Jetronic seems like a horrible Achilles' heel but perhaps it is just "of its day" technology...

EDIT: Ah, I see from your sig you have a "SciVision MAF kit" - something to look at buying from Lindsey Racing then. Thanks for the tip

scam75 · **Posted:** Tue Oct 08, 2013 10:03 am

Hi Porker

It's a very good mod. It makes the car more driveable at lower revs, reduces lag and also offers better air flow at top end. And is more modern. 968's came standard with them as do all modern porsche and it's a much better solution than the "barn door" afm.

Stuart

Porker · **Posted:** Tue Oct 08, 2013 10:07 am

Thanks, yeah seems a good modernisation.

I know I could google it but could you indicate costs and whether it's a DIY job or best left to a mechanic?

scam75 · **Posted:** Tue Oct 08, 2013 12:03 pm

Hi Chris

They're are a few options available. The SciVision is around £700 and is an easy enough installation for the DIY mechanic. It mimics the signals that the old afm would have sent to the ecu but gives you the benefits of maf technology. You can then go for something like a Vitesse system which is a true MAF and is a more complicated installation but gives you lots of tuning options. I think around £1,500 for a vitesse kit. It all depends how far you want to go. My car is as tuned as it will get at around 310 bhp and to make the step to 350bhp plus a lot more cash is required! There is also MAP systems that can be used like with Barks944's augment automotive solution. This then involves modernising the whole ECU as well as seemingly limitless options. As I say it depends on where your overall goal is power wise but for me the SciVision, which I got for £400 second hand, is a handy upgrade and adequate for my requirements.

Stuart

DaveM · **Posted:** Tue Oct 08, 2013 1:41 pm

Just checking the obvious but when was the fuel filter last changed?

I've got the same MAF and it does make a big difference to the drivability/response of the Turbo. I am comparing it to the previous knackered AFM though. I got mine second hand too for a similar price.

phil21turbo · **Posted:** Tue Oct 08, 2013 11:58 pm

DaveM wrote:

Just checking the obvious but when was the fuel filter last changed?

I've got the same MAF and it does make a big difference to the drivability/response of the Turbo. I am comparing it to the previous knackered AFM though. I got mine second hand too for a similar price.

Good question. replacing the fuel system was one of my next jobs, so would probably make sense to check it...

Cheers for the input guys. I'd wondered what a scivision would cost. See it on US forum, but want to keep my 944t standard as poss... Anyone know what the damage would be on a new AFM?

AlpineTurbo · **Posted:** Thu Oct 10, 2013 3:05 pm

I have had a similar issue hit my car:

Quote:

My 944 has bee quite dependable as of late. It is a good job really since it became a daily driver with me putting on more miles in 6 months than the car covered over 5 years.

However it seems it may have taken its toll. A short while ago now and again on rare occasions (it used to do it more when cold ) the car will idle OK (if I am honest, it would stumble a bit more, and hunt slightly the longer it was left to idle), yet when it came to revving the car it would not rev beyond 2krpm. This would soon clear itself with business returning to normal (idle is generally very steady on this car, and it pulls well), although sometimes it would idle at closer to 2000rpm for a short period of time before settling back to its normal idle within 15 seconds or so.

Today this problem came back to haunt me twice, but regardless of engine temperature. This time the car was barely idling, with revving it causing no change in RPM but for it to attempt to cut out, and at one point it did just stumble and die. I restarted it and within seconds the issue went away. When it was close to dying with no throttle I noticed that the boost gauge went close to 1 bar, indicating that very little vacuum was present (at idle it tends to set at or lower than 0.4 IIRC).

It even did it today on the motorway. From what I can tell, the one consistent thing with this issue is that it occurs when I got from no throttle to throttle (be it pulling away slowly, or accelerating on the motorway).

I was thinking along the lines of AFM or TPS, but I cannot see how it would tie in with a change in vacuum.

It has been suggested either the AFM or Fuel Pressure Regulator is at fault.

A new AFM is £400+. There are firms who recondition your current item including FrazerPart (£220 delivered to your door) although they take 5 working days to refurbish your existing item. Alternatively, Design911 also sell refurbs off the shelf, for the same price, but they can get them from their supplier within a day. Of course, there is a surcharge to pay with Design911 until your old unit is returned.

Depending on what is causing my issue (It's now gone to behaving itself again!) I shall let you know if I do go for a recon AFM and what changes it make. My thinking is whilst a MAF would be great, I would rather sort a couple of other small issues with the car to get it to the standard I want, and that a fresh AFM should still be alot better than something which is worn and now over 20 years old. Saying that, I may be keeping my eyes open for a MAF going by how many people are impressed by the changes.

How I do love intermittent faults.

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