AB-Oz

Hi all,
I dont post here too often as there doesn't seem to be much input from Australia, but here is my tale of woe.

Bought my 1990 C4 in May '05. I'm the 3rd owner, the 2nd imported it from Hong Kong. It now has 56000km on it.

After a month of ownership it started to develop a sort of hesitation then surging when on constant throttle or acceleration. Hot or cold doesn't matter. I tried the DME reset trick a few times to no avail. Now I feel it is just not safe to drive.

Heres a list of items that have been replaced/repaired. Over a year later the problem has yet to be fixed.
1. Throttle position sensor, car ok for a month, problem returned.
2. Full service, replaced bank angle sensor, ok for a while, problem returned.
3. Replaced manifold air temp sensor, ok for a while, problem returned.
4. Stupid dealer just replaced the fuel filter, car worse than before
5. non-dealer detected ECU not reading the air mass properly, sent it off to Melbourne for repair.
6. 2 months later, annual service, problem returned, took it back to repairer, he said he did nothing to fix it but it seemed fixed.
7. 1 month later, problem has returned.

I'm close to my wits end, the local Porsche dealer is hopeless, seems not to be interested ina 16yo car, and his head mech. just retired.
To top that, the alternative repairer who seemed to know what he was on about has just sold his business.

So, I either have to go back to the dealer for the 4th or 5th time with the same problem in the hope that they can finally fix it, or go interstate to Sydney (3hours drive) or Melbourne (7 hours), in the hope that someone else can fix it.

I'm also wondering if the next time it is "fixed" to sell it to some other poor sod who will get the problem a short while later when the gremlin returns...

Anyway, thats my rant, hope no-one else experiences the shattered dream that I am

Cheers
Adam

DaveK

For point 5) what was sent off for repair - the AFM or the ECU?

I had a hesitation problem, which was the AFM and a replacement cured it.

You don't seem to have replaced any ignition parts (coils / rotor arms / dist caps). Could it be them? I suspect not since they often cause idle problems as well - but just a thought.

AB-Oz

G'day Dave,
The ECU was sent off - the AFM was consider ok, as were the coils/rotor arms/dist caps - but who knows? It could be any of these...
Cheers
Adam

DaveK

For me, the AFM seemed to have broken tracks. And I know at least one other person who has had problems with their AFM.
Actually - you know that there was a TSB on the routing of the wiring to the AFM? If you search you should find it - it would be worth making sure yours has been done.

mark lintott

Air flow meter I reckon - had a similar problem with mine after a serious rebuild job by the main dealer here. Eventually tracked to the AFM (after trying 2 replacement units the second one worked) Also some poor connections to the ECU under the seat. Car would surge, hesitate, cut out the whole lot.

Good luck though - can't say it was an easy fix.

Cheers

Heirsh

When it bucks and such have you tried nailing the throttle all the way? It triggers the ecu to run in open loop mode with preset curves. When my car is having similar problems I can do this and cure it.

My persistent problem, that I dont think is the same as yours, drives me nuts. It ruins the enjoyment of my car.

dougn

these on again off again problems sound like the ignition/ arcing problems. look for unwanted arcing. make sure your plug wires are properly plugged in....they're easy to screw up and mis-plug

wsybert

Mine was similar under wide open throttle (WOT). The WOT cam was broken, but not all of the way. It was actually cracked in half, but still able to push (slightly) on the WOT switch. Mine felt more like a surge of power on and off, and not really a hesitation. Worth a look.

colo964

Could be bad coils, ignition wire or dist cap arcs. But these would cause a christmas tree on your warning lights - or will soon. I'd suspect your fuel pump or pressure regulator are on their way out or burnt contacts in your distributor cap/rotors.

AMF error would likely kick on your CEL.

AB-Oz

Hmm, thanks for the advice everyone.

Update, yesterday I disconnected the battery for a few hours, then connected up and drove it like a maniac for about 20km, with only 1 slight hesitation at the start. All fine, drove home for 10minutes at 60km/h and all good. So I thought, maybe it just need the DME reset thing done again.

But this morning, I hopped in it and nothing, it just stalled a couple of times, then no power, i sat at the bottom of my street praying it would right itself so I could back it back to my house. After about 3 mins of it almost cutting out, no power, revs dropping to almost zero, it righted itself and I got it back home. Hopped on my m/c for the commute to work.

So I'm no better off, and I've got no one to turn to other than the local dealer. So I've got a list of things to tell them not to do coz they've already doen them, and a list of things to try doing!!

Dammit I'm starting to hate this car when I deamt about owning one for so long!

I'll let you know how I get on.

Cheers
Adam

AB-Oz

Hey Dave, what does TSB stand for ? Is this like a service advice notice or something?

edit = it means Technical Service Bulletin.

Cheers
Adam

Heirsh

Sorry for your woes. I really enjoy my car, but ike anything if it gives you enough grief it can be depressing.

Too bad you cant find an enthusiast nearby to have a look at it. I have no idea, but it sounds like something is just loose and once you find it all will be well.

Good luck!

Wikkid911

I know you said you've reset the DME a few times but have you actually replaced it? They are literally pennies in the overall scheme of things, like maybe £18 and they do go wrong occasionally.

dfinnegan

Here is a link to the TSB that was:

Engine - Erratic Idle, Loss of Power, or Stalling

AB-Oz

Thanks dfinnegan and also Adrian for the pm,
I read the bulletin and so checked the AFM this evening. I discovered that one of the PO's had done the "drill holes in the airbox cover mod" but thats another story. I also discovered that the wiring of the AFM had been "got at" by someone in the past, and pretty shodily at that.

The heat shrink and rubber boot had been stripped back and left hanging, and theres a good chance it was coming in contact with the vent hoses. So a bit of a tidy up, some taping up of the wires, and cable tying as per the TSB, and I've now got it clear of the hoses.

I took the car for a run, driving very sedately up to normal operating temperature, and so far so good. Our relationship is hopefully back on track

It idles smoothly, there is no hesitation or loss of revs at any engine temp, nor when holding constant throttle.

I'll try it in the morning for the drive to work instead of taking the bike, and report back.

Cheers
Adam