Help Required - Rough running - Page 2 - 911/Carrera GT - PistonHeads UK

You may recall my previous post about my OPC keeping my car for four months, awaiting parts from the Fatherland. Well it returned with its' Targa roof fixed and working perfectly. Car had trouble starting though as it had been off the road for four months, so they kept it for a couple of extra days and changed the DME relay (replaced the original 964 part number DME with the updated 993 model). Drives ok round town but once you floor it, in any gear (it's a Tip- I know) it reaches about 4000rpm and just stays there, lots of small backfires from the rear. Returned it to OPC within one week, they kept it for another week and diagnosed fuel problems. Replaced fuel filter, fuel pump and all 12 plugs, all expensive items for a 1996 911. I have had it for a week and it is still playing up. Floor it and it just struggles at around 4000rpm. Tried it in manual and the same thing. Think I got a speeding ticket yesterday as I went past a radar at 140 kph which is about top speed trying to get it to go faster. In neutral though no problem with revving it way past 4000 rpm. Anyway it's booked in to OPC next week and I know they are going to ask me "what's wrong". As a non-technical bloke what should I tell them to look at next? Don't fancy another huge bill for stuff that does not need replacing. My gut feeling is dirty fuel injectors as it has now down 100,000 kms and I'm running it on 95 RON. Only stuff available. Tried fuel injector cleaner, no improvment though. Any help much appreciated.

Well a bit more research on t'internet says try, in no order of success: 1. Check fault codes 9101 9122 9142 9143 2. Check cam control valve 3. Check for vacuum boost leak 4. Check MAF sensor Seem to becoming a bit more knowledgeable on my own then.

It's a hard one expat. It's frustrating that you have to do the donkey work because a main dealer can't fix it. Next time it goes in though I'd be saying that you want them to keep any old parts they take off and put them in the boot. If what they do doesn't fix the problem you want a refund and the old parts refitted. Otherwise they'll just carry on throwing parts at the problem at your expense.

A 964 or 993 that struggles to go past 4000 rpm and back fires at that point is a symptom of a broken distributor belt.

Thanks guys, will put all that on my list when it goes in Sunday. Will keep you informed of progress. Good job we just got paid our 2013 bonus. I know I get free petrol but the wine out here is very expensive.

Well good luck with it. That is good thinking by Steve and if it is that you've had a lucky escape, as failure of the distributor belt at high revs can be catastrophic. In rare cases mind. Edited by marky911 on Wednesday 5th March 10:30

Nightmare that the OPC don't have a clue and you have no other options. As Boxsey says get them to check that both distributors are running - yes there are two - joined by a belt. Another possibility is the spark-plug leads, but that's another wodge of money so try renewing various engine sensors before renewing the leads. Varioram vacuum might have failed, for various reasons. When you disable the immobiliser, and TURN the key one position but NOT start the car, do you get a loud 'clack' from the engine? DME relay failure means the car will turn over but not start/run at all, so rough-running is NOT a DME problem. It won't be causing your revving problem, but for starting/rough idle problems on a 100k engine, I would clean your Idle Control Valve (the americans call it an ISV), which on a Varioram sits on top of the engine and only slightly awkward to get at. You will NOT need a new one, it just needs to be taken off the engine and ideally to sit overnight in brake-cleaner or similar. Here's a few photos to help you locate it and point it out if you can't do it yourself. http://www.orangecurry.com/993/icv-clean/

Thanks for the tips, just been to the car park to see if I can hear a clack. 22c and sunny, no-imobiliser in my car, just turned the key to position 1, no sound of a clack. Tried a couple of times to make sure. It is safe to drive? Just had my second car back from its' service yesterday, new plugs, oil change and pads replaced, and it is now misfiring too so it has just gone back in as well. Begining to wish I had not bothered with this servicing malarky

Just let me pop outside to check the exact key position.... 12 degrees and very sunny here in Sussex AFAIK if the vacuum/electrics are not working, it won't cause any damage - many variorams have run around in this state. It just means that the varioram system doesn't operate. This came up on a Google search - have a read whilst I'm enjoying the sunshine..... http://www.instant-g.com/Products/36Conversion/VRA...

sorry - position 1 is just the steering lock... I meant Position 2 - the ignition lights come on. If no 'clack', try starting the engine, let it run for a few seconds, then switch it off. Then return the key to position 2 and listen for the loud clack.

On my way...funny have to wear a jacket in the office (fierce AC) and take it off to go outside, now where are my sun glasses.

The suspense....... Your 1996 is a varioram I hope?

Yep its a 1996 varioram. Well turned key to position 2, heard a gentle 'click' from under front bonnet RHD side. Repeated it a couple of times, just a gente 'click' each time. Then started car, no problems, idles great. Turned off no loud clacking noise. Was worried about driving it if there is a distributor belt problem?

how old is the fuel in the tank? I've had similar with a car running really badly and not liking full throttle as the fuel was 5 months or so old. filled up with fresh fuel and all was good again....

New fuel in tank (we make it). I filled it up when I collected it end of February.

Had a similar problem with my 993 after body restoration. The engine came out for the resto to get to the rear chassis area, but when they re-assembled everything it ran as rough as a badgers arse. We thought it might be fuel etc because it had been sat, and would clear when I ran it but it didnt. Took it straight to my usual indie who investigated and found a miss-aligned air manifold intake pipe, which they refitted and that cured the problem.

Expatboy said: Then started car, no problems, idles great. Turned off no loud clacking noise. Did you return it to position 2? Expatboy said: Was worried about driving it if there is a distributor belt problem? How far is it to the garage? You've been thrashing it about until today anyway? Impossible to advise you from here, but if it were me I'd nurse it to the garage. http://www.pcarworkshop.com/index.php/993_-_Distri... Can you, or any trusted mechanic/engineer have a look? From the Pcar article: Diagnosis There are a couple ways to verify operation of the belt. First, remove the secondary distributor cap and see if the rotor spins freely. If it spins – at all – the belt doesn’t have a hold of it. The other way is to remove the input plug from the top of the primary distributor cap, forcing the car to run on only the secondary distributor. If it starts and runs – no problem. No start, no belt.

Yes, returned it to position 2, just the gentle click under the bonnet. OPC is five minutes away but will not do anything until Sunday which leaves me stuck without a car for the weekend. Will nurse it home to the villa tonight and use our bus service into work tomorrow. Will brief you all once the OPC has looked at it.

Boo152 said: Took it straight to my usual indie who investigated and found a miss-aligned air manifold intake pipe, which they refitted and that cured the problem. I know Boo has a pre-varioram, but what he/I are saying is the same - anything wrong with any of the pipes or electrics to do with the inlet/air/fuel mix will give you your problems. I don't think the MAF tends to go wrong on the 993, so don't let them change that yet. But I'd hate to let them try and find the issue with the varioram system as they don't seem to have a clue about the older engines from what you've said. Fingers-crossed it's just the dizzy belt.

Expatboy said: Yes, returned it to position 2, just the gentle click under the bonnet. OPC is five minutes away but will not do anything until Sunday which leaves me stuck without a car for the weekend. Will nurse it home to the villa tonight and use our bus service into work tomorrow. Will brief you all once the OPC has looked at it. If you've spent all that money recently, I'd just turn up at the service desk with the car (no I don't mean drive it into the showroom ) and say 'can you please send someone out to check operation of both distributors'. If not, can't you nab an engineer from your company somewhere? It's not 'seismological interpretation' y'know.

'seismological interpretation'. Lol, my son does that but he's in UK, local 'indy' is away at the moment. Might try and borrow a pool car for the weekend. Will remind the OPC of my good service on Sunday, there is an expat in the organisation somewhere, usually in glass fronted office behind the coffee machine and leather sofas.

OPC's considered opinion is that I have dirty injectors, they are giving them a clean and see how it runs. Also getting a quote for replacment bits in case cleaning does not do the business. Hopefully a cheap visit this time?

So finally picked it up, it was dirty injectors, runs fine now, all for a shade under £200, phew. Ready for a weekend spin round the island with the roof open. F1 next week too and the sun is out again. Tough life in the Gulf.

...I thought you said YOU make the petrol? So this was all your fault?

Yep, looks like it's down to me, the chaps and chapesses stoking the furnaces. Only sell petrol to our local market and only up to 95 RON, no detergents addedd or so I'm told.