mtonks

Hi I'm new to the forum,

I recently bought a 2005 Porsche cayenne 3.2 v6 on a 2005 plate.

The vehicle has covered only 47000 miles or so, since December I've had a problem. When the vehicle is stone cold I.e. In a morning after been stationary for the night , the car starts no problem and revs higher during the cold start process at about 1k revs, when the vehicle drops down to .5 revs I can here the engine popping / banging like a mis fire, when I set off the vehicle has the same performance but sets off in 1st gear rather than the usual 2nd.

After perhaps 3/4 minutes of driving I do not get this problem again until I finish work 9 hours later.

If the car has been driven and is warm it never does it, it's literally when it's cold.

I took it too a German specialist who changed the oil, sparks and coils. The problem persists, we thought it could be the mad but after unplugging it and running the vehicle it still does the same without the maf.

Question is has anyone seen this before. I have no cel light, when plugged into diagnostics cat error code came up but only in cold. However appears it is not the cats.

Very frustrating and mystical! Any help appreciated

mtonks

Maf not mad! Blooming iPads!

duh

When fuel injectors start to clog, they misfire when cold and then as they warm up spray better. Its probably a good place to start. Ive had to change the occasional injector on cayennes at work, but not many.

CaptJim

Remember the days of an automatic or manual choke on a carburetor. It was an attempt to manage fuel air mixture the engine was cold. Liquid fuel does not burn, only vapor at around 14.7 air/fuel ratio, for Gas engines. Today's cars, no longer use all that mechanical stuff. They use computers and external pressure and temperature sensors to manage it all. They do an excellent job when all the inputs are correct.

Best case is that you plug it into a computer to read faults and an easy fix is discovered. Could be injectors too. I don't know how bad of a job this is on the Cayenne. The coils and plugs was a good place to start. Keep us informed as this may be a good thread to follow. I am new to this Forum, but have not yet read a thread on a fault that was caused by poor or failing injectors, maybe I just didn't find one yet.

rymo926

I have the exact same problem but not as continuous. It pops every couple of secs. I also replaced the plug and coils.
Injector make sense.

Also replaced fuel pump but not related.

I don't feel it missing if I'm driving the car only if left there idling from a cold start.

So I just drive it easy with no warm up.

mtonks

May look into getting the injectors cleaned at some point,

The cars daily use it just to and from work which isn't a long drive at all perhaps 10 minutes, so to be honest it never gets a good run. I took it out for a good hours blast yesterday, then when I started it this morning... no problem.

The cars previous owner used it to take the kids to school and to get to and from the stables, hence the low mileage so I don't think its had much of a life which probably doesn't help!

I'll keep you guys posted if it gets better or worse and what the outcome is!

My symptoms are definitely the same as your rymo926, literally if I leave it to idle. I too just drive off now if I can help it, but fingers crossed it may be resolved for me.

CaptJim

I remember reading in the Manual to start and drive off. Do not leave the car to idle while sitting to warm up it said. Now, I don't know why, the book did not say, but maybe there is a component that needs airflow across it or it will overheat?

I would also try some quality injector cleaners to see if it helps. Maybe its like you said, you just need to drive out the problem. Sounds like a long distance trip is in order, at least one or two tank fulls?

dryadsdad

Before you pull / clean / replace injectors, at least try BG Fuel Injector cleaner.

mtonks

Thanks guys, will try a reputable injector cleaner and report, fingers crossed it's just that.

Apparently when I bought the car it had been stood for nearly 12 months due to a gearbox fault (which was rectified) when I test drove the car the petrol gauge was quite literally under the 0 mark and I could feel it was running on fumes so can only assume all the crap got pulled through!

mtonks

Fuel injector cleaner seems to of done the trick to for anyone reading up this post

dryadsdad

Which brand did it? I favor and recommended BG.

duh

We use BG at work and have good luck on manifold injection. Not so much on direct injection, but i doubt any cleaner has had luck with the carbon buildup of direct injection yet.

mtonks

Was just carlube nothing expensive seems to of done the trick though! Worth a try anyway it was Carlube injector cleaner

rymo926

Hmm. I tried a bottle of chevron techron and no love

virkdoc

HAve the same car but a 2006 and it does the samething......Well as far as starting off in D1 is concerned..that is normal....when cold it will strat in D1.
Regarding the sound its the throttle body...clean it up and it gets better.lot of carbon deposition...but the small box which is a bosch part probably needs replacement to which the throttle body is attached.