VW Passat TDI 130 Jerky Acceleration  
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Dear All

I recently had an Intercooler hose burst and now replaced but the car has developed a problem when accelerating up to about 30mph and occasionally when slowing down.

The mechanic who carried out the repairs has checked with an analyser but no faults were showing and have since had the pump and injectors on a cleaning system all to no avail.

It passed it's MOT Emissions test without problem just after the repairs

The car has just been serviced with a new fuel filter fitted but still jerky from time to time over 40 mph no problem and fuel economy is OK but just a bit lower I think.

No apparent problem with power because I tow a caravan and it seems to be OK when towing

I would like to sell the car soon as I am buying another one but would like to sort the problem out first

I would be grateful if anyone has had this problem and had it cured or can suggest where to look my mechanic is puzzled

Many Thanks




Tags: technical issues towing caravans

VW Passat TDI 130 Jerky Acceleration - Screwloose
dd

Could you describe the fault in a bit more detail; particularly what happens on the over-run.
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi Screwloose

Thanks for the quick reply

I'm not a mechanic so I'm not sure what you mean by "over run "

Inter cooler hose burst and replaced (my mechanic thought that oil in the hose hase rotted the rubber) (152K Miles on clock) ran perfectly up to the hose bursting

The symptoms are a hesittant or jerky acceleration (Like an elastic band) from 0 - 30mph above this speed no noticeable problem plenty of power
Tickover is sweet as a nut according to an ex mechanic friend (pre Electronic Mechanic)
Occasionally a lag of power and a puff of black smoke
When climbing a steep hill a I get the smoke for a brief moment
Also I forgot to mention earlier with the window down I noticed a Hissing Noise from the engine when under load (sounds Like an Air line Hiss)


Hope this explains better

Cheers

Dodgy
VW Passat TDI 130 Jerky Acceleration - Screwloose
Dodgy

The intercooler hoses are oil-proof, so they shouldn't have rotted. If you can still hear a hiss; you've still got a leak somewhere.

This will need looking at by a diagnostics specialist as it's an unusual fault that could well be the air-flow [MAF] sensor or a sticking boost pressure sensor. The extensive live-data available from these systems will determine which; but only in experienced hands.
VW Passat TDI 130 Jerky Acceleration - Quinny100
Sounds like either a sticking/clogged EGR valve or a MAF sensor fault.

The engine shouldn't be injecting any fuel on the overrun, but the EGR valve will be operating so from the details you've posted I'd look at that first.
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi Quinnie

Thanks for the reply

Not sure what the EGR valve is or where to find it

How do you test it when you find it ?

Cheers for the help

Dodgy
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi again

My mechanic put his analyser on my car and showed me the output of the MAF which showed a varying output as he revved the engine suggesting that the MAF was working

He also commented that there were no error codes saved or showing live.

I did a search on the EGR and found another website which explained it's purpose and operation and I must admit the problem does sound like it could be the EGR. see link

www.fordscorpio.co.uk/egr.htm

I will ask my mechanic to investigate

Cheers once again

I will report on progress

Dodgy

ps I'm not really a dodgy dealer !
VW Passat TDI 130 Jerky Acceleration - 659FBE
I'm assuming that your engine is a 130PS PD type diesel, in which case how was the "pump" cleaned? - there isn't one other than the tandem fuel feed pump. Injector trouble on these engines is very unusual and there are not many test fixtures around which will take them.

Assuming it's a PD, there is a quick but not foolproof way of testing the EGR valve - assuming your car has a manual gearbox; the autos are different.

Showing through the engine top cover is the "silver" dome of the EGR actuator with a rubber pipe attached. With the engine off, disconnect this pipe - push it off with a screwdriver, dont try pulling it on an old engine. Now connect a short piece of suitable hose to the stub and suck.

You have to suck quite hard as the spring is strong, but you will be aware of the EGR valve opening as you suck. Hold it open by putting your tongue over the end of the pipe, and check that the vacuum is held. Release the vacuum, and you should hear the valve shut smartly with a soft "click". If you can't hear this, it's probably stuck.

659.
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi 659FBE & All

Thanks for the info on the EGR Valve my car is an 02 (2002) TDI 130 Highline Estate Manual. not sure if it's a 130PS PD though ?

My mechanic took the car to a specialist Injector/Pump cleaning firm but not sure how it was done but apparently it was on the machine for about an hour cost £47

Amazingly I located the EGR Diaphram unit as you described and also found a piece of plastic pipe which I managed to fit tightly on the nipple.

Yes ! it responded exactly as you said it would once I had mastered building up a vacuum (6 Sucks) on releasing the vacuum it made a satifying clunk. (Back to the drawing board ?? )

On my way home tonight I called into the mechanic to pay him for my service and announced that I may have found the problem Faulty EGR. He advised me that he had cleaned it and checked it when replacing the Intercooler Hose. He also said the Hissing noise was probably the Dump Valve relieving pressure build up.

I decided to check the symptoms again after leaving his place and confirmed the hessitant acceleration up to 30 mph and on a steep hill climb below 30 mph in traffic a definite flat spot accompanied by a puff of greyish exhaust smoke.

On another hill at above 40mph nice and smooth with no noticable loss of power, I did wind the window down and heard the Loud Airline like Hiss.

I think with all the expertise on this board it's only a matter of time before I find the solution !

Thanks all once again I am very grateful for you help

Dodgy

VW Passat TDI 130 Jerky Acceleration - Screwloose
Dodgy

You need a new mechanic who isn't ripping you off and laughing at you behind your back.

"Clean pump and injectors" - yeah? How? [There isn't one... this is a PD.]

"The hissing is the dump valve." On a diesel??? With electronic pressure control? Under load? You've got a leak!

Ask around for a clued-up tech; or take it to a diesel specialist. This could be anything from a MAF or MAP fault to a tired injector feed loom.
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi Screwloose

Thanks for the info and tip

I doubt whether my mechanic is deliberately ripping me off as I've known him for years and has got me out of a jam a few times but you never know ?

I think maybe he has not come across this before and is struggling for an answer ?, I was thinking of taking it to a VW Dealer but I think I might definitely get ripped Off there

I live on the Wirral but don't really know of any purely Diesel Specialists !

I will do some research if I get a result I'll report back

Cheers once again !

Dodgy

VW Passat TDI 130 Jerky Acceleration - Screwloose
Dodgy

Have a look on yell.com for diesel places.

There are quite a few switched on garages around; but the vast majority thought that they could just carry on as normal and ignore the onrush of the electronic car and they are now doomed.
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Cheers Srewloose

I'll report back

Dodgy
VW Passat TDI 130 Jerky Acceleration - AndyT
"Clean pump and injectors" - yeah? How? [There isn't one... this is a PD.]


Don't some garages offer a fuel system flush/cleaning service, where they connect the fuel feed into an additive filled machine, and run it for a time?

I've probably asked that in a bit of a simplistic way, but I'm not totally sure of the process, and whether it was for petrol or diesel, or both...
VW Passat TDI 130 Jerky Acceleration - Screwloose
Andy

Yes; a pointless process anyway, but this car doesn't have an injection pump to clean and the injectors are electronically fired so you can't push fluid through them.....

What they were charging for....?
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi Screwloose & Co


I have spoken to AW Diesels in Darwin today very nice helpful people but they just build engines

They offered help though and think my problem is a hose leak

Also spoke to another local mechanic who works on modern diesels and he thinks it is a hose leak, he is going to have a look tomorrow

Cheers

Dodgy
VW Passat TDI 130 Jerky Acceleration - dodgydealer
Hi Screwloose and All !

You were bang, on I asked one of our Mechanics at work to give me his opinion of the fault and he said let's put it on a hydraulic Ramp and wee'll have a look.

After undoing the plastic tray under the engine he showed me a Botched Up hose connection between the rubber and metal pipe !

My Mechanic must have snapped the original taking the old hose off I bought the correct VW Hose Clip on the way home 47p including VAT.
Our company mechanic is going to fit it for me in a week's time when I get back from a hort trip.

I think my mechanic has been the problem all along

I can't believe he would string me along knowing that he had botched the hose job in the first place luckily the last cheque I gave him hasn't hit my account yet

I think a call to my bank tomorrow should sort that out

I have used this guy for well over 10 years and treated him almost as a mate, just goes to show you don't know who you can trust.

I will let you know how the car runs once the correct spring clip is fitted

Thanks once again

Dodgy
VW Passat TDI 130 Jerky Acceleration - jc2
The Scorpio site is one of the most useful to appear on here and not just for EGR!

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