2007 Skoda Octavia vRS 2.0 PD TDi.

DPF Delete and map to match.

 

A strange symptom has started developing when the car boosts for the first time.

 

It hesitates and pulls back through the revs and eventually catches up.  After this initial problem, it tends to boost OK thereafter (I think... the hesitation/pull back effect lessens).

 

Any idea's what this could be?  I've become nervous of putting my foot down now incase it's causing unnecessary damage.

 

I'd blame it on a bad map, only, the map and DPF removal has been in place for 12 months, and only now has this symptom developed (irrespective of gear).

 

Any ideas guys?

 

Thanks,

James

Poor initial fuel flow, part blocked fuel filter/tandem pump issue?

Poor initial fuel flow, part blocked fuel filter/tandem pump issue?

 

Thanks for the response MicMac.

 

I'll get a new fuel filter today and try that firstly.

 

Tandem Pump issues normally result in oil mixing with fuel right?, is there an easy way for me to diagnose/check this?

 

Thanks

Blocked or failing EGR valve resulting in insufficient air flow?

Turbo vanes clogged ?

re tandem pump, I was thinking more like an external leak via a degraded rubber hose/clip allowing fuel to seep out characterised by obvious smell and allowing air in to system, or a worn out pump.

Internal leaks would be evident by oil level gradually increasing with distinct diesel aroma from filler hole.

As previously mentioned it could be a sticky turbo in the first good run of the day while relatively cool, a leaky vacuum pipe would show up consistently not just on initial boost.

Do you boot it?

Many diesel drivers don't venture above 3K rpm and labour the engine looking for mpg, combined with distances driven it's no wonder many just soot themselves into poor running.

Change the fuel filter if due/looking for possible fuel issues and enjoy the full range of revs and see how she goes.

Possibly a loose joint in the inlet pipework?

I had a joint pop off recently when the metal U clip wasn't fitted properly, she hesitated, lacked boost, was flat as a witches t!t and struggled to get to 50mph, no dash lights indicated and no noticeable unusual sounds but then that's easy on a diesel as they are so well sound insulated.

Blocked or failing EGR valve resulting in insufficient air flow?

 

Hey Anddenton, the EGR is blanked and mapped out of the car.

 

Turbo vanes clogged ?

 

Hey radders567, Yeah I could check these... need to find where they are first lol.

 

re tandem pump, I was thinking more like an external leak via a degraded rubber hose/clip allowing fuel to seep out characterised by obvious smell and allowing air in to system, or a worn out pump.

Internal leaks would be evident by oil level gradually increasing with distinct diesel aroma from filler hole.

As previously mentioned it could be a sticky turbo in the first good run of the day while relatively cool, a leaky vacuum pipe would show up consistently not just on initial boost.

Do you boot it?

Many diesel drivers don't venture above 3K rpm and labour the engine looking for mpg, combined with distances driven it's no wonder many just soot themselves into poor running.

Change the fuel filter if due/looking for possible fuel issues and enjoy the full range of revs and see how she goes.

Possibly a loose joint in the inlet pipework?

I had a joint pop off recently when the metal U clip wasn't fitted properly, she hesitated, lacked boost, was flat as a witches t!t and struggled to get to 50mph, no dash lights indicated and no noticeable unusual sounds but then that's easy on a diesel as they are so well sound insulated.

 

Hey MicMac,

 

I'll get the car on the ramp this weekend and check for leaks, smells of fuel or cracks in the rubber hosing.

 

Regards the leaky vac's, I thought that too, but it 100% improves after the first initial symptom... but still, worth checking over anyway to be safe.

 

I tend to boot it from about 1.8K revs.. it judders upto 2.5, then catches up and pushes strong through the 3K range.  I 'will' push her when needed... to be honest, there's a fair mix of Eco/Non-Eco driving with this car... she gets a good 60mile round trip to Knutsford twice a week and I don't hang around.

 

I'll get the filter changed this weekend, and take her for a blast.  Interesting comment regards the inlet, it was replaced about 4 months ago... will check/double check all that out.

 

I was reading up regards the filters... and people advising the need of a VCDS after replacing it.  Otherwise startup issues occur.  is that true?, I thought I could replace it carefully, then flick my ignition on a few times to allow the housing to fill back up with fuel before starting the engine and cracking on as normal?....

 

Cheers for all the help guys!... Will keep you posted.

Hey Anddenton, the EGR is blanked and mapped out of the car.

 

 

Hey radders567, Yeah I could check these... need to find where they are first lol.

 

 

Hey MicMac,

 

I'll get the car on the ramp this weekend and check for leaks, smells of fuel or cracks in the rubber hosing.

 

Regards the leaky vac's, I thought that too, but it 100% improves after the first initial symptom... but still, worth checking over anyway to be safe.

 

I tend to boot it from about 1.8K revs.. it judders upto 2.5, then catches up and pushes strong through the 3K range.  I 'will' push her when needed... to be honest, there's a fair mix of Eco/Non-Eco driving with this car... she gets a good 60mile round trip to Knutsford twice a week and I don't hang around.

 

I'll get the filter changed this weekend, and take her for a blast.  Interesting comment regards the inlet, it was replaced about 4 months ago... will check/double check all that out.

 

I was reading up regards the filters... and people advising the need of a VCDS after replacing it.  Otherwise startup issues occur.  is that true?, I thought I could replace it carefully, then flick my ignition on a few times to allow the housing to fill back up with fuel before starting the engine and cracking on as normal?....

 

Cheers for all the help guys!... Will keep you posted.

The turbo vanes become sticky because of a build up of carbon. Take a look through this thread

 

http://www.briskoda.net/forums/topic/243533-the-mr-muscle-vnt-turbo-treatment-thought-we-needed-a-guide-of-sorts/?hl=%20muscle