Lumpy throttle - Cutting out

**gazz1** · 12-01-2011,09:21 AM

Hi guys,

On way to work this morning, pulled out at a junction and the car stalled, felt like it was starved of fuel and/or air. Switched car off, waited for a little while and continued.

Got on to motorway and similar experience, bar the stalling, whereby I put pedal down and it slowly picked up and then jolted forward like the turbo kicking in. I kept the revs above 2000rpm for most of the journey and I have arrived at work, but have a feeling I am going to have to be towed home, as the car runs, but not very well.

1. Any ideas on the above? (I know VAG COM should identify, but had similar symptoms this time last year, was sent to local garage and they could not find anything on their diagnostic)

2. I joined RAC a few months ago (package whereby I can get home rather than nearest garage). Will they have diagnostic equipment?

Cheers guys and gals.

**gazz1** · 12-01-2011,09:22 AM

Sorry, the car is 1.9 tdi sport

**nickeym1** · 12-01-2011,11:51 AM

Originally Posted by gazz1

Sorry, the car is 1.9 tdi sport

When i bought my a4 the egr was blocked off and when i noticed i unblocked it and reconnected the car kept cutting out and ran really bad and smokey so i blocked it again and it was ok. Im far from an expert but worth a try mate

**yaman** · 12-01-2011,12:29 PM

The RAC will have a code-reader, unlikely to be a VCDS diagnostic scanner.

A fault-code might not be recorded for things like a dirty fuel-filter or
a fried injector loom.

Regards
Jim

**gazz1** · 12-01-2011,12:37 PM

Thanks guys.

Came out and told me it was EGR valve. Did not put it on diagnostic.

He said it was driveable, but will not enoy the 40 mile motorway commute tonight, by virtue of the fact that the car does not really want to move.

How much are EGR valves replacements? Is it an easy job?

Cheers,

Gaz.

**TapMyHed** · 12-01-2011,12:45 PM

Take it out and clean it in oven cleaner. That should be enough.

Also consider your MAF...if you have changed this and put on a cheap chinese part, you'll get similar symptoms. They also wear over time and in the USA it is considered to be a service item.....not in the UK though.

Not cheap, but DO NOT replace it with a chinese part, either use Hitachi or Bosch. Both are good.

If you have VAG Com software on a laptop, you can run a trace of mass air flow whilst driving, see what the flow rates are for foot down driving (in 2nd or 3rd gear) see where it peaks out....should be 0.8 times the BHP of your car...roughly this, with a nice smooth slope from low revs to high revs (no dips or peaks)

Also, you could try disconnecting the MAF and then drive it...the ECU will use a flow table with approximate values (it uses this to compare to the actual values for fault diagnosis). It wont be perfect, but if it improves, its another pointer towards the MAF.

**TapMyHed** · 12-01-2011,12:48 PM

Also the Turbo may need a clean. Off the top of my head I forget what the actuator is called...something to do with veins. These can get blocked with exhaust gas soot, but can be cleaned.....this can affect low rev performance as it takes a lot of header pressure to eventually get the turbo to kick in, which sounds like your problem.....looses the finesse of a smooth running engine across the rev engine and gives you a peaky monster instead.

Hope that helps you some more.

**nickeym1** · 12-01-2011,12:51 PM

Originally Posted by gazz1

Thanks guys.

Came out and told me it was EGR valve. Did not put it on diagnostic.

He said it was driveable, but will not enoy the 40 mile motorway commute tonight, by virtue of the fact that the car does not really want to move.

How much are EGR valves replacements? Is it an easy job?

Cheers,

Gaz.

Ya egrs are expensive bout 250 euro on ebay i dread to think what they would cost in a dealers. I took mine out myself and im no expert believe me. Try blocking off the pipe at the top with a bearing or bolt or something and drive it and see does it improve. A good clean should do the job i dont think that much can really go wrong with them apart from getting clogged up and if your doing it yourself make sure you have a new gasket to put back on

**gazz1** · 15-01-2011,12:01 PM

Hi guys,

I am going to block the pipe feed into the egr and see how it goes. If it solves it, will clean the egr next week and re-connect.

I do about 80 mile a day motorway driving, so just wondering if I am going to cause any damage by blocking it?

With regard to the MAF, if I take it off, will this cause any issues in terms of performance? May need to do it for a week?

Cheers,

Gaz.

**nickeym1** · 15-01-2011,02:46 PM

Originally Posted by gazz1

Hi guys,

I am going to block the pipe feed into the egr and see how it goes. If it solves it, will clean the egr next week and re-connect.

I do about 80 mile a day motorway driving, so just wondering if I am going to cause any damage by blocking it?

With regard to the MAF, if I take it off, will this cause any issues in terms of performance? May need to do it for a week?

Cheers,

Gaz.

Dont think it would cause any damage. As for taking out the maf well when i unplug mine the turbo does not kick in at all and the car is seriously dead. Dont know if this is normal maby someone could let me know if this happens if they disconnect the maf. And gaz if your going to unplug it youll need torx head bits or drivers i think. Those screws are a bitch to get out with a pliers. Let me know how yours runs after you unplug and also how it runs after you block the egr. Does your a4 have a rough idle??