Hesitation when engine cold - any ideas?

4.2 V8 32v Naturally Aspirated - 414 bhp
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MikeFish
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Re: Hesitation when engine cold - any ideas?

Post by MikeFish » Mon Mar 18, 2019 6:14 pm

FaisalJ wrote:
Mon Mar 18, 2019 9:26 am
This is common behaviour for a deflapped car - mine does it too (and I too thought something was wrong and asked MRC to check).

As to why it did this before - are you sure your flaps were operational? They can get stuck.


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Mine started doing it after it had the stage 2 map and removal of the SAI but before it was deflapped. Possibly defective flaps but doesn't that normally throw an error?

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alex760
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Re: Hesitation when engine cold - any ideas?

Post by alex760 » Mon Mar 18, 2019 7:18 pm

Jaheenormous wrote:
Mon Mar 18, 2019 6:03 pm
JamesBaby wrote:
Mon Mar 18, 2019 8:10 am
It affects fuelling based on engine temperature.




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That's interesting i didn't know that.. Seems to read ok on the dial but it would be good to confirm with a digital read-out.. Problem is, with no error codes and without putting a thermocouple on the coolant circuit you've got no way to tell if the sensor is off..
I'm pretty sure you can see it in measuring blocks in VCDS

markcookie7
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Re: Hesitation when engine cold - any ideas?

Post by markcookie7 » Tue Mar 19, 2019 10:50 pm

fairzy wrote:I’ve had my RS4 for about 6 months so far and aside from some large bills (Michelin Pilot 4s all round, deflapping / stage 2 at MRC etc) I love it.

I’ve noticed that until the engine has warmed a bit (water gauge has started moving) the engine can stutter / doesn’t accelerate cleanly under partial load but if you put your foot down it’s fine. I mentioned it to MRC who couldn’t find anything.

I’ve since run VCDS and it had a ‘left engine mount solenoid valve N144 P1573 - 004 - open circuit intermittent’ fault but don’t know if its linked.

Can anyone help?


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I had same problem changed maf sensor ,sorted.

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demon8991
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Re: Hesitation when engine cold - any ideas?

Post by demon8991 » Wed Mar 20, 2019 12:43 am

markcookie7 wrote:
Tue Mar 19, 2019 10:50 pm
fairzy wrote:I’ve had my RS4 for about 6 months so far and aside from some large bills (Michelin Pilot 4s all round, deflapping / stage 2 at MRC etc) I love it.

I’ve noticed that until the engine has warmed a bit (water gauge has started moving) the engine can stutter / doesn’t accelerate cleanly under partial load but if you put your foot down it’s fine. I mentioned it to MRC who couldn’t find anything.

I’ve since run VCDS and it had a ‘left engine mount solenoid valve N144 P1573 - 004 - open circuit intermittent’ fault but don’t know if its linked.

Can anyone help?


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I had same problem changed maf sensor ,sorted.

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Do you have a part number for the sensor?
RS4 B7 • Phantom Black • Centre Resonator Delete • Wireless Apple CarPlay
SQ5 TDI • Ibis White • Fully Optioned • Wireless Apple CarPlay

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fairzy
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Re: Hesitation when engine cold - any ideas?

Post by fairzy » Wed Mar 20, 2019 8:16 am

FaisalJ wrote:This is common behaviour for a deflapped car - mine does it too (and I too thought something was wrong and asked MRC to check).

As to why it did this before - are you sure your flaps were operational? They can get stuck.


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I’m pretty sure the flaps were operating ok before - MRC said they were in good condition when they were taken out and there were no errors in VCDS.

Changing MAF sounds like an option - will have a look around to see how much a replacement is and if it’s a DIY job.

Also am I right in thinking there are flaps in / below the air box that you can test with VCDS? Wonder if they could be part of it...


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alex760
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Re: Hesitation when engine cold - any ideas?

Post by alex760 » Thu Mar 21, 2019 8:35 pm

There is an airbox flap that is indeed in/below the airbox, it opens above 5500rpm. And yes it can be tested during the vacuum tests using VCDS, There's a guide in the FAQ post.

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