Warning light & MAF

[Rocky Rocastle]

Just got a couple of questions to clarify some points.

When i start my car from cold on my LCR the revs go to about 1300 rpm and take roughly a minute to die down to normal speed. First of all, from what i can gather your car is supposed to rev higher due to auto choke on start up but should it be this high?

Also, if i accelerate slowly during this process the car is a bit hesitant and jolty for want of a better term (but it doesn't cut out) if this helps any confirm it could be the MAF on the way out?

Im going to check this anyway to see if it clears by unplugging it , which I assume will trigger a warning light on the dash, am i right in saying this will disappear automatically after a while of being plugged back in.

Finally is it safe to drive a short distance to see if it cures the above without causing damage

Any help much appreciated

 

[Rocky Rocastle]

anyone want to try and sort this before long drive down south

 

[LEE69]

1300 is about right
Might be the MAF try the latter and see, the light will go out when re-connected.

 

[skahigh]

Also, if i accelerate slowly during this process the car is a bit hesitant and jolty for want of a better term (but it doesn't cut out) if this helps any confirm it could be the MAF on the way out?

Mine does this and my MAF is absolutely fine.

 

[Rocky Rocastle]

hmmm wonder if it's normal then, just makes me wonder when i start driving and it hesitates a bit a constant speed then if i pick up speed i get a larger jolt then it seems to be fine, suppose it could be auto choke.

thanks for the replies

 

[skahigh]

hmmm wonder if it's normal then, just makes me wonder when i start driving and it hesitates a bit a constant speed then if i pick up speed i get a lrge jolt then it seems to be fine, suppose it could be auto choke.

thanks for the replies

Don't think its normal mate, my car never did it before it was mapped. Just can't pinpoint exactly when it started happening.

Have changed my TIP, upper boost hoses, some vac hoses and dv spring and still doing it.

 

[noodle]

Mine does this and my MAF is absolutely fine.

yeah mine too, it also occasionally makes a sort of chattering noise at about 2k rpm!!

 

[Rocky Rocastle]

not sure then, i know if i wait for the auto chocke/revs to drop down to normal (800ish) then start to go it's fine, it's just if i go straight away which then leads me to think potentially the temp sensor or coilpack if not the maf if it's from cold but i'm only guessing, which i know isn't the best thing to do! Need it logging really which will be done prior to mapping, hopefully that may show something?

 

[skahigh]

You can log the MAF to get an idea of whether its working or not. As far as fault finding this particular issue not sure what you could log.

I changed my temperature sensor about 2 years ago.

 

[noodle]

what problems did the faulty temp sensor give you?

 

[Rocky Rocastle]

without getting mine out so to speak i don't know what sensor it has as i haven't had the car too long, could be the old prone to go one for all i know.

When it comes to logging, i'll embarrasingly (sp) hold my hands up and say i haven't got a clue what means what and would need to rely on someone else to do it lol

 

[Cupra Ross]

Rough running when cold is a 1.8T trait. Its possible that its the MAF but you'd have to do some logging of block 002 to confirm this. Its also possible that its your N249 opening the dump valve when it shouldn't, they are quite famous for this.

I'd bypass the N249 if you haven't already done so, check you have a green top coolant sensor fitted and then log block 002 on VAG-COM. Do a power run in 4th gear on full throttle from 3000rpm to the redline. You should be pulling about 180g/s mass air flow on a standard LCR 225. If its much less than this its either time for a new MAF or you have an underlying problem.

Mine ran pretty rough when cold when I had a split breather hose on the bottom of the intake manifold, it needed a new MAF too. I've done all this and removed N249 and N112, it runs sweet even when stone cold now.

 

[Rocky Rocastle]

Rough running when cold is a 1.8T trait. Its possible that its the MAF but you'd have to do some logging of block 002 to confirm this. Its also possible that its your N249 opening the dump valve when it shouldn't, they are quite famous for this.

I'd bypass the N249 if you haven't already done so, check you have a green top coolant sensor fitted and then log block 002 on VAG-COM. Do a power run in 4th gear on full throttle from 3000rpm to the redline. You should be pulling about 180g/s mass air flow on a standard LCR 225. If its much less than this its either time for a new MAF or you have an underlying problem.

Mine ran pretty rough when cold when I had a split breather hose on the bottom of the intake manifold, it needed a new MAF too. I've done all this and removed N249 and N112, it runs sweet even when stone cold now.

great post, cheers

 

[Cupra Ross]

No problem Tim, hope you get it sorted to your satisfaction.

 

[greesha]

My Leon had this hesitation when cold as well. I have changed my spark plugs and all is fine now .

 

[Rocky Rocastle]

unfortunately i think it's one of them problems that could be a number of things, more than likely nothing major but an arse to pinpoint, i would hope it's not the plugs though as i had these checked when serviced 3 week ago and was told they were fine, plus this was going on prior to that.

I will go in the order of checking as Ross as stated i think, been meaning to do the bypass anyhoo so now i've got an excuse.

 

[skahigh]

I've got the green top temp sensor (changed about 2 years ago as stated), I've bypassed the N249 and I changed my spark plugs a couple of months ago. Have checked all the pipes that I can easily as well and no signs of any cracks or splits.

Anyone got any other answers that I can immediately rule out? It is actually really annoying me. What I get when cold and using part throttle is a normal whoosh from the air intake but no boost whatsoever. If I then increase throttle or ease off and throttle on again then it works as normal.

 

[skahigh]

I've been wondering if its my coil packs which are 6 year old originals but I'm not getting any missfires.

 

[Cupra Ross]

I've got the green top temp sensor (changed about 2 years ago as stated), I've bypassed the N249 and I changed my spark plugs a couple of months ago. Have checked all the pipes that I can easily as well and no signs of any cracks or splits.

Anyone got any other answers that I can immediately rule out? It is actually really annoying me. What I get when cold and using part throttle is a normal whoosh from the air intake but no boost whatsoever. If I then increase throttle or ease off and throttle on again then it works as normal.

If you're not getting missfires, its not the coilpacks. Have you logged your N75 duty cycle? Did you check the breather hoses at the side and the underside of your intake manifold?

 

[skahigh]

If you're not getting missfires, its not the coilpacks. Have you logged your N75 duty cycle? Did you check the breather hoses at the side and the underside of your intake manifold?

Nope on the N75, what blocks mate?

Checked the breather hose on the side but can't really get at the underside ones to check them, will go and have a feel and see if I can feel the difference.