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RDS1972

Active Member
Dec 19, 2011
265
0
Essex
I have read through different threads and see this could either be a coil pack or the MAF.
I have had a cold start issue for a while where sometimes the car can be driven from cold, and sometimes it idles perfectly, but as soon as you put the car into forward motion it starts cutting out as if it's going to stall. The throttle has little effect, although it can be revved in neutral. At this point I can either let it warm up whilst parked, or I can switch it off, and switch it back on. A friend in the trade suggested when I switch it on, to pump the gas pedal once prior to cranking the starter, and that has on occasion meant I can drive the car issue free.
Today I have driven the car 6 miles home after parking it 8 hours ago. It warmed up as usual, and seemed ok till I detected a slight sensation of it holding back on boost. When the road was clear, I revved it through to 5k and it definitely did nt feel at full power. I could feel a slight misfire when the revs dropped down under constant throttle. I parked the car up for 5 minutes, and when starting it again, the misfire was still there slightly, and the traction control light has come up.
Torque app is detecting no faults.
The MAF is about 6 months old.
Last week, I had the throttle body reset using a Snap On workshop diagnostic. This improved thing s for a few miles, but now its back worse than ever!!
I intend to get it fault read again, and to try it with the MAF disconnected. I don't want to buy coils unless I have to, as I plan to sell the car this month.
Poo!
 
I've run it up again on idle. There's a periodic, but regular lull in the revs from 750rpm when warm down to 680 or so for a second then back up to 750 again. I disconnected the MAF and it sat at a solid 800 rpm with no variations. (If it was a Ford I would have said it was an idle control valve, as they loved them :) )
 
Ok, update:
Warm running has been fine, no coil errors, no persistent codes or symptoms.
I spoke to someone who's had some experience with mapping and EGR deletes, and he suggested that as the problems are most pronounced when cold, he suggested I disconnect the EGR before starting the car tomorrow when it's cold, and see what difference it makes. I'm up for doing this, but am not overly confident I'll find it amongst all the pipes and cack, although I think it might be towards the front of the engine. I ve searched youtube, here and google for a location but can someone in the know help? Its a 2001 Auq 1.8t.
Thanks
 
On the auq, if you look at the front if the engine bay, it's on the right side o the head, with two medium size flexible plastic (NOT rubber or silicon) pipes going to it, this for sai aswell.

Coils normally are worse under load than at tickover,

the first symptoms sound like maf. Do you have the old one? What make Is the new one?
Also, check for leaks (boost and vacuum) under inlet mani, and the breather hoses, like the 'Y' shape one and nearby,

It's possible the maf was previously needed/replaced due to a fault that caused the maf to READ wrong the first time...(like a split hose, causing un metered air to get in)

Hope this helps mate, good luck.
Reece


Made in Spain, made better in England;) 223.3hp 263.8lbft
 
Thanks Reece.
The garage said there's no vacuum leaks, and the MAF being disconnected does nt improve the cold running.
All the codes have been cleared so hopefully tomorrow mornings EGR (Combi valve) test will move this along. The mapper will remove the stage one if needs be, but I'd rather leave it on and fix the problem rather than detune the engine to mask it.
Car will be for sale soon so needs to be right...
 
Bosch are pretty good, but occasionally they fail. I heard from an auto electrician today that Mercedes maf meters (perhaps irrelevant) have a life expectancy of 3 months or less

INLESS genuine parts (NOT even Bosch) though I haven't had this issue before myself tho.


Made in Spain, made better in England;) 223.3hp 263.8lbft
 
EGR makes no difference. Return to base map then!.
Be a shame to see this car go, someone with more clue than me can have a go!!
 
MAF Sensor knackered. Mine doesnt have a MAF sensor (mapped out) and the traction control light is permanently on.

Duff coilpacks would make the engine management light flash
 
Funnily enough Lodey, I tried the car without the coolant sensor connected and it was MUCH better. I'll run it over the next couple of days but so far so good.............
 
After all that, a £15 coolant sensor has sorted it. Bye bye Cupra, you were a great little car and I hope you treat your new keeper well. :)