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Ongoing MAF/Running Issues

CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Hey all, new member here!

I've searched through and can't see any threads that show the exact issues that I'm having, please point me in the right direction and accept my apologies if I'm mistaken!

Car is a 2001, Seat Leon Cupra T (180), standard engine/map/air intake wise.

Bought in January, started having issues in March.

First issue I had was it running badly, and misfiring when the car was first started and cold. If the car was warm, I could turn it off, and straight back on and it would work fine. I also noticed a slight jerkiness when pulling away. I read through some posts at that time and someone advised pulling the MAF and seeing if it ran better, I pulled the MAF and the car seemed to run better, but now with the traction control, and engine management lights on.

I took it to my garage to confirm and scan the codes, and they had advised the MAF was indeed shot. I told them that I wanted, and had read I would need a Genuine Bosch MAF, they advised they had a mid range one that they supply to others and work fine, so I was talked into that (Possibly my first mistake?) We went ahead with it, MAF replaced, codes cleared, job sorted, car running well.... For two weeks.

Same symptoms come back, no lights on dash, but I'm misfiring on startup until warm. Back to the garage I go, they test the MAF and come back that it's shot. Replacement brought in on warranty, codes cleared, and the car runs fine. But alas a few weeks later, same symptoms return.

Garage want to keep the car for a bit as they think something else is going on, and after a few days I get a call saying they think my ECU is faulty, and is frying all the MAF's we try. I take the car back, sort another ECU out, get the immobiliser deleted put it in the car and it runs fine (but still with a shot MAF and lights on the dash) Until I start it later that night, and the car runs at 500rpm for a few seconds, then dies. Over and over, I unplug and replug the MAF in and it seems to work fine.

Get to the garage the next day, and put in a new MAF, (Again not bosch) clear the codes, Annnnndddddd it runs like absolute :censored:! Misfiring horrifically, running lumpy, not playing game. They are saying at least now there is a signal between the ECU and the MAF (not present before) so that's a step in the right direction I suppose. Heads are scratched, and the throttle body is re-aligned at which point the car runs fine. I get the car back and have a few days of easy driving.

Went up to center parcs at the weekend, and give it some beans on the open roads. Few seconds after, traction control light comes on. Pull over, turn the car off and on (Starts fine) and no traction control light, go up the road, give it some beans, and again traction control light comes on. The light stays off on easy driving, just comes on when under full boost but will disappear after car being turned off.

I'm halfway to my weekend break, and there's nothing I can do, so I park up and leave it for 3 days whilst I'm on holiday. Start the car up after the 3 days, and it's misfiring again until warm. Drive home, and an hour in I get the engine management light up, but no traction control light as before (Even after full boost), I am yet to get this scanned and will update when I do.

Sorry about the wall of text, but wanted to get everything written up in case of of the symptoms gives anyone any ideas!

Just wondering what my next move should be, should I buy a genuine Bosch MAF and try that?
Or can anyone think of anything else I should try next?

Thanks!:D
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
Do you have a method of reading any fault codes that appear - using VCDS or a code reader?
There's obviously something going on, but getting the fault codes yourself would make it much easier to diagnose.
You've had two goes at a non-Bosch MAF - are the garage willing to put in a Bosch one under the warranty? I assume the parts that are failing are covered by a parts warranty from the garage that fitted them?
 

CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Do you have a method of reading any fault codes that appear - using VCDS or a code reader?
There's obviously something going on, but getting the fault codes yourself would make it much easier to diagnose.
You've had two goes at a non-Bosch MAF - are the garage willing to put in a Bosch one under the warranty? I assume the parts that are failing are covered by a parts warranty from the garage that fitted them?

I had VCDS but my laptop has now broken as well (Everything seems to go at once with me:() so I'm reliant on the garage with their OBDII reader at present, I have dropped a friend with access to VCDS a message to see if I can get them scanned today or tomorrow.

Regarding the garage replacing with a Bosch MAF, I'm pretty friendly with the owner and guys in the garage so I'm sure that would be taken care of, I just wanted to check that replacing it would be a smart move and there wasn't a glaring issue with something else that I may have been overlooking, but could have been apparent to you guys!.

Will get codes scanned, seems like the best move at this point.
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
They are saying at least now there is a signal between the ECU and the MAF (not present before) so that's a step in the right direction I suppose.

This sentence makes me wonder if you could have a wiring fault. Is the ECU connector dry and clean, and have they continuity tested the wiring between ECU and MAF?
 

CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
This sentence makes me wonder if you could have a wiring fault. Is the ECU connector dry and clean, and have they continuity tested the wiring between ECU and MAF?

As far as I could tell all looked good, I will have a deeper look into it tonight with some light. They have tested this before as well as communication between ECU and MAF when they diagnosed the second MAF, and apparently tested it again before suggesting the ECU was at fault.

Now you mention it, I'm guessing it could be possible some muck got in there from when it first went wrong and I was driving with it unplugged for a few days:think: Possibly worth buying some Electrical Contact Cleaner and spraying the connectors?, will see if I can pick any up on the way home.
 

mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
Hi mate, sorry to hear of your issues.

As for the MAF saga, it's hard to say what the issue is without the help of any fault codes. However anything other than a bosch MAF is usually a waste of time, so that could well be the issue. I would get the codes read, clean the connector like you said and then if you still have the code, replace with a bosch MAF.

From reading the story the garage doesn't sound like they know what they are doing tbh. There are plenty of garages out there that are fine swapping brakes and suspension etc, but as soon as it comes to diagnostics they just start chucking random parts at it in the hope one of them will fix it.
Any garage that uses a cheap MAF sensor rather than a bosch one, i would have to question their compatance tbh. Also I very much doubt you needed to replace the ECU either, another case of throwing parts at something, at your expense. If you need to take it back to a garage again, then i would go to a VAG specialist rather than them.

As for the misfire and jerkiness, does this only happen for the first 90secs or so when started from cold? If so then that coincides with when the secondary air system (SAI)running and it's almost certainly related to that....... most likely the combi-valve on the side of the engine.
 
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CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Hi mate, sorry to hear of your issues.

As for the MAF saga, it's hard to say what the issue is without the help of any fault codes. However anything other than a bosch MAF is usually a waste of time, so that could well be the issue. I would get the codes read, clean the connector like you said and then if you still have the code, replace with a bosch MAF.

From reading the story the garage doesn't sound like they know what they are doing tbh. There are plenty of garages out there that are fine swapping brakes and suspension etc, but as soon as it comes to diagnostics they just start chucking random parts at it in the hope one of them will fix it.
Any garage that uses a cheap MAF sensor rather than a bosch one, i would have to question their compatance tbh. Also I very much doubt you needed to replace the ECU either, another case of throwing parts at something, at your expense. If you need to take it back to a garage again, then i would go to a VAG specialist rather than them.

As for the misfire and jerkiness, does this only happen for the first 90secs or so when started from cold? If so then that coincides with when the secondary air system (SAI)running and it's almost certainly related to that....... most likely the combi-valve on the side of the engine.

Hi Matty,

Thanks for your reply, I'm sorry about it all to but still happy overall with the car. When it works it's so good, I want to stick with it and get it sorted!

After the saga I've just had, I'm questioning the competence of my garage too. Went to go try and find some contact cleaner, (I couldn't!) And come back to the car to have it start and idle at 500rpm, same as before, with no effect even when pressing down on the accelerator pedal.

I'm luckily with a mate, we pop the bonnet and unplug the MAF, and I think I'll check out the plug for any muck etc and I'm met with the attached picture:
2586362a5b54b943cdf27e6580d6d9f7.jpg


The third pin in, is cearly (CLEARLY!!!!) mashed up and pushed back! And with damage to the red surround. With some mcgyver level car key and club card wizardry we pulled the pin back out and separated the mashed connector, plugged it back in and guess what. Runs great, no hunting, best it's driven since the saga has begun. FS!

I still have the Engine Management light on as before, but now after full boost no traction control light comes on so I'm fancying that a clear of the codes will put the Engine light at bay too!

I'm now questioning how they've changed 3 MAF's and tested it each time, but not noticed the mashed up pin! Phone call tomorrow me thinks!

Moving on, I am going to replace the MAF with a Bosch one anyway as per your advice. Tomorrow will tell if this also fixes the misfire on a cold start (which continues until the cars been running for a few minutes to answer to your question)

Looking at that picture I'm guessing there isn't meant to be a connector in the 5th hole on the plug?

And do you (or anyone else?!) know where I can get a replacement housing and connectors for this plug as I want to do it all properly myself considering it's current state of disrepair!

Think I'll start using this forum a bit more before taking her straight to the garage from now on.... Lesson learnt.


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Gaz20VT

Active Member
Aug 5, 2011
122
15
Wow, well that would explain it! If there's a blanking plug in the back of the 5th wire then no - there's not supposed to be a 5th wire in there.

You will need to clear the codes to reset the engine management light, as you've said.

For new parts, there are a few people on here, for instance there's a guy on the forum from Listers SEAT, username mjr901 who can help with parts. There's a dealers section here:- www.seatcupra.net/forums/forumdisplay.php?f=140

For part numbers, you can use an online catalog like www.oemepc.com - it's a bit of detective work to find what you want but it's all there!

Hope that's of some use, glad you got to the bottom of the issue!
 
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CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
As for the misfire and jerkiness, does this only happen for the first 90secs or so when started from cold? If so then that coincides with when the secondary air system (SAI)running and it's almost certainly related to that....... most likely the combi-valve on the side of the engine.

I have got in the car this morning to start it up, and now that I believe the issue with the MAF has been sorted I have been met with exactly what you have described here! Rough running for approximately the first 90 seconds from cold! I don't know anything about the SAI and the combi-valve, so will try to do some reading up on it today:D Thanks!
 

CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Glad to read that you've found the cause of the problem. How on Earth did they manage to bodge the connector like that?!

God Knows, I'm unsure if they even noticed it! I'm gonna phone them on my lunch break about the whole situation anyway... I'm thinking that possibly the cheaper MAF's they've been using didn't line up 100%. Either way I'm going to stick to a forum first rule from now on if I get any other issues! :happy:
 

CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Thanks for that Matty, interesting! Have done some reading and can see it's a common (and easy-ish looking) job to delete it. Would yo recommend a repair, or delete of the SAI?
 

mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
It depends really mate. In an ideal world i'd delete it, but then you will need to get it coded out from the ECU so that it doesn't continually trigger a fault light. This can be expensive, but maybe the place that did your IMMO delete could do it for a reasonable price?
 
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CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Looking at his eBay store it seems he only sells an immo delete service and pre-remapped ECU'S for 1.8t's. Will have to have a think on that one then see if there's anywhere else that can do it, or if I can fix it for now!

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CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Driving to work this morning, and got in a little race with a EP2 (I won, don't worry ;)) but noticed after what was probably a quarter mile of pedal all the way down that my traction control light is back on!!! When at work I turned the car off, and then back on and the Traction control light didn't come back up. Does this mean anything to anyone or is my best move at present still going to be to clear the codes, and put a genuine Bosch MAF on the car?
 
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mty12345

Active Member
Jun 17, 2011
3,907
538
bristol
Having seen the state of your MAF connector, i would get one of those first mate. Then if you still have issues swap the MAF after checking the fault codes.
If you have an android phone, then the "torque" app and a ELM327 adaptor from ebay will allow you to read the (OBD2) fault codes until you get VCDS sorted.
 
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CaptainProne

Active Member
Aug 7, 2017
30
0
Bridport/Dorchester
Ok mate, I am looking at ordering one tonight. Do you know if the clip and wiring for the harness is the same for TDi? Had a mate write one off who has offered me the connector for free. Could save time and money. Either way I'll sort the clip out first clear the codes and see how I go.

I have my laptop getting sorted. I do have an android so I'll look at getting that adaptor, will keep it in the glovebox (when I fix that too)

Thanks for all your help mate!

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