SEAT Ibiza 2010 (Petrol) Revs Maxing Out Approx 2500-3500

[Ben Edmunds]

So a quick run down of my situation. PS not much of a car guy so sorry if my terminology is off, please bear with me.

Car was running fine until a couple of weeks ago, driving back from a day out along the motor way (slight incline) I realised it was gradually slowing down and didn't seem to be pulling as it should, tried to gear down and it struggled even more, car started to judder and continued to lose power, rinse and repeat until I succumbed to pulling over.

AA came and did a bunch of basic tests, but found nothing clear or definitive but said it sounded like it was getting to much air, check the airl filter, throttle body etc and drove it round the car park saying it sounded a bit off still but otherwise was driving okay, until you go full throttle.

In the end, I managed to drive it home taking a non-motorway route, reaching 50-60mph as long as I was easy on the throttle and accelerated gradually.

Since I have been home and driving it around town, I can still tell something isn't right. Its pulls and accelerates fine on flat or downhill much as is need for 30-40mph roads but it particularly struggles going up hills as my rev counter just seems to max out between 2500-3500, no matter the gear, inclination or how far to the floor I go, it's just seems to be capped.

My fiancé's brother is a mechanic with the same car, so he did the usual checks, and brought some parts of his car to interchange and see if anything could fix it... new throttle body, new spark plugs, new belt of some kind, new injector rail, new coil packs, nothing made a difference.

I then saw a few forums about limp mode, so today tried to disconnect the negative battery terminal and leave it for an hour or so for residual power to fade and reconnect, still the same issue.

Really odd thing is no dash lights and no diagnostic codes, car doesn't seem to recognise any issues at all.

For the most part it drives and feels normal as it revs enough to accelerate fairly normally on flat and down hills, like I say it just doesn't want to pull.or accelerate up hill.

I'm thinking some sort of electrical, sensor or timing issue but thats just a stab in the dark and my fiancé's brother (and his older guru colleagues) are pretty stumped as most of the issues they expect to cause something like this would be detected by the dash lights and or diagnostic codes but no dice.

Only other thing to add is there hasn't been any juddering, signs of misfire or unusual knocks or sounds since the initial motorway issue, but also haven't been on any motorways since as don't want to be paying out for AA again lol.

Anyone experienced something like this or have any suggesting, don't want to.just keep paying out for more and more parts on a whim without being able to test and diagnose this issue definitely.

 

[mty12345]

Seems crazy that it could be that far down on power and not have fault codes. If it was actually in limp mode then you would certainly have some. Would suggest to check live data as you're driving it, Fuel trims and misfire counters, MAF, turbo boost (if it has one)

What code reader are they using? If it's only a basic one then maybe worth scanning wth VCDS

 

[Ben Edmunds]

Seems crazy that it could be that far down on power and not have fault codes. If it was actually in limp mode then you would certainly have some. Would suggest to check live data as you're driving it, Fuel trims and misfire counters, MAF, turbo boost (if it has one)

What code reader are they using? If it's only a basic one then maybe worth scanning wth VCDS

Yeah, that's exactly what's throwing myself, my finances brother (the mechanic) and his colleagues off.

Okay, thanks for the suggestions!

We did only scan it while parked/not running, so maybe I will see if he can come around again and try getting live data.

Also not sure exactly what type of reader they use, he brought one from work, I know he works at a local Halfords if that's any indication (if they use a standardised reader or something), I will follow up with him to ask and get back to you with the results.

 

[mty12345]

Yeah, that's exactly what's throwing myself, my finances brother (the mechanic) and his colleagues off.

Okay, thanks for the suggestions!

We did only scan it while parked/not running, so maybe I will see if he can come around again and try getting live data.

Also not sure exactly what type of reader they use, he brought one from work, I know he works at a local Halfords if that's any indication (if they use a standardised reader or something), I will follow up with him to ask and get back to you with the results.

You're welcome mate. These kind of strange situations are interesting cases. If i was you i would try removing the airbox, air filter and intake system and checking for any obstructions that are limiting airflow somewhere. That's the kind of thing that could seriously limit power without setting a code.

If that is all good then the same applies for the exhaust system. I've seen cases where the catalytic converter has started to break up, and that has caused power loss due to the honeycomb obstucting the exhaust gases. Again that's another thing that could happen without setting a code.

 

[Ben Edmunds]

You're welcome mate. These kind of strange situations are interesting cases. If i was you i would try removing the airbox, air filter and intake system and checking for any obstructions that are limiting airflow somewhere. That's the kind of thing that could seriously limit power without setting a code.

If that is all good then the same applies for the exhaust system. I've seen cases where the catalytic converter has started to break up, and that has caused power loss due to the honeycomb obstucting the exhaust gases. Again that's another thing that could happen without setting a code.

Thanks man! I'll keep these in mind as well. He's taking another look this weekend (live data while driving) so we will see how it goes from there.

Pretty sure air intake is all good, the AA guy checked/ tried that when I broke down on the motor way, and he semi-suggested it could similarly be the exhaust side of things.

Will keep you posted.

 

[Ben Edmunds]

Hey, just me again with an update.

So he came round and tinkered with it a bit more, was hoping to test some electrics and fuses but his gauge wasn't working (the tool itself, not the car) but we did have a slight development nonetheless. He had done some more reading and now agreed it seemed to be in limp mode with no dash lights or faults for some reason.

I mentioned you highlighted the MAF sensor and when he took it out give it a blow and put it back in, it seemed to rev up to 4000 (the expected soft limiter given it was in neutral and stationary).

After a few minutes, it would flick back to the seemingly forced limitor of 3200 and you can hear (and see on the rev counter) a significant difference in the limiting itself.

So this is the first semi-definitive sign we found.

It was also interesting we tried to drive it with the MAF completely disconnected and there was still not dash lights (didn't have diagnostic in at this point so not sure about codes) but thought this could be an indicator it's this was the issue since the complete lack of a sensor still showed no dash lights as before.

We will try some cleaner/ a new sensor and go from there.

Thanks again!

 

[mty12345]

Cheers for the update

I wouldn't assume it was the MAF without codes and live data first. Genuine sensors aren't cheap and you can't fit aftermarket ones as they won't work properly. It needs to be bosch or whatever the OEM brand is fitted to your engine.

The fault light on the Dash usually only illuminates when the fault is directly affecting emmisions. It's possible for it to go into limp mode without it coming on, especially if the fault is related to something like the turbo etc. There should still be a fault code stored though! It needs to be read with a professional scanner or VCDS, an OBD2 reader won't surfice.

If the mechanic can't give you a definitive answer, you'd probably be better off taking it to a vag specialist for diagnosis with VCDS, which is the dealer level software. It sounds like he's already swapped half the parts and not got anywhere with it. There are lots of people out there that are good mechanics, but don't have a clue when it comes to diagnostics and electrics. I know it's difficult when it's family, but you really can't diagnose a problem like this without good live data, that should be the first port of call. Fuel trim data especially!

 

[RUM4MO]

One thing, you wrote that the engine could be rev'd up to a high rev level without the car being driven - or moved, that should not be the case, it should only rev up to the 2500>3000 RPM that you originally observed - yes older cars could be rev'd to the "red line" while parked, but not newer cars which have emissions to consider and so use the "road speed" to work out if they are parked or moving.

One maybe extremely red "herring" - I've read in the past about the effect the brake vacuum line pressure/vacuum sensor's effect can have - maybe either check if that sensor is still okay and the line pressure okay - but as I've said, that is a very unlikely source of trouble, and if I could remember the exact effect it can have on engine running, I would have either pushed this further or not mentioned it. Just one possibility for a really weird set of circumstances - that is all.

Finally, please "spill the beans" on the exact model of engine that is in this car.