Hi all,

 

Just had a call from the Mrs regarding her '14 1.2 Tsi Combi.

She said the EPC and traction control lights came on and there was some shuddering.

From what I read, the car may go into limp home for this fault so I imagine that this is the shuddering? 

 

I told her to turn off the car for more than 30s, which cleared the faults, but they came back again after a bit of driving. This has happened a few times since, so it seems that it wasn't just a "one off" spurious fault.

 

She did then say that the car had "jerked" before the faults came on (which may also be the shuddering) so I'm wondering if this is actually the throttle position sensor reporting incorrectly causing the jerk.

 

Does this sound plausible? 

 

It's had new brake disks on the front but that was several months ago and I'm wondering if a wheel speed sensor has been damaged or disturbed but the jerking is making me think it is not that.

 

When I get home, I'll try to read any faults off with a OBD2 reader. 

 

Any other suggestions? 

 

Thanks in advance for any help.

 

I've seen some other posts regarding EPC / ESC faults and misfires due to coil pack or plug lead so I'll investigate this, along with the fault code, when I get home from work(!)

Let's wait for the codes, there's enough rampant guessing and speculation cluttering other threads without subjecting this one to a similar 'dirty' protest!

1.2tsi CBZA/CBZC engines. I know them well

 

2 possibilities in order of likelyhood.

 

Reading OBD codes will tell you which it is. (A cheap OBD reader can be had for under £25)

 

Ignition fault, usually number 3 lead has gone open circuit or/and ignition coil pack failed. Check lead first. Plugs may be worn which can trigger this chain of events.

 

or

 

The turbo waste gate (electrical) actuator has failed, either the actuator has itself failed (depending on turbo fitted, this may be replaceable for around £250) or the waste gate may have jammed. May be freeable but could need a new turbo/actuator at around £1300+

 

If the car is juddering when trying to accelerate its the ignition fault as it will be running on 2 cylinders.

 

Turbo problem is simply limp mode, difficult to get above 30mph, but otherwise smooth running

Edited 28 August, 20232 yr by xman

Thanks for the replies.

 

Turned out to be an easy one!

 

Put my reader on and there was a P0303, cyl 3 misfire. So, I thought it'd be the lead being the problem.

 

Had a look at the lead and it's flopping around the top of the plug. The plug terminal has some white spots where it's been arcing, too.

 

I've pushed the lead on properly and cleared the fault code. Seems to be ok on a short drive so I'll monitor it now for if it comes loose again. The plugs were changed about 4 years ago so it's probably due a new set anyway.

 

Mrs is saying that she perhaps needs a newer car now after seeing the £1200 for a turbo! Can you not get refurb ones for a lot less or are they false economy?

 

Again, thanks for the help and advice.

Turbo failures are relatively rare. Ignition problems are far more common.

Turbo failures are only common on cars that get neglected for oil changes, usually because they do a low mileage round town which are the worst conditions for oil to be left unchanged!

14 hours ago, sepulchrave said:

Turbo failures are only common on cars that get neglected for oil changes, usually because they do a low mileage round town which are the worst conditions for oil to be left unchanged!

Mrs car tends to do short journeys most of the time but I change the oil and filter about every 10 months with 507 spec which is probably overkill. 

8 hours ago, briscaF1 said:

Mrs car tends to do short journeys most of the time but I change the oil and filter about every 10 months with 507 spec which is probably overkill. 

 

In that case the turbo will last however long you decide to keep the car.

The spec is VW 504 00 / 507 00 for fixed or variable servicing anyway.

VW 504 00 because a TSI and if it was a TDI it is VW 507 00 even if on Fixed Servicing.

 

Fixed on the TSI could be VW502 00 but the difference in price is only Ooo or Ahhh.

On 28/08/2023 at 19:11, sepulchrave said:

Turbo failures are only common on cars that get neglected for oil changes, usually because they do a low mileage round town which are the worst conditions for oil to be left unchanged!

Not true, the common turbo related failure on the 1.2tsi and later tsi engines is failure of the electric actuator. Happened on my sons fabia, at 110,000 miles of high speed mostly motorway miles. 504.00 oil changes every 8-9k miles. My other sons 1.2tsi Octavia went 170k miles without any turbo issues with a lot of 20k mile oil changes.

44 minutes ago, xman said:

Not true, the common turbo related failure on the 1.2tsi and later tsi engines is failure of the electric actuator. Happened on my sons fabia, at 110,000 miles of high speed mostly motorway miles. 504.00 oil changes every 8-9k miles. My other sons 1.2tsi Octavia went 170k miles without any turbo issues with a lot of 20k mile oil changes.

 

Actuators are available separately these days so replacing the entire turbo is not necessary.

1 hour ago, sepulchrave said:

Actuators are available separately these days so replacing the entire turbo is not necessary

It all depends, different revisions and suppliers, some have replaceable actuators others don't.

On 29/08/2023 at 18:46, toot said:

The spec is VW 504 00 / 507 00 for fixed or variable servicing anyway.

VW 504 00 because a TSI and if it was a TDI it is VW 507 00 even if on Fixed Servicing.

 

Fixed on the TSI could be VW502 00 but the difference in price is only Ooo or Ahhh.

The oil is usually Castrol Edge 5W30 LL, which is 504/507, I believe.

Correct.  Because the VW504 00 is what the TSI requires, but you could use VW502 00 fixed service.   the TDI,s need VW507 00.

Hand that it is the same spec. 

Update to this.

 

Car was running ok for a week then partner complained about it jogging occasionally, mostly in 3rd, although it never did it when I drove it.

 

Yesterday, it was really bad again, although no fault codes were logged,

so I thought I'd start with changing the leads after comments about them breaking down.

 

Bought a set of Bosch leads and swapped them over.

 

When I measured the old lead resistances, they were 9k, 10k, 17k and an intermittent 40k. I think they're supposed to be 6k and it's recommended to change them if they're 8k+.

 

Seemed to run well on the test drive so, hopefully, that's the end of that!

 

 

Edited 9 September, 20232 yr by briscaF1

Yes, leads only last a couple of plug changes, they're consumables as well.

 

I reckon you've fixed it.

59 minutes ago, sepulchrave said:

Yes, leads only last a couple of plug changes, they're consumables as well.

 

I reckon you've fixed it.

I hope so. Been faffing with this, off and on, for a few weeks

6 hours ago, briscaF1 said:

 

When I measured the old lead resistances, they were 9k, 10k, 17k and an intermittent 40k. I think they're supposed to be 6k and it's recommended to change them if they're 8k+.

 

 

Factory OE leads are made by NGK and all have a nominal 9k resistance even though different lengths. The VAG OE plugs are also NGK and have a built in 1k suppressor. Pregapped at 0.7mm

 

Equivalent Bosch iridium plugs have a 6k suppressor pregapped 0.8mm, they work fine despite these differences.

 

Resistance is largely irrelevant to HT systems, the resistance is only there to reduce RF interference.

The resistance across the plug gap is infinite, however the HT voltage can jump across it easily.

2 hours ago, xman said:

 

Factory OE leads are made by NGK and all have a nominal 9k resistance even though different lengths. The VAG OE plugs are also NGK and have a built in 1k suppressor. Pregapped at 0.7mm

 

Equivalent Bosch iridium plugs have a 6k suppressor pregapped 0.8mm, they work fine despite these differences.

 

That's useful to know. It'd explain why two were around the 9k if that's what they're supposed to be 

 

I should have measured the new leads to cross check.

 

The leads on it were marked "Bremi", which I'd seen for sale on GSF yesterday. I'd never heard of Bremi before that. I think these are the factory/original leads as the car was almost new when we bought it and still being serviced by Skoda.

 

1 hour ago, sepulchrave said:

Resistance is largely irrelevant to HT systems, the resistance is only there to reduce RF interference.

The resistance across the plug gap is infinite, however the HT voltage can jump across it easily.

 

I'd read somewhere that the resistance doesn't matter until the spark jumps the gap and current flows, then it governs how long the spark is maintained due to it limiting the current. I guess this is where the RF suppression comes in, too 

 

Higher resistance should prolong the spark, then, which probably isn't a bad thing necessarily unless it overly weakens the spark.

 

I imagined that the resistance of the leads is intended to match other components in the system, hence them supposedly being a specific value.

 

I guess the important thing is that none are completely short or open circuit!