Underpowered after fuel injector change

[JonDP]

Hiya guys,

Been having trouble for some time now with my Cupra TDI, basically, injector 1 crapped out about two months back, so thinking the others might not be far behind, I bought a fresh set from a lower mileage PD150 engine and swapped all of them out, balanced them, and had the cam timed up again. I've had it plugged into a VAG COM and all the injectors are running as they should be, and the timing is fine.

For some reason though, the car is struggling to pull it's weight. 1st and 2nd gear are completely underpowered, only starting to move when the turbo kicks in, and in 3rd the engine gives a consistent and fairly faint vibrating judder.

Checked the MAF sensor by unplugging it and seeing if the car behaved any differently, it wouldn't rev past 3k, plugged it back in and it revs the full range. Two new boost pipes to and from the intercooler, the rest are sound so it isn't turbo pressure. The VAG COM showed normal exhaust flow so the cat isn't blocked. Turbo vane has been cleaned out recently too.

Basically, I'm flat out of ideas, anyone had a similar experience, or have any more clues what to try next? Any and all suggestions are welcome as I'm pulling my hair out!

Cheers guys

 

[JonDP]

Forgot to add that there is no black or blue smoke, so it can't be over fueling.

No oil leaks either that I can see.

 

[JonDP]

Ok, so I've done a whole bunch of research, and my thinking is that the intake system is clogged up with carbon, probably made worse by over fueling from the dodgy injector. Going to remove the inlet manifold, EGR and MAF and clean the lot.

On a side note, when I had the car diagnosed, the following faults came up:

PD unit injector, cylinder 1
P1666-35 00 elec malfunction ABS fault
(01314) engine control module

Does anyone know if a dodgy injector could cause an ABS fault or is the ABS fault a separate issue? Could an ABS fault cause underpowering problems?

Cheers!

 

[David McMahon]

Sort of good timing to mention that when hot, water! can be sprayed to help clear a car out

Seems exactly the type of thing that 1, might not work, 2, might make things worse and 3, well possibly good.

Anyway :

http://www.youtube.com/watch?v=KFtp_jmLF3k&list=UU_q-UNDJeEBSHqKzAP_8x_A

I tried this on my Seat, but was unable to get it to run with maf taken out (I don't recall unplugging it though)

... Indeed, just looking at the comments on the vid gives an idea of why this might help, or might kill the car!

 

[JonDP]

Hiya, thanks for the link but to be honest, with the luck I've had with my car it'll probably blow up! Did you put the water through the air intake then? I unplugged my MAF and it seemed to go into limp mode, wouldn't rev past 3k.

Did the water clean make any difference to your car? Think I'm just going to take a pressure hose and some oven cleaner through the inlet manifold, seems the safer, if more time consuming job haha!

 

[Adam4D]

water will not clean off the build up of black sludge that's in the inlet manifold

and I highly doubt the inlet manifold is the power

blocked the egr and see how it drives?

Checked the vacuum system holds vacuum and is leak free?

able to run vagcom logs to speed up diagnosis?

 

[David McMahon]

Hiya, thanks for the link but to be honest, with the luck I've had with my car it'll probably blow up! Did you put the water through the air intake then? I unplugged my MAF and it seemed to go into limp mode, wouldn't rev past 3k.

Did the water clean make any difference to your car? Think I'm just going to take a pressure hose and some oven cleaner through the inlet manifold, seems the safer, if more time consuming job haha!

I didn't get that far with mine as it cut out when I detached the MAF (I think I left the electrical connector on in case I got an EML light.

 

[JonDP]

water will not clean off the build up of black sludge that's in the inlet manifold

and I highly doubt the inlet manifold is the power

blocked the egr and see how it drives?

Checked the vacuum system holds vacuum and is leak free?

able to run vagcom logs to speed up diagnosis?

It's hard to tell, I've been reading up on causes for underpowering and anything related to the airflow can result in bad acceleration/power. I've had the EGR cleared out recently (March ish) and checked it earlier, the valve isn't sticking though there's a fair bit of crud in there. My dodgy fuel injector was over fueling, this occurred only a few months after the EGR jammed open from carbon build up, so this is why I think the inlet manifold could be clogged. I haven't done a vaccum test but the turbo pressure was fine before the injector change. Since the change I've had two pipes replaced so I doubt it's that. I have a friend that has the vagcom software but I wasn't planning on asking him to check it out until we'd cleared the air intake system.

 

[JonDP]

I didn't get that far with mine as it cut out when I detached the MAF (I think I left the electrical connector on in case I got an EML light.

To be honest, I'd avoid putting any fluid into your air intake, seems like a sketchy path to follow! haha

I unplugged the connector from my MAF rather than taking the MAF itself off, and the car still started, no warning lights, though as I said it wouldn't rev past 3k. The more I think about it, the more I think it went into limp mode as opposed to just proving that the MAF is working fine. Inspected it earlier, there's some oil in the pipe, could well need a clean, perhaps that's contributing to the underpowering issue?

 

[Dan FR]

water will not clean off the build up of black sludge that's in the inlet manifold

and I highly doubt the inlet manifold is the power

blocked the egr and see how it drives?

Checked the vacuum system holds vacuum and is leak free?

able to run vagcom logs to speed up diagnosis?

Adam,

I looked at this car with VCDS a few weeks back. The issue then was fuel injection related with a huge imbalance of the injectors reported by VCDS. It was barely within the maximum range shown by VCDS at idle, and as soon as you drive the car, 2 of the cylinders flatlined off the end of the scale (each one the opposing end, +3 and -3).

Unfortunately i can't remember which cylinders were at at fault, i know one of them was cylinder 1.

I believe some of the injectors have been out/changed/re-fitted since then but it sounds like it's exhibiting the same issue

Unplugging the MAF won't prove anything as it run's from a default value which is barely more than the idle value. Nothing else looked untoward with VCDS at the time, it isn't N75 or turbo control related, there was plenty of airflow but no fuel

I still think it's an injector issue

 

[Adam4D]

Injectors changed with correct AL marked units? Wondering if he was sold the wrong injectors

Other than that only basics of fuel filter blocked or tandem pump not giving enough very rare tho

 

[Dan FR]

Pretty sure they were the same part number . Woudln't a lack of fuel through the tandem or filter be an issue for all cylinders? I'll admit my knowlede of the hardware side isn't reat so any other ideas or suggestion would be good. I really think the injectors need to be tested properly to rule them out

 

[JonDP]

Hiya lads, the injectors I bought were from an ARL PD150 from a Golf GT TDI so should be fine. The codes matched the injectors that came out so that shouldn't be an issue. I messaged the seller asking if he'd had them flow tested etc before he sold them. No answer as of yet.

@ Dan, we changed cylinder 1 which was playing up as you said, I didn't realise the others were playing up too? I thought they were over/under fueling to compensate for injector 1... I'm reluctant to send them off for testing as I can't afford it at the moment. I still have the original injectors which were fine asides from cylinder 1, do you think I should put the old ones back in?

Bloody cars, who'd have em eh?

 

[David McMahon]

I'd consider playing lego with them and having a good swap around! Perhaps one of the new ones is faulty?

Don't forget to mark them all.

 

[JonDP]

I think I'll have to. I need to get a vagcom on it to see which injectors work and which don't and then demand my money back from the guy that seems to have ripped me off. Forgot to mention as well that it wont' be an issue with the fuel filter as I replaced that very recently along with air and oil filters.

 

[anni25pd]

Have you considered the fuel injector wiring harness which is internal in the head may be breaking down famous for it on high mile PD's ??? just a thought

 

[JonDP]

Have you considered the fuel injector wiring harness which is internal in the head may be breaking down famous for it on high mile PD's ??? just a thought

I did read something about it but had no idea what it is. Do you know where abouts it is/how to check it for wear? Thanks for the suggestion, could well be the problem!

 

[Adam4D]

Normally the loom would cause a missfire rather than lack power but hey stranger things have happened

 

[Dan FR]

Hiya lads, the injectors I bought were from an ARL PD150 from a Golf GT TDI so should be fine. The codes matched the injectors that came out so that shouldn't be an issue. I messaged the seller asking if he'd had them flow tested etc before he sold them. No answer as of yet.

@ Dan, we changed cylinder 1 which was playing up as you said, I didn't realise the others were playing up too? I thought they were over/under fueling to compensate for injector 1... I'm reluctant to send them off for testing as I can't afford it at the moment. I still have the original injectors which were fine asides from cylinder 1, do you think I should put the old ones back in?

Bloody cars, who'd have em eh?

Cylinder 1 was playing up initially, but VCDS will only tell you the balance. So it could effectively be an over or under fuelling injector so could be 1 or 2, no real way of knowing which.

There are no fault codes or misfires reported which would indicate that it was the loom.

 

[JonDP]

Ok, I'm still waiting on my mate to come and check the wiring loom to see if it's all working. We couldn't manage to get the inlet manifold off as we don't have the right tools. Short of that, I'm fresh outta ideas. Dan, did you say the airflow was fine?