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Large MPVs -- Ford Galaxy / VW Sharan / SEAT Alhambra: => Ford Galaxy / VW Sharan / SEAT Alhambra => Topic started by: swfsnapper on July 19, 2012, 03:10:48 PM

Title: Rough running when gears engaged
Post by: swfsnapper on July 19, 2012, 03:10:48 PM
Hi,

All of a sudden my Seat Alhambra Mk1 (With a VW engine) has started to run very roughly when the gears are engaged.. i.e. Idle is fine and revving up in neutral is fine, but no power when being driven, it just chokes.

I've had a lot of trouble getting the car though it's last MOT last month on emission, where basically I had cleaned lots of sensors, replaced air/fuel filter, plugs and used engine/injector cleaner, but eventually it passed.

I was away when the car failed but my father in law was in the car and called the AA - The AA man spent an hour checking everything but couldn't fix at the road side. He suspected some sort of injector problem?

I checked for faults codes with none found and disconnected the MAF to see if that made a difference, plus I disconnected the battery for 5 minutes to reset the ECU, all to no avail.

Any thoughts on what to check next?

Thanks in advance.
Title: Re: Rough running when gears engaged
Post by: Mirez on July 20, 2012, 11:33:53 AM
So is it missing then (skipping) or its just got nothing to give but still smooth?

It could be a coil pack or lead breaking down, or it's not unknown for a new plug to be faulty or to come loose.
Title: Re: Rough running when gears engaged
Post by: swfsnapper on July 20, 2012, 10:32:33 PM
Hummm,

I'm surprised the AA man didn't identify it as an ignition problem, maybe if I have the old plugs kicking about I'll refit them. The Coil I replaced about 4 years ago, it was cheap one so It could of gone, the leads look mint, no cracking or wear and tear.

Not that I don't doubt you but why would it idle smoothly and rev up to 4000 rpm with out obvious issues, but under load choke?

When in gear it kind of just runs roughly, kind of missing. Tomorrow will inspect the plug tips, leads and coil pack again. Take it for a run and describe better what it's doing.

I have VCDS lite, any checks I can do with that?

Thanks for your help, will report back tomorrow.
Title: Re: Rough running when gears engaged
Post by: swfsnapper on July 24, 2012, 01:46:06 PM
Ok.. I systematic-ly replaced and tested the following items...

 

In fact it slowly got worse and worse, the car barely idles now and occasionally misfires. No chance of driving it anywhere. checked for large exhaust and in take leaks, none obvious found. Not sure where to go next. Any thoughts?

Title: Re: Rough running when gears engaged
Post by: swfsnapper on July 25, 2012, 08:45:12 PM
Today I stripped out the throttle body and inlet manifold, disconnected the fuel rail and had all the injectors out. I wired them up to the battery via a switch and ran some carb cleaner through them while testing. All were fine apart from one that was stuck open!

Thinking this was the problem I rang around for a new injector but wouldn't get one for a few days and it would cost me £126 each new...

Off the the breakers yard I managed to get 4 injectors off an old Golf Mk3 (Same part number) for £15. Cleaned and tested them all ok.

I replaced the one faulty injector, rebuilt the intake and started the engine........!

Still the same.....???  :(

More investigation to do tomorrow, will update but any thoughts would be nice.


Title: Re: Rough running when gears engaged
Post by: Chrispb on July 26, 2012, 08:47:05 AM
With your problems with emissions and the age of your car maybe cat converter is blocked or breaking up!!
Title: Re: Rough running when gears engaged
Post by: swfsnapper on August 13, 2012, 07:25:01 PM
Yes, nice idea but I'm reluctant just to replace the cat. I compared the exhaust flow with another 2 litre petrol engine and they are almost the same, whether that is a good indication or not, I don't know, but it certainly rules out a completely blocked cat.

Next, when the engine was cold, I removed the pre cat O2 sensor (left it plugged in to the loom) and started the engine. It wasn't as noisy as I thought it would be and even though I thought this would be a good test for a blocked cat it made no difference what so ever =(

I'm 95% sure the exhaust isn't blocked, but am open to any further thoughts on the subject.
Title: Re: Rough running when gears engaged
Post by: Mirez on August 13, 2012, 08:36:24 PM
When was the fuel filter last changed?

You may need to do some logging with vagcom now you've covered most of the mechanical items - hopefully a log will show up what the different sensors are reporting and if any are amiss.
Title: ***SOLVED***
Post by: swfsnapper on August 28, 2012, 09:11:48 PM
Thanks for all your help guys, so as it turned out the whole problem was due to a failing fuel pump!

Now, I know I had mentioned that I had checked to fuel pump and it was producing a good flow and a fair pressure, but as it turned out it wasn't producing enough pressure.

I had a mechanic give the car a good look over in the vain hope a fresh pair of eyes would find the problem but after a couple of hours he hadn't come up with anything new. A passing comment as he left, he suggested fuel pump wasn't producing enough pressure? which got me thinking.

Keeping in mind that a fuel pump was £250 non returnable item from VW (And I'm not one for just randomly replacing expensive items, especially when they aren't returnable  ) I tried to think of a way I could check this.

I stripped out the fuel pump again to see if the tank strainer was blocked but it wasn't, what I did notice that the fuel return line was dry, connecting up the pump and running it produced no fuel out of the return. Which left 1 of 3 things.

Blocked lines (checked clear)
Fuel regulator stuck closed (Had a spare from a breakers - no difference)
Fuel pump (replaced - car runs perfect)

So there you go, nowhere in all my hours of research did I hear of anyone with this problem or suggest checking the return line for the pump as a matter of course for a failing pump or rough running engine!
Hope this helps someone out there, or at least tick one more thing off things to check. Good luck

SwFsnapper

PS I still wasn't prepared to replace the pump with a genuine Seat spare at £250, but unfortunatly GSF didn't stock a pump for the car.... but they did stock a pump (£75) for a VW Golf Mk3 which happens to have the same ADY engine... Ordered one up on the off chance the pump was also the same (at least I could return it if it wasn't) and as it happens the pump was the same, it was just the sender unit needed swapping over. I am also aware you can get pumps and pump motors off ebay, but I didn't feel confident they were a good match.

PPS A plea to anyone that posts a problem on a car tech forum... please please come back when the problem is solved to explain what fixed it, even if you had to scrap the car or it was something stupid like the petrol tank was empty - I found 90% of all posts left unresolved. Thanks

PPPS Working on cars, especially fuel systems can be a hazardous past time. Please take every precaution necessary to protect yourself from injury.
Title: Re: Rough running when gears engaged
Post by: Mirez on August 28, 2012, 09:38:06 PM
Excellent news, glad its sorted and for a great price!

Thanks for taking the time to update us, it is indeed annoying when you never hear back on issues - so thanks!
Title: Re: Rough running when gears engaged
Post by: gregers on August 28, 2012, 10:41:20 PM
 [WAVE] clapping and jumping [WAVE] [agreed]