Intermittent loss of power - causes!?

[Jay A3]

Looking for advice on this,
Only started happening today, popped down to the shops and was fine. Coming back the drive was occasionally juddering, where it throws you back a bit. Driving casually between 2k and 3k revs, it seems to drop in power for half a second, then picks it back up again. In a 15min journey it happened at least 6-8 times, any ideas? Dont have access to vcds so unable to get is scanned...

Any help and advice appreciated

Cheers

 

[voorhees]

Vac leak would be the obvious first check,then check the dv is working correctly.
Then I would do a scan.

 

[Shane-Ireland]

When were your spark plugs last changed ?

 

[Jay A3]

Vac leak would be the obvious first check,then check the dv is working correctly.
Then I would do a scan.

Thanks for quick responses!
I had a quick look earlier and no pipes were coming off, i will go and check to make sure

When were your spark plugs last changed ?

Car is due for a service soon - last changed about 9k ago, but could they really be a cause?

 

[Jay A3]

Just ran the car for about 20mins checking for leaks, couldn't find any (by eye) Seems the car is doing it even on idle. I can hear the engine drop once every so often as if it wanted to cut out but then picks up again

 

[actualeddie]

Could this be the.old coil pack problem?

 

[ShaunS3]

Sounds like coil pack to me, had same issue with mine.

 

[Shane-Ireland]

Thanks for quick responses!
I had a quick look earlier and no pipes were coming off, i will go and check to make sure


Car is due for a service soon - last changed about 9k ago, but could they really be a cause?

Could well be a cause but if the plugs are only in it for 9k then i'd be surprised.could also be a fuel issue i.e dirty fuel filter,dirty petrol.Probably going to be hard to diagnose it on your own though.

 

[Jay A3]

Could this be the.old coil pack problem?

If your referring to the recall, the AGU coil packs were exempt

Sounds like coil pack to me, had same issue with mine.

I think one of my neighbors has a vagcom, so going to hopefully get that scanned later on.

Could well be a cause but if the plugs are only in it for 9k then i'd be surprised.could also be a fuel issue i.e dirty fuel filter,dirty petrol.Probably going to be hard to diagnose it on your own though.

Maybe worth changing the fuel filter and ultrasonic clean the injectors?

 

[ShaunS3]

Regardless of the coil pack recall, they can still fail....even more so on a car of this age. The issue does sound ignition related to me and my money is on the coil pack.

 

[Jay A3]

Cheers Shaun

Just went back out in it again, it is idling inconsistently as well now, i will have to try and source some coils and on the bank holiday weekend.. somehow i don't think that will be possible.

 

[Shane-Ireland]

If it's idling roughly here's what you do.

With the engine running pull out the first coil pack,if the idle gets rougher then that coil pack is fine,move on to the next.If you pull out one and the idle remains the same then that coil pack is the faulty one.go through all four and see what happens.

 

[Prawn]

AGU coilpacks VERY rarely fail at all, mine still has all 4 original coilpacks at 213k, running at twice the factory output too.

On an AGU, it's more likely the ignition amp breaking down, or coil pack wiring.

Jay: I found mine went through a period of dropping onto 3 cylinders breifly then coming back again, I pulled everything out, used WD40 on all coilpack and spark plug connections, cleaned up the plugs, and heat shielded the coilpack wiring, and it doesn't seem to have come back at all.

Also check the ignition amp connections and give them a spray up too

 

[Prawn]

oh, and what shane said above is sound advice! If it's missing on idle it's dead easy to diagnose which is faulty, although I find it easier to pull the injector plugs off whilst it's running rather than the coilpack plugs.

 

[Jay A3]

Thanks guys, yeah i did have a problem with the ignition amplifier module recently where it did exactly what you said prawn. When warmed up it occasionally went for 4 to 3 cylinder's. I managed to find another one in the garage from another AGU we stripped a while back. I swapped that over yesterday and it ran fine for the time being. I did think it could be this, i slapped the old one back in; the idling was worse and the mis-firing came back.

I will check each plug connector as you guys have advised, might pick up some new spark plugs while i'm at it - any recommendations?

Just hope its a simple fix....

 

[Jay A3]

Small update...
Dean from 4 rings kindly came out today as he is local and had a look at my car.
VCD didnt pick up any faults, the issue i had, had gone!?
Just my luck, when i get a professional to come out and check it, the car behaves! Took it for a spin and it was fine, going to monitor it over the next few days. I rather the problem came back so i can get it fixed, instead of playing the waiting game.

 

[Prawn]

This might sound really daft jay, and looking back it probably is.....

A few years back I developed a misfire that I couldn't trace. The car ran perfectly when cold and warming up, but within a few minutes of reaching full temperature it'd start misfiring terribly on another over 10psi of boost.

I spent several months changing MAFs, ign amps, coilpacks, spark plugs (for new Denso IK22's), all sorts, until eventually I got chatting to the guys at Atspeed Racing in Rayleigh, I was only there with a mate and mentioned my issue, and the guy immediately said it was plugs, I explained that it couldn't be because I'd recently stuck new Densos in, and he laughed and repeated it's definitely plugs. I thought he seemed pretty rude to be honest, but he kept insisting it was plugs, so I went to the local ECP there and then and bought a set of standard plugs. Dropped them in, and the problem was gone! 100% solved.

Turns out the densos didn't suit the car and just made it all ****. Been on those ECP plugs ever since and trouble free!

 

[Jay A3]

Cheers Prawn,
Yeah 4 rings let the car warm up and the problem didn't rear its ugly head again.
I'm currently running plugs i got from TPS. It might be worth changing them again as a service is due.
The denso's are good plugs, just not for our cars? I used to use them on my honda with no issues...