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Model specific boards => Golf mk4 => Topic started by: fishfingerface on 14 May 2012, 13:09

Title: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 14 May 2012, 13:09
Hi All

i'm a newbie and need  some advice on my 1999 AGU Golf 1.8T

The car seems to mis-fire badly when it gets hot....

Its had a code reader plug into it and nothing shows...i have changed he Igntion control Unit by the Air box...thinking that was it

am i right in saying it could now be the Coil packs....it seems odd that nothing shows on a fault code reader...

the car seem to splutter then cut out...this could happen on a junction and with my baby girl onboard this is not good


any help or advice would be great
Title: Re: AUQ Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 14 May 2012, 13:11
AGU ENGINE CODE
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: Toby on 14 May 2012, 13:15
Ignition amplifier on your air box is usually the culprit, unlike ye coils to go on a agu

Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: Granta Gti on 14 May 2012, 13:16
Try changing plugs  :wink:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 14 May 2012, 13:48
I have changed the ingnition amplifier back last week..but this didn't sort out the misfire when hot

Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: BarryMKIV on 14 May 2012, 13:57
Have you had it scanned yet?
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: richw911 on 14 May 2012, 14:00
No codes could mean the MAF sensor  :smiley:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: xxChrisxx on 14 May 2012, 14:26
Pointless doing a scan on an AGU as nothing ever shows up. Better to do it the old fashioned way. :nerd:.

Doing it when hot, I would say fuelling rather than spark.

1. Whip the plugs out and see what they look like.
2. Clean the throttle body, if it hunts for idle even remotely.
3. Use some injector cleaner, and give it a run.
4. Unplug the MAF and try to replicate the problem. It may run worse, but if it stops the cutting out it's a fault with the ECU diddling with fuel trims, not necessarily a duff MAF.
5. Check for air leaks.


If you know someone with a copy of VAGCOM do a log of the air flow values.
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: km on 14 May 2012, 14:41
my car used to misfire and cut out an awful lot. a new maf sorted it!
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: xxChrisxx on 14 May 2012, 14:53
People needlessly changing MAFs at £80 a throw (or whatever it is) has to be one of the biggest earners for Bosch.
It's money for old rope; recon it by giving it a little wipe down.
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: richw911 on 14 May 2012, 14:57
People needlessly changing MAFs at £80 a throw (or whatever it is) has to be one of the biggest earners for Bosch.
It's money for old rope; recon it by giving it a little wipe down.

From experience of people cleaning it only delays the inevitable  :wink:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: xxChrisxx on 14 May 2012, 15:08
From experience of people cleaning it only delays the inevitable  :wink:

But for the amount of people that have changed it when it's something else screwing up the fuelling.
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: richw911 on 14 May 2012, 15:21
From experience of people cleaning it only delays the inevitable  :wink:

But for the amount of people that have changed it when it's something else screwing up the fuelling.

Ah I see what you mean indeed I agree check the basics first  :smiley:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 14 May 2012, 15:26
so first port of call is.................

Clean the Maf Sensor

Possible plug change
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: xxChrisxx on 14 May 2012, 15:37
so first port of call is.................

Clean the Maf Sensor

Possible plug change

Check the plugs.
It'll tell you a huge amount about whats going on in the cylinder. It'll give you a good indication why you are getting poor combustion.

Clean the throttle body.
It'll stop any hunting for idle, and is free.

Check for vac leaks, specfically on the PCV system hoses to the inlet manifold and the breather pipe.

Unplugging the MAF makes the engine fuel on a default map, as it doesn't know how much air it's getting.
If you don't start to misfire when you get up to temperature you know it's something that messing up the fuelling.
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 14 May 2012, 15:40
Thank you  Chris
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: inggti on 14 May 2012, 18:05
I've got this problem with my agu. The past four weeks the only code that came up was temp sensor. After changing that still the same just come bak from we're I had it remapped and I know now the culprit is tha lamba sensor it only showed up wen the remap man did a live scan and the sensor reading was all over the place. So new lamba tomorrow and then bak to sort remap out
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 16 May 2012, 10:47
Hmmm Interesting  :wink:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: inggti on 17 May 2012, 12:59
Ok still got the same problem. Even changed lamba sensor.  Any ideas before I scrap it
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: harlemex on 17 May 2012, 13:13
Agreed with Chris on the maf sensor. Loads of people shell out for the miracle maf sensor cure and its a waste of money. My guess is the camshaft sensor.  :tongue:
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: fishfingerface on 17 May 2012, 14:15
This is a pig of a Fault

do really want to start changing loads of stuff and it still dosen't fix it...there has to be someone who has had this and sorted

we just need a quick answer.....

inggti...i'm the same as you..........had a right scare the other day...slowing down to turn left onto a side road with cars right behind me the F**king car decides to stall

two cars nearly plough into the back of me

Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: Granta Gti on 17 May 2012, 14:20
What have you done/ changed so far?
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: richw911 on 17 May 2012, 15:31
As above what have you done so far?

Was the temp sender a Genuine part? Are the plugs new / OK?

It could be a coil pack AGU coils don't usually go but they can

Have you cleaned the throttle body as suggested?

With a faulty Crank sensor you usually cant start the car when it is warm.
Title: Re: AGU Engine Mis-fire When engine is hot...advice needed
Post by: inggti on 18 May 2012, 13:16
Sort to jump in. I've changed ignition amp coil packs temp sensor. And still the same oh yes and lamba sensor. Yesterday had it pluged into snap on machine and it came up throttle position sensor. And it's getting harder and harder to start over the last few days. Thinking about new crank and cam sensor next. After that who knows. Anubody