Slight misfire on 1.9tdi AWX audi a4

**Buzzoff** · 19-10-2009,11:18 PM

Hello people,

I'm a new member to this forum.

Sorry for the essay but here we go!

My Audi A4 1.9tdi awx (130) has covered 167K it was full VAG history up to 140K and since I have owned it I have had it serviced using all of the correct genuine Audi parts including the £16 a litre oil.

Roughly 2.5miles ago I had a longlife oil service and almost straight away the engine started to sound tappety, 700miles later & No3 tappet exploded killing my top end.

Stipped the rocker cove off to find the damage was done including all of the tappets were cracking and the cam lobe on No3 cylinder was scored badly (no3 tappet seating in the head was trashed too).

I sourced a brand new head (AMC) from a Cylinder head specialists called “Corrys” based near Tring in Buckinghamshire. I supplied them my old head of which they re used what they could (Valves, injectors and injector cams & harness). They put it all back together with a new cam and tappets. Basically they rebuilt the head so all we had to do was to refit it back on the block.

The only issue I had was that when we stripped the head originally we removed the injectors but did not note which cylinder they came from so the injectors were not put back into the original positions that they came from.
I’m not sure if the injectors will need to be re-sequenced back to where they are now via VAGCOM or does this matter at all? I have made a note of the injector id as to where they are now.

We put the engine back together using all genuine VAG parts along with the correct locking tools to time the engine up correctly. We flushed the engine through and now I’m running with Quantum fully synthetic oil (I’m now going down the road of oil service every 5k) Fingers crossed the oil will not sludge up now as it did with the long life service.

The issue I have with the car now is that there is a noticeable misfire in 4th and 5th gear at around 1500-2000rpm.
I have changed the fuel filter today but this has not cleared the issue. Could it be a problem of the injector sequencing or could it be the internal injector harness. I did replace the MAF about 3K ago so I’m currently ruling that out however the car still does not seem to be boosting as well as it did.

I have also replaced the intercooler seeing the original one was split down the seams and was blocked with old oil and road muck.

The only other thing I did notice was that the wiring harness going upto no2 glow plug was split showing the wire, I have taped it back up but I’m not sure if this is making any sort of further electrical problem?

I have not had the car read for any codes yet though.

Any ideas / advice will be appreciated

Cheers,

Buzz

**Alan02** · 19-10-2009,11:56 PM

Did you set-up the injectors when you fitted them? ie,Cam at maximum stroke on the Injector.Loosen off the adjustment on the follower and screw bolt down on injector fully,till it comes to a stop,then back-off 1/2 a turn and lock the check-nut up?Just an idea!

**Buzzoff** · 20-10-2009,12:05 AM

Cheers for the quick reply,

The chap a the head rebuilders (Corrys) said they set everything back to standard spec, I guess they set the injectors to the necessary positions.

I'll have to give them a bell and double check how they did it!

Keep the replys coming please,

Cheers

Buzz

**Camb-Tech** · 20-10-2009,08:59 PM

The injectors have to be lined up with a Dial Test Indicator and jig as well as the for mentioned tappet clearance.

If thats all ok then you may have disturbed the injector loom as they go brittle over time. You know how to replace it as you've already had it out.

**Buzzoff** · 20-10-2009,09:47 PM

Thanks for the reply Camb-Tech

I understand that the injectors must be sat in the correct position ie set distances apart to allow for the fuel flow but I don't understand the need for the dti apart from for the process of setting the injector height as stated in the reploi from Alan02.
Is the dti used to set the injector up square? What is the Jig?

I'm hoping that it is the injector harness however it looks like a bit of a tight job (there is limited space between the back of the head and the bulkhead)getting the new harness in.
Will I need to warm the new harness up to allow it to bend to insert it into the head or are new ones more flexable?

Cheers,

Dan

**Camb-Tech** · 21-10-2009,06:56 PM

the dti is used to make sure the injectors are aligned within the head. i.e. the rotation of the injector in its housing before it's clamped in. This is so the injection of deisel into the chamber is in the correct place and not hitting the side etc.
We're probably talking about the same thing though.

**Camb-Tech** · 21-10-2009,07:20 PM

This is what i mean.

**Alan02** · 21-10-2009,08:31 PM

Originally Posted by Camb-Tech

This is what i mean.

The Dealers use a very large Vernier Guage to measure each Injector body from one side of the Cylinder Head,as mentioned,so the Injector sits squarely in the clamp.Each Injector obviously has a different dimension.But this is for info.only as it seems this isnt your fault.

**Buzzoff** · 21-10-2009,09:54 PM

Cheers for the info chaps

I've had a price from my local Audi garage for the injector harness,
it's £45

.

The helpful parts chappie had a word with the mechanics regarding my issue however all they told him was that they had only changed them on the later 2L diesel engines, he also said that there had been some sort of injector modification that would involve purchasing now injectors

, I don't think so.........
Anyway all he could say was they understand replacing the harness was a fiddley job.

My question is with the head fitted to the head it looks like a really tight to insert a new harness, is the new harness flexible enough to bend or will it need to be warmed with a hairdryer?

Any ideas? Has anyone done this an a A4?

Any advice will be fantastic!!!!!!!!!!!

Cheers

Dan