No turning back now

[Mechcanico Lee]

Was the injector genuine part ? do the petrol injectors need coding in

Yes check for any loom connectors , check for any corrosion at ecm plugs

At this stage i would be scoping signals and scoping amps signature waveform on injector ....but obviously you need a scope for this .

Load test the wiring to injector with a halogen bulb so you know it can take load

[Delboy]

Was the injector genuine part ? do the petrol injectors need coding in
The injector was new from Audi, no coding required on these and in the short video of the injectors you can see the new one on the test rig to ensure it worked and flowed the same as the others.

Yes check for any loom connectors , check for any corrosion at ecm plugs
I did look at the injector lugs prior to plugging back in and none of them looked grotty, also had the plugs of the ecm and they too look fine.

Only split in the harness with plugs to the injectors are ones I cant get to easily and are down the back of the engine but I have never been in there or disturbed them.

At this stage i would be scoping signals and scoping amps signature waveform on injector ....but obviously you need a scope for this .
I do have a 2 ch scope with current clamp and I tested number 6 coil today to see if it was pulling current as it should. See video below to see if anything looks amiss.

VIDEO

Load test the wiring to injector with a halogen bulb so you know it can take load

Is it possible to back probe the ECM and if I can get access use the current clamp at the ECU end of the injector wiring?

It just that there is no access to injectors with the manifold in place.

I'm also waiting for a Vacuum gauge coming so I can do test with it.

As a side note the car is running better today after clearing the faults from ecu's which as you probably know sets the trims to 0

Annoyingly I need both inlet pipes now as I managed to damage both today with the on/off/on/off carry on.

They are on back order, but for the meantime I have effected a satisfactory repair.

[Mechcanico Lee]

Hard to see voltage values on the screen but traces look ok .....do the coils have 4 wires on them .

Yes you could scope injector at ecm plug , then compare to another injector .

[Delboy]

Originally Posted by Mechcanico Lee

Hard to see voltage values on the screen but traces look ok .....do the coils have 4 wires on them .

Yes you could scope injector at ecm plug , then compare to another injector .

Yes the coils have four wires, +12v, signal ground back to inside car, Trigger back to ecu and power ground to Cylinder head.

I checked both the Grounds and on that coil they looked fine at 0.2 ohms

[Goran]

Thanks for posting pics of the engine, looks like hell of a job.

[Delboy]

Daily update.

I went about getting a capture of the Injector pulse today and compared it to two others and they were the same.

See first video below.

Now in the video you will see the car warming up from cold and it also had the trims zeroed after fault clearing because I had EPC light on after disconnecting the ECU's while I figured out wiring.

When it was running there were no misfires, however the Bank3 Lambda control was flat at 0% and took a while to kick in. Is this a sign of a problem with that sensor??

Injector pulse video

I also took a short video of the injector pulse with the engine rev's increasing.

Is the tail end of the trace tailing off normal or ok? There was no misfires reported in vcds while doing this either.

Injector trace with revs

I decided to go for a drive to get the fuel trims back into the mix again and sure enough once the trims took effect the misfire returned. You can see in the video below what the status of the trims and misfires are.

Fuel trims

Only other thing to mention is that I started spraying contact cleaner around the air intake pipes while monitoring the lambda control figures and I found a small leak on one of the throttle bodies, i removed both cleaned up all the surfaces and resealed and adapted the throttle bodies after refitting.

I about to go for a test drive again and will see what happens to the trims and misfires again after the drive. Fingers crossed.



Well the Idle trims are different post drive but the misfire persists.

After Throttle body reseal and drive

[Mechcanico Lee]

Some good diag here Del I'm impressed , il be honest here I haven't done much work with current traces with high pressure petrol injectors , done more diesel and low pressure solenoid types of stuff , but if you have compared traces with other cylinders and the traces look the same you can surmise the injector drivers are doing what they should be . On the cylinders without faults holding revs on does it look the same were the waveform expands and contracts with revs ( the duration tails ) do they look the same as cylinder 6

Yes that bank 3 lamda does take time to come online , possible lamda heater not working as good as it could but I don't think it would have a bearing on the missfire .

The fuel trims don't look to bad ,the -4 % on that bank it's not excessive and the ecm is reducing fueling to get it where it wants to be .

You say you have done compression tests and all was well , have you done dynamic compression tests before ?

Stick your compression tester in that number 6 , ground the coil ht out so the spark has somewhere to dissipate to , I would say un plug the injector so we don't get cylinder wash ,but its difficult to access so for this test we can manage with that for now . Start the car up

Make a note of what it bulids up too ...it may surprise you !! it did with me when I first did it , press the button on your compression tester and let it build again ...just get a feel for what it does

Next give the throttle quick hard blip ...as the engine 'gulps' and picks up make a note of what compression gets up to .

Try all this again on a cylinder without a missfire count .

Cranking compression shows you the ability of the cylinder to seal itself ....no leaks from valves no leaks from rings ....dynamic compression tests show you the ability of the cylinder to flow air .

Have a go at these tests let's see if it shows anything

I will post them you tube captures up on the pico site
What year is the car , what engine code , and what miles it done

[Delboy]

Hi Lee

Thanks for sticking with me. Keeps my sanity in check.

I'll do the dynamic test as you mention today.

The car is s8 v10 engine code is BSM

It's got 75000 miles on it.

This engine shares the same injectors and overall design ethos as the other FSI V engines

So the v6 v8 and v10 all should have similar waveforms.

Thanks

[Delboy]

Well the compression tests and any other jazz will have to wait till next week.

Found out through soaking the inlet manifold interface to heads with brake cleaner that its bloody leaking.

It is so small a leak that it didn't show on a smoke test at my mates garage but lambda values change dramatically when brake cleaner was sprayed down there.

So I'm going to have to pull the manifold again next week.

So angry at myself for not getting a leak free mate up, but its a stupid design with only clamping forces along one edge against a silicone rubber gasket.

At least i'll be able to see how the valves look after a bit of driving

[Mechcanico Lee]

Good work Del , inlet leak on the one cylinder will definatly cause an issue with the missfire count

I would of thought that the bank number 3 lamda control would of been more towards the plus side for fuel trims though .....ecm adding fuel to compensate for the air leak .....perhaps that lamda on that bank being slow is masking the fault some what ??

I have seen a few times were smoke testing has not found leaks .....because you are slightly pressurising the manifold it can push o rings / gaskets back into place ....where as vaccum can pull them in if say a seal has got pinched on the build up .

Don't be to hard on yourself .....these things happen to the best of us myself included ......modern cars are a barsteward to work on .....back breaking hanging over the engine bay .....I don't need to tell you you know what it's about!!

Keep us informed how it goes , and I'm happy to stick with you till its fixed mate







This make you feel any better .....one of my jobs for last week 2007 Range Rover Td v8 .....blowing exhaust manifold at cylinder head .....one side blowing bad the other side just starting to blow ....manifold warped ...studs snapped off flush in the head , both turbo shafts excess play , intercooler leaking , air con rad corroded through and other stuff , 150k miles company owned £6k bill !!