How to check engine ignition timing?

[merlin's S4]

My S4 is running rich and has been for sometime. It no longer passes the MOT Cat test. I've checked most of the obvious stuff and have fitted a new Lambda. Car is running RS2 setup with RS2 Turbo and injectors. The ECU is an RS2 ECU which I bought from a forum member complete with Paul's switchable V and N Stream maps. Incidentally, the car runs well with the lesser map but it does not like the V Stream one bit with boost cut and knock sensors cutting in. I'd previously put this down to the standard intercooler not being man enough.

I was told when I purchased the ECU that it was taken from an S2 so should have been compatible with my AAN engine. I did try switching the 4bar FPR for a 3.8 in case the maps were done for the RS2 FPR but still no joy. I'm now wondering whether it's a timing issue but I don't know how to look at this. Can VAG COM be used to monitor ignition timing and if so what values should I be looking for?

Thanks!

[UrS4boy]

Ignition timing is totally controlled by the ECU and it based on having the cam and crank correctly timed together via the timing belt. With correct alignment of the crank and camshafts, the ECU uses the crank position sensor and the various other inputs, e.g. cam sensor, knock sensors, etc. and its Motronic maps to look up the correct timing for that particular situation.

I am running complete RS2 (MAF, injectors, turbo, exhaust cam, and exhaust manifold) with the original AAN 4Bar Fuel Pressure Regulator (FPR). I am running MRC Stage 3 software developed for RS2 hardware on an AAN with 4 bar FPR. I always passed "Air Care" emissions testing on a 4 wheel rolling road with numbers similar to or better than the stock AAN.

Found an old post that I made in 2013 on quattroworld.

"RS2'd and Air Care=pass with flying colours. Fresh oil,92 with 10% ethanol.Hot cats.Best pass ever."

Fresh oil (oil change) was always one of the emissions testing hints that we gave out on quattroworld.

Found an old Audiworld UrS forum post from 2009:

"Every two years I have to AirCare (rolling road sniff test) my 93 S4.

Make sure you go to Air Care with a clean oil change and hot cats, e.g. after a highway romp.

This year:

Hydrocarbons (g/km): Max Allowable: 0.5000, my car = 0.2132, Average Pass = 0.3842
Carbon Monoxide (g/km): Max Allowable: 9.3200, my car= 8.2967 Ave. Pass = 2.1424
Oxides of Nitrogen (g/km): Max Allowable 1.2400, my car = 0.1350, Ave. Pass =0.3273

The CO has always been high. Even before being RS2'd - but it always passes.

Gotta love OE Bosch injectors and MRC software."

First thing to check is the cam timing:

http://forums.quattroworld.com/s4s6/msgs/136943.phtml

[terrybullwon]

Got to go old school and get a timing light on it.

[UrS4boy]

Got to go old school and get a timing light on it.

Good luck with that. Even *IF* you get to see the tiny TDC mark on the flywheel with a timing light (how are you going to connect the timing light to No.1 cylinder by the way if there are no spark plug wires on an AAN? ) what are you going to do next? Adjust the position of the distributor? Oh wait. There is no distributor and there is nothing you can adjust mechanically while the engine is running.

Waste of time.

[Error404]

Typical. If you had real world experience not gained away from your keyboard you would know checking the timing WITH A TIMING LIGHT is the first thing you do to verify base timing on any engine


James is right. First check the base timing with a timing light to verify this is correct.
Use a degree wheel to correctly measure and mark TDC. You can do this on the front pulley to make life easier. Some timing lights will pick up off the low tension wiring to the coilpack, otherwise you can connect a short HT lead between the coilpack and the plug and trigger off that. You can use a dial-back timing light to adjust it to match your idle ignition angle which you can see in the measuring blocks in VAGcom (yes it will fluctuate a bit but should be reasonably stable.).
From this you can verify if the timing the ECU seeing is correct. It should be since you can't adjust it, but stranger things have happened, IE snapped TDC pin on flywheel repaired incorrectly, or timing offset accidentally reconfigured during the remap etc. Following this, you can check the cam timing is correct.

Are you sure your fuel pump is man enough and your fuel delivery isn't tapering off at the top end?

[newsh]

Try a different MAF
Clean MAF connector

Has the car ever passed an MOT on this ECU?

[merlin's S4]

Thanks for your replies!

I've not been able to pass The Cat emissions since fitting this ecu with the RS2 injectors. It used to pass fine with Stage 1 and original injectors.

In answer the other points, as it happens I do actually have HT leads as I'm using EFI Express LS2 coils. I have a Bosch 044 fuel pump. I did have the flywheel pin welded back on at some point but 99% certain that it went back in the right place.

I also have a digital wideband gauge but it doesn't log so only gives you an immediate reading. This is pretty erratic and jumps around the 14s at idle and cruise. I'm not sure how stable it should be.

Can I learn anything from the VAG COM timing measuring block? Plugged it in this morning and was showing a stable 9.8 BTDC but this got more erratic once warmed up, jumping between 9 and 12. The figure increases with engine revs up to around 30 BTDC at 3000rpm.

[Error404]

9-12 BTDC at idle is in the right ballpark. Of course that is just the ECU commanded angle, it could be different in reality, which is why you need to verify it is correct using a timing light. I’d use a degree wheel to find and mark 10deg BTDC on the front pulley then verify the ECU figure is correct.
If the car ran fine before then seems likely it’s an issue with the RS2 upgrade. Assuming you have fault codes?
I would replace the FPR as a matter of course as they are cheap. Check fuel pump delivery. As above MAF and MAP sensors need checking, MAF terminals may need to be replaced. (I have a few sets of the correct gold plated terminals left if you need).
That would be a good start.

[UrS4boy]

Typical. If you had real world experience not gained away from your keyboard you would know checking the timing WITH A TIMING LIGHT is the first thing you do to verify base timing on any engine

LOL. Don't worry I have lots of hands on knowledge. I've been playing with cars for over 50 years now (67 in May). Your response to my post was exactly what I wanted, i.e. details as to how one would go about checking the timing on an AAN, although you left a few details out. Like how with a stock coil "pack" plate, you need to pull the entire plate and connect all 5 coils to plugs with leads, like those used with a 7A or 3B. Luckily Merlin is running LS2 coils so he already has high tension leads.

I show this in my Missing and Hesitation Diagnostic post:

http://forums.quattroworld.com/s4s6/msgs/22611.phtml



I have also previously documented and posted about the position of the crank sensing pin, using info that I gathered, including from here.

http://forums.quattroworld.com/s4s6/msgs/51259.phtml



And yes, I did that from my key board.

[steve briance]

Is there a reason why the AAN timing pin is quite a chunky angular thing? The 7A timing pin is exactly that - a 4mm diameter round pin. I ask as my pin has just made a bid for freedom somewhere in the workshop where it is being refaced. getting the snapped stub out may be unnecessary as looking at the above pic the 'pin' appears welded in place.

[UrS4boy]

Use a degree wheel to correctly measure and mark TDC. You can do this on the front pulley to make life easier.

Error: I'm not walking away from this one. You might have a lot of 3B and ABY experience but I don't think you have the UrS AAN experience that matters here. Getting access to the front pulley on an AAN is nothing like a 3B or an ABY in an S2 because of the serpentine belt arrangement. You have to do a lot of disassembly to even try to attach a degree wheel to the pulley. And by the then the engine isn't going to be startable until you put it all back. Too much work for very little good information.

There are far more better things to check first on an AAN to try to solve this issue than trying to put a timing light on an AAN.

I suggest that the original poster have a look at this first:

http://forums.quattroworld.com/s4s6/msgs/210191.phtml

[Colesy]

Where did you get the ECU from? I had a switchable chipset ECU which I sold to someone in Weston Super Mare (I think) I don't know how many Paul made but the one I had wasn't for an RS2 setup. Worth checking before you check the more difficult bits.

[Error404]

Error: I'm not walking away from this one. You might have a lot of 3B and ABY experience but I don't think you have the UrS AAN experience that matters here. Getting access to the front pulley on an AAN is nothing like a 3B or an ABY in an S2 because of the serpentine belt arrangement. You have to do a lot of disassembly to even try to attach a degree wheel to the pulley. And by the then the engine isn't going to be startable until you put it all back. Too much work for very little good information.

There are far more better things to check first on an AAN to try to solve this issue than trying to put a timing light on an AAN.

I suggest that the original poster have a look at this first:

http://forums.quattroworld.com/s4s6/msgs/210191.phtml

Well maybe you should do, right after you apologise to Terrybullwon for your usual rude, sarcastic & scathing response to his CORRECT suggestion to the OP's question
Your response here again demonstrates you're out of your depth on this topic. You need to re-read the OP's thread heading again.
Feel free to post a dozen or so links to irrelevant topics though

[newsh]

Merlin your software is wrong or has the wrong R201 resistor.

IMO

And you other lot - play nice!

[terrybullwon]

As Alex said.

here is a video of a ABY with coil packs on a timing light. We used a HT lead to jump the gap. The white line is 0 to TDC with the metal bracket we G clamped to something solid to confirm the timing.