How to check engine ignition timing?

[terrybullwon]

And why would you ever try to look into the bell housing with a timing light that’s just stupid!

your always learn a lot more at the front pulley if the timing is wondering

[merlin's S4]

Thanks for your replies so far.

I suspect that it's an issue with the map. The ECU was bought from a long serving member who knows what he's talking about. However as far as I remember I was told that the ECU was from a customer's S2.
It is an RS2 (ADU) ECU but as it had come from an ABY I assumed that all would be ok on my AAN. I don't know what mods were done by Paul to the ECU and I don't know whether it was originally mapped for an ABY or ADU. I'm beginning to wonder if it's an ADU map and I guess that the problem may lie here. As I mentioned before I did suspect the FPR before and changed to a 3.8 bar to match the possible ADU software.
Could it be the difference between the ABY and ADU timing belt setups that's causing the problem?

[UrS4boy]

Terribulwon: Sorry if I hurt your feelings. I didn't realize that you were so sensitive and that you needed somebody (Error) to stick up for you. Sorry.

Now, as I was *trying* to contend (but words were falling on closed ears) , there are much easier ways to check the timing on an AAN - by checking the alignment of the cam timing mark, the crank timing mark *AND* the flywheel mark.

Good for whoever checked the timing on the S2 ABY but I notice that the entire front end is off the S2 in order to do that. That is too much work on an AAN. Merlin's problem is going to something other than ignition timing (assuming that the cam and crank are indeed lined up correctly).

If the car ran well before the ECU change, kind of leads you to think that the timing is fine but the problem is in the ECU, doesn't it? Swap the other ECU back in and see how it goes.

[prj]

Mechanical challenges aside (which can be sorted by simply making a mark on the vibration damper) the problem with the timing light on the stock ECU is that you have no way of forcing a fixed ignition angle. So it's all over the place.
I don't know how you would do it without forcing a fixed angle first. Most aftermarket ECU's have an option to set fixed ignition angle for verifying engine timing with a timing light.

But really with stock ECU you just need to make sure the belt is set right and all the marks align, and you shouldn't have any problems with the timing, because the correct offsets for the triggers are hardcoded in the ECU.
Checking timing with a timing light is usually done to set the base timing for standalones, as not all have a correct base map with the offset for auditrigger (or if you use a 60-2, it's a different story entirely).

[UrS4boy]

And why would you ever try to look into the bell housing with a timing light that’s just stupid!
your always learn a lot more at the front pulley if the timing is wondering

Sure. Maybe. If you had any hope of seeing the AAN serp belt pulley/vibration damper so you could mark it (as prj suggests). But on an AAN, that is a bit of a challenge with out basically setting up to do a cam belt change, i.e. removing the lock carrier and swinging the rad and condensor out to get enough access. As it is, this is what you are faced with on an AAN (taken 10 minutes ago). I am pretty sure Merlin was hoping for something easy. Not going to happen. Less work to remove the upper cam belt cover and statically check the cam timing mark with the TDC mark on the flywheel (the photo I posted earlier).

[prj]

Usually if you are installing aftermarket ECU for the first time, the nose is already gone due to previous work.
I've used an additional mark on the vibration damper as well as the mark in the bellhousing without issues.

[Thuppu]

It's fully possible to check the timing on AAN front damper. It's tight but you can just see it. And it helps if you have small dots of white paint on the timing marks.

[UrS4boy]

It's fully possible to check the timing on AAN front damper. It's tight but you can just see it. And it helps if you have small dots of white paint on the timing marks.

Sure. And just when did you paint on those white timing marks? When you had the front end a part to do a timing belt for example?

[Thuppu]

Sure. And just when did you paint on those white timing marks? When you had the front end a part to do a timing belt for example?

Yea, I have had everything open a couple of times, yes. But it's possible to do without white marks, but you had to have good eyes.

[Vorsprung durch Technik]

And you other lot - play nice!

Quite agree, the problem here seams to be as with many forums "little clicks" that form where they are only ever interested in their own egos instead of spreading the love around evenly amongst everyone.Some people need to remember to just be nice remember they've been treated well on many occasions so return it! It doesn't cost anything and it makes you feel good to boot.

[Chaos0211]

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.

I think I have your old ECU bought it with the car

[S2central.net]

Any of those few switchable ECUs that I did back in the day will have been for ABY or ADU. The ADU version will have used 3bar MAF, RS2 instance of R201, RS2 injectors (360cc) & FPR (3.8bar). If its running silly rich now (when it used to be ok) then its either getting more fuel as a result of bad MAF signal, faulty FPR or an air leak. The latter would also explain boost cuts. If its running towards rich on part throttle then it could be a lambda probe problem. There are better experts than me on AAN specifics but I am not aware of any significant differences in engine timing.

If you have VAGCOM then posting some measuring blocks at warm idle will help determine if something is off (if I can find the right book to remind me)... any of my pokery for increased boost etc will not be interfering with factory diagnostics and such 'basic settings'. If the ECU cannot adapt fuelling correctly for an MOT test then you either have a bad lambda, bad MAF, too much fuel (the wrong injectors) or an air leak.

[merlin's S4]

Thanks for your response Paul !!

Just to clarify, the S4 has never passed the MOT cat test with this ecu. Unfortunately I no longer have the AAN ecu so can't swap the injectors and ecu back to test. The car has been off the road for some time on and off in the last few years so I've never really gotten to the bottom of this. I'm pretty sure that it's been running rich since changing the ecu and injectors. You can smell the rich running from the exhaust.

MAF was a new RS2 item that Martyn sorted for me before Vagparts closed (I know several years old but I've done less than 20k miles in that time)

Lambda is brand new.

Injectors were low mileage used RS2 ones from a forum member.

Originally had the 4bar FPR but I fitted a used 3.8 to try and solve this issue.

I have a pressure test kit and compressor and there are no obvious leaks. - The car will pull pretty hard with the N Stream Map and showing around 1.5bar on the boost gauge. It does not like the V stream one bit and pulls back as soon as the 1.9bar boost comes in.

I have a digital AFR gauge in the car but it doesn't log and is obviously difficult to read whilst driving. It is usually in the 14s whilst idling and cruising but I wouldn't say it's a steady 14.7. It almost seems like it's fighting to get the correct numbers but maybe that's just because it's an instant reading.

I have a basic version of VAGCOM and posted some details from the timing block earlier in this thread.

Interesting that you mention there's no significant difference in the timing between AAN, ABY and ADU as I was kind of leaning towards it being some discrepancy between the ADU ecu and AAN engine (standard cams etc). I have had the flywheel timing pin welded back on at some point but it was so obvious where it had fallen off that I can't believe we'd have put it back in the wrong place!

I will have another look at some point and try to double check everything, however in the meantime any help would be very much appreciated!

Thanks again!

[quattro4sprung]

Ahoy fellas!

I don't mean this as a thread jacking, but whatever was the outcome here?

I am experiencing similar on my 93 UrS4, which has an MRC Stage1 tune and an RS2 turbo. Everything else is pretty much standard.

Oh and I must comment on how tasteful the arguments and nitpicking was on this thread, I found it rather charming actually
Today's social media warriors are not half as entertaining

[varia]

Ahoy fellas!

I don't mean this as a thread jacking, but whatever was the outcome here?

I am experiencing similar on my 93 UrS4, which has an MRC Stage1 tune and an RS2 turbo. Everything else is pretty much standard.

Oh and I must comment on how tasteful the arguments and nitpicking was on this thread, I found it rather charming actually
Today's social media warriors are not half as entertaining

I really like PRJ style, extremely knowledgeable, sometimes arrogant, can be an ***-hole, but: you always know where you are standing with him, a straight shooter. Back in the days, I used to search all his post and read them. Learned a lot, saved many of them, and laughed a lot

Anyway. as he posted:
"But really with stock ECU you just need to make sure the belt is set right and all the marks align, and you shouldn't have any problems with the timing, because the correct offsets for the triggers are hardcoded in the ECU."

https://www.s2forum.com/forum/techni...n-timing/page2