5-cylinder Audi + factory sensors = success!

[elaw]

All,

I've seen some posts here from time to time relating to using factory sensors to trigger MS on 5-cylinder Audis (particularly in this thread: http://www.msextra.com/forums/viewtopic.php?f=4&t=19335). If you own one of these cars, you know you can't use the sensors directly because MS-extra (at least 1 and 2) doesn't work with a) 3 trigger signals and b) 135-tooth wheels.

Well there's now a solution to that problem! Jean from JBPerf.com ("racingmini_mtl" on this forum) has designed an interface board that takes the factory signals and translates them into something MS can work with. I now have the board installed in my 4KQT and it works like a champ!

Feel free to post if you have any questions about this setup or have a 20VT motor you'd like to sell me for cheap.

[drgolf16vt]

I am very interested in this, as I'm about to remove the cis off of a '87 5000TQ.
I plan on using MS2 Extra and need all the details.

[elaw]

Well let me start by saying this: if you possibly can, go with MS3 instead of MS2. "Word on the street" is these engines don't run very well with batch-fire injection and that's certainly true in my case. I'm going to be switching to MS3 and sequential as soon as I'm able.

Having said that, my car doesn't run *that* badly, probably as well as a CIS car with components that are a few years old. And it absolutely runs better with crank triggering than with the dizzy, the dizzy at least on my engine has a lot of slop and it showed in the smoothness of the engine. It also allows you to do a better tune, since if you're doing batch-fire with a dizzy the injectors can fire at any of 5 different times during the cycle, randomly selected each time the engine is started. With crank triggering, they always fire at the same time in the cycle. It's one of those things that theoretically makes no difference, but at least with my engine it definitely does.

The details of the crank triggering go like this: I think you have the right distributor already? You need the one with a 1-window hall wheel, not a 5-window one. You basically connect the hall sensor directly to the 2nd-trigger input on the Megasquirt and it becomes the "cam" trigger.

Then you get in touch with Jean, and get him to send you one of his "wheel translator" kits (he's got a web page for it but it's not linked on his main site). The kit is a little board with two LM1815's and a custom microprocessor that's designed to fit inside the Megasquirt case. Assemble the board, and connect the two VR sensors on the flywheel to it. The board generates an output signal that mimics a 45-1 tooth crank wheel... that signal goes to the main trigger input on the MS box.

Then you configure a few settings in TS and you're set! You don't even have to set the timing, as with the sensors in a fixed position, the timing will automatically be correct based on the numbers you program into the Megasquirt.

[drgolf16vt]

MS3 is certainly a posibility, but I'm getting a MS2 from a friend that had it set up on a 10v that progressed from Digifant1, K26/K27 hybrid to MS2, HX35/40.He is currently working on a 20V motor and is contemplating MS3.
Regarding the batch fire on 5 cylinder engines, the factory didn't seem to have any issues with the Eurovan and performance wise, we had no trouble putting a few cars on a 20V type 89 running crank trigger,COP,sequential this...034, Pantera EFI, ball bearing that...closed course...of course!
I understand the "mechanical" side of things and I'm slowly learning the "software", anyways, I really appreciate your help and all y'all getting this done.

[elaw]

That's interesting, I did not know the Eurovan used batch-fire. Many people on Motorgeek.com say batch-fire is awful, but they're probably a little biased since 034's system does sequential.

I've been struggling trying to figure out whether this engine's issues are caused by batch-fire or the wrong fuel injectors. I've currently got a set of S4 injectors in there which, being designed for a multivalve engine, I assume have a wide spray pattern. Since this is a single-valve motor designed for CIS injectors which potrude farther into the intake, my theory is the wide pattern is causing most of the spray to hit the side of the ports rather than go toward the valves. But when I mentioned that theory on MG everyone acted like I was nuts.

Doesn't the Eurovan also have the injectors in the manifold rather than the head?

I should add that most of my complaints with this engine relate to cold starting, idle quality, and light-load smoothness. At WOT it pulls pretty well given its goofy intake plumbing (long story) and how much boost it doesn't have.

[drgolf16vt]

Yes, the injectors in the Eurovan are in the manifold, but in this application I wouldn't worry too much about injector placement.
Did you try different spray pattern injectors?....different fuel pressure?
When we first converted the 10V to EFI, as a test, we used a bone stock Digifant1 ecu, originally "designed" for a 4 cylinder application running @26lb/hr. We didn't have any stock injectors around, but we did have some 32# from a Saab, some 3B and some 50# Delphis and from what I remember these all had slightly different spray patterns.
Cold starting actually improved from CIS and even though the tuning of the stock ecu was sub optimal, it had no trouble maintaining a smooth, decent idle at 730-750 rpm.
Are you using MS idle control or are you using the factory "standalone" idle control?

[elaw]

Aah, the Digifant I system... the one that came out after Digifant II! Sorry, dumb inside joke from when I used to work at a German repair shop.

Unfortunately my selection of injectors is pretty limited. The car came with 1.8t injectors that were a bit low on flow so I bought the S4 injectors on ebay. Unfortunately they're both wide pattern injectors, and the engine runs about the same with both. I've got a bunch of Saab 900 injectors around but they don't really flow enough either and they're made for a 4-valve engine too.

It seems like the only way to get injectors with a known spray pattern is to buy new and I don't have the budget for that. Even then, the info seems very hard to come by.

For idle control, originally the car had the CIS idle air regulator, now it has a 2-wire PWM valve off some random VW at the junkyard. Runs about the same with both, with regard to smoothness.

I suppose maybe I should check harder for vacuum leaks. I replaced all the o-rings on the injectors, but one of the IM bolts is broken off, and it's got one of those phenolic spacers between the IM and head so there are a lot of potential leak spots. Gonna check compression too, maybe there's something to be found there.