hacker-pschorr

FWIW I figured out the cause of the Audi randomly dying running VEMS. It's power steering related. I was able to recreate the complaint from the customer multiple times in a row.
Push the clutch in, as the RPM's are falling, crank the steering wheel and the engine will die. Not every time but consistent enough to confirm this is the issue. Seems worse on a very hot day.
I'm not so sure this is an issue with VEMS or the tune, but a potential problem with the power steering pump.

Crumpler

I was just posting to say mine died today, apparently I jinxed myself.
Hot day, coasting to a stop light. Restarted fine, did not/ could not reproduce issue.
Also had a bizarre start up this morning, hunting all over the place. Then normal start immediately after.
Grounding should be bulletproof after all the work I did last time. I don’t know it doesn’t feel like a hardware issue. Unfortunately neither event was logged.

My impression, and I know absolutely nothing about coding. Is that Vemsware gets progressively glitchy the more you burn changes.
I don’t know if this affects the config files. I have re-installed vemsware several times on my laptop and it seems to “help”.
I don’t know if that’s even a possibility. This is half observation and half question.
What I need is clarity, and I’m not going to get it. I got a track day coming up and I thought I had rectified all the above. I should cool off before I post but there you go.

grepin

Hi everyone. Just to join in I dont run cruise control. It has never worked since I had the car. My VEMS install is pretty basic on a stock car. It generally has been pretty good. I changed my fuel system as I was getting erratic fuel cut symptoms above 5000 rpm. As pointed out from kingwildh change the CPS. It fixed the issue straight away. I am getting to the stage of getting a pro to tune it. Other issues not related to VEMS keep cropping up. I am keen to get it to a sequential injector setup and maybe something to do with the spark. Maybe during engine out stage for head gaskets and access is easier.

kingwildh

Are the injectors wired in the stock way? It is possible that you overcook the injector driver...take a look in side and see if you injector driver leads are turned blue...

kingwildh

See the differents in the leads..

85euro928

Any idea of what caused that?

kingwildh

Yes, the stock solution is that all the injectors receive their power from one injector driver. As such, they build an ECU that can handle the power draw for four injectors per batch fire.

VEMS is not built to put four injectors on one injector driver at the same time. For normal driving, this isn't a problem because there's time for the driver to cool down. However, if you run at high speeds (above 150 mph) for let's say, 15 minutes, the driver can become overheated. This could cause the driver to shut down, resulting in your engine dying. If you have a boosted solution, this can happen even quicker.

85euro928

I noticed that the drivers aren't touching the case. Seems a missed opportunity to not take advantage of the large aluminum heat sink. Also, I know it's not ideal, but a bunch of holes for air flow might not hurt.

85euro928

Another thought, I'm running 30lb (actually 29.4lb) injectors and plan on bumping up the fuel pressure from 2.5 to 3 bar to help with atomization. This puts my duty cycle at around 65%. Not ideal, but that may help by working the drivers less.

kingwildh

Yes, you're correct, the drivers should make contact with the aluminum body through a heat sink. The drivers get hot, so this is essential.

I replaced my VEMS because I wanted dual O2 sensors / dual knock sensors, etc., but without the built-in Bluetooth, so the heat sinks could be connected to the body.

Also, because of the heat, I changed the wiring to individual drivers per injector. I drive on the German autobahn, so I want to avoid any overheating issues.

kingwildh

It could help with shortening the injector opening times, but at WOT, this difference is very small. I don't think that it will change anything.

I tested how long the car could maintain WOT, and it was between 10 - 15 minutes, depending on how much time the driver had to cool down.

85euro928

Yea, they don't have any roads around here where you're going to run WOT for more then a minute.

Crumpler

Thanks for posting the info on the drivers. I will check on that. Another potential issue I was not aware of.
Yes stock injector firing and FPR, but 42 pound injectors.

I did a little bit of everything for my higher revs to closed loop idle event. Slightly increased timing and fuel in those lower KPa/rpm sweep cells. Also increased the IAC duty cycle somewhat at hot operating temps on the ref curve.
(also, being that guy, I re-installed vemsware )
No further events, but time will tell.

85euro928

Made this mount and poked some holes in the box. This will be mounted in the stock location.

hacker-pschorr

How much space is between the drivers and the case?