205 GTI on MS1 troubles

[greggwynne]

Hi guys how are we all

Just so you know, I'm not a mechanic by any means!!

So has anyone any experience running Megasquirt 1 on their little pug? I got my car a couple of year's back as part of a midlife crisis and it's well and truly given me grey hairs!! The plan was to buy it, so a little resto work and enjoy it......2 year's later it's still stuck in the garage......why you might ask.....

It's a phase 1.5 '89 1.9 gti UK import. The plan was, with my mechanic, to drop the engine, have a look and replace what needed to be replaced. Then we noticed the ECU and a couple of odd things. It is running MS1 or Megasquirt 1. The car started fine, drove alright, bit rough on idle but that was probably due to bad earthing and possibly the fact the person that installed it tapped into the old wiring loom.

Long story short, we got the correct wiring loom and replaced the old. All the engine is back in and hey presto......won't start!!

What's the problem?? Car just keeps ticking over. First off no fuel getting to the manifold, got a new fuel pump, replaced, fuel pumping, but not sure if it's got enough pressure, done bridge the relay pins and got fuel upto the rail (took a while), bolt back on.....nothing, just keeps ticking over. Spray a bit 'degreaser' in front of the minfold air inlet and the thing wants to start. This tells me it's a fuel problem?? Next......injectors?? Turn ignition on the injectors pulse only once, apparently these are meant to be continuously pulsing??

The injectors are dry.
The immobilization device is off.

My mechanic was kind of lost and he owned one of these back in the UK.

Any advice other than 'replace the loom and ecu back to original' would be greatly appreciated.

Thanks guys

 

[schlitzaugen]

I don't know anything about MS1, but if it run before re-wiring, I would start there and check the wiring again.

When working on electrics, drawing everything on a piece of paper clearly is the way to go, especially for the future repair man (or owner).

Also, how did you decide it is a fuel problem? Checked spark?

Fuel pressure is not hard to check (or shouldn't be) for a mechanic workshop. So is the pump. These things need not be second guessed. Even I can do it and I am not a mechanic, nor do I have a workshop.

Once this is cleared, I am afraid you will have to look into the MS1 and see if it is doing its job. I think MS still supports the model, have a look on their website and the many forums on it.

But first things first. Get your pencils out and inspect the wiring job closely drawing up everything as you go. I would be surprised if you didn't find the problem.

 

[PeterT]

1. Hook up a laptop and check if the ECU is getting an input.

 

[GRAHAM WALLIS]

When you turn on the ignition the fuel pump will run for a few seconds. Get this happening first. You can download the tuning program for Ms1 from the ms website. You wil need a serial to USB adaptor if your computer doesn't have a serial port.

 

[GRAHAM WALLIS]

The fuel pump output from the ms is an earth, so the other coil connection of the relay should go to volts. I can lend you another ms1.

 

[ng850]

With the engine being cranked over by the starter motor or if it is running, the injectors should be pulsed appropriately... altogether.

Check that the tachometric relay is operating correctly in the new wiring scheme.

I'd also suggest sticking a fuel pressure gauge onto the end of the fuel rail so you readily see that appropriate pressure is being maintained.

Does sound like your replacement wiring is missing a specific requirement for the ECU to be happy to get the ball rolling.

 

[GRAHAM WALLIS]

With the engine being cranked over by the starter motor or if it is running, the injectors should be pulsed appropriately... altogether.

Check that the tachometric relay is operating correctly in the new wiring scheme.

I'd also suggest sticking a fuel pressure gauge onto the end of the fuel rail so you readily see that appropriate pressure is being maintained.

Does sound like your replacement wiring is missing a specific requirement for the ECU to be happy to get the ball rolling.

No Tachometric relay needed,the MS1 has its own fuel pump relay output. If you can't hear the fuel pump run for 3 seconds on switch on then carefully check the wiring from the fuel pump output of the MS1 through the relay and then to the pump.