S16 On Jenveys & Emerald Ecu - Not Starting

[wildejon 7]

OK so... Currently the fuel pump primes and the car turns over OK but not starting...

 

The initial symptoms before I had to get towed home were occasional hesitation, first time it wouldn't rev very high, then it popped and all was Ok again. Next drive it gradually got worse (over a single 20m trip) the cut out. It would start after once after but then cut out pretty soon although I did have a chance to move it off the road. After that, nothing.

 

Initially we thought coil pack but I've swapped it to no avail.

Connected up to the ecu and all looks OK as far as I can tell, it picks up a crank signal when I turn it over and air temp is correct.

 

Unsure where to go from here, clearly it is either not sparking or the injectors aren't firing. I'm not sure how to check this though.

I know I can pull off a HT lead and earth it on something to see if it arcs but I'm not 100% sure where to put it... being that it can only really be one of these 2 things, where should I head next?

 

What is strange is this happened on a few occasions before it failed, which I would assume meant something degrading and failing rather than a connector?

 

I've read a few posts about earthing, unsure where I would find how to check this though.

 

Any help welcome!

Thanks

[welshpug 1,657]

just earth the plug to anything metal, i.e the head, then crank it

[wildejon 7]

Done, seems like there is no spark, hard to tell if it's that or we did it wrong though

Unsure where to head next?

[Dizzee stuff 33 1 Cars]

Check with a test light or meter if you have a live feed at each injecter and centre pin of coil plug with ignition on

[Miles 331 1 Cars]

Either as said check for live at the main coil, (Thick wire) then if you can plug a laptop into the ECU to see what's going on when cranking

[wildejon 7]

Thanks guys, I'll try to pop over there this eve to look.

I did connect my laptop to the ecu , all looked OK to me, where should I be looking to see if there are any issues?

 

Forgive my ignorance but for checking the coil voltage, should I just have the ignition on, and test between the center pin and an earth point yes? Any idea what I should read there?

Same goes for the injectors actually

(I am terrible with electrics but this is certainly helping me learn!)

[welshpug 1,657]

you should see battery voltage, i.e 12v+.

[DrSarty 90 1 Cars]

When you turn the ignition on, coil, injectors and fuel pump should all see 12v one on one their terminals. A simple multi-meter on 20v range should show you this.

 

The fuel pump will actually only prime/run once the ECU grounds the appropriate pin (just for your info).

 

It's this grounding, i.e. completing the circuit that makes all of those components work, e.g. the injectors receive 12v as stated above, then actuate when triggered (grounded) by the ECU, so you can imagine that injectors and coils get triggered a lot and very fast, whereas the FP only gets grounded (constantly) whilst the engine is running and the ECU receives a cranking signal. The latter is catered for by the tachy relay on a standard GTI.

 

The other thing to test if you haven't already, is that the ECU via your laptop is seeing a cranking signal from the CPS/CAS, which will show as engine RPM when cranking her over.

 

Best of luck. Without any of the above, it won't start.

[wildejon 7]

Laymans terms, cheers

I was definitely seeing a reading from the crank sensor so can rule that out.

 

Cheers!

[Dizzee stuff 33 1 Cars]

If you have the cranking signal I think you will find you have lost the 12v feed to injectors and coil, this could be wired in a number of ways from the car as its not part of the Emerald wiring loom.

[Miles 331 1 Cars]

As said the 12v will be at one point on the injectors, Pin 3 for the coil if Valeo, The fuel pump you can catch during initial turn on, handy to have 2 people here

[wildejon 7]

OK guys, I've checked it. Between both the injectors and the coil outputs to earth with the ignition on I get 1V only...

The pump primes Miles so I would say that is all good.

 

Where next?!

[welshpug 1,657]

ok, so you have no live feed from the relays, now check if you have a permanent live TO the relays, this will usually come from the shunt box.

[Dizzee stuff 33 1 Cars]

The 12v feed could have been wired in a number of ways as said before possibly through a relay or there is a ignition live feed through the smaller of the 2 brown plugs in the drivers footwell into the engine bay (red wire) this may be worth a check.

[wildejon 7]

Holy crap, it's been THIS long since I've not started it, ouch...

 

I was over there the other day, fired up for a bit (properly running and not just turning over) then died. I'm not sure if it isn't related to the crank sensor as I took this off and gave the connections a clean before it worked.\

 

I was chatting to a friend mechanic, he seemed to think that even though I was getting a signal from the sensor (as confirmed by ecu) it might not be kicking out the 1V that it is designed to do.

 

That to me made no sense, could it be a possibility?

 

Is there anyone close to Brighton that fancies taking a gander?!

[welshpug 1,657]

what does the ecu say?

[wildejon 7]

When I turn it over it is seeing a signal in line with the rpm. This is all I have checked though, not sure if there is anything else I could glean from plugging back in again?

Thanks mate, would be lovely to drive her again!

[wildejon 7]

Thought I would update on here as it might be of use to someone in future.

 

Dan popped over yesterday and kindly spent 2 hrs in the freezing cold trying to get it started. Checked the entire ignition system and also the continuity of all wires. We saw a signal from the crank sensor (also tried a 2nd known working unit). There was power at the coil and the injectors. But no spark and no fuel.

 

ECU was earthed OK.

 

What was strange was that we initially saw about 5V at the injectors, on each of the 2 connections. Then after cranking it this went up to 13V, again the same at each connection. This seems to be the issue, in that the voltage changed and that there was a voltage at both connections, when only one should have a voltage

 

Thinking it is likely an ecu fault. Next step, call Emerald.

[Dizzee stuff 33 1 Cars]

The live feed to injecters and coil is not take via the ecu, this is taken as a ignition live straight from the car, you need to sort this problem first. I think the ecu has 2 injecter drivers to switch all 4 injecters so the fact you are seeing voltage on two at a time may not be a problem. You need to start by checking for High resistance joints on the live feed.

[wildejon 7]

Ah, OK. This is interesting, cheers!

[pugpete1108 62 1 Cars]

one connection on the injectors should be a switched earth through the ecu surely? and one is constant live when the ign is on.

[Richie-Van-GTi 71 2 Cars]

^{When you say voltage at both connections do you mean on both pins of the plug? Are you seeing both as the same polarity? Ive seen small voltages through a triggered earth lead before as it picks up a kind of residual voltage through the cars earth system. Never seen it as high as 5v but if you have a bad earth set up on the car and your putting your meter between the cars earth system and the pins on the triggered earths it doesn't sound an unreasonable amount to see. Have you checked all earths properly, or tried a dummy earth set up with some decent jump leads between block, chassis and battery? Does it actually fire the injectors and coils?}

Edited February 25, 2013 by Richie-Van-GTi

[wildejon 7]

one connection on the injectors should be a switched earth through the ecu surely? and one is constant live when the ign is on.

 

This is what we thought, but both were the same voltage AND polarity I think. We also saw 13V after trying to start it, weird that it changed.

 

Doesn't fire the injectors or plugs, no.

 

Not checked the earths because I'm not sure where to look...

[dcc 855]

have you unplugged the ecu and loom, and reconnected it?

[Dizzee stuff 33 1 Cars]

Sorry, think I may have confused things a bit. All four injecters should have a live feed (12v) with ignition on taken from a live supply on the car. The ecu then will switch the negative's of the injecters to make them pulse.