FREE MATZ Non Start Issue

[Royalratch]

Correct diagnoses wins a prize from my Aladdins cave of E30 swag.



318iS has been parked up for a few months with a non-start issue and haven't had time to look at it till yesterday.


Starter OK
Fuel / DME Relays OK (I think - continuity OK)
Spark OK
Fuel Pump OK
Crank Sensor - how to check conclusively?
Relevant Fuses OK


Suspected ECU after a chat with PacerPete. Swapped out ECU for spare and it started and ran fine. Went back to it this morning and now won't start again.

What now? What could be killing ECUs? What pins could i check on the DME connector for 12V or the ECU itself for continuity maybe?

Any help much appreciated, would rather not have the hassle of RAC and a garage for what could be a basic fault.

If it helps I have a decent diagnostic computer with the C101 adapter but haven;t bothered using it as a car this old won;t throw up any useful error codes?

[bigbird76]

Not sure if your ecu has the same issue or i am barking up the wrong tree but on the S14 engine the ICV gives problems and fries the little transistors inside the ecu, Might be worth a look to see if anything is burnt inside your ecu. If so your ICV needs replacing, And the ICV wiring loom can be modified to accept a 2-3 amp fuse.

Here is an example of what to look for

http://www.s14.net/forums/forum/s14/faq ... ics-inside

Hope that helps

Leigh

[Grrrmachine]

Have you checked the blue temp sensor readings? I'm no master with Motronic 1.7, but if you swap ECUs without going through the learning process, then it won't store a correct value for the temp sensor and won't provide the correct mixture for cold starting.

Try undoing the two battery terminals and joining them together for 30secs, then reconnect and see if the car starts. If it does, let it idle for about 10 mins to warm up before shutting it off.

[Brianmoooore]

Very much doubt if the ECU is at fault.
If you have sparks, then the CPS is OK at the time you test it.
Try to start it on brake cleaner or propane straight into the throttle body to get some idea whether it's a fuel or spark fault.

[Royalratch]

Thanks for the reply guys.

I'll try all this.

@Grrrmachinem - Not a bad idea - it only got to 1/4 temp when I shut it off again.

@Brianmoooore - I removed the fuel pump from the car and tested it on bench and its strong. It also started when I replaced the ECU so thats what led me down that route. There is also the 'factory immobiliser' leading off from the ECU Plug which is triggered by the OBC - a 2-pin connector sat under the ECU? Mine is not connected.

[HairyScreech]

The diagnostic reader should be able to pull up a bit of info from a M1.7.
Even if it is just capable of giving the sensor voltages and resistances to confirm the data the ECU is seeing.

[Royalratch]

Nice one - cheers dude.

[Royalratch]

Many thanks dude - will add to the to the list!

[Royalratch]

So the ECU Reset test didn't work.

Diagnostic Tool showed no error codes from both ECUs.

So I'll try starting with fluid straight into the throttle body - you guys mean remove the intake boot and literally spray into the butterflies?

Whilst cranking or before?

[Royalratch]

Pre or post AFM?

Excuse the dumbness dude!

[kam-325i]

Before the AFM......

[Royalratch]

Well, tried this and the engine caught and ran just for a few seconds - till the brake cleaner ran out I guess.

I assume this is deffo a fuelling fault then.

Just don't get it. No fuel issues in 17 years then I stop for a few seconds and it won;t start again. Then I swap ECU and it starts and runs. Then I start again and it won't start.

[Brianmoooore]

Right, we're making progress at last! Now do as willnz said a few posts above, and pull out and inspect a spark plug immediately after trying to start the car.

"Just don't get it. No fuel issues in 17 years then I stop for a few seconds and it won;t start again. Then I swap ECU and it starts and runs. Then I start again and it won't start." This just illustrates why you should try to logically diagnose a fault, rather than diving in and swapping random parts.

[Royalratch]

So I cranked and then pulled 2 different plugs - having first tested for spark which was present.

The heads were dry and no smell of fuel - the threads were quite oily - re-torque head? Thats another story”¦

If not, remove main relay, bridge pins 87-87-30 and check again.

So this means running a 30A cable between these pins? From 87-30?

Sorry I don't get how you can bridge 87 to itself”¦?

[Royalratch]

I also retested the Orange (fuel pump) relay and did not get continuity between any of the pins this time”¦?

[Brianmoooore]

There are two pins labelled 87 on the DME relay, so you need two wire links to bridge the three pins. Any wire is suitable, but don't push anything into the sockets that's likely to permanently bend the buckets.
Fuel pump relay should show a few ohms between 85 and 86, and it's very unlikely that yours doesn't - not what normally fails. All the orange relays in the fusebox are the same type, apart from missing the retaining lugs.

[Royalratch]

Just to be clear - on a 318iS the White and Orange relays on the bulkhead are DME and Fuel respectively right?

The fusebox relays are not relevant...?

[daimlerman]

DME relay is usually white and has five legs,two of which are marked 87.

FPR has just four legs,one of which is connected to a green/violet wire.

[kam-325i]

The only relays in the fuse box relevant to starting are the two un-loader's...

[Brianmoooore]

The only relays in the fuse box relevant to starting are the two un-loader's...

They are controlled by the starter motor, but don't actually affect the engine, other than making a little more battery power available if certain things are turned on.
The only thing in the fusebox relevant to the starting and running of the engine is fuse #11 for the fuel pump.

[Royalratch]

So I bridged 87-87-30 on the White DME relay - nothing.

The is 12V arriving at pin 30. There is continuity in the relay also.

12V also arriving at the FPR - no continuity in the relay - but that's normal in a 4-pin type?

Checked the supply to the pump again and when I crank I get around 11.5V to the pump. Not enough to make it fire?

There's no power to it at all when key in position 2.

Can I get to the injector wiring plugs without removing the intake manifold?

I'm doing all this on the original ECU by the way...

[Speedtouch]

You're best off using the multimeter to test the continuity of the relay switching contacts, as you energise the relay coil from a 12V power supply/car battery.

Set the multimeter to continuity buzzer or low ohms (0-200 ohm) range. You should hear the switching (relay clicking), and see that the multimeter responds.

Work out from a diagram which relay pins do what, as there are normally open and normally closed contacts, in addition to the two coil terminals, such as the one below:

[Royalratch]

Thanks for reply.

So I should energise the coil pins to make it latch, listen for the latch and check continuity to ensure.

In your diagram that's 85 and 86.

Shit I should just go buy 2 new relays now and be done with it..

[Brianmoooore]

You'll never get the engine to run with one of these! This is a change over relay.
DME relay is a double pole relay, although in practice, is often a single pole relay with the two 87s solidly linked.

11.5V at the pump is quite good under cranking conditions, but, as you suggest, it's quite common for a pump that works happily normally, to quit while cranking. That's why you need to connect up a fuel pressure gauge.

[Speedtouch]

Thanks for reply.

So I should energise the coil pins to make it latch, listen for the latch and check continuity to ensure.

In your diagram that's 85 and 86.

Shit I should just go buy 2 new relays now and be done with it..

Yes, the coil should be energised with a 12V supply, but beware; some relays have a diode connected accross the coil (to prevent back emf) and if you connect it wrong, you'll blow the diode. The supply needs to be connected so that the positive (+12V) goes to the cathode (-) side of the diode and NOT the anode side.

Diode:



So, wire the relay like this:

[Royalratch]

Thanks guys.

I should add at this point that I removed the fuel hose after the filter and cranked it - nothing. As in no jet fighters f fuel spraying everywhere.

Which is why I went down the electrical / ECU fault.

Does that info help?

[daimlerman]

Let's get back to basics for a moment!

You have a spark but no fuel?

[Royalratch]

Yes.

Fuel pump is okay as I tested it on my bench and its strong. There's also power getting to the pump on cranking.

There's poeer to both relay sockets too.

It must be the relays - or ECU. But spare ECU doesn't work either which can't be a coincidence.

I'll test relays but then I'm stumped...

Are these relays available at Halfords etc?

Can anyone send me 2 known working relays...? Or I can meet someone in London...

[daimlerman]

If you have a spark,that rules out DME relay and the ECU.
If you are getting power at the fuel pump,when cranking,that rules out FPR.
If the fuel pump works on the bench,but no fuel is exiting the filter,this suggests two possibles to me;
A Fuel filter is blocked
B fuel pump is now connected the wrong way round,not as daft as it sounds,took me a while to figure it out when I did it a while back!

[Royalratch]

But the car started fine when I switched ECUs. Even if it was for just 15mins. Then wouldn't start again.

I thought the cold start issue was a good lead as it has been sat for a few months?

It's not out of fuel as its full of Shell's finest.

Doubt fuel filter but I can change it.

Not fuel lines the wrong way around as they're too short to fit any other way. Plus it ran recently.

So bored now...

[daimlerman]

Not fuel lines the wrong way around as they're too short to fit any other way. Plus it ran recently.

No,not the fuel lines.
You wrote that you had 'bench-tested the pump',now that implies to me that you have dis-connected the electrical connections....


....if you re-connected them the wrong way round(like I did!)the the pump will still run,but it will suck instead of blowing(add your own actress and bishop joke here)and no fuel will leave the tank.

It's just a thought,most breakdown's,non-running issues are usually basic and simple things.

[Royalratch]

I removed and tested the whole assembly so no wires tampered with.

I'll remove the fuel line before the filter tomorrow and see what happens but I doubt it's a blocked filter - is that common...?

[Speedtouch]

No, blocked filters aren't common but it is a possibility if it hasn't been changed in yonks.

Have you followed the Zone Wiki troubleshooting guide?

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot