M40B18 Trouble!

[_ethrty-Andy_ 2132]

Hey guys! My mates 318i (Will to those wellington boys that have met him) has developed starting issues. Ill write down what i/he/we have checked

- no spark

- no fuel

- CPS is mounted correctly/plugged in. have not resistance checked or whatever you do to test that

- Cranks over fine

- Turn key to ON, all lights come up on dash like normal

- Turn key to ON, ICV etc does not whur in engine bay, and fuel pump does not prime

- Checked other stuff too, but the above are the main parts

- Battery is sweet (would not crank over otherwise right?)

- All fuses have been checked. Have not checked relays (i dont think he has anyway) as its a time consuming process. Anyone know which ones to check specifically?

From what i know, i am quite sure its the ECU thats at fault, however hesistant to run with that as i thought they seemed to be more of a temperamental sort of issue, not a 'come out to the car one day and it doesnt go'

He is going to dismantle the ECU and check for condensation inside it when he gets a chance, will post results up.

Have not scanned as yet. Will do if no further suggestions come up and the ECU is not damp.

Cheers all

Andy

[_ethrty-Andy_ 2132]

btw its an E30!

[Silver Fox 43]

Best guess, check fuel and main relays, or dry connections at the fuel pump at the tank, cover under rear seat behind driver. Have also had to change one ecu,

Most likely fuel relay, try another if you have one, it's one of the orange ones behind the cover on the firewall in the engine bay. Try jumpering the relay, if the fuel pump goes it's the relay at fault, if it doesn't then check for dry connection at the tank, or you have a fuel pump problem. Terminals 30 and 87 are the 2 to connect, you should use a fused connection, pump should run continuously.

[_ethrty-Andy_ 2132]

Can do. I dont have any spark either though, so its not 100% fuel issue. dunno if you missed that part? forgive me if you did see that

[Silver Fox 43]

It won't supply spark if the fuel pump doesn't go. ECU must know somehow? Been there, done that as well.

[_ethrty-Andy_ 2132]

It won't supply spark if the fuel pump doesn't go. ECU must know somehow? Been there, done that as well.

Okay thanks! i didnt know that one or other of this will check this out and see how we get on. is it the same relay (as in type of relay) as the rest of the ones in the fuse box? ill take one of my known working spares over.

If its not this, what would you suggest to check next? (just trying to kinda get a plan of action so im not making 10 minute visits every other day). Thanks for your help on this sort of thing as always!

[Silver Fox 43]

It's an orange 4 pin relay from memory, the middle one of three, the left one is a white main pwr relay, not sure what the right one is, but think it's to do with the auto, it's not used in the manual cars. If it's not that, I'd be checking the ecu next.

[_ethrty-Andy_ 2132]

sweet. Hes (hopefully) drying out the ECU at the moment. We will see if that fixes it, if not then check the relay, and then steal/borrow/buy an ECU.

Im going to be daft and throw it out there, a B16 ECU wont work for this purpose to rule that out will it? i just have a B16 one here..

[Silver Fox 43]

Yes it should, so long as it's from a M40B16, not M10.

Should run fine actually.

[_ethrty-Andy_ 2132]

oh wow was not expecting that answer at all! yeah its from M40B16. sweet ill take that over as well then

[Jono51 59]

hey andrew,

we have all the relays , ecu's etc

get him to bring the car in if you get stuck

also, your scan gear won't tell much with this one

let me know how you get on with it

[willm/// 0]

Hey Guys thanks for the Help. Before i pulled apart the ECU and there was water in it so dried it out with a hairdryer and then plugged it back in. Car started first time after this. There obviously had been a significant amount of water in here as some corrosion on the bottom plate had occurred. Luckily the ECU is still going. I will be leaving the ECU to completely dry out in front of the fire tonight, then will now have a working car again!!

[Silver Fox 43]

Hey Will, check you don't have rust holes in the battery tray, they are prone to rusting under the back ledge and dripping down onto the ecu.

[willm/// 0]

Yea area around the battery is very wet and car has been in the garage for the past four days and still hasn't dried. Tonight i will take the battery out and dry and check all around the area.

Thanks for the help

[_ethrty-Andy_ 2132]

Bimmersport at school eh? they must have unblocked it ha, i got it blocked there

Good that you got it sorted

@Jon yeah didnt think it would come up with much if anything, but would have used it as a last resort

[*Glenn* 854]

Water in a DME is a common problem on E30's & E36's all for different reasons. Rust and grommets on E30's , blocked lower cowel drain tubes or vegitation (leaves etc) build up in the housing next to the DME & EGS housing.