m20b25 issues

[quinn_656]

lads

i fell in with an e30 325i sport mtec 1 local car, lay up in a garage for over 10 years good history, good body, good suspension, good interior however i bought it understanding the engine was scrap it was ungodly smokey and the oil was everywhere it was dripping from the exhaust clamps and even in the air filter.

on further inspection looking at the dipstick the oil was full of petrol and obviously off a few cylinders.

i changed the oil and it is not "as" smokey

a compression test has yeilded good results on all cylinders. and a bore scope has shown nothing out of the ordinary.

it is getting spark to all the plugs however i do have a new distributor cap rotor arm and plugs to fit. a resistance test across the leads look good around 6 ohms each

a resitance test across the injectors read 16 ohms each i think that is ok. however when i touch my test lamp to the injector plugs it stays on on both terminals i was expecting a pulsing action.

this has led me to believe that something is telling the injectors to stay full on and the excess petrol is getting into the oil thinning it out and its going everywhere.

i am beginning to think that the brain (motronic 073) may be at fault but i am not a car mechanic and know that some of the guys on here are well clued in with these m20 engines

i think the car has been started and stopped alot that may be a contributing factor

anybody seen this before or any advice on where i should look next would be much appreciated

willy

[murran]

you need to scope the injectors. you cant see it with a test lamp. the signal duration is literally milliseconds!

[Jeroen]

Well first of all, what are the problems with the car? Not delivering power? Over fueling? Plugs extremely wet? Plugs very old?

On these cars, the injectors have a constant + and ground (-) is switched so the test lamp is of no use. For now I'd say the Motronic DME is not the first suspect as then it would not switch 2 or more injectors at all. My first guesses related to over fueling:

- O2 sensor (if applicable) not working right, try to disconnect and then have a test drive
- wrong temp inputs: coolant temp sender is on the thermostat housing, air temp sender is inside the AFM (air flow meter)
- AFM has been tampered with giving wrong values, try to borrow one from another 325 to test

Otherwise it might be an ignition problem, weak spark because of bad coil cable, dizzy car or arm, or worn coil.

I'd check these things first. If she's running on 6 cilinders I wouldn't expect injectors or compression to be the main cause.

[quinn_656]

ok footered at it a bit more tonight put on the new distributor cap, rotor arm, picked the best set of ht leads i could gather and a new set of plugs i blew the cylinders out with the air line and checked the connections of everything in sight i could see nothing out of the ordinary i cleaned the air flow meter and excess oil from the airbox turned it over and it fired up on all six pots... great job all sounded well until i let it warm up and took it a quick run up the road, way down on power like a big flat spot in the rev range when u put ur foot down very smokey. i didnt look into it any further. i think it is overfueling itself but cant be sure.

i've also noticed that there now seems to be some water in the oil too

if it weren't for bad luck i would have no luck lol

[quinn_656]

started it again this evening and its was off 4 cylinders let it run and its now off them all... head scratch... i'll pull the plugs out and heat them up see if i can get her firing again.

[Rav320uk]

You sure the plug leads are on correctly??

[murran]

have you tried a coolant temp sender in it?
under the inlet manifold is a round plug where the injector/temp sensor loom connects to the engine loom. unplug it and check for corrosion and loose wires behind the rubber boots. corrosion can wreak havoc in this plug and its a very common fault!

[quinn_656]

lads

i have a feeling that it run out of petrol its not much of an excuse sayin the guage doesn't work so i put some in and she's firing on all 6 she still seems to be full of oil though as the smoke hasn't totally cleared yet but its no where near as bad as what it was i think a good long run will blow all that crap out of the system

i don't like to speak too soon but considering i thought the engine was scrap and was begining to source a new engine the car has really come on it sounds brave and healthy i'll set the tappets and hopefully i'll be back to the e21 sooner than i thought.