help, i have a problem with my 1986 325i se e30

[indi325i]

Hi I have a e30 1986 325i se, it is in original condition and I’m the first person to drive her in the last 10 year (been garaged)
I’ve been driving the car for the past 3 months; I had a mechanic to do some work on the car to get her up and running. Radiator change, spark plugs +leads, filters, alternator and some work on top of the engine and maybe pre pump (which is making a wining sound). Car was running fine for 3 months but drinking too much fuel


Ok here is the problem since I’ve been driving the car for 3 months I’ve only got 13mpg, yep that’s it. (That includes motorway driving)
Second problem is the car started to cut out when stand still at traffic lights or going low speeds
Then 1 day the car just died on the motorway. The rac recovery guy had a look at it and said the car is starving of air. Once I got the car towed back home. The battery was charged up again (due to hazards being on).
So when I start the car the revs go up and down and cut out after 10-30 seconds. The car is choking.
I’ve changed the rota arm and distributor cap, and the throttle body has been cleaned with carb cleaner.

If anyone can give me some advice it would be much appreciated.
Also I will upload some pictures soon as it is in original condition since 1986with original mtech 1 body kit and side skirts, no welding and has an original Bosch car phone

[BenHar]

Check the intake side for air leaks.

Ben

[Speedtouch]

Also test the blue temperature sensor, often a cause of overfuelling:

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

[Grrrmachine]

If it's starved of air it means either your air filter is completely blocked, or your throttle body isn't opening fully. I find either of those unlikely.

If you're running rich I'd say it's more likely that you're overfuelling. That's normally caused by something we call the Blue Plug:

http://www.e30zone.net/e30zonewiki/index.php/Blue_Plug

There's a chance that by running around for three months with a knackered one, your spark plugs are now coated in a thick black powder that's stopping it running properly. So get it TESTED (not just swapped) according to the guide in the Wiki, and report back.

[Speedtouch]

^ Oi! I just said that!

[Grrrmachine]

Speed v Eloquence

[Speedtouch]

Where does "Blue Plug" come from - I've never heard it referred to as that before?

[Grrrmachine]

That's what it was called in the Wiki when I took over the project, in direct contrast to the Brown Plug. Hence the redirect page to "Blue Temp Sensor" - it was quicker than cleaning up all the existing links within the Wiki.

Doesn't matter what it's called; a quid says that's this boy's problem

[Speedtouch]

Oh, fair enough, I'll let you off lightly this time round then.

Yes, definitely prime suspect in this case.

[indi325i]

thanks for the quick replies, ive had a look at the air intake it seems fine, it has a new air filter and also the rac guy took the intake stuff off to see if it was opening and closing and gave it a clean. the car has had new spark plugs and leads. but i will check them to see what condition they are in. ive had lots of black stuff come out the exhaust and i know co levels are hight. i will check out the blue plug but i can only do cold tests because the car cut out after 10-30 seconds

[Grrrmachine]

If the car cuts out after 30 seconds/three minutes, but then restarts if you leave it for half an hour, then it's 99% related to the blue plug - it's over-fuelling.

Remember that you're testing two things; the sender, and the wiring itself, which is why you need to pull out the ECU. To start with, test the resistance of the blue plug when cold, then check at the ECU to make sure it matches. You can then stick a bit of wire (paperclip) across the two pins of the blue plug connector, and again measure at the ECU to make sure the reading is now 0 Ohms. From there, whip the blue plug out, pop it into a mug of hot water and measure its resistance again. If it hasn't changed, buy a new one.

[Speedtouch]

Just a thought; if the OP's car is a 1986, it may have the earlier 35-pin Motronic ECU socket, in which case he'll need to test at pin 13 and 16/17 (Ground).

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

[indi325i]

thanks for the info, will do the checks tomorrow. fingers crossed it is the blue plug

[indi325i]

spark plugs are totally black, ive also taken the blue temp sensor out, looks ok.
i set my amp meter to 20k, cold reads 3.10
and hot reads 1.24, maybe 60 degrees water.
do i still need to check the wire to the ecu?
going to go buy new spark plugs and the blue temp sensor is only £14 so im going to buy that too

[Speedtouch]

Yes, check the wire to the ECU, as if it's not connecting properly, it won't matter how good your blue temperature sender is!

[indi325i]

after doing a couple of adjustments to the air intake allen key slot and the throttle rev slot( which i dont think i really should of played about with), the car stayed on for 10 mins, if i press the accelerator between 2 and 3 thousand revs the car stays on ( pressing and letting go to keep it in between).
i will do the ecu check tomorrow because i dont really want to mess about with wiring.
the car does move forwards and backward but very very slowly.

[indi325i]

changes have made a slight difference to the car 5% better. if there is any other checks please let me know thanks.

[Grrrmachine]

You really shouldn't have touched the air intake. You've now covered one problem by fiddling around with something else, which means you have two problems.

You REALLY need to test the blue sensor wires, as the Wiki states. This is one of the most common problems on these cars, which is why a) it was so quick for three of us to diagnose the problem and b) there's such a comprehensive guide in the Wiki, which you didn't follow.

Now you NEED to take the car to a mechanic with a gas analyser to reset the air flow meter and to ensure the throttle body is set correctly. He should also do the blue sensor wiring test.

If you don't do this, you will be buying new spark plugs every three months and paying 30% more for fuel until you do.

[indi325i]

I checked the blue new temperature sensor this morning and it read 5.4k ohms, wiki suggested it be between 3.5k-4k ohms, i'm guessing the difference it down to how cold it is today. as suggested i then checked the leads to the ecu. the plug was a 35 pin unit. again the reading came back the same as what was read at the sensor, therefore the leads are fine and the readings are getting to the ecu. the problem is still there and any suggestions would be greatly appreciated.

[Brianmoooore]

Get the injectors properly cleaned. Injectortune on here does it for a good rate for Zoners. As the car has stood, it is most likely they are not sealing/spraying properly. And they have been in for ~25 years so deserve some TLC..

Check the fuel pressure in the rail is ~3bar and check the relief valve's diaphragm is intact. You do this by removing the actuating vacuum pipe from the manifold and sucking on it. If it holds vacuum, it is ok, if you get a taste of petrol it is fooked and will be allowing petrol to be sucked directly into the intake manifold. Not common but who knows..

Make sure the throttle position sensor is working and properly adjusted.

Blue temp sensor/blue plug is a prime suspect.

Etc. WIKI has a full list of checks to do to make sure everything is working properly.

AND DON'T MAKE ANY ADJUSTMENTS TO THINGS THAT NEVER NEED ADJUSTING.

[Green]

For the sake of like £20 I would have just changed the blue temp sensor to rule it out. Check the injector loom wiring underneath the manifold. There's a small connector that attaches it to the main loom that twists to undo, undo it and check for corrosion under the rubber grommets use a bit of contact cleaner and reassemble.

If your exhaust fumes are strong smelling of fuel then it will be either blue temp sensor or your now incorrectly adjusted air flow sensor.

[indi325i]

sorry should have mentioned that i did put a new blue temp sensor in.

[Speedtouch]

5.4 kilohms does seem a tad high - this is with the new sensor, I take it? Try measuring the old one under the same conditions and compare the readings.

[indi325i]

hi all, i just uploaded a movie of the issue on you tube, hopefully you'll be able to see what the problem looks like.

[Budgie325]

Interesting.

I was in exactly the same situation with mine having had it sit for ten years.

Gave mine an Italian tune-up using some of Shell's finest and it seems to have cleared up.

[indi325i]

new blue sensor reads 5.4 kilohms

and old blue sensor reads 4.4 in roughly the same conditions

[Speedtouch]

Both are outside of the normal range - they usually measure around 3300-3600 ohms cold, however, this could be down to the extreme cold climate we have at the moment.

[indi325i]

sensors go to correct temperature when in normal conditions

any ideas how i can check the air intake??

im also thinking of changing the dme relay

the below link shows some pics of my car. i picked it up for £1200.

[indi325i]

the car is going to a mechanic today.

what other things should i be checking?

[Speedtouch]

I would be checking the inlet manifold gasket for air leaks - with the engine idling (if possible), spray WD40 around the gasket; if the idle speed briefly rises then you have a leak, and need to fit a new gasket.

Also look for any splits in the hoses around the throttle body, and check that the TPS is clean and set up correctly, and clean the ICV.

[indi325i]

the car seems like its running on pure petrol, petrol even comes out the exhaust and also back fires in to the intake ( i think). All hoses, seals seem fine.

if you hold the accelerator pedal at a steady rev it will drop and cut out. but if you press the pedal in short bursts it does not cut out

[Speedtouch]

I would be tempted to try a different ECU in it, as the 073 type fitted to the early 325i is notorious for problems caused by dodgy solder joints, etc.

[indi325i]

the car is kind of up and running, it runs ok-ish for about 10 mins then i think the fuel pump is getting hot . It then starts too lose power and cuts out. The pump i can hear is struggling. because the fuel filter which i changed was totally dirty im now thinking about changing the fuel tank(must be very dirty inside), pump(it looks new but it could be off another car) and taking those 2 round regulators/ absorbers out ( next to the external pump)

any idea where i can get hold of a fuel tank?
is it ok to remove those fuel regulators/absorbers ? i think there must be lots of crap inside them. they look like they are original from 1986

[indi325i]

advice would be appreciated thanks