Running on three cylinders

[Stevieabz]

1989 325 touring manual.

The car was sat for five years and the in-tank fuel pump had seized.

I got the car dropped off. I did the following:

- New fuel
- New fuel pump
- New brake discs and pads all round
- new air filter
- new oil filter
- new spark plugs
- oil flush and new oil
- When I went to replace the fuel filter the fuel line snapped.

It has now been in the garage for two weeks. They have done new brake and fuel lines front to back. They then told me it's running on three cylinders as three injectors were squirting out a single jet of fuel when they aren't supposed to... The other three weren't doing much and apparently, that was correct. I'm not too sure about this garage...

When I took them to an injector cleaner, he said they are meant to produce a straight jet of fuel. And that all of them were working fine. £90 gone.

I went back this morning to see if the clean injectors did the trick. And no they did not. I'm now taking the car out of that place as I'm not sure they know what they're doing.

Does anyone have any other ideas I can give to the new garage as to why it's running on three cylinders?

Cheers.

[paultv]

The injectors are fired by two pulses, one of them feeds cylinder injectors 1,3 and 5 from ecu pin 16 and the other feeds 2,4 and 6 from ecu pin 17.

If the car is really lumping along on three cylinders, I would suspect a cabling fault - first stop, the plug under the inlet manifold which connects the injectors to the harness and then off to the ECU. Open this up (twist) and separate, chances are its full of shit and may have a broken cable, corroded pins etc.

Confirm a good electrical connection from the ecu plug pins 16 and 17 under the drivers side kick panel (RHD) to the injector plugs - test each one for zero ohms good connection.

Paul

[Stevieabz]

Hey Paul,

Thanks for the fast answer.

Once the car is out of that garage today, I'll pass this info onto the new guy / have a look myself. I'll confirm whether or not that is the case. If its good, I'll get back to you. If that is the fix, I'll send you some beer!

Steve

[arrisbmw]

sounds like the issue, have a look at this too

http://www.e30zone.net/e30zonewiki/index.php/C191

[arrisbmw]

sounds like the issue, have a look at this too
sorry to jump in but check this out
http://www.e30zone.net/e30zonewiki/index.php/C191

[Stevieabz]

When I dropped it at the new garage, he checked that plug and all seemed well. He said it should be an easy fix but hard to find exactly where the problem is.

I’m not sure how adept at electrics he is but we’ll see.

The original garage said he was going to try a second hand fuel pressure regulator but surely if it was that there wouldn’t be three working just fine and three not at all?

[arrisbmw]

i,d be surprised fpr. have you worked out what 3 are not working. ?
and you didn,t mention the dizzy cap and rotor arm defo worth a clean . my dizzy cap needed a claen even after 3 K, what plugs are you using ?

[arrisbmw]

i suppose you could have blocked injectors, if that were the case car would run o,k fro a short while if you remove the rubber boot and give a good spay of easy start or carb cleaner or petrol in throttle body .

you need to ascertain if your issue is fuel or electrical or mechanical no compression on certain pots.

[arrisbmw]

i suppose you could have blocked injectors, if that were the case car would run o,k fro a short while if you remove the rubber boot and give a good spay of easy start or carb cleaner or petrol in throttle body .

you need to ascertain if your issue is fuel or electrical or mechanical no /low compression on certain pots.

[Stevieabz]

Not yet, I've had no time with the car for the past 2 and a half weeks... I'm not sure these local garages are very knowledgeable about e30's.

The injectors were cleaned. Not those. The plugs are plugs I've been using for years, not those. Not the twisty cap. Need to check the dizzy cap and the rotor arm.

It's had a new fuel pump, ALL new fuel lines, new fuel filter, and injectors cleaned. I'm thinking its electrical, not mechanical or a fueling issue.

The new garage didn't seem to confident about finding and fixing the problem. I'm tempting to take it back off him Monday, get it in the driveway and get looking and testing myself.

[arrisbmw]

twisty cap what is that ? ha sit been on a code reader yet.
quite specialist thru as its obd1 , generic code reader won,t work. needs to be e30 specific.
main agent arm and leg or bmw specialist .

89 should be motronic 1.3 which does store codes .

the reason i said what cylinders are not working , it might help rule things out . as the injectors are fired in 3 ,s
if its all 1,3 ,5 or all 2,4,6, you know its something to do with the wiring to pins 16 or 17 in ecu, ground side
or worst case knackered ecu . you need the whole circuit checked . but if 3 cylinders are working fine,
you can ruleout blue temp sender. afm tps . cranksensor . i don,t think its fuel pressure as all would be affected. (has hat been checked )
could be as simple as a broken or shorted out wire somewhere.

[Stevieabz]

This twisty connection - " first stop, the plug under the inlet manifold which connects the injectors to the harness and then off to the ECU. Open this up (twist) and separate, chances are its full of shit and may have a broken cable, corroded pins etc. "

That's all good.

Three injectors are squirting and three aren't. The first garage didnt tell me which ones. But agreed that only one pulse was getting to them. So I'm pretty sure three of them aren't getting a signal to open.

The car is now stuck in another garage over the weekend. Monday morning I'm going up there to find out which set isn't working.

All aren't affected so its not the fuel pressure.

If it is as simple as a broken or shorted wire it'll take some time to find exactly where it is which is what I'm worried about paying for and is something I can do myself.

Thanks for the help so far guys.

[Stevieabz]

Hasn't been on a code reader. I doubt he has one.

[Speedtouch]

If you have a spare ECU, or can borrow one, it could be worth temporarily swapping to see if it solves the problem; it's not unknown for solder joints to go dry or output transistors/idle control diodes to fail, particularly with the later 0 261 200 380/381 ECUs.

[Stevieabz]

Good thinking Speedtouch.

I forgot to mention I dropped off the ECU from my 325i sport restoration on Friday night.

That worked perfectly a year ago. But for some reason, I don't think that's the issue. We'll see.

I didn't give him much time to check it out, but Monday morning I'm going up there and will do it myself if he's too busy. I've Had it for three weeks now and still haven't driven it. It's driving me mad.

[Stevieabz]

So I have the car back.

I've made sure there is a good connection between pins 16 and 17 to the 7 and 6 in the c191. And I've had the injector rail harness out and that all tested good.

I've now just tested the connection from the pins to injector rail plugs with the c191 plugged in and everything is good.

Sparks are all good and in time

I've put a new FPR in.

And it's still running super rough.

About to do a compression test.

Any ideas?

[arrisbmw]

if compression test o.k
your obviously back to the injectors not firing . to find out which ones are not firing get a long srew driver run the engine . blade on metal injector ear to the handle you should be able to hear a clicking , tell ing u the injector is firing. work out what injectors are not firing.
if you go one whole bank of 3 not firingf and youyve checked wiring from c191 to the ecu plug . no shorts to earth anywhere, next step gotta be swap out the ecu



as a basic injection sys on the e30s they don,t fire individually like a modern car, they fire 3 at a time.

[Stevieabz]

Compression was great. Around 145 across the board. Held the compression well also.

I have an ECU on the way. Although we've had this open to looks for signs of ware and there was only a very small bad spot. Could be enough...

I'll do the ear test first thing tomorrow morning. The electrical tests we did showed that there was a signal getting to the injector rail.

So could this be caused by a corroded sensor?

[arrisbmw]

So could this be caused by a corroded sensor?
sorry what sensor are you referring too ?
good news about the internals of th eengine , ecu sounds a bit iffy .

[Stevieabz]

Any of them. I had a very dirty crank position sensor. Cleaned it and no change.

It's almost impossible to do the ear test because its so lumpy and hardly stays running.

I've tried almost everything now. I'm really not sure.

New bits:

in tank fuel pump
fuel filter
oil filter
air filter
spark plugs
new oil
intake pipe (had leaks)
complete fuel lines
complete brake lines
injectors cleaned and balanced
Bake discs and pads all round

Tried:

DIfferent MAF
DIfferent ICV
DIfferent TPS
DIfferent FPR
DIfferent HT leads
DIfferent Distributor cap and arm

Tested:
pins 16 & 17 to 6 & 7 all good. And all the way to the injector plugs.

What else should I test?

Cheers for your help so far.

[blazed]

Only other thing to check is blue temp sensor but it doesn't sound like that's your issue. As said above ECU seems most likely.
You could take one of the injectors that is not 'working' and plug it in to the wiring of one that is just to rule out a blocked injector or 3 but it's not likely that 3 are blocked and three aren't.

[Stevieabz]

I have an ECU being shipped out today first class. Should be here tomorrow?

Currently, the car starts and dies straight away. The throttle does almost nothing. In doing everything I have done so far, I've had the car running very lump and idling on its own kind of, to not at all.

My throttle body intake boot is ruined. Splits everywhere and it was covered in a plastidip like material. God knows. I put the one from my other E30 on with the other ICV also as they are different shapes. And the TPS. Do these parts need to be engine specific? Although they are the same engine, just 2 years different.

I'm about to go out there now and check out the blue temp and the brown one.

I'm really not sure what is wrong here.

[Stevieabz]

The injectors were cleaned and balanced last week. As the first garage thought it was bad injectors. The inspector guy said they were a little dirty but all good. didn't think it was my problem and he was right I think.

Cheers blazed.

[Stevieabz]

I got the car to idle mainly by changing out the second broken TPS.

Now the car is idling rough and I can hear that injectors 1 3 5 are ticking and the others aren't.

I'm tempted to cut the plug out, but that looks fiddly and an ECU is arriving tomorrow.

If the ECU doesn't do it, I'll cut it out.

I was going to test the wires coming out of the back of the ECU that go to the injectors but after starting it and letting it run a few times it wont stay running.

[arrisbmw]

sounds like you making progress now, at least you knowits an electrical issue power not being send to the 2 nd bank of injectors 2 4 6 . get hold of a wiring diagram and work thur it.

what plug ?

[paultv]

Do a definite test - connect a multi-meter to pin 17 of the ecu plug (which drives the even numbered cylinders)

Connect a long piece of wire to the other multi-meter connector. Set the meter to read the lowest ohms setting, don't turn on the ignition. Connect the end of your long wire to pin 7 of C191 - after opening it up. Connect to the bottom part of the connector coming from the ecu, it's the middle pin 7.

You should get Zero ohms, i.e. a direct connection from the ecu plug pin 17 to the base pin 7 of C191.

Then test between pin 7 of the upper part of C191 and injectors 2, 4, 6 again this should read zero ohms.

Another point to remember is that the idle control unit earths through C191 - if this connection is crap, you'll never get a good idle setting, especially with corroded, high resistance joints.

C191 lives under the inlet manifold.

This is the best I can do without getting in my car and driving to the UK to fix your issue!

Paul

[arrisbmw]

i got a wiring diagram for a 1989 bmw 325i , which includes the 6 fuel injectoors.
if you can,t find one p.m me. your address i can post.

but looking at it now if 2,4,6 are not working, one side of the wiring to the injector plugs is red /white to all 6.
other side of injector connector is brn/whit 1,3,5 yours is good


but

brn/yel 2,4,6 which go into a single brn/yel wire all the way to the ecu , ( that wire is your problem provided the ecu is o.k ) goes to pin 17.

[Stevieabz]

Hopefully, I can pinpoint it today. Cheers for your help everyone.

[Stevieabz]

Okay. I have a correctly set up and working TPS. The car will now idle 'nicely' on three cylinders. I can say for a fact injectors 1 3 5 are not clicking, but 2 4 6 are.

I'm trying to work my way through the brown and white wire and the grounds but it's tough. everything with the injector rail is perfect, I've had it apart and thoroughly tested inside and out.

The main plug for the injector harness is good. and when I test the br/wh cable straight out of the ECU I get a constant reader.

The ECU may have a bad ground?

[Stevieabz]

We have just tested the ground to see whats going on and its all very confusing.

A ground to ground connection gives a 12.7v reading.

There is no ground, its all live?!

[paultv]

If 3 injectors are working, then the ground is not an issue as they are all connected together, follow my instructions without the ignition on and test using ohms not volts -

1) Is there continuity between ecu pin 17 and the bottom half of C 191 pin 7 ?

and please, not "yes there is 12 volts" I need the ohms reading.

answer this and we go to the next stage

Paul

[Stevieabz]

popped the new ECU in and BOOM 6 injectors ticking. FINALLY, ITS DONE! Thank you guys so very much.

[Speedtouch]

Speedtouch wrote:

If you have a spare ECU, or can borrow one, it could be worth temporarily swapping to see if it solves the problem; it's not unknown for solder joints to go dry or output transistors/idle control diodes to fail, particularly with the later 0 261 200 380/381 ECUs.

Good to hear! Which ECU did you have, out of interest?

[Stevieabz]

Part number is 0 261 200 174

[Speedtouch]

How odd. A 174 ECU is for a 1988-on 316i with the M40 4-cylinder engine - hardly a surprise that it wouldn't run all six cylinders!