BMW-Driver.net Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hi all. This will be my first post and unfortunately it's a cry for help.
I have a clean E34 1993 520i touring which developed a lack of power after about a year of ownership. A friend recommended a someone, let’s call him ChrisB.

He had the car for over 4 months and after replacing fuel pump, filter- coils, vanos, injectors - (Inlet manifold gaskets & hoses by the way which were never actually replaced).

By February I took the car back. It was completely the same way i sent it off. Despite him telling me the car was driving 80% - it felt like it only had about 50 bhp and it was now backfiring which it wasn't before.

This is not the reason for the post and I can some back to that story again another time as there is a lot more to that story to the tune of €3000

Anyway after taking the car back and it being no better I decide to pluck the engine and loom from a slightly older model A 91 525 sports, which I fitted with a little help from my friends and we wired in with all the new bits from the old engine. however she refused to start!!!
I had no power to the fuel pump or injectors and I couldn't get any spark from the plugs.
Initially I though it to be a bad earth - no joy.

I tried swapping my old loom back in to see if the car would run. It tried to fire but it was firing early so the crank would't do a full rotation without stopping dead. This was still more life that I had gotten with the 525 loom and ecu.
I then started to check all the connections across the two looms and low and behold I found what I believe to be the issue.
The big round plug that the loom attaches to - Located just beside the top of the shock on the left. I can see there are blank pins on the cars original setup. I.e Pin 1 & 2 and also Pins 9 10 and 11 are all blank on my 93 body - however these pins are populated on the loom from the 91 525 - whats more they run to the crank sensor and fuel relay (orange unit that wasn't even present on my old loom).

I was told by the guy I bought the engine off that it's a plug and play affair and that he'd done it loads of times without issue. Unfortunately the car the engine came out of is now scrapped as I thought I might take the remainder of it's loom out and try to fit it to my 93 car...:frown:

Has anyone else ever come up against this issue?
Is there a way around it?
Can i run feeds to these wires or do I look for another 91 and get the remaining loom from it? Will I need any other parts like the clocks?, or are there any other relays inside the car that I would need to make it go.

At this stage the alternative would be to walk away and the car stands me over 5K now so Id rather not.

Can any of you advise me the best way to proceed? Perhaps some of you might have the spares - in which case Id be happy to discuss purchasing these from you.


Any advice you may have going on previous experience would really help guys

Id also like to mention I have always had old cars. I've owned 3 corolla coupe's and a couple of Mini's which is where I started out.
Id love to keep it and have er running right....
Thanks for reading
 

·
Registered
Joined
·
118 Posts
There is way around every thing , where are you located , you can probably re arrange the pins in the plug to suit , I have done a lot of engine swaps , swaps these lumps into chassis they where never designed to be in . There are not very many wire needed to get these engines to run . They body plugs do tend to change quite a bit from year to year and if the donor car had aircon you will have a few extra wires spare .
 

·
Registered
Joined
·
989 Posts
best of luck with it mate, give dicko the job! 3000!!! you could buy a mint one for that???:confused2:
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #4 · (Edited)
Hi. Thanks for coming back.
Think the doner car had the computer in the dash. Mine doesn't but it has the air con.
I'm in wicklow town. Can take pics of the two plugs of that helps.
I stopped short of putting the loom back in so that's the way she's sitting since last week.

Would love to get her back on the road before the winter as my run to work is currently done on a speed triple.

Will Pm you soon
Cheers
Clayton.
 

·
Registered
Joined
·
62 Posts
Does your ECU have a red label on it with a number starting 026? and does the 525 ECU have a red label ECU as well?

And is either car an auto originally?
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #6 ·
Further deveolpments.

Hi.
Did some further digging since.
The ECU is a BOSCH 402 Red sticker - the ECU engine and loom are all from the same 1991 sports.

I took a look at the X20 pin outs on the two looms and I'm happy they are as neigh on identical so it's not that issue. There were only slight differences on two or three pins and these weren't the main ones needed - all wires for temp sensors - alternator fuel relay etc all mated up 100%.

Have a question - on my 2L engine there were 2 round black things about the size of a 2 euro coin and 20 mm deep they bolted on just underneath the loom over by the starter and one just under the temp sensors. - they look like they may be earths that the run up to the ECU - these aren't on the older 525 loom. They bolt up on a long size 13.
I'm beginning to think I have an earth problem. I plan to run straps from these holes and onto the body to see if that closes a circuit - I should hear the pump activating right?


I believe I can also run additional earths to some of the pins on the ECU for the fuel pump to see if that sorts it.
Like I said - I got no pump - no injector's firing and I did have a live feed to the coils but no spark.
As for the coil i simply unbolted it and sat a plug into but I may have forgotten to run an earth to it as well so this I will try this again over the weekend.

My car is March 93 so I don't believe there is any EWS involved.

Failing all this I may take a look at the ECU but I will come back here and let you know how I got on first.

If you have any recommendations as regards the earth please fire me back a reply.

The 91 loom didn't have any additional earths - just a single hoop that goes onto the bulkhead on a size 10 nut. My old loom actually had two of these so there is a difference and perhaps I've overlooked something obvious.

There is only one other earth that goes from the air con pump (now removed) and the chassis leg on the driver side.

Thanks,
Clayton
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #8 ·
Hi all.
Sorry for the confusion.
The original 520 engine was indeed a Vanos setup.
The replacement engine ecu and loom was from a 91 525 - I swapped over the sensors and loom and ecu in an attempt to coax some life into the car - It didn't work and I now know the cam sensor is of a completely different type as is the ignition angle (think I have that right). So no joy there.

I swapped back in the 525 ECU and Loom over the weekend.
I know the pins on the X20 are the same across the two engines so the car and loom should be compatible. Also the car is march 93 so there is no EWS to compound the problem.

Next up I'll run some extra ground wires to the block and see if the fuel pump comes back on when I install the battery. - I believe I can ground some of the pins on the ECU to see if that makes the fuel pump work. I would begin to suspect the ECU after this but Id make sure I'm getting a live feed up to the ECU just to be 100% sure it's not the loom or something silly.

I will soon have access to a diagnostic machine as well so hopefully if the ECU is responding I can discover what the problem is.
Failing that i will be on the hunt for a Bosch red label 0261200402.

Bilbo Baggins didn't have this much hardship...:mad:
 
1 - 9 of 9 Posts
Top