Some Issues In My '91 520i Euro Spec - BMW Forum

backindauk · 04-19-2005, 07:57 AM

Hey all,

I have a 520i euro spec, australian delivered E34 BMW. It has done 114,000km so far in its 14 years.

It's a great car which i intend to drive for a while

It seems to have a lag in the acceleration.
If i floor it, it takes around half a second then we experience some massive G forces, then at 3500rpm it holds for a bit, then goes full tilt.

I'm running it on 98 octane fuel (Shell optimax) and for a while, when i wasnt driving it... mum was putting 91 octane (Standard Unleaded) through it.

i plan to stick some kind of performance chip in it (it has a 405 ECU) to get a little more power from it and hopefully it will be a little less sluggish in the Economy mode and a bit more powerful in the sport mode.

Im curious as to why the car may be lagging a bit. It seems like it struggles a bit, and the engine does not idle properly... The whole car shakes, as if the engine was loose.. But i dont think that is the case. I think when the idle drops below around 800rpm, the rattling/shaking is at its worse. I am curious as to why the idle drops to this level and then jumps back up. Its very weird!

It has recently been serviced (113,500km) but this made no real difference to its running.

Im not sure what may be the problem, i'm just 17 and dont have a huge mechanical knowledge, especially with issues that seem to be fairly non-standard.

Maybe i should take it to the BMW dealership just across the road and get charged an arm and both legs to have them go over it, or just try and acertain what the problem may be and have my usual mechanic fix it - he is very good also, but BMW may be able to learn things he cannot.

Any help would be nice

Andrew

ambush360 · 04-20-2005, 01:25 PM

I hope that I can help you here. I also own a 91' Euro Spec. 520i along w/ my 97' 528. But about a year ago, my 91' started doing the same thing, the idle was very low when I was in neutral at a stop light, and it would even cut off. The acceleration would lag really bad at times, like yours, and I had no idea what it was. I took it to my mechanic, and they didn't and told me to take it to the dealer which was the last thing that I wanted to hear. But upon taking it there, I started my car for them, and 5 seconds later he told me that the chip had gone bad. They replaced it at a cost of 164 euro, which was much less than I thought. But what it came down to was the dealer was the best choice for me. But I can bet money that you chip is going bad.

The Autobahn is awesome!!!

backindauk · 04-29-2005, 12:50 AM

I just booked it at my local BMW dealer for a service. They said "they will spend a few hours on it"

Suggested problems:

Mass Air Flow meter
ECU
Fuel pump

backindauk · 05-04-2005, 12:48 AM

The car was in at BMW today.

The problem was that Cylinder 1 has not been firing. They are working out the wiring as we speak

Also, the automatic transmission warning light was occasionally coming on, so they are looking at that as well.

ambush360 · 05-04-2005, 05:28 AM

So it was not the chip. Ok, now I am 0 for 1. Hope all goes well at the dealer.

Later

backindauk · 05-05-2005, 01:23 AM

I got a call today from my friends at BMW Pennant Hills

It seems that a part (which i cannot remember the name of - will write it down later) has become broken - something in the electrical system, i didnt really pay attention

Cost to fix is $1800.

sp0rky · 05-05-2005, 01:36 AM

the idle control valve or idle computer could be causeing the funky idle issues.
As for sluggishness, MAN theres so much goin on.
Cyl 1 not firing? Thats odd. That would cause a crazy idle if it fell too slow. Find out the part thats bad, I'd be interested in knowing what happened.

backindauk · 05-05-2005, 05:07 AM

Problematic part is the DME unit - complete unit
$1800 part cost + three hours labour

sp0rky · 05-05-2005, 11:27 AM

Quote:

Originally posted by backindauk@May 5 2005, 04:07 AM
Problematic part is the DME unit - complete unit
$1800 part cost + three hours labour

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Maaaan. Are you having it replaced? Thats EXPENSIVE considering the value of the car. I mean... If i were to have 1800 in accident damage, it would declair my e34 totaled. Yikes!!! Well hope you enjoy it!

backindauk · 05-06-2005, 02:11 AM

The car is valued at $18,500 for insurance purposes.

(We're talking Australia here man!)

Total cost was $1810.05

They even detailed it and replaced the radiator cap (Warranty?)

It runs amazingly well now! I am very pleased!

sp0rky · 05-06-2005, 02:13 AM

oo I'm thinkin US $, sorrry.. lol
e34 525 is only valued at $4800 in *EXCELLENT* condition in US dollars, so when I saw 1800, I was lthinking "Ohhhh dear!"

haha.
glad to hear it's all sorted out

backindauk · 05-06-2005, 02:54 AM

I am very happy indeed.

Now all i have to do is get rid of those crappy stock wheel covers and replace the wheels with some nice 17" alloys, replace the rather crap stock stereo system and speakers and also fit the OBC and a leather steering wheel. Piece of cake!

"Why do you buy a BMW?" So in 15 years when things go wrong, i can still get parts

sp0rky · 05-06-2005, 11:10 AM

ooo sounds fun.
I enjoyed going through all those stages!
Then I decided to lower it, a turbo is in the works, and this summer custom fiberglass enclosure for the subs are going to be made

These kinds of projects keep me entertained.

Do you have any pictures of your car?

Heres a small one of mine if you haven't seen it elsewhere already: