sporatic low power, shop cant figure it out

[micjordan]

Hello, I have a 1993 740i with 130k miles. Within the past couple days it will have great power and then suddenly the check engine light comes on and it has almost no power at all. Its still drivable but barely and I wouldnt chance it going up steep hills. Then for no reason the light goes off and the full power is back. It also doesnt seem to idle correctly when this loss of power/check engine light happens. I took it to the shop and they've spent about 10 hours looking at it and still havent figured out the problem. I called today and he said they had checked most of the wiring to ox sensors and the like and they all seemed fine so he said it might be "the computer".

First of all does anyone have any ideas as to what this might be aside from his conclusion?

And second what does he mean by "the computer"? The DME chip? The boards that hold it? The whole thing? If this is the case could I just buy an EAT chip and put it in? Or if its the whole thing (boards or whatever) is there a place online that would sell this for less than the mind numbing price he is probably going to quote me for it? Would this computer be interchangable with an e34 540's computer if I found one from that at a salvage yard or something?

-Adam

[shogun]

and it is not for sure that this is the culprit. Do they have DME's for testing just to exchange?
Did they make a diagnosis with the computer? If not, go to another specialist which has the right equipment to do a DIS. With this it is much easier to find the real problem. The other thing like checking this or that is like a backyard mechanic is doing it.
Even I have a PEAKE fault code finder, which costs only $ 150, and that money was a good investment.
To change the DME's you need the exact number (part number). Others might not fit.

[MarkD]

Hello, I have a 1993 740i with 130k miles. Within the past couple days it will have great power and then suddenly the check engine light comes on and it has almost no power at all. Its still drivable but barely and I wouldnt chance it going up steep hills. Then for no reason the light goes off and the full power is back. It also doesnt seem to idle correctly when this loss of power/check engine light happens. I took it to the shop and they've spent about 10 hours looking at it and still havent figured out the problem. I called today and he said they had checked most of the wiring to ox sensors and the like and they all seemed fine so he said it might be "the computer".

First of all does anyone have any ideas as to what this might be aside from his conclusion?

And second what does he mean by "the computer"? The DME chip? The boards that hold it? The whole thing? If this is the case could I just buy an EAT chip and put it in? Or if its the whole thing (boards or whatever) is there a place online that would sell this for less than the mind numbing price he is probably going to quote me for it? Would this computer be interchangable with an e34 540's computer if I found one from that at a salvage yard or something?

-Adam

Have they checked the TPS (throttle position switch) ?
It may not be working correctly. Or maybe your MAF is failing.

You should really take it to a garage that is equiped to diagnose this problem.

All the M60 motors use a 0 261 200 404 DME (until 12/94 build date) and you should be able to use any DME with that same number as long as you remove the EPROM chip from your DME and insert into the new DME.

Mark

[micjordan]

problem solved. this according to the mechanic. he said the problem was both the fuel pump AND the old o2 sensors creating what seemed to be a single problem but really wasnt which was why it was so hard to determine until after 2 days of testing the fuel pump finally failed completely (thank god). anyway, the final bill is $985. 290 something for the pump, 350 something for the 2 o2 sensors and the rest for labor. anyway, its running fine again.

btw, heres my repairs for the last 6 months (some wear items included)

$659 -tires
$495 -water pump
$65 -AC belt
$190 -brakes
$2095 -new transmission
$1600 -new transmission installed
$985 -new fuel pump and o2 sensors

=$6089 and counting