the wrong coolant temp sensor?

[der affe]

so i have been trying to figure out why all of the sudden that my milage has been getting worse and i have an off idle stumble out of no where.

i ohm'ed out the wires they are all with in .50 ohms except the coil wire which was 2.0006 (is that correct?)

my fuel pressures are within spec.

my MAF is clean and i swapped it out with another know good part with no changes. this is what i have:

http://www.bmpdesign.com/product-exec/product_id/1077/category_id/44/search_year/1991/search_model/34

so i go to ohm the coolent temp switch and it is the one for an ETA, SETA, the WHITE top one.
i checked in the bentley and my car requires the BLUE top one.
since the the ohm range is lower, it would make the car run richer. when i ohmed it, i get a reading of 0 ohms cold. ok i head down to get a new one at autozone.

is there some benifit to running this or was the PO a dumb ass and put the wrong one in there? the car has always run richer than i though it should, no matter how i adjusted the signal conditioner.

when i went to get the new temp sensor, i brought my VOM and tested the new one and it was giving me a reading of 1.520 (M) ohms. all three of them tested more or less in the same range. the range that it shows for 68 degrees is 2200- 2700 and it iwas in the 70's in the store as an ambient temp. is that an excepable range difference?
are all their sensors wrong?

[Naplm00]

if i were you...i woulnt buy that at autozone.
do you think they can get this shit correct? buy the dealer one

[bimmerboy08]

I have one coming from bavauto, should be here wednesday. If you like I could test it and let you know what readings I get.

[der affe]

yea, if you would.
the manager was helping me and he told me if i didn't work, to bring it back and he would refund my $$.
i wouldn't go there normally, but they are the only people that i could find that had one today and since it reads totally dead, that has got to be better than what i have now.

napa did not carry it and the one that checker had as the right part had a SCREW ON electrical connector???? WTF?????

i have one comming on monday at BAP too. i'll check it against the one that they have (should be OEM) and see what the reading is.

[delatlanta1281]

if i were you...i woulnt buy that at autozone.
do you think they can get this shit correct? buy the dealer one

That coolant temp sensor is used on many many cars. It doesn't matter where you buy it from.

[der affe]

well here is a break down of the different reading (although none of them jive with the bentleys numbers though) this was all taken unplugged and uninstalled
new BLUE top from autozone = 1.527 (this one also broke the housing before i even got a chance to tighten it, total crap!)

old WHITE (eta one) = 1.674

new Green one =1.470 (supposed to be BLUE tested it and decided to wait for the EOM/Bilstein that would be there in 1/2 hour)

new BLUE Bilstein 1.472

do any of these numbers make any sense to anyone?

the car runs great now with the new sensor and injector seals, so i am at a bit of a loss

[nando]

the resistance depends on the temperature.. is that at room temp? the resistance curve I use for MS with the stock sensor is:
-40c/12000 ohms
30c/1600
99c/150

I've found the bentley values to be pretty far off actually, I wouldn't use that as a reference.

it's also not a thermoswitch.. that's only on cars with a cold start injector.

[der affe]

ambient temp/room temp.

i was getting my values from the motronic 1.1 section fo the bentley. even though the books stops in 90, it is still concidered motronic 1.1 right?
(my car is a 91 325i)

hey at least someone tries to correctly diag things through the manual still, and at least you (nando ) knew what i was talking about to tell me that the values were wrong. thanks BTW.

the bentley did not call it a thermo switch (thermo time switch) so i was pretty sure it wasn't, but i figured i would try to align my readings with the spot on the chart closest to the room temp i was in.

[nando]

yours is Motronic 1.3 actually. 1.1 was the 153 ECU. they are basically the same though except some wiring differences and 1.3 having more diagnostic abilities. 1.3 is also built better and has better idle control.

the bentley is a great reference, it's too bad there are so many inaccuracies and they have never updated it.

[der affe]

wow, did not know it was a different version. is it worth it to get an..E-36 bentley???? to get the benifit of the better diag abilities?

[nando]

the E36 is motronic 3.0 and up, and later siemens, so no luck there.

[der affe]

well doesn't that blow

[izickc]

i have an issue along these lines, car stalling and sputtering.....replaced just about everything then accidently unplugged coolent temp sensor and all of a sudden started running fine. replaced sensor plugged it in and started to stall and sputter. would just leave it off however, i am getting aweful gas milage...... any thoughts

[Balleristic31]

if i were you...i woulnt buy that at autozone.
do you think they can get this shit correct? buy the dealer one

I work at autozone. Not everyone who works there are BMW idiots.

[nando]

I work at autozone. Not everyone who works there are BMW idiots.

Dude, that post was 4 years ago...