I need an L JET HERO!

[e9allan]

I'm actually working on an 81 e12 Euro528i. It wants to idle ata pulsing 300rpms. Seems to be running very rich. Oil was thin with a strong smell of gas.

What I have done so far:
Checked for vacuum leaks with starting fluid
Cleaned and adjusted throttle body
New distributor cap and rotor
Swapped coil to check old one was good
New throttle position sensor
Rebuilt AFM
New coolant temp sensor and connector
New temp gauge sensor
New fuel pressure regulator

The brake booster is about to go. About every third time I apply the brakes the pedal will get hard. To eliminate that as a possible vacuum leak, I disconnected the hose going to the intake an plugged it.
The only other thing I can think to add is that if I unplug the coolant temp sensor the idle immediately picks up.

Any insight would be appreciated. About to pull my hair out on this!

 

[sfdon]

You have a challenge there.
Be smart- check for your spark at coil wire and at plug number 5....

It’s easy, it’s free and will tell if what you have is spark related (more likely) or fuel related.

Measure the resistance at the NTC2 (water temp sensor) cold engine
Make sure it has a white body and last 3 digits are 023

You swapped TPS?
Last 3 digits please- there are 2 different ones that operate backwards from each other


301?

302?

Question- what happens when you pull vacuum line from FPR?

 

[sfdon]

Which sensor are you disconnecting?
At the thermostat or at side of block?
If side of block - which one? #7 or number #9?

 

[sfdon]

Which sensor are you disconnecting?
At the thermostat or at side of block?
If side of block one is cold start sensor

 

[e9allan]

Hey Don,
Thanks for lending a hand. I have a spark tester that I stuck in between the spark plug and the end of the wire. All had spark. Unfortunately it isn't clear - it's red, so I can't tell how hot the spark is visually.

The coolant temp sensor has a black body. I will get the number off of it in a few minutes. I will also get the TPS part number. When I first put that in, I tried moving it to the extremes both ways to see if it would change the idle. I will also update on pulling the FPR line shortly.

Disconnecting the one on the thermostat housing. The one with the fancy connector and not the single barb one that goes to the gauge - number 8 in the diagram.

 

[e9allan]

TPS part number is the same as what was on the car - 0 280 120 206
Everybody can chastise me for using a rock auto part - I probably deserve it- but I was in a hurry to get it back on the road and I'm on the east coast. So the coolant temp sensor is this one:
https://www.rockauto.com/en/moreinfo.php?pk=40586&cc=1012217&jsn=17&jsn=17 It is exhibiting the same behavior as it was with the old one when I disconnect it.
I just tried to cross reference the part number from real oem - 13621362599 and see that the one I have doesn't match up. So, is that the likely culprit at this point? I should have done my homework. Still a problem all these years later...

 

[sfdon]

Ummmm number 8 is a crush washer in the diagram.
Got a pic?

 

[e9allan]

Sorry. Meant number 9.
Pulling FPR makes no difference.
I do have a ground that is going to nothing? Pic coming.

 

[e9allan]

Ground wire...

 

[sfdon]

Grounds must be connected- especially that one.
The temp sender (black) does not belong in this car.
disconnect number 9- it is making your cold start injector run continuously

 

[e9allan]

Thanks Don.
Where does that ground go?
I will order the right coolant temp sensor today.

 

[sfdon]

Ground the lug to the intake for now.

 

[sfdon]

13631358473 appears correct = 0 280 120 206

 

[e9allan]

Thanks again. I put the ground on and ordered the right sensor based on the Real Oem diagrams.