Bimmerfest BMW banner

1 - 7 of 7 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
Can anyone shed light?

My e39 520iA is a bitch to cold start. It starts and is lumpy and cuts off until it warms up then the idle stabilizes.

It seems under powered when initially driving off after stops and seems to overall be low on power.

I basically bought it like that as I've always loved that style BMW.

I've replaced all plugs as they were definitely shot, and cleaned the ICV. While cleaning the ICV I did a quick inspection for hose leaks and found none. I'll do an in depth inspection when I get time in the week.

I bought a code scanner and cleared all codes and the codes in the pic attached keep returning.

I pulled the DISA and checked for vacuum by turning the flap and placing my finger over the hole. When I did that the flap snapped back. No vacuum.

So I'm assuming the issues are caused by the bad DISA.

Am I on the right track? I'm asking as I've never owned a BMW before and I'm basically learning about the repairs as I find the issues.
 

Attachments

·
Wingnut
Joined
·
3,724 Posts
per the codes youre seeing, theres probably a vac leak, and your aux fan isnt working. what year is your car?
testing the DISA as you did, the DISA flap should have held open when you covered the port. this indicates a blown diaphragm. that is a vac leak, and an inop DISA will effect overall operation of the engine.
getting the live data regarding the fuel mixtures with your scanner will aid you in troubleshooting. you may also have other vac leaks, reading the fuel mixtures after replacing the DISA will tell you more of this.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #3
Thanks for the info. My car is a '99 model. The previous owner did an aux fan install as far as I can see, but research has led me to believe that it wasn't properly done or has failed as the fan is always on. I'm currently doing further research to figure out how to remedy the issue.

Soon I'll disassemble all the vacuum lines and properly inspect them. I'll try to get someone more experienced to give me a hand there.

I'm also doing research into what the fuel mixtures should be so I'll check again.
 

·
Wingnut
Joined
·
3,724 Posts
fyi, on your year model, you have the later PWM controlled aux fan. its not controlled directly by B+ voltage, but by a PWM signal from the DME, to the controller which is part of the fan unit. on startup, the DME turns on the fan full speed, then shuts it off, and reads the back EMF signal generated by the motor to check if the fan came up to speed. im wondering if an earlier fan was installed, which is relay controlled, applies B+ directly to the motor, and is a two speed fan, and then hot wired up. if so, that would explain what youre seeing, the fan always on, and a DME fault for the fan.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #5
From what I've seen the fan appears to be directly hot wired, once the key is in on position, whether the car has been started or not, the fan turns on and stays on until the key is turned off. I haven't checked the relay or attempted to properly trace the wiring yet. But based on your info, I'll have an idea what to look for.
 

·
Wingnut
Joined
·
3,724 Posts
your year model should not have a relay, there is a 3 wire connector to the factory fan, the two heavier wires are B+ and B-, the smaller wire is the PWM signal from the DME, which controls fan speed by sending a varying frequency signal to the controller. im guessing (hard to tell from a distance) that someone got an earlier model fan and wired direct to the power wires.
 
1 - 7 of 7 Posts
Top