ajricker

I had a rough running issue that started late this summer. When I started the car it felt like it was only running on 4 cylinder's.
So since wet weather has set in I decided it was time to work on it. I ordered ignition control units, throttle position sensor, since I didn't replace it when I had the motor out 11 years ago.
And an idle air valve.
Replaced the ignition control units. Easy job. Then oved on to the TPS. That requires taking the whole intake assembly off. But I'm retired. So I can take my time. And while the intake is off
idle air valve is easy. Get it all back together and it runs great. With one exception. High idle. It was idling at about 1400 RPM.
I read through a few threads and decided it must be an air leak. One of the threads mentioned after testing many thing multiple times it turned out to be the new idle air valve.
So I pull half the intake apart. Pull the new valve. It was a Lowe. Take the old Bosch Spray it down with PBBlaster and clean it as best I can whit Q-Tip's. Put everything back together
fire it up and it idles around 750.
Sometimes saving money ain't worth it. I'm glad we have such a strong community here to give us the resources to do these jobs.

BIMMERMIKE

Should I be concerned with removing Bosch ICV (only 73k miles) and replacing with new Lowe unit?
I didn't have any idle issues but want to update while intake is off.
I really don't want to back and remove intake, etc.

soontobered84

Yes, you should be concerned. Lots of history concerning aftermarket ICV's and it's not generally good.

Darklands

Put the spare icv in the glove box, so the original one will last 300.000 miles!

BIMMERMIKE

What’s the best cleaning process for original Bosch ICV?

ajricker

Wish I hadn't replaced the Bosch unit. I only did because I was already in there.

928FIXER

I'm always worried about aftermarket electrical items that are being handled by the engine ECU(S?) due to current draw .A good deal on a aftermarket part that has to low of internal resistance can and will consume the drivers that control it in the ECU turns out not to be a good deal when you have to send out a 40 year old control unit for a rebuild, if it can be fixed.

davek9

Thank you for posting this info about the "Lowe" ICV.
I recently installed one on an 86.5 and now have the same Hi idle issue, swapped ECU's checked for vacuum leaks etc..
I'll follow up if replacing the ICV resolves the issue, however it won't be until this spring as the car went into storage.

ajricker

I just used PBBlaster and a Q-Tip. I shot PBBlaster down both orifices the let it soak for about a half hour the wiped it out with a Q-Tip.

davek9

They (ECU's) can be updated and repaired.

Also the S3 ISV's can not be cleaned as as described, their construction is different utilizing Brushes for the electric motor and will wear out over time, unlike the S4's.

Mark Anderson

We have 2 good used Bosch for the 85/86 that have been tested
also a dead one if someone wants to experiment

JBT3

And this is why I cleaned my Bosch unit and stuck it back in. You can bench test it with a 9V when you have it out.

brim32

Had the same problem, Found an ICV using Bosch number, from a BMW ‘85 5 series. I think the number was 0280140509. Used Superzilla, great stuff, which is a penetrating oil and great lube. Doesn’t attract dust/dirt. Sprayed valve and worked vane back and forth a few times. The thing could be flicked back and forth with a wrist snap after sitting for a while. Put the valve in and the engine runs like it should, around 750 rpm’s. Tried the Lowe valve and had same results as above with high idle. Drove me crazy trying to locate that famous vacuum leak til I changed it out. Top refresh was done too.
Just shows that the Bosch ICV IS THE TICKET. Oh yeah, it’s a 85 with stock parts, if I can find them. Use the Bosch stock number when you search the interweb.

ROG100

I agree - however the Bosch units are NLA unless you want to pay Porsche prices $700. The 85/86 is also NLA from Porsche.
I have sold a lot of the Lowe ISV's over the last few years. I have also replaced some that did not work as they should.
You should reuse what you have if at all possible and/or buy a used Bosch from Mark.
Why does a Lowe unit, in some instances, cause a high idle? Is there a way of ensuring a Lowe unit is good prior to use?
The 87 to 95 ISV has a rotating valve - if it does not shut correctly can it be modified?

Jason89s4

3x I have had high idle on a 85/86. Did all things, smoke, etc. Was either the MAF or ECU.. Your ICV may be fine but MAF or ECU not telling it what to correctly do. Swap in a known good ECU and MAF and see. One at a time.