528i Funky Idle on Start Up

JoshInAtlanta · Post by **JoshInAtlanta** » Sun Feb 28, 2010 11:14 pm

Lenny,

I'll take a look at this tomorrow. I am NOT good with electrical stuff, so please be patient with me when it comes to that. I'll check it all out and report back (or attempt to repair if necessary).

Thanks.

Lenny D. · Post by **Lenny D.** » Sun Feb 28, 2010 11:52 pm

If you're not good with electrical stuff, find a friend who is. The repair is really simple but you have to know how to properly (effectively) solder for a solid connection.

Best of luck.

thomas_m535i · Post by **thomas_m535i** » Mon Mar 01, 2010 4:38 am

Very interesting stuff. You guys should be writing a FAQ about it

.

By the way, Lenny D: how did you find out about those values (resistance) for the cool water temp. sensor?

cpalmer · Post by **cpalmer** » Mon Mar 01, 2010 11:11 am

thanks swatter.

I have cleaned the AAV out a couple months ago after reading the board and the car was much better. It use to just start and go straight to 2,000 rpm .....It did not do that anymore once cleaned and actually seemed to go to 1,400 for a little while and drop to 1,000. Now is jumps around a little-
800, 1,200, 1,500, back to 1,000.

Lenny, I think I confused the grounds and have not seen the ones just mentioned. I thought the ones on the exhaust side up towards the radiator were for the aav and couple other things I am spacing. I'm going to look around the AAV today. I looked for every ground I could a few times before but am sure I missed some.

My mileage seemed best around 60-65....once I got on the 5 though, I had to get up to 85 sometimes to keep freakin' trucks off my ass doing 75.....hate the 5....and, of course when I hit hills for the last 35 miles, it went way down...I had a heavy car. Flat was good.

Lenny D. · Post by **Lenny D.** » Mon Mar 01, 2010 12:54 pm

thomas_m535i wrote:Very interesting stuff. You guys should be writing a FAQ about it .

By the way, Lenny D: how did you find out about those values (resistance) for the cool water temp. sensor?

I did, it's sprinkled all over this (and the old) board.

Those values come from a copy of the wiring diagram for E12s that I picked up from someone on the old board years ago and also from the book 'Bosch Fuel Injection and Engine Management'.

Lenny D. · Post by **Lenny D.** » Mon Mar 01, 2010 1:06 pm

cpalmer wrote: Lenny, I think I confused the grounds and have not seen the ones just mentioned. I thought the ones on the exhaust side up towards the radiator were for the aav and couple other things I am spacing. I'm going to look around the AAV today. I looked for every ground I could a few times before but am sure I missed some.

1000 words dept. (I will start calling this the L-jet 'sacred ground'

):

As I have posted before, those grounds are at the REAR of the intake manifold!

Now you have a pic for the upcoming FAQ y'all will put together from my old posts.

JoshInAtlanta · Post by **JoshInAtlanta** » Tue Mar 02, 2010 3:57 am

Thanks for the picture Lenny. I replaced the CTS today, no change in the idle.

I looked at the wires briefly, but they all are all wrapped up very well. The motor is a low mileage BMW replacement, so it's pretty clean (and so are the grounds), but I am going to cut back tomorrow hopefully and see what I can find.

I did get a spare AFM from a friend, so that will be my very last thing to check if the grounds don't make a difference.

Wil · Post by **Wil** » Tue Mar 02, 2010 9:23 pm

I don't know if anybody has done this to the AAV , but worked like a charm for my car
The AAV was working , but not opening enough when cold to increase idle , even with the adjuster all the way open.
I guess from being old and tired, so I took dremell tool and I ground the plate that opens and closes the air , I took a couple of millimeters and that got me 300 or 400 more rpm during warm up.
Don't change the valve without trying this first
Cheers

JoshInAtlanta · Post by **JoshInAtlanta** » Wed Mar 03, 2010 2:04 am

Thanks for the tip. My AAV has the adjustment nut, so I can move the strip. I opened it a little, but no difference. I think I will jam it completely open and see what happens.

JoshInAtlanta · Post by **JoshInAtlanta** » Sun Mar 07, 2010 8:43 pm

So today I took care of the ground. I also cleaned the AAV one more time and adjusted it so it is more than half open.

When I fired up the car, it is idling at 2,000 RPMs and it still has the low surge, just not as low now that it is idling so high.

BTW, I also replaced the coolant temp sensor earlier this week.

What else could it be? I've got a spare AFM that I am going to try and swap over to.

1st 5er · Post by **1st 5er** » Sun Mar 07, 2010 8:53 pm

I recently replaced the brake booster hose and check valve and most of my funky idle / acceleration issues disappeared.

May or may not help you, but WTH, if it's hard it won't hurt. and it's cheap to do.

Thanks for the update.

JoshInAtlanta · Post by **JoshInAtlanta** » Mon Mar 08, 2010 12:44 am

That's a good idea. However, I am not sure it's a bad hose/vacuum leak because it only surges until I start driving, then it is fine (and I have also replaced almost every hose). I will definitely check it out tomorrow though, would be nice to find an easy fix.

I did get a spare AFM from an '81 that I am going to swap over. Other than these ideas, I am at a total loss. I have the Bentley manual for Bosch injection, and I keep reading it over and over...

1st 5er · Post by **1st 5er** » Mon Mar 08, 2010 12:49 am

It's a weird thing, your symptoms.
Looking forward to your happy ending, just in case, IYKWIM...

cpalmer · Post by **cpalmer** » Mon Mar 08, 2010 12:37 pm

I'm still thinking it's the AFM.

And, on my 78' the ground for the AAV was on the front of the manifold on the passenger side, not on the rear back by the firewall.

I cleaned EVERY wire I could find again, Starter, battery, altenator, grounds. It runs good when warmed up. But starts low still, 800 rpm, then 1400, then 1000.

Hope your close Josh. Really want to know what happens when you swap the AFM

JoshInAtlanta · Post by **JoshInAtlanta** » Mon Mar 08, 2010 2:21 pm

cpalmer wrote:I'm still thinking it's the AFM.

And, on my 78' the ground for the AAV was on the front of the manifold on the passenger side, not on the rear back by the firewall.

I cleaned EVERY wire I could find again, Starter, battery, altenator, grounds. It runs good when warmed up. But starts low still, 800 rpm, then 1400, then 1000.

Hope your close Josh. Really want to know what happens when you swap the AFM

I hope we are close... I think we are!

Since I purchased the car in 2007, I have replaced quite a few things. Some because they needed it, others as a preemptive strike against potential failure.

When I first got the car, Lars suggested I replace the negative battery cable and clean the area where it grounds. This was a huge success for weird electronic happenings, so I made sure to clean all that stuff up as I found it.

My AFM replacement is on temporary hold. I found one of my spark plug boots had snapped. The cables looked pretty good, but then who knows how old they are. I'm trying to get a spare from a yard while I gather all the new parts.

Once I get that replaced, I will go ahead and swap the AFM and see what happens.