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deforiginal · Joined: 10 Sep 2015 Posts: 23 Location: San antonio, Tx

Ok, after getting all vacuum leaks covered, timed and a new AAV (70 bucks brand new, apparently an 81' 528i AAV works perfect) the car starts and runs. When it warms up you can hit the gas and vroom RPMs go up great but when cold it bogs out. Previous owner messed with both idle and CIS screw so I know it needs to be tuned. What's the best way to tune this without the CIS pressure tool?
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DEF Original Automotive

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

You can't really "tune" with the CIS pressure tool unless your really interested in deep "tuning" of control pressures and system pressure etc..

What you want to do to tune it up is adjust the mixture screw on the fuel distributor and that has nothing really to do with pressure gauges..

If you have a lambda system, O2 sensor, there is a factory test plug just ahead of the firewall in the corner next to the driver's side fender under the hood.. It has 3 pins..

Get yourself a dwell meter and put it on the black wire on that test plug, you are going to aim for 45% duty cycle on 4 cyl dwell scale..

Get your car up to operating temp, get your idle right around 900 ish, nd then tune that mixture screw on the distributor at idle to get your dwell meter as close as you can achieve to 45..

What you are doing is monitoring the duty cycle of the frequency valve and your setting your fuel map/mixture to the middle of your lambda systems adjustable range..

If you don't have lambda then you just want to tune that mixture screw to seat of the pants/plugs/wideband/CO meter, whatever you got..

With your CIS all working well and pressures in spec this is what you do to tune it in, it moves the entire fuel curve slightly richer or leaner throught its entire range, the different/differing fuel pressures and the CIS components themselves set the fuel curves shape.

The airplate opens your system pressure to your injectors, it's like a MAF and a lot of the fuel curve is built into its cone shape, system pressure is the responsibility of the fuel distributor..
Control pressure is responsible for the airplate's resistance to move..
Warm control pressure is for operating temp running, cold control pressure is like a choke along with the cold start injectors help, if you have a turbo then boost also alters your control pressure to richen on boost, all controlled by your WUR - Warm Up Regulator - or control pressure regulator some books call it.

A CIS pressure tester is mostly just to make sure your pressures are in spec, and then tune from spec with that air screw on the distributor..
If you're crazy and want to tune your fuel pressures out of spec for any reason you also use the tester to see your changes, the tester goes into the fuel line between the fuel distributor and WUR with a gauge on the distributor side and a valve on the WUR side completing the WUR line and allowing you to isolate the fuel distributor from the WUR with the valve to see system pressure/distributor pressure, with the valve open you see control pressure/WUR pressure..
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80 Turbo - Slightly Modified

nickthompson · Joined: 26 Mar 2013 Posts: 873 Location: Central Georgia

You could realize CIS is crap and dump if for something better.

deforiginal · Joined: 10 Sep 2015 Posts: 23 Location: San antonio, Tx

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

deforiginal · Joined: 10 Sep 2015 Posts: 23 Location: San antonio, Tx

Thanks again. So far it has a new pump, filter, WUR has been rebuilt, and all vacuum leaks taken care of and hoses replaced. I guess that leaves me wih:

1. Fuel Dist.
2. Lamda system

How much does the lambda system matter? If it controls mix Im not sure why the fuel dist still needs adjustments. Would it be better it kill the lamda and just tune like a carb? On most cars we work on we do dwell off the ignition coil, that is still the same despite the lambda? I will rebuild the fuel dist in the morning to rule that out.
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DEF Original Automotive

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

ThomasJoseph315 · Guest

Based on what you have written,.. I think not only is your Fuel Distributor tuned lean, but your injectors are leaking as well. Here is what I would do.

1) Check the plugs,.. bare bones check for rich lean. Also, is any plug worse then the other?
http://www.tuningmatters.com/wp-content/uploads/2014/07/spark-plug-lean-rich-optimal.jpg

2) Check the injectors. The injectors themselves over time don't seat correctly. If they are original injectors, chances are they are bad. A way to check is to get 4 mason jars and with the fuel lines still connected place them in the containers. Next turn on the key to get the fuel pump working, but don't start the engine, just watch the injectors as the pressure builds in the lines, do you see any fuel dripping out of any of the injectors? If so replace any that leak, personally I replaced them all as they are only like $40 each to replace, not too bad and you solve the possibility of clogged injector filters too. If the injectors are leaking, you will never get your A/F ratio tuned right. To check for clogged injectors, raise the fuel dizzy plate with the pump on while injectors are in the jars (take out air filter and push up on it don't pry from top). make sure the jars fill with gas evenly. Also, look at the spray pattern, is it a nice cone pattern to atomize air and fuel or does it look like someone has their thumb over the garden hose? Finally, do a similar leak test with the Cold Start Valve/Injector to check that one as well.

3) Install wide band O2 Sensor, this will help get your A/F ratio fine tuned. A rough tune would be once it's running and up to temp, turn the screw both ways till it begins to stall from being to rich and lean, then put it in the middle. the fine tune would be from driving it on a long stretch of road, getting out and adjusting it based on the gauge reading. The screw you will find once you get into fine tuning is very touchy, any small movement can effect the fine tune. a Hot tip, these cars run better a little rich because German fuel is nearly 100 Octane Vs Us shitty fuel mixed with corn syrup. So 14.7 won't be the ideal, you will have to fiddle with this as everyone's climate and elevation varies. Once you get the optimum right foot feeling, mark it down and use that for reference point for tuning. You will notice that the summer and fall months or day to day temps have an effect on this reading, but general rule of thumb is to tune the car on your yearly average climate temperature day and just deal with the tiny variance for days it's hotter or colder.

4) Idle has nothing to do with A/F ratio. Get the car to idle at 1,500 rpms and adjust the fuel trim as said above, once you got that dialed in, set the idle with a timing gun that you can see the RPMs in the display. Reason for this is you would be surprised what 40 years of resistance can do on a tach. most people are off by 100-150 rpms these days and don't even know it.

5) Check your connectors for AAV and WUR. They are color coded. For me the first year driving having start up issues, one of the many things I've had found is that some monkey swapped the connectors for the WUR and the AAV during the engine swap. They should be connected to the same color male and female. I know sounds simple, but it's happened on my car.

Few other things to check is fuel system filters, The one under the hood is easy, but the tank 90° elbow one is non existent. I got mine rigged up with 2 90° elbows and a straight filter, it works.

Wish you luck! Post a video of the car when it does the issue you describe!

Also, If you need it:
http://www.amazon.com/Tool-Aid-33865-K-Jetronic-Injection/dp/B0002SR5NU

Your just dealing with "Old car" stuff is all.. all the parts you're replacing are beyond the original life expectancy.

Cheers!