E28 Megasquirt FAQ

alijonny · Post by **alijonny** » May 07, 2009 11:53 PM

alright a few quick questions:

grounds: I wired my grounds from the Motronic box straight to the db37 connector, I noticed pics of turbodan's (I think) setup where he has the grounds on eyelets going to the body. should I do it this way also?

Idle control: Brad, I notice you have an option to input actual frequency as seen in the pic on the bottom

MS2extra has a different option where you enter a number from 0-8. WTF?
Also the car will start and surge slowly from 400-600 rpm and eventually die, I can try to give it some throttle only to kill it. It will start back up. I tired changing the idle control settings with no help, the car seems to be running edit> LEAN by the looks of the WB (about 17) Any ideas?

Post by **Brad D.** » May 08, 2009 12:14 AM

A wideband reading of 17:1 is lean. Remember for gasoline stoichiometric is ~14.7:1. Anything below this considered rich, above lean. That is probably far to lean for it to ever idle right. Try it around 13:1 and begin to lean it out until the quality of the idle goes away then richen it back up, say half an AFR point. The screenshots are from my earlier beta code. The box you are referring to is a scaling multiplier. The frequency will be the value you enter times 30.5Hz. At my setting it valve works in 1% steps. This probably isn't a major factor right now in your idle settings. It can be used to increase or reduce sensitivity of the frequency to aid the PID.

alijonny · Post by **alijonny** » May 08, 2009 12:21 AM

my bad I meant lean. let me play with some numbers tomorrow and see what happens.

Post by **mooseheadm5** » May 08, 2009 12:23 AM

The reason it starts up again is because of the priming/cold start squirts that give it enough fuel to run for a short time. As BBR says, your motor is running super lean.

alijonny · Post by **alijonny** » May 08, 2009 12:24 AM

I have the priming set at 0 across the board

Post by **mooseheadm5** » May 08, 2009 12:29 AM

It must be running off cold start then.

alijonny · Post by **alijonny** » May 08, 2009 12:43 AM

It very well could be. Anyone with larger injectors find it necessary to use the priming pulse? I know I haven't had the car running long enough to do warm starts, so I don't know if i need to consider plugging some small numbers in.

Post by **Brad D.** » May 08, 2009 12:48 AM

alijonny · Post by **alijonny** » May 09, 2009 7:11 PM

ok, it starts and runs but really lean. like 19-20. it idles at about 1300 rpm which is a bit too high and if I try to make any changes nothing really happens. what am I doing wrong?

Post by **mooseheadm5** » May 09, 2009 7:57 PM

VE table? Improper injection flow rate setting? How is your fuel pressure?

alijonny · Post by **alijonny** » May 09, 2009 8:09 PM

all tables are going by what brad has posted on the first page. The fuel pressure I don't know. N/A everything was just fine, however I have not checked the actual fuel pressure or flow since I have owned the car.

req fuel is set at 9.0

Post by **Brad D.** » May 09, 2009 9:09 PM

What size are your injectors?

Post by **mooseheadm5** » May 09, 2009 9:45 PM

And what type are they? Have you got lowZ injectors in there?

alijonny · Post by **alijonny** » May 09, 2009 10:11 PM

42lb green injectors 14 Ohm PN: BOSCH 0280155968 EV6 body Ev1 plug

M. Holtmeier · Post by **M. Holtmeier** » May 09, 2009 10:39 PM

I wonder if the wideband is programmed correctly. The car wouldn't idle at 19:1. Also, remember that the sensor cannot measure unburned fuel. So if you're way too rich you may be getting a false reading.

alijonny · Post by **alijonny** » May 09, 2009 11:11 PM

possible... however I calibrated the WB according to the instructions for open air calibration. Nobody answered my questions about grounds, might that be causing the problem?

M. Holtmeier · Post by **M. Holtmeier** » May 10, 2009 2:22 AM

alijonny wrote:possible... however I calibrated the WB according to the instructions for open air calibration. Nobody answered my questions about grounds, might that be causing the problem?

I grounded mine the sam way you did, except I did make a complete seperate ground for the sensor heater. Double check your wideband settings, double check the ms settings. Make sure that the voltage params are the same and that megatune is set correctly as well. Seemed like on mine when I first getting things set up, the lc-1 wanted to lose it's voltage parameter settings. I must have free air cal'd that thing a dozen times. Just to get the car idling and moving, turn off the idle and just bump the throttle open a little with the set screw. Get the fuel map set up a little first. I've got 60 lb/hr injs and my priming map looks about identical to Brad's. I use all the tables I can for cold starts, so you'll have to go back and mess with it over and over, but it's got to pull from a correct fuel map. If you have some numbers in the fuel map already, bump the req fuel up until it stays lit, then when it's warm you richen the fuel up and set you req. fuel back to where it's supposed to be.

alijonny · Post by **alijonny** » May 10, 2009 5:12 PM

sometime monday, I am going to check the timing from the crank and re- calibrate the WB. I am going to hook up my fuel pressure gauge and see what that is sitting at and go from there.

alijonny · Post by **alijonny** » May 11, 2009 12:14 AM

should I have my VR sensor setup for inverted or non inverted?

FirstFives Dictator · Post by **FirstFives Dictator** » May 11, 2009 6:57 AM

alijonny wrote:should I have my VR sensor setup for inverted or non inverted?

Depends on how you wired it; if it syncs and you show rpm, you've got it set right (MS2 extra - MS1 is more promiscuous and tries to sync on just about anything)

alijonny · Post by **alijonny** » May 11, 2009 10:39 AM

it syncs, I noticed that when I try to give the car any small amount of throttle, it breaks up horribly and the rpm's are all over the place. I am going to test the crank sensor as it is a junkyard sensor.

turbodan · Post by **turbodan** » May 11, 2009 10:43 AM

I would avoid utilizing the priming pulse. It just dumps fuel in every time you turn the key to the run position. Unless you start and run the car every time, the fuel will just trickle down into the oil. You can get it starting easily with the correct cranking PW and probably some afterstart enrichment.

alijonny · Post by **alijonny** » May 11, 2009 5:26 PM

the car loses sync at anything above 1700 rpm. RPM goes to 0, I tested the CkPS and got some funky numbers from pin 1-3 and 2-3.

Post by **mooseheadm5** » May 11, 2009 5:35 PM

Check air gap on the sensor, post your resistance test readings.

alijonny · Post by **alijonny** » May 11, 2009 7:13 PM

air gap is 1.02mm, 1-2 is 544 ohms, 1-3 is 2.41 M ohms and 2-3 is 2.46 M ohms.

readings are supposed to be 520ohms give or take 30 ohms for 1-2, 1-3 and 2-3 is supposed to be >100 K ohms

I am using a sensor from a 1990 525i (m20), it bolts to the b35 sensor bracket just fine and I think it has longer wiring.

Post by **mooseheadm5** » May 11, 2009 7:42 PM

Those are good readings for that sensor for gap and resistance there is supposed to be a lot of resistance on those two pins, and that is what you are showing. You will want to make sure that the wire shielding is good, and (remember that I am not experienced with MS) that your VR pots are adjusted properly. I guess it is possible that your signal is breaking up and that it is giving you less fuel than required because it thinks that the motor is turning slower than it really is.

alijonny · Post by **alijonny** » May 11, 2009 8:29 PM

I don't think the 3.57 box has adjustable pots...

Post by **Brad D.** » May 11, 2009 8:55 PM

From the v3.57 manual

The two VR input circuit potentiometers (R52 and R56) have been replaced with a 5-turn surface-mount variant. So instead of 25 turns, only 5 turns are required - but they should still be fully counterclockwise to start tuning.

alijonny · Post by **alijonny** » May 11, 2009 9:55 PM

heh reading does it again. Thanks brad..

alijonny · Post by **alijonny** » May 12, 2009 6:23 PM

this is killing me. IT STILL ISN'T CHANGING. IT STILL BREAKS UP AROUND 1700 RPM AND SEEMS TO HAVE A HIGH IDLE OF 1100-1300.

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E28 Megasquirt FAQ