Utter refusal to run at reasonable AFR's, noise problems

[Xnke]

Having a hard time getting my (essentially) L28ET going on MS2Extra. I am having random misfires while driving, feels similar to a reset, and have sensor spikes indicating noise on the sensor lines. I NEVER had any issues with resets when I was using MS1-Extra!

 

I don't have a reasonable length datalog (I hate how MLV cuts you off now) to post up here yet, but I'll work on getting one.

 

Engine is a P90 head, 9cc dished 88mm piston, for a compression ratio of 8.3:1 on 2883cc displacement. Head has been ported and the car pulls like a train, even with the random misfiring. Cam is a 280* duration, 0.480" lift, on 113 lobe split. Love that 2nd gear rubber!

 

Injectors are 450cc blue-top DSM injectors, wired as 1-2-3 on bank 1 and 4-5-6 on bank 2. Fuel pressure is 43.5psi, and it does wobble around a bit at idle, according to my (no longer liquid filled) Summit mechanical gauge...not sure how much of that is injector and how much of that is vibration.

 

RPM input to megasquirt is via the EDIS6 module, using a 36-1 wheel on the crank. RPM in MS matches the engine, and the Maxima tach actually is correct at all RPMS!

 

I started out working with CygnusX1's timing and AFR maps, but used the VE table generator and some time with VEAL to get the fueling map so I could drive the car.

 

No boost yet, need to get this stuff straightened out before I put the supercharger back on. I know that the super will signifigantly change my tuning.

 

This engine really doesn't care for any AFR's leaner than about 13.0, at any point in the map...and simply won't idle with anything leaner than 11's. It stinks horribly at idle, and I am sure it's not doing the cylinder walls any good. Smooth idle at 950RPM with the A/C on, 1300 with the A/C off, will be adjusting this when I get IAC going. For now, I'll live with the high idle with the A/C off. Target idle speed is 950RPM.

 

Got an error saying I can't upload the .MSQ file...so I will change the file extension to .txt. You will need to change it back to .msq before you can open it.

 

I would like to try out some of the noise filtering settings prior to re-working my injection harness with shielded wire...I know a LOT of noise comes off the injector drivers and I am going to un-wrap the harness and wrap the injector wiring in shielding tape if I can't get the filter settings to straighten things out.

 

Also, MAP sampling? I think I should probably change the values to "starting angle : 55*" and "window length : 10*" for a 6 cylinder. Looks like the default is for a V8, putting the sample window at 45*BTDC instead of 60*BTDC, which is what I think it ought to be for a 6??

 

Any help with the above issues is appreciated...I have a crapload of MS-extra work to do before the super goes back on...and I hope to make it to the drag track by the 21st to get some baseline times!

Runningtune.txt

[winstonusmc]

You can post up msq and datalog files zip format.

 

I had a pretty bad noise issue that I discussed in one of the other threads and posted IP my MS3 settings. I noticed the ECU would just reset itself at certain RPMs. You should bypass the EDIS module and drive the coils directly with the MS2. There are some mods you would have to do, but the three circuits for wasted spark should be good to run with the LED circuits. Might be an issue with the EDIS module. My car idles happy at 14.7 and doesn't seem to mind as high as 15.5 before it gets cranky.

Edited September 10, 2013 by winstonusmc

[skirkland1980]

Watch your tps signal. If the wire isn't shielded this may happen. Our you can set your tps control to 0%.

[Xnke]

TPS is completely disabled...the noise comes in on ALL the circuits, but ONLY on MS2...MS1 has completely clean signal lines.

[AkRev]

Are you using the same wiring harness that you are using for the ms1. Main reason I ask, I had to add a few ground wires when I moved to MS2

http://www.diyautotune.com/tech_articles/grounds.html

[AkRev]

Sorry I should add that had to add wires due to the fact I only had 4 of them as grounds and my MS2 is running a few other options that I did not have on MS1.

 

Hope this helps

[loy]

Any voltage dips while you have those "reset" like misfires?

[Xnke]

No voltage tips, and yes, it is the MS1 harness. I'll likely just rewire the whole damn thing again to get rid of this problem.

[BLOZ UP]

How's your alternator? Where do you get the power to MS from? Where are the grounds?

 

Where's your oxygen sensor located, and when did you last calibrate it? Do you have another sensor you can try?

 

Any misfires will render the oxygen sensor's reading useless to you, but you didn't say if it misses when idling. Does it?

[Xnke]

Misses occur at random, at all RPMs. I idled the car at a reported 12:1 AFR and then shut it down and pulled the plugs. Clean white, with only the slightest HINT of tan. Re-calibrated the sensor, tested the sensor with unlit butane lighter...will go full lean in clean air, and full rich with the butane spewing into it. Installed the sensor, fired the car, MS still reads out a 12:1 AFR at idle. Plugs are STILL clean white, with only a little hint of tan on some spots. If it was a carbed car, I'd richen it up just a smidgen and call it a day...they are that consistent, cylinder to cylinder. Musta got lucky on my junkyard injectors!

 

Same alternator, same entire wiring harness..I put the S12 jumper and the MS-2 daughterboard into the car. That's it. Alternator is a GM unit, it's fine...scope shows some HF noise that is shunted with a bypass cap, very little noise on the power circuits in the car.

 

Sitting still in the car, ignition on, but engine NOT running...MAP signal is fluttering around all over the place, TPS flicks around 0.5%, coolant temp flickers 1 degree up/down, MAT flickers up/down 1 degree.

 

With engine running, nothing changes except that the MAP is +/- 0.8kpa of the center value, wideband flickers +/- 0.5AFR, coolant temp is nice and clean, MAT signal nice and clean, TPS has spikes of +/-1, up and down.

 

The missing is possibly that the car is just lean. I've never seen a car that could idle at 12:1 AND have plugs that show a slight lean condition on every plug, so consistantly. I've seen where a mismatched or leaky injector could have one plug black, the others much lighter, and show a rich reading...the one cylinder just got drowned in fuel...but nothing like this.

[Dan_Austin]

Which wideband are you using, and do you have a separate gauge for it?  Your descriptions

sounds like you have a calibrated sensor, but TS is using the wrong calibration curve.

I have no experience with the Extra code, so I may be talking out my lower orifice.  On

the B&G code I know I needed to identify the sensor in the project properties, calibrate

it in the sensor tools and I seem to recall needing to tweak something in VEAL, but I do not

have my tuning PC handy so I am not sure about the third location.

[NewZed]

The missing is possibly that the car is just lean. I've never seen a car that could idle at 12:1 AND have plugs that show a slight lean condition

Doesn't the unburned fuel from a miss skew the O2 sensor's reading to the rich side?  If it's "false rich", adding fuel should make the AFR reading show leaner, as the lean misses go away.

[Xnke]

It's the same thing, Dan, and I have matched the calibration curves a dozen time now trying to figure that out.

 

Unburned fuel from a miss will read as lean, because the sensor compares Oxygen levels, NOT fuel levels! If it detects oxygen in the exhaust, it reads as lean, regardless of if it is a true lean (not enough fuel to combine with all the oxygen) or a miss (unreacted oxygen due to lack of combustion).

 

I think I may simply just have a worn out sensor. I don't know. The car acts rich, driving wise, except for the little stumbles and misfires. I probably am running too much timing and too rich a mix at cruise, even the the car is getting great milage, comparatively. I normally set cruise by ear...lean it out till a drop-throttle event gives me the nicest sounding snaps and pops out the exhaust, then turn overrun fuel cut on to kill the popping.

[Xnke]

The noise issues can't be attributed to MS2 any longer....it's the V3 mainboard in conjuction with low-Z injectors.

 

This is actually a known problem from back in 2004! There are a few known fixes, and I tried one on the ZX Turbo last night with good results.

[loy]

You can try a .1uf cap on h1/boot.

[SleeperZ]

The noise issues can't be attributed to MS2 any longer....it's the V3 mainboard in conjuction with low-Z injectors.

 

This is actually a known problem from back in 2004! There are a few known fixes, and I tried one on the ZX Turbo last night with good results.

 

Can you post some more detail on this?  I am trying desperately to get my Z running this week so I can have a chance to pass an emissions test to keep my classic plates, and this is an issue I am experiencing.  MS3, 440cc lowZ injectors, single coil, DIY trigger wheel. 

[madkaw]

If you blew a HG and ANY coolant got to the O2 sensor it's done.

[Xnke]

SleeperZ, solder a 100uF cap between the center pin of Q3 and the center pin of Q9. Negative lead of the electrolytic cap goes to the center pin of Q3.

 

That's the "stage 1" noise mod...from there we go into cutting traces, lifting pins, pulling outside wires into the case, ect.

[SleeperZ]

Thanks, I will look into that.  I fired it up last night, and it's almost perfect with an occasional sync loss, but it is correcting and maintaining 13.5:1 at idle so I am almost there.  I am thinking I can get access to an oscilloscope and look at the DIY wheel signal to verify noise.

[Xnke]

Check your injectors; look for a 36V spike or so at the end of the injector pulse. it SHOULD be there...if it's not, then it's getting shunted into something else.

 

The biggest noise issues with MS-V3.0 are INSIDE the box! As long as you are running shielded wiring for the RPM input, and your coil and plug wires are not across your sensor wiring, then the biggest noise contributors are going to be the alternator and then the PWM flyback circuits installed on the mainboard...the PWM idle circuit can also contribute.

 

The PWM flyback circuits draw power directly from the same pin that feeds the main processor!