Throttle position closing when you haven't taken your foot off the pedal is very suspicious. Sounds like sensor issues, which you will never be able to tune around. Check all of the input signals you can against what you would expect them to be--in particular, be suspicious of sudden changes during relatively stable inputs.

Checking grounds like SVO says is always a good idea. Might be worthwhile to set up a dedicated ground circuit for the sensors if you can. Even if it's just sandwiching a wire or a loop connector in between the mounting screws or whatever.

--DD

Yeah, it's looking like there is a noise issue. I guess I didn't look close enough at the logs because the RPM vs. Time changes recorded are physically impossible. We'll have to see about shielding the VR sensor wire as a first step.

Mark the best way to trouble shoot your problem is to make up a external tooth wheel and run it to the VR sensor. Turn off the fuel pump first!!!!! You can now look at all the signals and disconnect them one at a time to find your problem. Thats what I did.

That's a good idea. I'm going to try shielding the VR sensor first because this harness was a prototype and doesn't have the same shielding rwilner's harness did.

You may be looking at a sensor issue, but the MAP and RPM readings you are seeing in the logs make no real sense. I would upgrade the firmware to MS2Extra (http://www.msextra.com/forums/viewtopic.ph...101&t=43433). I find it more robust and easier to tune, and it's the default firmware for the MS3 in any case. I have tuned somewhere around ten cars on Megasquirt, and I've never bothered dealing with the stock firmware.

The only thing I know is a little hard to tune is throttle bodies with big cams, but as far as I understand, you're not running throttle bodies?

Feel free to PM me if you have questions (I'm in San Diego these days).

Good stuff. Thanks to you all.

Sometimes having the prototype is a bit tough, but I'm sure Mark is sorting the process out and will have something to test pretty soon.

We'll keep you posted.

Mark
I looked at the log. Is the signal ground separated from the dirty (engine) ground? If not, that could be the source of the problem.

For the cleanest signals, the signal ground and engine ground need to be tied together in only one place -- inside the microsquirt, which they did on the PCB. If they're tied together anywhere else you'll create a ground loop.

It's easy to test if the grounds are tied together outside the microsquirt. Pull the connector at the MS and test for continuity between the signal ground pin (20) and the power ground pins (21 thru 23).

good luck and feel free to call me if you want someone to bounce ideas off of.
Rich

Progress today. Mark got a VR sensor with a shielded wire installed. Didn't have to remove the engine.

Still left a bit of noise that causes some bucking generally at 1400 rpm - give or take.

He's looking into a couple of solutions and should have something in a couple of weeks.

Glad to hear you're getting it sorted out Jim, Still plenty of time before ax season.

Jeff

Actually, it'll drive better at the AX than on the street. Since if you're cruising at 1400 at an AX, you're doing it wrong.

I had noise problem with COP'S that drove me crazy!!! The problem turn out to be
the wires from the COP'S was resistive wire (5K) to resistive plugs (5k) which was
causing noise and engine missing at times. The fix in my case was to change the
wire from the COP'S to the plugs to solid core wire (0 ohms). This clean up the noise
problem I had. If you use the stock sparkplug connectors they have a 5K resistor
build in ( You can check this with a OHM meter) so you have to use non-resistor plugs.

Hmm, but I thought people usually added resistor wires and plugs to cure EMI issues. Such as this thread.

It occurred to me that we should have installed a vacuum gauge on the MAP sensor line to see if the needle movement corresponds with the MAP output. If it does, it's an engine vacuum issue, if not it's a noise issue.

So true, Mark. I autocross 4-6 miles a month and drive 10-15 miles a day. So it has to work for the daily stuff too.

Last week Mark rewired the VR sensor with shielded cable. Altho the car seems to run better, the problems remain. He is probably going to build a new shielded harness.

For your viewing pleasure, here are a couple of data log files as well as the 'tune' setup that we're using.

The December 18 file is a cold start file (less than 50 degrees). I had to crank it a lot before it started. Then I shut it down, started the datalogger and restarted the car. It seemed that it started better if I had the throttle open a bit, so the TP is about 10% and the rpm about 2000. The noise is evident and seems to disappear a couple of minutes into the log.

The December 21 file is also a cold start file. This time I didn't open the throttle and ran the log for the whole start cycle. You can see where the key is turned off and on and the cranking resumes.

I'm not sure what I'm looking at, but sometimes the TP and the PW seem to follow their own drummer.

https://www.dropbox.com/home/ms

Please let me know if this link doesn't work.

The link doesn't work....

I'm not so sure this will help but, I shielded the VR circuit and all of the 5V stuff so, MAP, TPS and cam sensor. All of the shields grounded at the MS. I Would say that the hardest area for me to deal with noise has been around 3K rpm. I really don't know why. I have had a couple of weird issues that really were tough. One was a loose CHT sensor that gave inconsistent coolant temps and would kick in warmup enrichment (as I remember it was always in mid rpm range). The other was a loose wire in a terminal block.

Dave

You can also try an additional battery ground cable. Battery to engine block. The battery itself can act like a filter and reduce noise.

Look at the factory ground path: Little stud next to the battery and a strap at the rear trunk to the tranny. There is a lot of spot welds and corrosion in the chassis between the two points...

Try the link in this older message. I updated the folder from a previous post

and like we say at work.... no shield in the field..... meaning, you only ground one end of the shield. usually at the source. if you ground both ends of the shield it becomes an antenna.

I haven't been driving much, waiting for a new harness from Mark. Should be ready real soon.

But, I drove it today using the same tune that I've been using and it ran real rough. I hooked the laptop up and see that the AFR is bouncing all over the place.

I tried with a couple of different tune setups but there was no change. Any ideas why this would suddenly happen?

Here is a link to the tune and to the datalog showing the AFR

https://www.dropbox.com/sh/p593bw6iyebgwjn/bANp3X25ic

Thanks,

Air Leaks? Gas turning sour? Not it has been a while try fresh fuel. And maybe injecor cleaner.

thanks, Zach. I'm sure the gas is good. I'll try some cleaner.

Jim

Okay, my post was nearly unreadable. Thanks iPhone.

anyway, yeah you got the drift. If nothing else has changed, could also check for loose grounds / rodent nibbles.

Zach

If your o2 sensor takes a crap and you are running AFR targets this can happen.

Thanks. Injection cleaner didn't work, I had a feeling it was something like a sensor. It's never easy.

Jim

Little has changed.

Mark built a fully shielded harness and installed it a week or so ago. Although it, generally, runs better, bucking remains an issue at a little over 2000 rpm.

There is a new issue, or one that just became evident when other things were cleaned up. The car runs rough when first started and then, a couple of minutes later, rpms drop to almost 0, the AFR spikes to 19. I realize that the AFR is an effect not a cause, but can't tell what the cause is.

Mark also put in a cold start/idle control gizmo. So the car starts better, but not really good.

Here is a link to the current tune and to a datalog done this morning on a cold engine.

Mark thinks this is because of the cam and/or lightened flywheel, but before I junk the MS or start to depower the engine, I'd like to get second opinions or options.

https://www.dropbox.com/sh/p593bw6iyebgwjn/bANp3X25ic

Any suggestions appreciated.

inline fuel pressure gauge.
Suspect the fuel pump??

rich

Before you junk it, Why not try a heavier flywheel and measure the difference? Process of elimination. I bet Mark has some lying around.

You really need to buy some dyno time. just sit there and tune for 8 hours at various load conditions.

Looking at your datalog the car is running really lean. AFR 15 is too lean on these air cooled engines.

Are you running ITBs? YOu should have a lot more vacuum than close to 90kPa at idle. Even with big cams and itbs you should at least have about 65 kPa at idle with a big drop as you get abve 1800rmp or so.

To me it looks like you need to tune the fuel delivery (VE table).

I agree with Mike. At this point you need a dyno and a guy with a lot of experience tuning EFI. Your cam is mild enough for CIS. I'm not sure how a light flywheel would effect this. I am confident you can tune this out.

Zach

I went out this morning and got a pressure gauge (3 FLAPS and finally to Vic Hubbard Performance).

The gauge reads 24, Haynes says 34. I'm gonna guess that a 10 pound drop makes the pump essentially useless. And may have been contributing to the problems since MS went in.

Good thing I like the guys a Parts Heaven.

Mike, do you know where there is such a place in the Bay Area? I have not done a lot of tuning because there have been, hardware, noise and cold start issues since the installation. Now that those have been taken care of and the fuel issue will be solved shortly, I will spend some time tuning.

I searched for dynotuning in the Bay Area and found one shop in Pacheco that says they tune MegaSquirt. Others tune 'other efi' systems and a whole lot of the sites are for shops that don't exist anymore.

Phone calls on Monday, after I get a new fuel pump.

Sounds like the same place.

BRG Racing is the place I used. I tuned my self but If I did it again, I would have them fool with it. The price is about the same.

110 2nd Ave S. Unit D 12 - Pacheco, CA 94553 - Phone: 925.680.2560 - Fax: 925.680.2567
Toll Free # 1.877.ride.brg
email: kc@brgracing.com

Thanks, Mike, that's the place I found, too.

Glad to hear your making progress Jim, hopefully this will take care of it.


Jeff

Mike, your project is the only successful Micro/MegaSquirt project that they've had. And one that didn't work. They'r going to do some research and may take the project. I'm not sure that's progress.

There are other dynotuners in the area, I have many calls to make.

Sorry to hear you are struggling so hard with the system.

Good luck, but your fuel pressure is to low.

Just saying.

Rich

Try Sias Tuning. Vic Sias is a former SCCA National SoloII champ. He is a former Z car guy and I think autocrosses the snot out of a BMW these days.

I know, Rich, thanks.

I bought the pump (rebuilt) less than a year ago with a one year warranty. I talked to Jeff at Parts Heaven on Saturday and they replaced the pump. The replacement jumped all the way to 27 psi and is really loud.

I went back to Parts Heaven today and explained to Spencer what was going on. Take another pump, he said. I did.

I won't get this on in til Friday. Wish me luck.

Redline sells a 'uiversal' pump for $71. anyone have any experience with it? Are there other options?

Good luck Jim!

I would seriously contact Mario Velotta at www.thedubshop.net. Mario is the absolute best Megasquirt tuner I know of, bar none. If you e-mail him your .msq file, he can probably find the tuning issues and correct them. Either way, I would definitely call him and discuss your issues. Tell him Nate set you. . .

There is a dyno shop in hayward. They specialize in Haltech and ricer cars but they may be able to help too. I forget the name but they are located around Huntwood/Whipple area.

I am using a MSD 2225 pump. It's kind of loud, but not too bad. I have it mounted in the front trunk. I think it was about $100 from Summit.

-- brett

I use the Ford F150/Crown Vic external pumps. They are cheap, reliable and deliver plenty of fuel. Just put a regulator on the return line and you are good to go.

Progress!!

In the last week or so Mark and I have made some changes: put in a new fuel pump and filter and straightened out a couple of fuel lines, a new ECU, and new trailing arm bushings.

I think the fuel issue and the ECU have cleared out the background issues and left the real problem clearly in view. Between 2000 and 3000 rpm it bucks. The PW and MAP bounce around a lot. I'm not sure which is the cause and which is the effect.

I have done a lot of reading and made many changes to the tune without ever changing the bucking. Here is the most recent tune and a short log showing the bucking and system changes.

Does anyone have any idea what might be causing this?


https://www.dropbox.com/sh/p593bw6iyebgwjn/bANp3X25ic

Thanks for looking.

Sweet! logs! ill take a look. Is that the MSQ that was in use when the log was generated?

I have had the same pump on mine for 8 years now, works great and cant beat the price. It is a bit loud though.

Yes. Thanks.

I've sent Mario my files, not quite as current as I just posted, but pretty much the same. He's looking at them.

thanks, Nate.