Another MS conversion, Progress, at last. Options

[904svo]

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.

[McMark]

Hmm, but I thought people usually added resistor wires and plugs to cure EMI issues. (IMG:style_emoticons/default/confused24.gif) 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.

[JimN73]

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. (IMG:style_emoticons/default/laugh.gif)

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.

[JimN73]

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.

[draganc]

The link doesn't work....

[DNHunt]

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

[Mike Bellis]

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...

[JimN73]

Here is the tune file that I'm using and a log file from a recent test run. The log file starts out idling, accelerates in low gear and shifts to 2nd.

Then the fun begins, you can see the bucking. It's interesting that the throttle position closes, but I have't taken my foot off the gas pedal. Is the TPS causing the problem or is it the effect.

The engine is a 2056 type IV with a 9.5:1 compression ratio and Raby's heads. Has Raby's 9530 cam (Web's Cam #494), lightened flywheel and other lighter components.

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

Any help figuring this out will be appreciated by me and by those who will follow.

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

[mrbubblehead]

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.

[JimN73]

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,

[VaccaRabite]

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

[JimN73]

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

Jim

[VaccaRabite]

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

[scotty b]

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

(IMG:style_emoticons/default/rolleyes.gif) (IMG:style_emoticons/default/drunk.gif)

[JamesM]

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,

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

[JimN73]

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

Jim

[JimN73]

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.

[r_towle]

inline fuel pressure gauge.
Suspect the fuel pump??

rich

[Mike Bellis]

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.

[jpnovak]

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).