Aftermarket EM question

[Drscottsmith]

Ok so my setup is microsquirt but I don’t think that matters. I think the answer to this question will unlock the mysteries of the universe for me…

I am dealing with an issue where at present, at idle or revving just off idle, I am seriously fouling plugs - evidence of running too rich. Other than backing it out of the garage I have not “driven” anywhere at all.

I can do several things based my simple brain to lean out the mixture:

1. Adjust fueling in the VE table by bringing values down so less fuel
2. Leave the VE table alone and open the throttle slightly to all more air in
3. Adjust timing in the ignition table - but I don’t think this is the answer
4. Adjust the AFR to a more lean target in the idle cells and let autotune fix it


There may be other solutions, and I think the answer lies somewhere around knowing what is really constant and what should be allowed to be variable, and I just don’t know what that is.


Thoughts?

[Bergerac]

Have you looked at your post start and warm up enrichment tables?

And have you confirmed your AFR with. Wibeband O2 sensor?

[Thom]

You must have some sort of "acceleration enrichment" function that may need adjusting, assuming this issue has been there since running the engine with an aftermarket ECU.

[Drscottsmith]

Ok I have not messed with that so it may have been there by default and I did not realize it. Will check there and report back. Have cleaned all the plugs but want to try to resolve before starting again (and fouling again).

I should have noted that this is a fully stock 951 other than the MS as far as the engine itself goes (stock rebuilt turbo, no cams, etc.). Am using LSx coils and Ford Mustang Cobra injectors.

[Tom]

Do you have a wideband O2 sensor? Without that, you are pretty much shooting in the dark. Something like the Zeitronix ZT2 allows you to see your air fuel ratio in realtime, which is pretty much a necessity if you are tuning engine management maps. Separately, how do you know you are fouling plugs? Is that based on symptoms?

[Drscottsmith]

Hey Tom -

More info...sorry for not including earlier. Yep - I have a Wideband. The Wideband is leaning out (the gauge in the car goes to "- - -" and the gauge on tuner studio is going beyond 19 and turning red, but I have plugs that are black with soot and wet. Interestingly cylinders 1 and 2 are worse than 3 and 4. I have cleaned them all off again and reinstalled.

I had it working pretty well with EGO turned off and a static timing setting (just to get it running). When I turned EGO on and added a dynamic Ing map is when things went wonky. I used an ignition map I found from a stock 951 setup posted on pelican.

I would think that most of these maps would be the same (or very close) for any relatively similar 951 engine - especially something like VE - as long as an engine has not had its bore or stroke changed I would think the VE would be relatively constant save for slight manufacturing tolerance issues. Maybe not? I would think a timing map would also be the same, since the factors related to that have not changed.

Thoughts? Forgive my noobness!

[Tom]

I see, that's helpful. When you say the plugs are wet, I assume you mean wet with gasoline (and not coolant or oil?). If your motor seems to be running ok while the wideband is showing super lean like that, I'm wondering it you have an exhaust leak that is letter air into the exhaust and tricking the sensor into thinking the car is lean, when in fact it's super rich? A leak would also make your narrowband close loop system add gas, which would just make an already rich mixture even more so. Any signs or sounds of an exhaust leak anywhere?

In theory, a good map could be transferrable, but I'd say in the real world there are too many variables -- was the map good in the first place, are all the sensors exactly the same, is the software the same, are the injectors and fuel pressure the same, etc., etc., etc. Something as little as a slightly different MAP voltage curve or similar but different injectors could though the whole tuning map off ...

[Drscottsmith]

Ok that makes sense - I thought things related to the engine itself would be more consistent but that makes sense about sensor variation, etc.

I did find that my enrichment curve never dropped all the way down, so I have corrected and maybe that will help. it also makes sense about the exhaust leak. I will do some checking about that as well. It did seem to work fine when on the fixed timing and no EGO however.

Thank you all as always! Will report back.

[Bergerac]

Hey Tom -

More info...sorry for not including earlier. Yep - I have a Wideband. The Wideband is leaning out (the gauge in the car goes to "- - -" and the gauge on tuner studio is going beyond 19 and turning red, but I have plugs that are black with soot and wet. Interestingly cylinders 1 and 2 are worse than 3 and 4. I have cleaned them all off again and reinstalled.

I had it working pretty well with EGO turned off and a static timing setting (just to get it running). When I turned EGO on and added a dynamic Ing map is when things went wonky. I used an ignition map I found from a stock 951 setup posted on pelican.

I would think that most of these maps would be the same (or very close) for any relatively similar 951 engine - especially something like VE - as long as an engine has not had its bore or stroke changed I would think the VE would be relatively constant save for slight manufacturing tolerance issues. Maybe not? I would think a timing map would also be the same, since the factors related to that have not changed.

Thoughts? Forgive my noobness!

Turn ego off until you get your base map right, it's trying to add fuel to correct your lean condition. I would confirm your wideband is working correctly and your inject data is correct in the ECU. Sounds like your spark plugs and wide band are telling two different stories.

You can adjust fuel globally with the req_fuel setting or the VE in each cell on your fuel map.

[Bergerac]

Turn accell enrichment off too you can drive the car without this on, it's a fine turning setting you do once the cars driveable.