On-demand timing/ECU control with OBD2

[mike7]

New to the forum- hi all. Have been browsing a lot of information on woodgas lately and I am curious how people do woodgas setups with modern engines that have EFI and individual coil (non-distributor) ignition systems.

How is timing advance usually handled on these? Will the computer automatically advance the timing far enough based on the knock sensors, or is it necessary to do modification to the ECU?

If modification is necessary, is there anyone out there who has made a switch that can turn the extra advance on or off through connection with the OBD2 interface? (Basically like a custom multi-position tuner like what people put on diesels, but with parameters based on woodgas in gasoline engines)

Just general curiosity, I’m not doing a project right now, but have been thinking about it. My main interest would probably be in GM engines, either a LS-based 5.3 or 6.0 or an older 454 TBI

[Matt]

To adjust timing I think you could just mod the MAP sensor signal. Maybe add a potentiometer to the signal wire. Just my two cents I have never attempted it but If I were that would be the first place I would go to tune timing.

May just use a second sensor set for different parameters and use a switch to flip between the two.

[Wayne]

Hello Mike and welcome to the DOW ( drive on wood )

I don’t have any experience with the OBD2 vehicles but have a lot of miles from vehicles 96 and older .

I have a V-10 Ram that advances the time about 35 degrees when wood gas is put to it . Also I have dodge dakotas 96 and older that I rotate the distributor enough to make the fire jump to the next peg.

The timing issue can get very complicated !!

Here is a tread in the general discussion that might help.

The answer to Mysterious Dodge Timing advance

Anyway I saw a nice v-6 dakota for cheap (1000$) and in good condition. So I really wanted to understand what was going on when you advance the timing on a dodge v-8 (and more specifically if I could find a way to make advance on a v-6). So I asked a man a question and got an answer. In slightly oversimplified terms the answer is that the ignition timing is determined by the computer through a combination engine sensor observations and the position of the crankshaft (ie. crank fired ignition). F…

[mike7]

Hey, the man himself! Thanks for the response.

I’d figure based on your comments and some others that it may advance the timing automatically. I know it does that for gas, but I just asked originally thinking it might cause an error code since gas doesn’t usually need that much advance.

I don’t have the workspace (or really, the time) to do a build right now, but I’ve been reading a lot lately. I’ve seen people on here talking about the “Keith style” gasifier- is that just your specific dimensions for a common gasifier type (open top/stratified downdraft, Imbert, etc.), or have you developed a significantly different concept? I saw that you have a book available, so I’m not asking you to give away too much detail, I’m just interested in the general concept

[Wayne]

may advance the timing automatically.

Hello Mike . I think some will advance but I know from a build on this site that the 4.7 dodge will not advance enough for the woodgas.

The gasifiers I build are a down draft with a huge amount of heat recovery .

[mike7]

Hmm, that sounds like a clever idea to simulate certain inputs. Seems like it may be more useful for remapping fuel than timing to me though. Do you have any links to more info about this?

[Matt]

Yes it controls both, but when in a wood gas mode, we dont care about the fuel mapping only the timing.

The harder the vacuum the more advanced.

[Matt]

If you go with an LS based engine you can get the MSD ignition system. They supply you with a number crystals to tune the timing curve. This is all based on the MAP sensor and CPS

[Matt]

https://www.aa1car.com/library/map_sensors.htm

[paulstowing]

check my link getting obd2 legal gm you can do almost anything.

[mike7]

I looked at your thread, and it looks like you did what I was asking about- you said that when you turn off the fuel, it would automatically switch to wood timing. I did not see why that happens though. Is the answer to that in your screenshots of the tables, or what exactly causes the timing to advance with wood?

[paulstowing]

I have it hooked up so when I turn the fuel off the intake air temp disconnects and reads -40 degrees that part of the timing map I advanced I wont be out driving if its that cold out so when I flip back it reads the real temp and the timing runs stock.

[mike7]

Nice, that’s the kind of simple solution I was interested in. Glad I joined this forum