2x0

I would be very interested to know what tuning parameters you are using for cold ECT and IAT compensation.

I have been hearing two sides of this story. Some say, E85 cannot be tuned to run well in colder temps. Others say their cars run great at any temps, it's all in the tune. If anyone on here is in the latter group, please chime in so I can compare where I am currently at with fuel and ignition compensation, and make sure I am on the right track.

I have started adding fuel in 10% increments at 32 degrees and below to see if it helps or hinders. I fixed cold cranking by adding about 50% to the cranking pulse tables, now it fires up immediately. However, it seems to run good in the 12-14 AFR range for a few seconds, then slowly leans out til it either dies or just barely idles. If I go anywhere near the gas pedal it dies instantly.

The tough part about tweaking the compensation tables is that, according to Hondata it can take several minutes of the car running for them to take effect. So I have to sit there with the car stumbling and wait to see if there's a difference. After a few minutes, the ECT starts to warm up so I can no longer test my adjustments.

I am running a B18/B16 head and 1000cc FIC injectors. Last night while idling with 10 degree IAT and 40 degree coolant, my injector pulse was ranging from 2-3ms. So let's see where yours is at and compare?

Thanks in advance for any help.

LightningTeg

You need to look at post start compensation field and crank that up. There should be a table vs temperature for that as well. My car runs fine in the cold (although I really dont run it below freezing often because the oil is molasses). All in fine tuning those tables. I have 2000's btw.

2x0

Thanks, currently my post start is at 15%. My only concern is I wanted to avoid modifying anything that affects all running temps, because my post start is across the board. Car already starts and runs fine when ambient is >50 degrees.

Would you mind posting up what values are in your fuel compensation tables for IAT and ECT? It looks like mine started with the OEM values, and I know they can be different depending on which ECU or basemap you start from.

cruizinmax

iTrader: (2)

I have tuned 3 b series cars on e85 have never had an issue with cold start. My current daily has been on e85 for 3-4 years. All I did when I converted from my pump gas tune was add 30% to my global fuel trim and the fine tune the fuel map from there. turbo gsr, Id1000's, hondata s300.

When you guys are doing an e85 tune are you just adding 30% to all the cells on the fuel map or adding a global compensation? I have always wondered why I have never had an issue and some struggle with cold start.

2x0

I didn't do the original tune on mine so I cannot say what tweaks they made to the tables, but the overall fuel trim they added 20%. That is an important piece of info and thanks for sharing that.

When I compare my cold temp compensation values I would need to offset based on overall trim.

Thanks for adding the table also. Did you have to adjust the spark dwell angle at low rpm's to handle igniting the extra fuel?

cruizinmax

iTrader: (2)

I just added my fuel trim screenshot. Interestingly I found I removed some cranking base pulse. My car has always started just like OEM even down to 0* Fahrenheit. Only recently have I started having starting issues after adding an adjustable fuel pressure regulator. It doesn't have a check valve feature so it looses fuel pressure when sitting and I think there is no pressure in the rail at the time of the base pulse. It always starts instantly after the second crank.

2x0

Question on the post start trim. Does anyone know how long it actually lasts for with the stock decay parameters?

I ask because, immediately post start, my car runs great at 12-14 AFR, but it only lasts a few seconds before it leans out. Is this few seconds the post start, or is this the extra cranking fuel that didn't atomize getting burned off?

2x0

Strange, I wonder if that has to do with your injector size or other factors. Mine would crank several times before sputtering to life until I added about 50% to my cold cranking base pulse.

AZ_CIVIC

iTrader: (1)

Never had an issue with e85 but e98 holy cow when it is cold it is hard to start, I usually spray starter fluid into the turbo to get it going.

LightningTeg

It only lasts a few seconds. You can see in the data log the routine turns off. So you want to focus on IAT and ECT correction at whatever load you are working on. You always want to make broad sweeping changes to fuel table to get it in the ballpark before trying to edit detailed cells. So at 180 Degrees or w/e your normal temp is, corrections should be zeroed out and your main fuel table should be tuned to run the best here. Everything else will be a additive or subtraction multiplier to the main table.

2x0

Thanks. Sounds like the time it is running good is when it is getting that 15% extra fuel then. If that's the case, should be easy to add the 15% compensation in for cold temps. The only frustrating part is that when adjusting those tables, it doesn't update right away to see the results :

2x0

I am spending as much time as I can this weekend tuning the idle and low load compensation tables. It DEFINITELY needed way more fuel at lower temps!

I have already added 20-30% at all fields from 68 degrees and under on IAT and about 10% on ECT. I am not done yet, but it is finally running decent at low temps, still a bit lean. Need to add alot more in the 100-120 degree range yet, as it starts to lean out and die when it gets up to this temp.

Once I get it where I want it I'll post up my tables.

motoxxxman

About a year ago I converted from Mobil 93 to E85. with Precision 750cc injectors and 10.0:1 compression. I added 30% to the entire fuel table, added 4 degrees to the entire timing table (including idle and lower) then just went straight to street tuning which needed some tweaking for sure, but very little across the board. the only areas that needed more than tiny tweaks was wot high rpm needed a bit more fuel and a bit more ignition, probably because I was near knock limit before on 93. I also found that my car idles best around 13.8-14.3 afr (gasoline afr scale of course). The compensation tables did need some tweaking as well, but not as much as you might think, and actually in the opposite direction. I actually had to pull some fuel from super low temps. I did need to add 2ms to the cranking pulse across the temp range. Ignition, I did add a little at very low temps. With ngk 8's for plugs, I can start and idle almost flawlessly down to around 10*F. I say ALMOST flawlessly because I deleted the FIV, air boost valve, and the PCV system on my car. so colder than that and it simply doesn't get enough air so I have to hold the throttle cracked open a little while cranking and idling until ECT gets to at least 30*F when IAT is under 10.

The reason I quoted the above is because around 125 ECT, my car was leaning out as well and would stutter a little and almost want to die. It would pull through and idle normal again once it reached 135+, but it still annoyed me. I started by adding some fuel to the ECT tables, but that caused it to go a bit too rich below and over that temp. So I set it back to the way it was previously; fairly linear, and then found the cure; 2* more ignition at 125 ECT. Perfect afr from initial start all the way to hot idle without a single hiccup.

The best part is I'm on crome still too. and all my overall trims are still at 0%

I'll post shortly with my compensation table values...

2x0

Thanks for your post. I was actually working on an update to this but wanted to wait until I do some more trial and error this weekend.

Basically I am thinking I have a fuel system problem, which is why it is not getting enough fuel and that it may not be in the tune at all. Once I had it compensated to run at cold ECT's, it warmed up and again was way too lean. My strim was adding close to 50% compensation just to keep it idling and the AF meter was still lean!

So, I am tracking down problems with the fuel system, going to check pressure, FPR, filter, injectors and see if I can find a problem. Also going to try starting with a new base tune to see if it reacts any differently.

I'll post as soon as I find something.

motoxxxman

(remember this is for crome)

IAT fuel:
-22.....-11.....8.....42.....79....151...284
1.23..1.18..1.13..1.06..1.00..0.95..0.94

ECT fuel (open loop at all times)
-22.....3......25.....60....133...170...284
1.36..1.19..1.13..1.06..1.03..1.02..1.00

ECT fuel idle
-22.....25.....60.....96...133...170...284
1.36..1.13..1.06..1.03..1.02..1.00..1.00

cranking fuel (ms)
-22.....-8......3......25.....60.....79...170...284
50.0..40.0..36.0..27.0..15.0..11.5...5.5...5.0

IAT ign (retard)
-22.....98....133...160....284
0.00..0.00..2.00...5.00..5.75

Oh and I'm still using factory battery offsets.
I'll add ect ign tables later, gf is on her way home and it's Vday