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2G In search of the e85 hx40 guys.

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Cynxe

Proven Member
265
6
Feb 19, 2015
Ottumwa, Iowa
Looking for some help with a timing curve and fuel maps. Im currently at 30psi. And have adjusted fairly accordingly, but my car kinda bogs down at around 24psi. Looking for some pictures of maps or maybe even a tune i can reflash and modify.
Pte 1200s
E85
30psi hx40
Black box ecu
Speed density
 
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Super helpful conversation. Now, if we could just get Biglady in here to verify all this we will be good....
What do you need to be confirmed? kmetiuk hit it on the head as far as how/where to tune for openloop.

The only real time you want closed loop is for stop/go traffic or city driving. Beyond that, openloop for the win :) Its what I did when I ran SD. You can also lean out your 70mph+ for better gas mileage on the highway. Some multiplication has to happen for this though as I believe dsmlink only allows a max afr of 15 or something.

When I switched back to MAF I used mainly closed loop.
IMO MAF worked better for me due to living in Michigan. I saw too many fluctuations when on SD and closed loop. (I did a lot of city driving.)
 
By no means am I a tuning savant, but closed loop is for soccer moms. If something is wrong with my car and its relying on an o2 sensor to half ass fudge fuel trims to stay moving I want to know what's wrong rather than letting the ecu tune itself to whatever car manufacturers think is best. That sounds a bit negative but Its similar to actually calibrating your airflow where your car does what its told, rather than just playing guess and check with your AFR table and ending up with a table full of random values that make the wideband say what you want.

As for timing when I was on stock cams I couldn't take it above 16* peak at 25 psi or I would get knock. After some drop in 272's on e-85 I used all stock 2g timing till WOT. WOT@3k I was at 16* ramping down to 13* at 5500 and back up to 18* at 8k. My motor lived happy with that and 30-32 psi for 3 years and 20k miles beating the hell out of it. I eventually took the boost up to 38 psi with the same timing for a weekend to race some faster cars and shot a wrist pin out the block. Upon teardown I found busted ringlands on 3 pistons that were not there before the weekend, so obviously that was too much for that kind of boost. That's just to give a general idea for what timing worked at what boost for me. Our e-85 down here is usually mid70's for ethanol content.

Also for fuel I always shot for 13.0 wot 3k, ramping down to 12.2 for peak torque, and 11.8-12.0 up top.
 
Great info guys! Thanks for sharing your knowledge and best practices with cruise tuning.

For those who haven't used link and are looking at this info hella confused it will make sense once u use the actual tool. Let's have a mod sticky this. I'll probably borrow some info once it cools down from 106 degrees here :barf::pray:
 
Isn't there some conversions you need to do when locked in open loop? I think I just saw something on the link boards like this the other day.
Dave was explaining it, I'll see if I can find the thread. But it was something along the lines of fuel trim defaulting to a positive value in open loop below a certain rpm. Then that causes AFRest or wbfactor to not look right, as the ECU is using that fuel trim in it's calculations. Anyone know anything about something like this?

Asking as I too would like to try it out.
 
Yeah I was talking about cruise tuning in open loop. I run all the time in open loop. When you get your afr's close they don't seem to fluctuate as much. Also If you don't ride around with your laptop and your o2 sensor ever goes out, which mine has before, your car will run like crap if it runs at all and you'll be limping home. That's the main reason I keep it locked in open loop.
 
Isn't there some conversions you need to do when locked in open loop? I think I just saw something on the link boards like this the other day.
Dave was explaining it, I'll see if I can find the thread. But it was something along the lines of fuel trim defaulting to a positive value in open loop below a certain rpm. Then that causes AFRest or wbfactor to not look right, as the ECU is using that fuel trim in it's calculations. Anyone know anything about something like this?

Asking as I too would like to try it out.

I read that thread also talon, what he was talking about is if you don't have a stock narrowband or aren't simulating a NB with your WBO2 then link will automatically add a +5 fuel trim which will throw your afrest off. If you're locked in open loop your O2 will still cycle, your Ecu is just ignoring it.
So to make a long story short, no, you don't have to change anything to run open loop
 
I read that thread also talon, what he was talking about is if you don't have a stock narrowband or aren't simulating a NB with your WBO2 then link will automatically add a +5 fuel trim which will throw your afrest off. If you're locked in open loop your O2 will still cycle, your Ecu is just ignoring it.
So to make a long story short, no, you don't have to change anything to run open loop


Interesting..... that must be a safety thing then hey? If the ECU can't see a signal from the NB (or NB sim) then it assumes the O2 crapped out and adds fuel to richen it up to keep things cool and "safe". Good info. :)
 
Isn't there some conversions you need to do when locked in open loop? I think I just saw something on the link boards like this the other day.
Dave was explaining it, I'll see if I can find the thread. But it was something along the lines of fuel trim defaulting to a positive value in open loop below a certain rpm. Then that causes AFRest or wbfactor to not look right, as the ECU is using that fuel trim in it's calculations. Anyone know anything about something like this?

Asking as I too would like to try it out.
Talking about the 5.2%?
 
What Dave was talking about was that your fuel trims default to 5.1% when you lock in open loop which makes afratioest 5.1% richer than your table values. I tried to get Dave to elaborate a bit more but I think he misunderstood me.

What it all boils down to is having properly calibrated airflow. Technically you can take your global and ve table and make the Ecu say whatever you want it to say for afratioest and still have the car run dead nuts on any afr you want at any time if you have a wideband. It won't impact the drivability of the car one bit but all your numbers in link will be completely inaccurate. One thing I am confused about is if all fuel trims default to 5.1. I haven't tuned my car in a couple of years but if I recall, my afratioest under wot matched my table and I used to tune for 0% wbfactor, so it may just be for lower fuel trim values.
 
What Dave was talking about was that your fuel trims default to 5.1% when you lock in open loop which makes afratioest 5.1% richer than your table values. I tried to get Dave to elaborate a bit more but I think he misunderstood me.

What it all boils down to is having properly calibrated airflow. Technically you can take your global and ve table and make the Ecu say whatever you want it to say for afratioest and still have the car run dead nuts on any afr you want at any time if you have a wideband. It won't impact the drivability of the car one bit but all your numbers in link will be completely inaccurate. One thing I am confused about is if all fuel trims default to 5.1. I haven't tuned my car in a couple of years but if I recall, my afratioest under wot matched my table and I used to tune for 0% wbfactor, so it may just be for lower fuel trim values.

The only time your fuel trims defaults to 5.1 is if your locked in open loop and Don't have a o2 sensor assigned to the front o2. It's not the locking in open loop that does it, it's not having a front o2 sensor.

Here's Daves quote:
Since the missing front O2 sensor makes the ECU unable to determine fuel trims, the ECU defaults to +5.1% fuel trim for engine operation below 4000 RPM. It's this fuel trim that is causing AFRatioEst to be different from your fuel table.

Dave
 
@blktalon3 @kmetiuk @Vegas smith @jakelandry I just tagged you guys that seemed involved in the conversation.

So I went out and tried the lock in open loop deal and the ECU does most certainly default to that +5.1% even with a narrowband signal.

Sooo... If I'm understanding Dave right this is what needs to happen to get AFratioest and WBfactor to line up below 4000rpm no matter what. If not and I'm over thinking this please let me know.

"There is no way to disable this default operation. In those areas where the mixture is different from what you desire, you'll need to offset the values in the fuel table. For example, where you are seeing a +5.1% fuel trim, increase the values in the fuel table by 5.1%, e.g., change 14.7 to 15.4.

Dave"

"Take an example: The table has 14.7:1 and the fuel trim is +5.1%, resulting in an AFRatioEst, what the ECU is attempting to achieve, of about 14.0:1. If your WB reading is 14.0:1, WBFactor will be zero since the WB is reading exactly what the ECU is trying to achieve. If your WB instead reads 14.7:1, the mixture is leaner than the 14.0:1 that the ECU is trying to achieve and WBFactor will reflect that difference.

Dave"
 
@blktalon3 @kmetiuk @Vegas smith @jakelandry I just tagged you guys that seemed involved in the conversation.

So I went out and tried the lock in open loop deal and the ECU does most certainly default to that +5.1% even with a narrowband signal.

Sooo... If I'm understanding Dave right this is what needs to happen to get AFratioest and WBfactor to line up below 4000rpm no matter what. If not and I'm over thinking this please let me know.

"There is no way to disable this default operation. In those areas where the mixture is different from what you desire, you'll need to offset the values in the fuel table. For example, where you are seeing a +5.1% fuel trim, increase the values in the fuel table by 5.1%, e.g., change 14.7 to 15.4.

Dave"

"Take an example: The table has 14.7:1 and the fuel trim is +5.1%, resulting in an AFRatioEst, what the ECU is attempting to achieve, of about 14.0:1. If your WB reading is 14.0:1, WBFactor will be zero since the WB is reading exactly what the ECU is trying to achieve. If your WB instead reads 14.7:1, the mixture is leaner than the 14.0:1 that the ECU is trying to achieve and WBFactor will reflect that difference.

Dave"

I mos def run lock open and my AFR's are where they should be so I'm confused now.

Does the fuel trim peg at +5.1% and the AFR's reflects that change? I could swear my AFR's are fine when locked in open loop......

My front end i sin pieces or I would go check right now. :(
 
I could be wrong but, it's just that the ECU is seeing that 5.1% and using that in calculating the AFratioest, so while you can get your actual AFR where you want it, the WBfactor will reflect that difference between actual afr and the ECU's estimate. In other words you have to make the DA table 5.1% richer to make AFratioest match actual afr in those areas where it has defaulted to 5.1% fuel trim.
So one of those things not crucial to operation, just crucial to line up all the values. Again, if I understand correctly, I was hoping one of you guys could verify haha.
 
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I could be wrong but, it's just that the ECU is seeing that 5.1% and using that in calculating the AFratioest, so while you can get your actual AFR where you want it, the WBfactor will reflect that difference between actual afr and the ECU's estimate.
So one of those things not crucial to operation, just crucial to line up all the values. Again, if I understand correctly, I was hoping one of you guys could verify haha.


I dunno man. I could be wrong but I thought my fuel trim does peg at +5% but then the ECU does not use that value in the final injector pulse width. I'm like 50/50 on that tho....I can't go check or I would but I am pretty sure my AFR's stay where they are supposed to without messing with the VE table to account for the 5%.

I should have my car together in the next few days and I'll check.


Could you post a log of your car just idling and switching the lock in open loop on for a 5-10 secs and then off again? We'd be able to see the AFR change or the WB change for sure.
 
Yeah, the fuel trims aren't actually being used in open loop. It's just the AFratioest that's using the fuel trim. It's just a calculation inside the ECU, it should have no bearing on what your actual afr is. But it's what the ECU is comparing to your wideband to get WBfactor.

Again I'm not thinking this is gonna do anything to your actual AFR's in open loop, as that's completely up to deadtime and global. Just the value the ECU comes up with for AFratioest and thus WBfactor.

Like in the example Dave gave, the da table says 14.7 and the fuel trim says 5.1% so the ECU calculates an AFratioest of 15.4. Then say your actual AFR on the WB is 14.7, the WBfactor will show the difference.

Maybe one of the other guys can confirm, or explain what's really going on there.
 
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My WB is pinned to the rear o2 and I am simulating NB. I can post a log when I get home, but I'm not saying my AFratioest is off, I'm asking if it will be and if you guys had to do what Dave said... All I did today was check the box to see if it would indeed lock the FT at 5.1% I saw that it did and that's as far as I got. But from what I'm gathering from you guys is I don't need to do any of that, so just trying to figure out what the hell Dave is talking about LOL.
 
So let me get this straight. You guys are tuning on strictly open loop? And if im still needing fuel trims, they still do not log. I cannot get them to read at all
 
So let me get this straight. You guys are tuning on strictly open loop? And if im still needing fuel trims, they still do not log. I cannot get them to read at all

Just to try and clear this up, since I see a lot of discussion but a lot of confusion- if the car is tuned properly closed loop and open loop operation should be nearly identical at all aspects of idle/cruise.

All open loop is doing is saying "hey, the MAF/MAP says we have XX amount of air, let's add YY amount of fuel" it doesn't care what the actually AFR is, if it has XX air it'll add YY fuel. If you have a vacuum leak, clogging injector, mechanical failure etc it isn't going to compensate for it. So let's say you want a 14.7 AFR, the MAF sees you have 14.7 parts of air coming in (for calculation sake), it adds 1 part of fuel, which should in turn output 14.7 from the tail pipe. If you had a vacuum leak it could be say 15.4 out the tail pipe- but the computer doesn't care because it doesn't know that. So you'd be scaling your fuel down to make a richer mix to bring it back to 14.7, thus tuning around a mechanical failure

Closed loop says "hey we've got 14.7 air, add 1 part of fuel, look at the o2 sensor, it says 15.4 out the tail pipe" so now the fuel trims go positive ~5ish% to compensate for that automatically without you making a fuel adjustment.

Basically what I'm trying to say is, you shouldn't need fuel trims at all to tune. If you have no mechanical failures you should be able to command your entire AFR range to match your fuel table almost perfectly without having to look at the trims. The trims just correct for the tune being off at that point and give you a guide to follow as far as adding or removing fuel, but you should be able to look at your log and see "hey I'm running leaner at 3000rpm than my fuel table wants, let's adjust the MAF/VE to add fuel in those effected cells.
 
Just to try and clear this up, since I see a lot of discussion but a lot of confusion- if the car is tuned properly closed loop and open loop operation should be nearly identical at all aspects of idle/cruise.

All open loop is doing is saying "hey, the MAF/MAP says we have XX amount of air, let's add YY amount of fuel" it doesn't care what the actually AFR is, if it has XX air it'll add YY fuel. If you have a vacuum leak, clogging injector, mechanical failure etc it isn't going to compensate for it. So let's say you want a 14.7 AFR, the MAF sees you have 14.7 parts of air coming in (for calculation sake), it adds 1 part of fuel, which should in turn output 14.7 from the tail pipe. If you had a vacuum leak it could be say 15.4 out the tail pipe- but the computer doesn't care because it doesn't know that. So you'd be scaling your fuel down to make a richer mix to bring it back to 14.7, thus tuning around a mechanical failure

Closed loop says "hey we've got 14.7 air, add 1 part of fuel, look at the o2 sensor, it says 15.4 out the tail pipe" so now the fuel trims go positive ~5ish% to compensate for that automatically without you making a fuel adjustment.

Basically what I'm trying to say is, you shouldn't need fuel trims at all to tune. If you have no mechanical failures you should be able to command your entire AFR range to match your fuel table almost perfectly without having to look at the trims. The trims just correct for the tune being off at that point and give you a guide to follow as far as adding or removing fuel, but you should be able to look at your log and see "hey I'm running leaner at 3000rpm than my fuel table wants, let's adjust the MAF/VE to add fuel in those effected cells.


This is mostly true however I would disagree (respectfully) about the calculation part.

The ECU cannot tell if the AFR is 15.4 or 16.2 or 14.1 or any value at all, it can only see if it is one side of 14.7 or the other....which is why the value in the logs is AFREst as it is an estimation of the AFR and not a true empirical number from a WB. The reason being is DSMLink is basically a "hacked" ECU and is built upon the stock ECU's hardware. The stock ECU hardware does not allow the use of a true WB, it can only ever use the NB input (or the NB Sim if using an actual WB) pin to tell what side of the "switch" point the AFR is (see pic below).
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For the reason's stated above; the ECU does not do a calculation to add fuel trims, it continually bumps them up/down "slowly" until it starts to see a voltage change on the NB pinout. It will continue adding fuel until the AFR starts to go the other way asnd reaches the other side of 14.7 and at that point the ECU starts to pull/add fuel to start swinging the voltage on the NB pin the other way.

Because the ECU is just raising and dropping fuel trims back and forth until it sees a change in the NB voltage (or NB sim) it oscillates back and forth indefinitely. We can see this in the log at idle on any of our cars that the WB AFR cycles back and forth over the 14.7 point as does the fuel trim osciallte between +/- xx%. How far it cycles past stoich and what range the fuel trims are oscillating at is dependent on how well the car's MAF or SD table is calibrated. Well calibrated cars should see from about 15.4-14.2 (ish) and fuel trims around the +/-2% range.

As you stated b/c open loop says "XX air so add YY fuel" the AFR does not oscillate like you see in closed loop. So for tuning cruise/idle if you lock in open loop and remove that oscillation it becomes much much easier and waaaaaay faster to tune the car b/c you don't have to wait for the fuel trims to settle. If you add a little more VE in cell XX and you can instantly see the change in the AFR instead of having to wait for the fuel trims to "settle" each time. It cuts down on the amount of time it takes to tune idle and cruise ALOT...or it did for me anyways.

Because of that oscillation the AFR will always fluctuate no matter how well the car is tuned when in closed loop....its just inherent in using a "hacked" ECU like DSMLink that does not use a WB to calculate the fuel trim but instead uses a NB to estimate where the AFR is.


Lastly; b/c open loop removes that oscillation the AFR is much more stable in a very well calibrated car. As I stated I see rock solid 14.7 at idle when locked in open loop. Do a log and ehck for yourself....lock open loop creates a straight line instead of the wavy one closed loop does.

I spent a long long time at idle in open loop messing with the deadtimes and the global fuel % while watching the boostEst/MAP and grams/rev of airflow to nail my injectors down perfectly. Its so tight now that if I change my deadtime even 5ms or change the fuel by 1% the car will die and not restart. Granted I am running the 2150's so they are very very sensitive to deadtimes and fuel % at idle. When I was done I got rock solid 14.7 AFR's at idle and when cruising in open loop it does fluctuate a bit but that is due to is not being steady state and the ECU needing a fraction of a second to add/remove injector pulse width as I am cruising around.

Just to add; I ONLY lock in open loop for tuning b/c as you stated if anything happens (blocked injector, sudden boost/vac leak) you are fuuuucked. Closed loop is a safety net to limp home so I always like a lil buffer just in case.
 
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