FINALLY nailed down my tune/problems.. :)

T

Trav4011

Active member
After thinking about a previous project, where I had issues with a big cam/big flowing head, turbo 4 banger.. I realized that I may be running into driveability issues that simply can't be sorted out with this head/cam combo, and the factory ECU. High flow rates, and overlap is probably allowing raw fuel to dump into the exhaust.. giving the o2's false "rich" readings, but, the engine is really lean. It would make sense that my driveability, just like my Nissan project years ago, would go out of the window. Our sollution for that car (standalone powered), was to set the ECU to run in open loop only. We tuned on intake manifold pressure versus RPM. We then used the TPS/MAP blend function to fix tip-in issues. This car was notoriously nasty on tip-in, because it had HUGE cams, and a very short runner/big plenum manifold. It was designed to spin up 9K rpm, and made over 600whp.

So, just to try it, I asked James to set my ECU to run in open loop, 100% of the time. He sent me a revised tune file.. I loaded it up, and VOILA! No more stumbles, hesitation, lean misfire.. nothing.. The truck cruises at 13.3:1, give or take.. on E10 fuel (12.6:1 on a wideband set up for gasoline @ 14.7:1 stoich), and WOT is around 11.3-11.5:1 (10.7-10.9:1 on the same meter). We also firmed up the shifts a bit.. and James hit the nail right on the head.. the very first try. :)

Dale (Bad As L) had the same hunch, and sent me a PM earlier. His thinking was right in line with ours.. He was saying that Casey had the same issue with his truck.. and guess who's cams I have? ;) Thanks for the input, Dale.. I appreciate it!

So, it looks like my random lean issues are gone (cleaned my injectors), the tune is 99.9% perfect, and driveability is awesome. Tests for a head gasket leak (gas analyzer) showed nothing out of the ordinary.. and, so far, the new plugs aren't green anymore. I'll keep an eye on them just to be safe, but, I think we're good to go!

So, finally, I'll be able to focus on my suspension, cage, and misc. things.. Killer Chiller, cosmetics.. etc..

Thanks again for the help, everyone.. I appreciate the input and encouragement. :)

Travis
 
I'm really happy for ya. Don't crucify me I'm an electrician first and car guy second but what's it mean to run in open loop mode or closed loop mode and what's the purpose of switching and what problems can you run into buy running in open loop mode 100% of the time?


"A truely wise man has more questions than answers"
 
To put it simply.. Closed loop occurs at cruising speed/idle.. and is a function where the ECU reads feedback from various sensors, in order to achieve the perfect A/F mixture, to give you the best mileage, and driveability. Mainly.. your primary o2 sensors.

When you go past a certain throttle percentage, and/or engine RPM, the ECU snaps into Open loop. In open loop, the ECU ignores most of the sensors, and runs off of a preset table, to give the best performance for WOT, or near WOT operation.

While I'm not 100% sure of exactly which sensors this particular Ford ECU looks at, I'm pretty sure that the main ones in open loop would be MAF voltage, RPM, IAT2, and probably knock, up to a certain RPM, at least. I know that in some Nissan applications, the knock sensor is ignored past a certain RPM, as normal engine noise would be interpreted as knock past that point.

The problem with trying to tune a big cam/big flowing head engine in closed loop, is that during overlap (when the intake and exhaust valves are both cracked open for a split second), raw fuel gets dumped into the cylinder and straight out of the exhaust port. This is translated by the o2 sensors as the engine running rich, when in fact, it may be running at stoich, or near it. It may even be lean.. But, the ECU doesn't know this, and pulls fuel. You then get into a wacky fluctuation, where the engine goes rich to lean, back and forth.. creating all sorts of wacky readings and driveability issues.

So, by tuning in open loop only, you take the o2 sensors out of the equation. You then tune off of a wideband, and set your A/F up just like you would at WOT. This is not beneficial in any way, actually.. as it hurts mileage slightly, and gives off more emissions, but, in my case, it's pretty much a requirement. ;)

Travis
 
Thank you, that was VERY informative and definitely makes sense with all the problems you were having. I was really feeling sorry for ya, I know how it feels to have lots of money in something and it not work correctly and have no idea what the problem is. My old Lincoln LS had a $9,000 audio/video system I put in and ran into the same kind of situation and would sit in the can leaned back stressin/thinkin for hours but I also remember how good it felt and how happy I was when I finally found the problem, so congrats.
 
Adam041 said:
Thank you, that was VERY informative and definitely makes sense with all the problems you were having. I was really feeling sorry for ya, I know how it feels to have lots of money in something and it not work correctly and have no idea what the problem is. My old Lincoln LS had a $9,000 audio/video system I put in and ran into the same kind of situation and would sit in the can leaned back stressin/thinkin for hours but I also remember how good it felt and how happy I was when I finally found the problem, so congrats.
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So, you know how I felt.. ;) This kept me up at night.. honestly.. I was sick to my stomach, thinking that i was going to have to pull the heads, replace a head gasket.. and God knows what else. I spent so much time, making sure that everything was fresh/new.. down to the last nut/bolt. And, in the end, I almost killed the thing with a tuning issue.

Travis
 
Fade 2 Black said:
That is the quick and easy way to fix it, glad it's running good for you.
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+1. Awesome to hear you're happy again with the truck :heart:

It's a dark science when it comes to all the tables that affect that lean/rich off-idle issue with anything other than the stock cam. My Sniper tuning package leaves many of those tables out, so it's nearly impossible to get rid of that lean/rich pop.

If it wasn't for emissions testing using the ODBII port only, I'd run OL 100% of the time. ODBII test requires a complete drive cycle to pass :(
 
OK - you were tuned 'open loop' to less than stoich - was there any effort to try and tune 'closed loop' to less than stoich and maintain better control of fueling?


Bird
 
Some time was spent, by several tuners.. but, this ended up being the best way for me. I have no problem with it.. The truck runs perfect, and seems to be getting decent mileage still. I drove it about 100 miles since yesterday, running to New Orleans/back. Could it be tuned in closed loop? I'm sure that it could.. if you spent a lot of time on the highway with it, in real world conditions.. but, I'd be willing to bet that it would never be perfect.

Travis
 
Trav4011 said:
Some time was spent, by several tuners.. but, this ended up being the best way for me. I have no problem with it.. The truck runs perfect, and seems to be getting decent mileage still. I drove it about 100 miles since yesterday, running to New Orleans/back. Could it be tuned in closed loop? I'm sure that it could.. if you spent a lot of time on the highway with it, in real world conditions.. but, I'd be willing to bet that it would never be perfect.

Travis
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The reason I asked about closed loop less than 14.7:1 was that with the current E10, I found that controlling to a somewhat richer mixture to take into account the ethanol blend really helped my drivability and saw no noticable decrease in mileage in the past several months - results similar to yours, but with a little more control with the O2 sensors.

Bird
 
Casey02L said:
Just keep an eye on the A/F when the weather starts changing.
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Yeah.. James and I were talking about this.. I'll be heading back this fall when it cools off, just to get the rest of the map tuned. We're going to do race gas at that time as well, and crank it up. :)

BTW, did you have some of the same issues with these cams?

Travis
 
Bird said:
The reason I asked about closed loop less than 14.7:1 was that with the current E10, I found that controlling to a somewhat richer mixture to take into account the ethanol blend really helped my drivability and saw no noticable decrease in mileage in the past several months - results similar to yours, but with a little more control with the O2 sensors.

Bird
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We figured in stoich at 14.1-14.2 for the E10 fuel, versus 14.7 for standard gasoline. James actually clued me in on this.. as I didn't even think about the stoich point changing because of 10% ethanol.

Travis
 
Trav4011 said:
We figured in stoich at 14.1-14.2 for the E10 fuel, versus 14.7 for standard gasoline. James actually clued me in on this.. as I didn't even think about the stoich point changing because of 10% ethanol.

Travis
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That's exactly what I'm running on mine right now...........:eek:ldtu:


Bird
 
Trav4011 said:
Yeah.. James and I were talking about this.. I'll be heading back this fall when it cools off, just to get the rest of the map tuned. We're going to do race gas at that time as well, and crank it up. :)

BTW, did you have some of the same issues with these cams?

Travis
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There is a good bit of tuning on the Comp 278's, but I never had those driveability issues with mine. I had some issues when I made a custom intake 4.5" intake tube with a BA2400 MAF electronics in it. We could get the MAF curve good, but there were so many other tables that needed adjusting it ended up being easier to just run it open loop.
 
Casey02L said:
There is a good bit of tuning on the Comp 278's, but I never had those driveability issues with mine. I had some issues when I made a custom intake 4.5" intake tube with a BA2400 MAF electronics in it. We could get the MAF curve good, but there were so many other tables that needed adjusting it ended up being easier to just run it open loop.
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What heads are you running?
 
I think that Dale and I are onto something, in terms of overlap, and big ported heads, combined with a big plenum and 4.5" tube, causing a lot of raw fuel to pass right through, and give false rich readings. I've also got a huge TB.. I pull 8" of vacuum at idle..

BTW, I'd like to get up with you one weekend, and check out your truck. I'm really leaning towards a TH400, and getting rid of all this electronic crap. :)

Travis
 
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