Part throttle boost (closed loop) tuning for FI

I removed the techco Blower for 2 reasons! 1 I believe it was rushed to market and 2 The characteristics of this unit weren't to my likings. Didnt like the fact that it was creating way way to much KS activity due to the screw noise at idle and PT and WOT!, which meant adjusting the KS sensitivity thresholds past where my tuner felt comfy to stop the car from pulling timing. There were also a couple other issues I dont care to discuss because this isnt about actual blower's but tuning for F/I.

I do know about the PT Boost areas where the computer is still trying to go Stoich, I talked to my tuner about it, Like you said with the software we got and capabilitys we got that its not a easy fix, We have to trick the comp thru the software which has its own repercussions. Some tuners try and base it off Throttle position some dont. Either way theres other issues that arise as youve said. So its give and take a bit Id say. I do commend you for trying to get a discussion going about it. I think if the tuners get to dialogging about it maybe a solution will arise from it. Either way keep on keeping on!
Rome wasnt built in a day!

 

Thanks for the response, your observations are spot on with the discussion, even regarding the Knock issues, as they come into play throughout the power band. Your comments are in line with the majority I hear from others. It is a fine line, and many times things may be okay today, but not tomorrow. I think a lot of those issues arise from turning off or dumbing down adaptives.

Right now, I am running 3 degrees of retard on mine at 5 psi, and 4 degrees at 7 psi up. So far I have not logged any knock retard, and may back off by 1 degree over the psi range.

I know the sensors are sensitive, on another vehicle that was exactly the same with the exception of suspension, I was seeing random KR just cruising around. Only thing I could attribute it to was that the suspension was dropped and very harsh (bottom out on slightest irregularity).

Thanks for contributing.

 

Well, I think we now have an idea of what we should be monitoring and what to look for. Maybe an overview of your thoughts on tuning?

I assume you are speaking of the fuel adaptives? I could see where turning them off would allow tuning for a fixed value at any throttle but I guess the tradeoff is no automatic adaptation for things like altitude, DA, etc.

WOT uses fixed values and takes the long term adaptives into account (although they don't get updated in this mode) and I assume there is a value you can change to set the threshold over which the PCM goes into WOT mode. Taken to an extreme I suppose one could set that threshold very low. Like basically just off idle? something like 2K rpm or pedal position above 25% or something similar? That would allow the fuel adaptives to move at idle and the rest of the time you'd be in WOT with your boost settings.

I'm guessing the downside there would be running fat and sluggish when there is no boost or very little. Would that be so bad. How bad?

Can you give us an idea of what you would need, ideally. I have the impression that you could do this quite well with just the boost readings. Assuming the PCM is still taking care of everything else (like it handles the fuel adaptives now). The physical components like injector size, timing, etc., are known. If you divided up the boost range you could have corresponding cells for a relative fuel and timing adjustment (as well as meth on/off? Is boost level a pretty good indication of most/all the other factors? basically, if there is a good/best method, what inputs would be needed to make a relative adjustment to the N/A settings the PCM is generating or using for NA.

Then what's available/accessible in the PCM we have (excluding executable code changes). Do you think it's possible to do an acceptable FI tune strictly within the constraints of our PCM? Wouldn't have to be ideal, but safe and not much compromise on the performance end.

If you don't want to do it here maybe you could run a parallel thread in Moe's forum on how iEMS3 solves those problems? and its drawbacks and/or tradeoffs?

Apparently you've been hanging out in the wrong places... :whistle::grin:

 

Ahhhhhh Yeah! I guess so! It was :bs:, But Im home now :worthy:!

lease: carry on.

 

So if I've read all this correctly, I'm basically driving a ticking time bomb. It's just a matter of when not if. I'm running the ProCharger, 5-6psi, cooler plugs and the thermalnator spacers (not that these have any effect on keeping the motor cool just the manifold. Obviously that heat has to go somewhere. My car was dyno tuned and I was told it was VERY conservative under 11.0 AFR at WOT. Unfortunately that doesn't address the Part Throttle conditions you're discussing here. Not only am I concerned, I'm pissed.

 

It sounds like your tune could very well be conservative -- at WOT. Then it may deal with the part throttle boost to some extent as well. I don't think we've (Tim) has got to that part yet. It's also not clear how bad not dealing with it or partially dealing with it is. I'm hoping Tim will expound a bit next on the common approaches currently in use with only PCM tuning. He has outlined one or two of them already.

For example you can tune for WOT. That's because what the PCM has gets "frozen" when you go into WOT. Fuel adaptation to 14.7 etc happened while you were in cruise mode and that gets added in for WOT. In WOT you're adding adjustment from the PE table and that's tunable. So you can make your adjustments for boost in the PE table. Now the issue is part throttle and boost. That's going to be gradual from vacuum to whatever boost you get at part throttle. One method for partially dealiing with this range was dropping the threshold that puts you into WOT mode. Let's say WOT mode is triggered by pedal positions over 75% (I doubt it's that simple). If you change that to 55% then you're going to go into WOT at part throttle (over 55%). Maybe not ideal. And then at 50% you're going to be in cruise mode with some boost but a lot less boost. Not ideal there either. How bad? I don't know. You could know if you install a boost, AFR and EGT gauge (haha, see "part 1" above)

 

So here's the crazy part. Beating the piss out of the motor ensure that the fuel tables and tuning are in place to feed the motor properly. But driving around at part throttle under some boost can potential blow your motor? Crazy but probably true.

 

Exactly. But it hasn't been quantified yet and you may not be able to do that for the general case -- every car and setup is different right?.

You need adjustments for boost. You can (easily?) make those adjustments for WOT mode (open loop). You're still going to get boost at some partial throttle points (closed loop). It may not be so easy to adjust for those and it sounds like if you do there are/may be trade offs in driveability. Don't know if they're severe or the annoyance kind.

From above, if you have some way to monitor boost, afr, EGT, timing, iat... (sounds like EGT is the main one) then you would know if you have a problem or not. I think you could summarize with, if it isn't knocking and your egt is in range then you're pretty much ok?

 

So what happens if you just leave it in open loop mode. Tuning maybe more intensive but isn't closed loop just for gas mileage and emissions anyway? We know stoich doesn't produce the most power.

 

first - what is your real name MP??? i like the personal ways we do things here on the connection!! lol

second - i know the "hunting" of the a/f gauge is normal. i just use the term loosely. i noticed today that as i slowly roll into boost, the a/f drops to around 11.xx and as the boost ramped up, it began to creep upwards to a high of 14.xx. once in wot (for a small moment) the a/f went to 10.xx. my tune is a little on the "fat" side right now until my convertor issues are fixed and johan can dial in the open and closed loop tune. the car tends to "surge" a small bit as it hits boost.

last - i am running the aem boost and a/f gauge with a snow perf. stage 1 meth kit.

 

Might not be too driveable. Lets say you locked your tune into WOT mode. You'd be running 11 a/f or richer all the time with not much timing. You'd burn your cats up in a short amount of time (if you have them), you might foul your plugs?, etc. etc. If it did sort of work out then you might only run well between 11 am and 3 pm on days that it isn't raining and you'd never make it up to the snow line on your way to the ski slope in Tahoe. I'm hoping Mr. Mopar can give us a feel for that before we burn him out :flowers:

 

Why wouldn't it be very driveable? It would be about like a carb right? Just curious as I'm looking for a part trhottle boost fix like everyone else. I found one but don't know anyone using it and wanted some feed back on it. I spoke with the guy that sales it on another forum (Tim@NCTSLLC) and it seems like the answer but just wanted to hear someone elses review first. http://www.iems3.com/funkarPB_eng.html It definately looks like it will do exactly what we need but for $1300 I want to know for sure :bigwink:

 

Because the optimum settings for boost ("max") at WOT are different than the optimum settings for boost (partial) at partial throttle, which are different than the optimum settings for no boost at partial or full throttle. If you applied the WOT full boost settings all the time I don't think it would work so well.

I believe we're talking to Tim now...:grin:

 

See response in BOLD below.

 

Well, I would not say you are driving a ticking time bomb, but as both I and Trojan have mentioned, if you don't have one, get an EGT gauge on there and see how hot it is running in boost. Then you have a definitive point to work from. Water/meth does wonders, the meth adds a little octane that is generally not seen by the O2 sensors, and some cooling from the actual vaporizing of the fluid, but the water when it flashes to steam in the combustion chamber removes huge amounts of heat energy by latent heat of vaporization.

You may just need to add some precautionary measures. A lot of the discussion is related to drivability issues and what an individual is willing to put up with. I am certain there are vehicle out there with under tolerance ring end gaps, and these would be more prone to issues.

You can be running plenty of fuel and plenty of retard, and still have high combustion temps and never see a hint of knock retard. It is the heat that drives the gap closed and pops the ring land off the piston crown.

Check your temps then evaluate from there.

 

Funny you should have both these statements in the same paragraph.

I'm about to do an experiment on a stock 6.1 bottom end, heads, cam and a twin rotor. You may find it interesting Tim.


But we'll save that discussion for another thread.

Great info guys.

 

Indeed it is Tim lol

 

Well, that would be me, Tim is my name as Chris was asking for. Moe's and Sharadon are retailers, and I am primarily here to support them as they are the vendors on here, I provide technical support for them as other manufacturers will do.

But, as I have mentioned before, I am not trying to push anything in this thread, I am interested in having meaningful discussion, getting other owners first hand experiences, providing information to educate owners regardless of what or where they got their goods from.

I have always found that open honest discussion leads to an educated public, and then they are able to make a decision based on facts that is right for them. I have people call me quite often because they can't get answers else where, and I always do my best to help in anyway I can. I know of only one way to develop respect and a good image in the public eye, and in many cases, it is not making the buck where true satisfaction comes from, but rather doing what you can to help others with a common interest.

I don't know everything and don't claim to, but I know what I have seen and dealt with first hand over the years on these vehicles. I am simply trying to share these experiences.

 

Keep in mind, that boost is boost, regardless what is turning the rotating element.

Superchargers tend to be more linear in power production, closely tied to rpm since a belt is spinning them.

A turbo on the other hand, is load dependent, and you can develop boost over a much broader range.

A turbo will generally have a much wider range of potential to enter boost while still in closed loop, so it creates more of a challenge. But you have greater control, so it is a tradeoff.

Here are the simple things to keep in mind.

If you have boost present, you need additional fuel. Running boost at 14.X AFR is not okay.

If you can ease into boost and your AFR stays in the 14.X range, then your tune is not providing fuel correction for the situation.

If you don't have an EGT gauge, you have no idea how hot your combustion chamber is getting. And if you have the situation above, you really need to figure out what your temps are. Only then can you determine if you have an issue or not.

An intercooler is not going to remove as much heat from the combustion chamber as water/methanol spray.

FI is always going to result in compromises, the vehicle will drive different than a stock vehicle. The question is what is acceptable for you. Every car is unique, every owner has a different opinion of what is acceptable.

Modifying ECU parameters will result in a car that behaves differently, some better than others. See statement above.

Unless your supercharger or turbo sends shrapnel into your motor, then your supercharger or turbo did not blow your motor.

Failure to provide adequate fuel, timing control, and control of combustion chamber heat under boost WILL blow your motor. This is accomplished by your tune.

A forged engine can be blown just as easily as a stock motor. A forged engine just gives you more room to be sloppy with the tuning.

Part throttle tuning is not the same as Part throttle tuning. You must be specific, and ask the question if I go into boost while in a closed loop state of operation, is this tune going to provide me with fuel correction, or will it stay at a 14.X AFR? If it does not provide fuel correction, what can you do about it without leaving me with a bunch of drivability issues?

If you have FI, then YOU REALLY REALLY need to have vac/boost, AFR, and EGT gauges. Otherwise you have no idea what is going on and whether conditions are acceptable or not.

A "safe and conservative" tune is not going to make the most power, and one persons definition of "safe and conservative" will be different than someone else.

If your tune was developed strictly on a dyno with no time spent on the street looking for drivability issues, you need to go somewhere else.

If your vehicle does something weird, don't keep doing whatever caused it hoping it will go away, seek advice and get it fixed if it truly is an issue.

 

Well, we're moving right along .
1) we have an idea of what should be monitored and what it indicates.
2) we have some idea of what needs to be adjusted for a FI tune and how that's done presently (to some extent) within the PCM and it's constraints.

Not sure if we got quite enough depth on the effectiveness possible with the couple of approaches employed. maybe so. I believe most of the components were touched on individually but not put together as they're usually "packaged" in different approaches? I got a grip on the part where parameters A though G might be adjusted individually but not a clear picture of the common "packages" currently employed and the cumulative effect and effectiveness of each. I have the impression that not every tune uses the same set of parameters to address a given area? That there are a couple of different approaches commonly used?

I think at the end of the tutorial we're going to want to cover how these same things (which we will then have a clear understand of :stars are accomplished with a piggyback system and the pros and cons of that approach. We're going to want to know how that works.

Fair enough, but I don't think you need to worry about that so much here. Facts is facts and how it works is how it works. We have a pretty discerning group in that respect.