Flat spot at 4k after new 4 into 1 exhaust and PCV install

[Dr. Greenthumb]

I'm the new guy from Gainesville, Florida...thank you for letting me join your ranks!

I have a 2005 Hayabusa with 14.7k miles...pretty much bone stock until I bought the Delkevic 4 into 1 exhaust with 9" titanium xoval muffler...prior to the new exhaust the bike ran flawlessly....after the install I bought a PCV and uploaded the map recommended by dynojet (the two brothers 4 into 1 map)...from the start I have had a strange issue when in 3rd or 4th gear at a nice easy cruise speed say 45mph and at 4k rpm and it idles a little slow (just below 4k) , then back to normal, then a little slow, then back to normal...I call it a 'flat spot' for lack of a better term....at any other rpm, say 5k or higher in 4th gear it's fine...and the bike runs great at any other rpm or gear and no problems with hard acceleration either.

Well I bought the auto-tuner from dynojet thinking it just needed some adjustment to the Air Fuel ratio...long story short on the auto-tune I never could get the bike to lose the flat spot...

So I found a dynojet authorized tuner and brought him the bike...he put the bike on the dyno and showed me afterwards that he crimped the PAIR hose from the airbox when he tuned it...I guess I missed that I was to block that PAIR valve off I see Shnitz racing has a kit but he assured me he knows how to tune a bike with PAIR valve because later I asked if I still needed to block it off and the tuner says no.

Well I test ride the bike the next day and it still has the flat spot, seems like not quite so bad but this could be my imagination. Balls out it runs great and is noticeably faster. And it runs great at any RPM other than around 4k in 3rd or 4th gear around 40-45 mph.

I'm stumped at this point. I should mention she has a new OEM fuel pump...I replaced the old one when it had a high pitched whine but that was over a year ago when I still had the old pipes on and there were no issues. Also, I just replaced the battery with a new Yuasa. Not sure if it matters but I have not crimped the PAIR intake hose to the airbox nor installed the Shnitz block off modification. I guess I could crimp the PAIR hose and test ride but I can't logically see where it would make a difference as the air is not injected into the combustion chamber itself and I do not have any kind of back fire or flames shooting out the muffler like some threads I have read.

Can anyone advise me what to do? Thanks in advance, may all your rides be safe!

 

[Kiwi Rider]

That sounds to me like a 'lean surge' is what you are experiencing at 4k revs.
My '99 has a similar issue and has had it for a while now,
I have a full Akra system, 4 into 2 into 1, and a K&N A/Filter and a PC3. with a Dynojet generic Akra map loaded and installed.
I find that when my engine is still in the warm up phase, (rich fuel map) it runs fine, no surging at all anywhere in the rev range or in any gear.
But when it's at normal temp at 60 to 70mph in top gear it starts the surging again. This indicates it is caused by a fueling issue.
But it's only intermittent, comes and goes.
I had my fuel pump overhauled, tested fuel pressure, OK, removed injectors and tested them, all OK, PAIR valve is blocked off, still the same but marginally improved.
My next step is to get it Dyno tuned using the PC3 to correct the fueling at the 5 to 10% throttle position and around the 3500 to 4000rpm mark
If this does NOT correct the issue . . . I'm just gonna ignore it.
Or buy a Gen 3 when they are released.
Problem definitely solved!!
Good luck with your solution to this problem, maybe someone here can help you, I'll be watching this thread for sure.

 

[busakiller]

Do you have a picture of the dyno graph?

 

[Kiwi Rider]

Do you have a picture of the dyno graph?

Good point . . . that will reveal a lot.

 

[Dr. Greenthumb]

This is all I have...

 

[Dr. Greenthumb]

Do you have a picture of the dyno graph?

 

[Hayabusa Wannabe]

What @kiwi said. It is my understanding that one must use a loaded dyno to run the bike at cruising speed. Does this recommended tuner have such and did they comment on addressing this particular issue when working with your bike?

The throttle body vacuum balance affects cruising speed so that should have been tuned either by the dyno or previously on scheduled maintenance.

The consumer equipment like Autotune has a slow response time. It might require cruising right at the problem speed and RPM for a good amount of time in order for it to generate a correctional fuel trim. Were you able to generate the problem conditions for a good stretch of road?

Do sensors such as temp and pressure test good or were they replaced at least once in the life of this bike?

 

[c10]

No AFR reading ??

 

[Mythos]

I bought a PCV and uploaded the map recommended by dynojet

Dyno Jet maps are not known for being very good. Auto tune should fix any bad AFR if you use it correctly.
-You must have your AFR table zeroed in the 0% TP column so Autotune is unable to generate trims at 0% TP.
-Run the bike at the throttle position where it's having the issue up to and past the rpm where you have your stumble to generate trims for that TP only. You can't go back and forth on the throttle.
-Once you rev past your flat spot, cut throttle to avoid overwriting the trims Autotune just generated with new trims generated at some other TP. 0%TP, it can't generate trims if you zeroed the 0% TP column.
-Don't touch the throttle. Stop and immediately accept all trims. I usually look at the trims table to be sure I stayed at the TP I was tuning for before accepting.
-Do that about 3 times and you should be getting trims of about -1, 0 or 1 which means the target AFR in the map was achieved.

Of course, if the AFR table in the map is crap, all you are doing is tuning for a crappy AFR.

Road tuning takes practice and some study so you know what's going on a little. You need a laptop or POD-300 on the bike to view TP. I don't think the POD can be used to accept trims, a laptop is what I have used. Don't believe DJ that you can just ride the bike. It doesn't work like that even though they always said it did. It takes a more advanced system than DJ Autotune to work that effectively.

Not sure if it matters but I have not crimped the PAIR intake hose to the airbox nor installed the Shnitz block off modification. I guess I could crimp the PAIR hose and test ride but I can't logically see where it would make a difference as the air is not injected into the combustion chamber itself and I do not have any kind of back fire or flames shooting out the muffler like some threads I have read.

If the PAIR is open when you're on the throttle, it's shooting air into the exhaust which will give a false lean reading to the O2 sensor. You're reading the exhaust plus the air coming from the PAIR. If autotune was left on after the bike was dyno tuned, Autotune will try to correct for what it perceives as excess oxygen in the exhaust. My impression is that the PAIR only introduces air when you are decelerating. It's never been an issue I had to deal with because I removed or disabled the PAIR from both of my bikes as soon as I started running a 4-2-1 on each.

Did the tuner use his own AFR table or did he stick with the DJ one?

What is the target AFR at your TP/rpm flat spot? You have a tachometer, you would also need to have a TP gauge to know that for certain.

Finally, AFR tuning didn't solve the issue I always had with my other (not busa) bike. It improved it a lot but it's still there as it was when brand new. A very slight flat spot up to ~2500 rpm then it zips up to normal the whole rest of the way. Did it even with the stock exhaust like all other 08-2011 ZX-14s and I won't elaborate further since this bike is not a busa.

 

[Mythos]

It is my understanding that one must use a loaded dyno to run the bike at cruising speed.

Cruising rpm is easily duplicated with the bike stationary. Just put the bike in N and open the throttle to where the idle stabilizes. That's a cruising rpm. Same thing as if the bike were moving. There's a different cruising rpm for each TP of course. It might help to put the bike in gear and pull he clutch lever instead of sitting N. I always did it in N and it seemed to work (on my other bike which is not a busa).

It might require cruising right at the problem speed and RPM for a good amount of time in order for it to generate a correctional fuel trim.

If its an issue the guy is having cruising at 4000 rpm, Autotune should fix that in about two or three seconds of cruising. Problem is, when he rolls off the throttle, he might have now generated a new trim for that 4000rpm/x TP cell. When he reenters the 4000 rpm/x TP again, Autotune needs to re-correct.

What % fuel trim are you using? I always used +/-20% at most. I used a smaller range after I got close to hitting my target AFRs. You know, if all your trims are within -5 to 5, allowing autotune to correct by 20% could be counterproductive at that point. You'd be making it possible to overcorrect which is basic reason Autotune is inferior to some other self tuning equipment. It's slow so giving it a big range to work in allows a big margin of error to hone in on a very small target.

 

[Kiwi Rider]

Thanks for taking the time to share all that invaluable info @Mythos, I learned a few extra things that really filled in some gaps in my knowledge on the Dynojet 'autotune' application.

 

[Boosted Cycle Perf]

Cruising rpm is easily duplicated with the bike stationary. Just put the bike in N and open the throttle to where the idle stabilizes. That's a cruising rpm. Same thing as if the bike were moving. There's a different cruising rpm for each TP of course. It might help to put the bike in gear and pull he clutch lever instead of sitting N. I always did it in N and it seemed to work (on my other bike which is not a busa).


If its an issue the guy is having cruising at 4000 rpm, Autotune should fix that in about two or three seconds of cruising. Problem is, when he rolls off the throttle, he might have now generated a new trim for that 4000rpm/x TP cell. When he reenters the 4000 rpm/x TP again, Autotune needs to re-correct.

What % fuel trim are you using? I always used +/-20% at most. I used a smaller range after I got close to hitting my target AFRs. You know, if all your trims are within -5 to 5, allowing autotune to correct by 20% could be counterproductive at that point. You'd be making it possible to overcorrect which is basic reason Autotune is inferior to some other self tuning equipment. It's slow so giving it a big range to work in allows a big margin of error to hone in on a very small target.

No disrespect, but this is bad information.

If tuning part throttle was as simple as you said, I pissed away $20k on the Eddy Current load cell on my dyno, lol!

As long as the clutch switch isn’t bypassed the ecu uses a neutral map for when in neutral, or when in gear with the clutch in. The fueling and ignition is different in that map compared to what the ecu uses when in gear and going down the road.

The ecu also switches between two different fueling strategies when going down the road. From idle to 10% throttle it fuels based off of engine load that the ecu see from the map sensor. (VE) RPM vs KPA. 11% and up the ecu switches to Alpha N which is RPM vs TPS exactly like the power commander.

Depending on gearing, most bikes stay below the 11% throttle threshold at normal highway cruising. Then around 65-70 (again depending on gearing) is when you’ll finally be at or over 11% throttle.

So what does this all mean? At 11% throttle and up, the fuel map strategy and power commander lay on top of one another in sync because they’re both fueling TPS vs RPM. But below 11% the ecu is fueling based off the map sensor while the power commander is still in tps vs rpm. The map sensor is very sensitive. And the smallest fluctuations in throttle makes sizeable changes to what cell in the Ecus fuel map it’s currently using. And that’s where using auto tune can really shoot you in the foot. The auto tune is doing whatever it can to hit the target afr in the corresponding power commander cell, but underneath it is a constantly changing variable from the ecu. That’s when auto tune starts chasing its own tail and before you know it, you’ll have an area of the map that’s excessively lean or rich.

If you have Acess to an ecu editor flashing rig, there’s an option where you can change the throttle threshold. So instead of 11% I think the lowest you can set it to switch is 2%. I’ve found doing that, then tuning through the power commander that it’s really easy to get the part throttle areas buttery smooth.

If you don’t have that option then I suggest making note of what rpm your problem areas are and then set the auto tune action 200rpm blew where the problem starts. That way it’s only sampling data in the problem areas. I’d also suggest snugging down your correction trims to 6%. If working below 10% throttle, go with 2-3%. That will keep things from running away if the area is really messed up.

 

[busakiller]

To add what boosted said when using auto tune you will need a pod 300 to data log. The power commander auto tune only makes corrections in a set afr range. I believe it only auto tunes from 11.5 to 15 afr. Anything out of that range it doesn’t make any changes. How I know this? I put e85 in my bike and set that target afr that I wanted and the auto tune would make any changes to the map and bike wouldn’t run. So I added 30 to every number in the map and started the bike and that got me close to the afr i was aiming for. Do you have a fi light on by chance? Have you checked your plugs? Ecu flashed? I know a couple locals that got ecu flashed and they had similar problems like yours.

 

[Mythos]

@busakiller and @Boosted Cycle Perf , thank you both for that information. That should help a great deal when I tune my busa with my Bazzaz Z-AFM. I have your comments bookmarked, thanks!

Thanks for taking the time to share all that invaluable info @Mythos, I learned a few extra things that really filled in some gaps in my knowledge on the Dynojet 'autotune' application.

Here is everything I know about the ZX-14. Already we have found some of this (like the no load cell tuning in N) doesn't apply to the busa but it might still be worth a read.

http://zx14ninjaforum.com/messages.cfm?threadid=82EE3378-978F-4244-17A47B554179390E

If tuning part throttle was as simple as you said, I pissed away $20k on the Eddy Current load cell on my dyno, lol!

We'd all buy an Eddy Current load cell if it were affordable. The products made for the average motorcycle enthusiast is what we have to work with. I looked up a self tuning product mentioned by our member Dennis and it was about $700. It's a lot faster than a Z-AFM or Autotune so that vastly improves self tuning. It doesn't address the below 11% TP problem you mentioned however.

As long as the clutch switch isn’t bypassed the ecu uses a neutral map for when in neutral, or when in gear with the clutch in. The fueling and ignition is different in that map compared to what the ecu uses when in gear and going down the road.

So putting the bike in gear with the clutch lever pulled wouldn't put it in a gear map, the bike would still run on the the N map. You can't tune for cruising in the N map since the AFRs for Neutral are probably a lot different than they are for any gear map. The main value would be doing some learning experiments before you actually go out on the road and tune for real. The Neutral tuning would get overwritten with trims that achieve the correct AFR in the process.....or you could not accept the Neutral tuning trims or just toss the Neutral tuning map and reload the fresh base map before you start doing real road tuning.

The ecu also switches between two different fueling strategies when going down the road. From idle to 10% throttle it fuels based off of engine load that the ecu see from the map sensor. (VE) RPM vs KPA. 11% and up the ecu switches to Alpha N which is RPM vs TPS exactly like the power commander.

Autotune allows you to select to tune by Mass Air Pressure rather than AFR. That might be a solution for 11% TP and lower tuning. I have never tried that.

If you have Acess to an ecu editor flashing rig, there’s an option where you can change the throttle threshold. So instead of 11% I think the lowest you can set it to switch is 2%. I’ve found doing that, then tuning through the power commander that it’s really easy to get the part throttle areas buttery smooth.

WOW thanks for that tip! It just so happens I also have an ECU editor box laying on the shelf. I will try that.

If you don’t have that option then I suggest making note of what rpm your problem areas are and then set the auto tune action 200rpm blew where the problem starts. That way it’s only sampling data in the problem areas. I’d also suggest snugging down your correction trims to 6%. If working below 10% throttle, go with 2-3%. That will keep things from running away if the area is really messed up.

Yes, you don't need to only zero out the TP columns in the target AFR table you don't want to tune (like 0% TP column), you can zero out the entire table except for a single cell you want to tune. That might be an ideal way for a beginner to get their first learning experiences with Autotune. It can be overwhelming to keep a close eye on trims changing across the entire table or even just one column.

I've limited the range of enrichment/enleanment to +/-20% for my first tuning runs with Autotune. The base map I had was for my bike but not for my exact exhaust. I did see some trims in the teens on the first runs. Then I narrowed the trims to +/-10% and finally, I believe it was about +/-5%. As long as the numbers in the trims table are very small, there's no sense in allowing Autotune to accidentally make them big again. It seems to work by searching for a trim back and forth between lean and rich so it's not helpful to let it go farther in either direction when you're almost on the bullseye. I was afraid to ever set max enrichment/max enleanment higher than about 20%. I would NOT want to go 50% lean at high rpm while Autotune is searching for the proper correction.

The power commander auto tune only makes corrections in a set afr range. I believe it only auto tunes from 11.5 to 15 afr. Anything out of that range it doesn’t make any changes.

The system is able to detect AFRs that are out of that range because I see them on my AFR gauge at times. My Autotune is set to not intervene at startup but if it's cold out and the bike runs on fast idle after the first minute, Autotune will lean out excessively. If I'm not mistaken, I saw something like 16~17 AFR in this situation. Of course, the AFR gauge reads crazy lean on deceleration. If Autotune is not able to actually generate a trim that would cause AFRs outside of the range you mentioned, that is a wise precaution. Thay way, if you load a map that makes the bike run at extreme AFRs, it's your fault, not DJ's. I'm not aware of any reason a person would want to run at an AFR outside of the range you mentioned even if Autotune could allow that.

 

[Dr. Greenthumb]

No AFR reading ??

Here's the best pic I could take of the map

 

[Mythos]

Here's the best pic I could take of the map

That tells us the changes that have been made to the stock fueling. A dyno graph often has a line that shows the actual AFR the bike is running at across the rpm range. It would be interesting to see what the AFR is at around 4000 rpm. I would guess your throttle position is 3% or less no matter what gear you're cruising at 4000 rpm in. Autotune makes an average of the two adjacent cells when you are at a TP that is not specified in the fuel table (i.e. there is no column for 3% TP).

The only thing that looks possibly suspicious is the 4500 rpm row where you have -2 at 2% TP and then up to 10 at 5% TP. That could very well be perfect. It's not a huge swing but without seeing the AFR around 4000 rpm, that's the only thing that catches my eye. I also have some changes as drastic as that in my ZX-14 map. I don't think it's even proper to say it's "drastic" so I'm not jumping to conclusions.

You can set your PC5 to show a finer resolution. Right now, you are in 500 rpm increments. I have mine set at 250 rpm increments. I'm sure the PC5 always adjusts the map in 250 rpm increments regardless of which resolution you have selected. Go to Map Tools > Advance/Demote Map > RPM Resolution, select 250. If you want a more detailed look at the fueling changes around your flat spot.

Anyway, if you have a notion to view your AFR without buying a POD-300 or using a standalone AFR gauge, you could velcro your laptop to the fuel tank and USB up to the PC5. That will give you realtime AFR data on the screen. You could go run the bike at your flat spot and see what's up with the AFR. Clear all current trims from the trims table if you were running Autotune after the dyno tune. Shut Auto tune off. That will give you the pure AFR with the dyno tune when you ride. Be careful to also keep your eyes on the road!

 

[Mythos]

...and remember Boosted Cycle Perf's admonition about below 11% throttle. The bike is running according to Mass Air Pressure at that rpm. I do not know if AFR would necessarily be correct when the MAP fueling is correct. Seems both should be in the ballpark but I have no experience at all with MAP.

 

[Mythos]

Having MAP associated with something that is already called a fuel map is a little confusing.

 

[c10]

That tells us the changes that have been made to the stock fueling. A dyno graph often has a line that shows the actual AFR the bike is running at across the rpm range. It would be interesting to see what the AFR is at around 4000 rpm. I would guess your throttle position is 3% or less no matter what gear you're cruising at 4000 rpm in. Autotune makes an average of the two adjacent cells when you are at a TP that is not specified in the fuel table (i.e. there is no column for 3% TP).

The only thing that looks possibly suspicious is the 4500 rpm row where you have -2 at 2% TP and then up to 10 at 5% TP. That could very well be perfect. It's not a huge swing but without seeing the AFR around 4000 rpm, that's the only thing that catches my eye. I also have some changes as drastic as that in my ZX-14 map. I don't think it's even proper to say it's "drastic" so I'm not jumping to conclusions.

You can set your PC5 to show a finer resolution. Right now, you are in 500 rpm increments. I have mine set at 250 rpm increments. I'm sure the PC5 always adjusts the map in 250 rpm increments regardless of which resolution you have selected. Go to Map Tools > Advance/Demote Map > RPM Resolution, select 250. If you want a more detailed look at the fueling changes around your flat spot.

Anyway, if you have a notion to view your AFR without buying a POD-300 or using a standalone AFR gauge, you could velcro your laptop to the fuel tank and USB up to the PC5. That will give you realtime AFR data on the screen. You could go run the bike at your flat spot and see what's up with the AFR. Clear all current trims from the trims table if you were running Autotune after the dyno tune. Shut Auto tune off. That will give you the pure AFR with the dyno tune when you ride. Be careful to also keep your eyes on the road!

@4000 rpm the TP position will not be 3% in real world riding ( wind , friction , weight , drag ) typical is 12 to 20% top gear at this Rpm range .

Seeing -13 @4000 with 15% TP is negative fueling from 0 fueling stock .

 

[Mythos]

Seeing -13 @4000 with 15% TP is negative fueling from 0 fueling stock .

I believe c10 is saying that a 0 in the cell for 4000 rpm/15% TP would be stock fueling. Zero means nothing added, nothing subtracted = the value of the ECU's 4000/15% TP cell is unchanged.

Your PC5 map is subtracting 13 units of fuel at 4000 rpm / 15% TP. Looking at the adjacent cells, that doesn't look like an unusual adjustment to me. It's not possible to tell though unless we know what the AFR gauge is indicating on that cell.

You could manually edit that cell richer to see if it runs better. If you go too rich, your plugs foul. I would be reluctant to manually edit leaner because too lean is engine damage mainly at high rpm but 4000 is not really low rpm IMO. The right way to do it is have an AFR gauge.