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

[Dr. Greenthumb]

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!

Thank you...I followed your instructions and expanded the table to 250 RPM resolution.

The tuner had auto tune turned off and I removed the unit when I got the bike home so it's running 100% on the tuner's map. I did specifically mention to the guy the effects I was experiencing and he seemed to think he cleared it up. I'll have to pay close attention now to if this only happens when bike is warm...but I'm certain when warm the flat spot is there and remains there if I ride around the RPM I mentioned it seems constant...

 

[Mythos]

OK, now you have to do two separate screenshots to show your entire map but you see more detail. I prefer the 250 rpm increments.

Without being a professional tuner, it's hard to say much by looking at the numbers on your PC5 map but they look pretty consistent. I guess if I saw a huge change from one cell to the next, I would consider that a possible problem. Of course, The Target AFR table dictates the adjustments on the Fuel Table and maps normally have a few AFR numbers throughout the Target AFR table. If the target AFR changes from one cell to the next, I'd expect it would be more likely that you'd see a sudden change in the fuel table too.

Have a look at your Target AFR table and see what AFRs are in the 4000 rpm row. There might be a clue there. You still have to run with an AFR gauge to know for sure you are hitting your target AFR with the fueling adjustment you currently have in your fuel table.

We were speaking about throttle position earlier too. c10 rides a lot more consistantly throughout the year than I do so he would have a better idea of what TP you are at at 4000 rpm in sixth gear. Seems to me 15% is a tad high though. I still think you might be in the 11% TP zone where Boosted Cycle Perf said the MAP sensor is determining fueling. Now that I think about it, it seems possible you are right on the edge of exiting the MAP fueling zone and entering the TP/rpm dictated zone. That might have something to do with your flat spot right there, the ECU is unsure whether to determine fueling based on MAP or TP/rpm. I would think all stock bikes would have that issue too though.

I When I cruised my ZX-14 at 3000 rpm I was only at about 6~7% TP. I have a +4 rear sprocket on that bike but I don't think that would make a huge difference in TP cruising at 3000 rpm. If the busa is running at 4000 rpm in 6th gear, I think the TP is less than 15%. I remember tuning my 20% TP column and the bike was up into the triple digits before it settled into a steady cruise. It took some very long straight stretches to get those trims. Many seconds at high speed, super risky.

Here I am at 3000 rpm or just a little less according to the PC5 tachometer on the laptop. Note the TP% gauge is indicating between 6 and 7. This is a ZX-14 now! It's not a busa but it's all I got to show for an example right now.

 

[Mythos]

You mentioned heat. Does the bike run better cold? Could be the throttle sensor needs calibration. You can calibrate the TPS with the PC5. Your tuner probably already did before tuning. The throttle sensor is affected by the temperature of the bike. I would think you would experience problems at the very bottom of the TPS range or the very top if it were out of calibration. ---but that might be it, if you are running on MAP and your TPS is not calibrated to read the throttle position right at the point where the rpm/TP% fueling come into effect, you'd have a flat spot.

You can calibrate your TPS with the PC5 software. You can at least check your 0% TP without needing to calibrate, you just run the engine in N at idle speed and view the indicated voltage of the TPS. If you want to calibrate 100% throttle, you need to quickly zing the throttle to the stop with the engine running in N. I did it. The bike didn't blow up! I'd rather not do that any more often than necessary though.

Directions for throttle position sensor calibration are here, step 27.

http://zx14ninjaforum.com/messages.cfm?threadid=129B662B-CA75-AB2F-EB394CD496563332

YOU WILL NEED TO FIND THE SPECCED VOLTAGE RANGE FOR THE HAYABUSA TPS, the voltage specced in my tutorial is not for the Hayabusa. I'm sure the voltage spec is in the Hayabusa service manual under "TPS, testing." Maybe I will get around to making a busa specific tutorial on this order but for now, the ZX-14 tutorial is all I have. The process for TPS calibration should be the same other than the voltage.

 

[Dr. Greenthumb]

You mentioned heat. Does the bike run better cold? Could be the throttle sensor needs calibration. You can calibrate the TPS with the PC5. Your tuner probably already did before tuning. The throttle sensor is affected by the temperature of the bike. I would think you would experience problems at the very bottom of the TPS range or the very top if it were out of calibration. ---but that might be it, if you are running on MAP and your TPS is not calibrated to read the throttle position right at the point where the rpm/TP% fueling come into effect, you'd have a flat spot.

You can calibrate your TPS with the PC5 software. You can at least check your 0% TP without needing to calibrate, you just run the engine in N at idle speed and view the indicated voltage of the TPS. If you want to calibrate 100% throttle, you need to quickly zing the throttle to the stop with the engine running in N. I did it. The bike didn't blow up! I'd rather not do that any more often than necessary though.

Directions for throttle position sensor calibration are here, step 27.

http://zx14ninjaforum.com/messages.cfm?threadid=129B662B-CA75-AB2F-EB394CD496563332

YOU WILL NEED TO FIND THE SPECCED VOLTAGE RANGE FOR THE HAYABUSA TPS, the voltage specced in my tutorial is not for the Hayabusa. I'm sure the voltage spec is in the Hayabusa service manual under "TPS, testing." Maybe I will get around to making a busa specific tutorial on this order but for now, the ZX-14 tutorial is all I have. The process for TPS calibration should be the same other than the voltage.

Excellent...I have a manual that goes into detail on the TPS to check voltage and how to get a read out from the digital part of the instrument cluster that will tell me if the TPS is centered on the throttle bodies or needs to be rotated...maybe I should check that first, I never have on my Busa but did it once on my step-sons 2003 and it was out of adjustment. Then I'll check the TPS thru the PCV and see what I find.

I still want to plug or crimp that PAIR hose...the tuner showed me where he crimped it to do the tune...is this going to be OK?

About the temp: the thing was I picked my bike up after the tune just after dark here in Central, Florida about 2 weeks ago it was 50 degrees riding home and I never noticed any problems. Also, I rode a short distance from home to gas up the other day and after cranking up and riding out with a warm bike I noticed the problem immediately. I'll be more observant of that next test ride. When cold I'll hold it in 4th gear at 4k and see what happens.

I can also test the MAP sensor (and check condition of any vacuum hoses) and there is a temp sensor that sends info to the ECU that I can check also so I have my work cut out for me tomorrow...

Hoping to get it right before Bike Week...I ride to Daytona every year.

Thanks for your time mate!

 

[Dopey]

Excellent...I have a manual that goes into detail on the TPS to check voltage and how to get a read out from the digital part of the instrument cluster that will tell me if the TPS is centered on the throttle bodies or needs to be rotated...maybe I should check that first, I never have on my Busa but did it once on my step-sons 2003 and it was out of adjustment. Then I'll check the TPS thru the PCV and see what I find.

I still want to plug or crimp that PAIR hose...the tuner showed me where he crimped it to do the tune...is this going to be OK?

About the temp: the thing was I picked my bike up after the tune just after dark here in Central, Florida about 2 weeks ago it was 50 degrees riding home and I never noticed any problems. Also, I rode a short distance from home to gas up the other day and after cranking up and riding out with a warm bike I noticed the problem immediately. I'll be more observant of that next test ride. When cold I'll hold it in 4th gear at 4k and see what happens.

I can also test the MAP sensor (and check condition of any vacuum hoses) and there is a temp sensor that sends info to the ECU that I can check also so I have my work cut out for me tomorrow...

Hoping to get it right before Bike Week...I ride to Daytona every year.

Thanks for your time mate!

Don't crimp the house instead search for "marble mod " and do that or you can use a vacuum plug and put on the air box fitting and then the hose over it, when u order a brocks exhaust he seems you the vacuum plug to block it off.

 

[Mythos]

Excellent...I have a manual that goes into detail on the TPS to check voltage and how to get a read out from the digital part of the instrument cluster that will tell me if the TPS is centered on the throttle bodies or needs to be rotated.

You did it before so you have more expertise there than me. I've been told to never touch the adjuster screws on the TPSs. I've hear dof a guy doing it and carefully marking the position it was at before the adjustment. I'd try the TPS calibration through the PC5 before moving the sensor. It could be the sensor is worn out too. It might not register the whole range of volts it's supposed to any more.

I still want to plug or crimp that PAIR hose...the tuner showed me where he crimped it to do the tune...is this going to be OK?

I left the PAIR in and only plugged my clean air hose on my ZX-14 (sorry about the cross over info again) and it ran just fine. All it does is cut off the air to the exhaust so the unspent fuel burns out less. I plugged the hose with a dowel I tapered down a bit and I hose clamped it. I used a plastic end cap sanded down a bit to plug the air box hole. On my busa, I never left the PAIR on after switching to the aftermarket exhaust. I put on blockoff plates and used a 5/8" plastic chair leg tip I picked up at a hardware store to cap the clean air port from the air box. The marble might be hard to get out if you ever need to do that. I'd go with the dowel and hose clamp and chair leg tip.

About the temp: the thing was I picked my bike up after the tune just after dark here in Central, Florida about 2 weeks ago it was 50 degrees riding home and I never noticed any problems.

My ZX-14 has it's flat spot issue at 1~2% throttle at very low rpm. It's always done it. It's always been not too bad with a cool engine but it's very noticeable after the engine warms up. I suspect it's a TPS problem even though I have calibrated it.

I can also test the MAP sensor (and check condition of any vacuum hoses) and there is a temp sensor that sends info to the ECU that I can check also so I have my work cut out for me tomorrow...

That sounds like a couple week's worth of work to me if I'm motivated. ...at least in winter.

 

[Berlin Germany]

@Kiwi Rider
@Dr. Greenthumb
@ all others

mornin guys (it is 08.18 am here in berlin )

if i understood the starters (and kiwi´s) problem that there is a "constant - driving - jerking"

for that case i wrote together all possible issues who could cause this jerking ( we call this in german "KFR")
see my sites :
possibility 1.
possibility 2.
possibility 3.
possibility 4.
possibility 5.
possibility 6.

hope it can help.

 

[Mythos]

Could be fuel lines but I would expect the problem to get worse as the engine rpm increased.

The fuel pump was recently replaced

Number 6 sounds like a possibility.

Any of these might be tested by opening throttle during the flat spot. Does the flat spot go away immediately? If so, that seems throttle or fuel delivery related.

I'm still intrigued with the possibility that it might be the ECU trying to switch from MAP fueling to rpm/TP fueling at and below 11% TP.

Greenthumb, a zero map is the same as removing the PC5. Have you tried loading a zeroed out map to the PC5 and running the bike on stock fueling? If the same thing happens at 4000 rpm, I would conclude the fuel mapping is not issue.

 

[Dr. Greenthumb]

Could be fuel lines but I would expect the problem to get worse as the engine rpm increased.

The fuel pump was recently replaced

Number 6 sounds like a possibility.

Any of these might be tested by opening throttle during the flat spot. Does the flat spot go away immediately? If so, that seems throttle or fuel delivery related.

I'm still intrigued with the possibility that it might be the ECU trying to switch from MAP fueling to rpm/TP fueling at and below 11% TP.

Greenthumb, a zero map is the same as removing the PC5. Have you tried loading a zeroed out map to the PC5 and running the bike on stock fueling? If the same thing happens at 4000 rpm, I would conclude the fuel mapping is not issue.

I did replace the main snap on/off fuel line from tank with OEM.
I think logic dictates I load the zero map and test run...I initially felt like there was a conflict between ECM and PCV at that 10-11% throttle once I heard about the MAP sensor providing data below a certain throttle %...that comes from how it rides when it has the issue...it's not a jerky thing...it's much more subtle, as if one computer is trying to correct the other going back and forth. If you roll on throttle it disappears...never felt it at 5k or above OR below maybe 3.5k RPM.

I should say reload the zero map cos the place I bought the PCV from was supposed to load the dynojet recommended map but when I logged onto PCV with laptop it was all zeros. If memory serves it's had the flat spot since the first ride after all the installs. But I will re-test and confirm.

Decent weather today here in Florida I'll load the zero map and check it out...

Can't thank all of you enough...having other insight is key in life.

 

[Dr. Greenthumb]

Back from a test ride after installing the dynojet PCV zero map.

Before I made it as far as the gas station (5 minutes away) it was exhibiting the symptoms...

So I was in 2nd gear at 4k RPM and about 40mph...it might be even worse with zero map because when I brought it up to 5k it was doing it as well. Not with the new map from dyno tuner....at 5k it rides fine, at least thus far.

I still want to plug the PAIR intake and yes I won't rig it I will do it proper...I'll test ride again after that BUT also I need to examine the fuel system and those sensors that affect the below 10% throttle...MAP sensor, Air Temp sensor and TPS position...

It doesn't sound like a lack of fuel or fuel pressure as the bike runs fantastic when I open it up and rip the throttle back. If the bike was lacking fuel/pressure wouldn't the symptoms become worse when the need for fuel becomes greater?

Should I disconnect the PCV altogether and do a short test run with just the ECM at some point to be sure the PCV is not somehow defective?

Also, and forgive me I've never had a PCV before so I'm trying to learn fast, I guess the pics I took previously were not from the dyno tuner guy but a dynojet map perhaps...anyways long story short I brought up on screen and took pic of the tuner's MAP he has the date and his name on this one so I'm sure it's the one...my apologies.

Not sure if I'll get to break out the voltmeter and start testing sensors today but when I do I'll post results.

 

[Mythos]

If the bike was lacking fuel/pressure wouldn't the symptoms become worse when the need for fuel becomes greater?

Should I disconnect the PCV altogether and do a short test run with just the ECM at some point to be sure the PCV is not somehow defective?

I was thinking a fuel delivery problem would get worse as the demand for fuel increased. It might clear up with increased demand too though. If the fuel delivery system responds to a requirement for larger amounts of fuel, the increased flow might burst past obstructions that don't allow enough fuel at a lower rpm. If the rpm is really low, the obstruction might not reduce the flow enough to cause a problem. That's a guess on how a fuel delivery problem might only be present in a small range of the power band.

You could disconnect the PC5 altogether to be 100% sure it's not causing the problem but the zero map should be the same as running without the PC5. The only problems I have heard with PC5s is a loose ground. I'm sure the bike doesn't run at all when that is the problem.

If the bike had the flat spot at 4k and 5k rpm on the zero map, and only at 4k with the dyno tuned map, it sounds as if the tuner might have only partially addressed the flat spot.

If you were running in second gear at 4000 rpm you probably were at a very small TP. You would have been under 11% throttle for sure.

I don't know if this is a common problem with Gen1s. It could be the particular exhaust you have that's causing the problem. There was no flat spot with the OEM exhaust.

 

[SSGT_B]

Disconnect pcv and ride. See if you can reproduce problem

 

[Bumblebee]

..

Disconnect pcv and ride. See if you can reproduce problem

..and try not to drip any pie filling into the contacts...you will have a hard time licking it all out...

 

[Dr. Greenthumb]

Disconnect pcv and ride. See if you can reproduce problem

@Mythos

Man I'm so glad I did....disconnected PCV from bike's harness and ran on just the ECM....could not replicate the problem....got back home and reconnected the PCV and test ride the bike...bam! There is the stumble/flat spot.

So no matter what MAP I use I have a stumble/flat spot in 2nd gear around 4k RPM at 40mph....

I guess I'm going to contact Dynojet...

ALSO I should mention: the seller of the PCV I found on Amazon, I bought it directly from them and I wait a week and no PCV in mail. I email the guy he tells me the unit on the shelf tested defective and do I want to wait for another unit and I said yes. At the time I thought it was B.S. excuse because he went to shelf and unit was missing...so tell customer it's bad they have to wait another week for another unit to be shipped in.

Now I'm wondering if he shipped me the defective unit.

I'm going to stay positive about dynojet and hope they will replace the unit with a good one...

Oh yes I wanted to ask anyone who might know...can I run without the PCV and with no tune for the new pipes or am I going to burn up a piston?

 

[Dr. Greenthumb]

..

..and try not to drip any pie filling into the contacts...you will have a hard time licking it all out...

I spilled beer on it but yes, was able to lick it all up.

 

[SSGT_B]

It will run fine without it.

 

[Bumblebee]

It will run fine without it.

The beer or the pie filling?

 

[SSGT_B]

Only with pie.... but I mean it is beer so

 

[Mythos]

Oh yes I wanted to ask anyone who might know...can I run without the PCV and with no tune for the new pipes or am I going to burn up a piston?

If you have to ride it, I would stay away from high revs. That's what I've heard about running an aftermarket exhaust with fuel corrections. It's not something you hear about people doing every day so I can't say it's perfectly safe but I heard one person say he ran a full system without a PC5 for quite a while without having a problem. Looking at you map between the 2500 to 3000 rpm range, you will be running 20 units of fuel lean in some cells without the PC5. I don't know how much hotter that will burn compared to running with the map.

 

[Dr. Greenthumb]

If you have to ride it, I would stay away from high revs. That's what I've heard about running an aftermarket exhaust with fuel corrections. It's not something you hear about people doing every day so I can't say it's perfectly safe but I heard one person say he ran a full system without a PC5 for quite a while without having a problem. Looking at you map between the 2500 to 3000 rpm range, you will be running 20 units of fuel lean in some cells without the PC5. I don't know how much hotter that will burn compared to running with the map.

I'm going to park it...I just did a short ride long enough to feel the flat spot on the zero map...taking no chances.
Also I talked to Chris from Dynojet today and we double checked software settings to be sure something wasn't out of place but to no avail...everything looked good. I just sent him all my info so he can issue a recall and send another unit. I'll update this thread when I have the replacement installed and take a test ride.