I have had a gremlin in my bike build since firing it up at the end of winter, and I am pulling what's left of my hair out. It will start & idle all day, yet when I apply throttle, it surges from 2500 rpm to 3000, then back again, over and over and over. When I started the bike up, I had the Guhl ECU flash, a PCV hooked up, a MPS kill box, and a MPS air shifter hooked up. The bike would rev in neutral, but blubbered and stumbled when I hit the shift button (it did shift).

I have disconnected EVERYTHING so I could just run the bike off the ECU & determine if the PCV or kill box was faulty. No good, the surging is still there, and the bike will not take any throttle. Oil pressure is great; holds 30-35 psi at idle, jumps to 60 psi at 3K rpm. Check engine light is on and stays on. Code showing 32 which is sub-throttle sensor. I have noted that this sensor does not rotate when throttle is applied. Would that cause this issue?
Things I have touched/changed:
[list]
Brock's/GUHL ECU Flash
New spark plugs 21 April (did this with the old plugs too)
Removed secondary butterfly plates and screws
Removed PAIR valve and plugged airbox hole
Installed PAIR block-off plates
By-passed and removed the charcoal canister behind the RH side fairing (tried with it hooked back up, NG)
APE cam chain tensioner
Billet oil pump cover
Removed and inspected fuel pump assembly - no debris there or in tank
Checked for kinked/blocked fuel line, tank vents, etc. - even tried running with cap open (NG)
VOODOO Sidewinder exhaust
Alien Motion LIPo battery (tried with old battery too, thinking it might be low voltage - NG)
[/list]

If anyone has any ideas why this is happening I am all ears. Never had any problems like this with any of my bikes in the past!

* Last updated by: redzx14racer on 4/23/2019 @ 4:43 AM *

Hmmmm--good questions.

Something weird about the flash? It won't rev higher than 3000 rpm? Might be a dumb suggestion but it sounds like a two step launch rev limiter coming on all the time.

I have noted that this sensor does not rotate when throttle is applied. Would that cause this issue?

Does it have to do with your gear position sensor? Maybe it's stuck on 6th gear mapping? That still doesn't explain the fact that it won't rev over 3000 rpm.

Yep sure seems ECU "related" from the changes you described. If you could borrow beg steal or buy a known good one that would tell you if it is that component. If that is not possible I would sure be talking to who ever flashed it (Brooks/Guhul not really sure what this means ...) I would also be talking to Dynojet about whatever fuel mapping you have.m Have you reviewed the PCV map and tried to compare it to a "good" one?

I notice you said "after I fired it up after winter". Dud you store it with TREATED or UNtreated fuel in the tank? If UNtreated, that may well be a component of your problems, as modern gas is good for only about a month and then starts leaving deposits in the fuel passageways.

It is rather common for a bike that has been stored with untreated fuel for weeks or months to start but to reject throttle, as both the fuel quality and the deposits interfere severely with proper fueling.

I once bought a really nice 1979 6-cylinder Honda CBX for a song after the owner stored it for a season without fuel treatment. After he installed a brand new battery, It started, but would not accept throttle. He then found out from his dealer that the only way to remove the 6 carbs for cleaning on the tightly packaged CBX was to drop the engine from the frame (it hund from the frame like our ZX engines do, but had no "working room"). He gave up and offered it for sale at a very deeply discounted price.

I bought it and visited an expert at a local shop. He told me about a chemical cleaner that I could use that was so vicious that I was warned to wear chemical handling gloves and a mask, and not let it touch any paint on the tank, and feed a specific amount of it into the tank. The start it and let it idle. I was told that if I was lucky, after a while idling, it might start ti accept throttle. Then, slowly increase the throttle usage and with time the passageways MIGHT clear out and the engine might run ok again. It took 2 tanks of gas on that bike, but it did work. :)

Jim G

Answering the posts above:
The Guhl flash is supposed to have secondaries 100% open above 3500rpm. Before I removed the secondary throttle plates the bike was dead rich when applying throttle; that's how I found out it was feeding more fuel, but the sub-throttle wasn't opening AT ALL. I wired them open to test it and it revved OK. Now it won't even do that. The servo has no visible damage. Time to call Guhl Motors.

The bike was purchased in late December and came with a nearly full tank of 91 octane. I drained it all, and put in 2 gallons of 89 octane (no ethanol) for testing. I have yet to pull the throttle bodies and take out the injectors for cleaning; if the bike didn't idle so well I'd suspect the fuel system. I think it may be the ECU, as pulling the PCV completely off didn't affect the way the bike runs. I think I will follow the advice given and seek a good used ECU to test. I'll always have a backup if that's not the issue.

Would a faulty TPS do the same thing? When I calibrated it, the zero throttle was 2.38V but 100% throttle was just 3.89V. Doesn't seem like much of a difference.

Thanks guys...

YEah have Guhl check it, more than a few ECU have become bricks in the past. You never know, Guhl may have a standard flash process and the day your's was done a new guy was at the mouse ?? shit happens

Where are you at?

* Last updated by: cruderudy on 4/23/2019 @ 5:51 PM *

Southwest WI, Crawford County - out in the sticks.

my 2013 zx 14 sat half full for 3 years.Never even started it.When I got my motorcycle license back Dec last year.I started the bike...rode it.Ran the fuel down and refilled.Nary a peep of a fueling issue.Bike ran strong as always.Gotta say...the what I call 'the myth' about gas going bad in a few weeks or months is just that...a myth..IMO.Saw a guy on youtube had a bike that sat unstarted for over 10 years.He decided to get it ready to sell.He thumbed the starter(this was a video that he did for this specially).It fired right up after about 5-6 cranks.Ran fine.

Yeah, it's not the fuel. What's in the bike is less than a month old. This has GOT to be an ECU issue, nothing else makes sense. Just sent a message to Brock's about my $400 flash; let's see if they stand behind what they sell.

I wired them open to test it and it revved OK. Now it won't even do that. The servo has no visible damage.

Would a faulty TPS do the same thing? When I calibrated it, the zero throttle was 2.38V but 100% throttle was just 3.89V. Doesn't seem like much of a difference.

Thanks...low voltage per the manual is ~0.75V, high voltage level is ~3.9. I match the high end perfectly, but at zero throttle I am way high @ 2.38V, which may be adding a lot of fuel down low in the rev range. I am looking for a spare TPS to install and check to see if it reads any different. Unfortunately, they aren't GIVING them away. I did find a used stock ECU on a ZX14 forum and have it coming my way. Really appreciate the help, gents!

Now you're getting somewhere!

Well, gents,
I don't believe it....I replaced the primary TPS 1st, just to sneak up on the issue and see if the simplest fix made a difference, and knowing the idle voltage was reading way high. I kept the Brock's/Guhl-flashed ECU in place to see if I needed to return it to them for diagnosis. The bike not only takes throttle, but it revs like a mofo! I take it up to 4500rpm and crack the throttle quickly in 1st gear, and it pops right up to ~9K. Have any of you ever experienced problems with the TPS and had these types of troubles before? It's hard for me to believe that this is the only issue, but I literally changed NOTHING else.

Thanks again for your advice and support! I also now have a spare ECU just in case I ever run into trouble with the one in there now. Spares are GOOD... Jim

Wow, a TPS failure?? How old is the bike, and how many miles on it?

And, I wonder what could cause a TPS to go bad. Corrosion on its terminals if stored in a humid climate? Water entry into the terminals? I haven't run into a failed TPS before.

Jim G

Never heard of that one. Always possible. I suppose that's why the book recommends testing them.

Did you ever figure out why the subs weren't opening? I thought they were always supposed to be open in Neutral when the engine was running.

Rook: WHY would the secondaries be open at idle in neutral??? The engine certainly does not need the extra air at idle in neutral! That would really puzzle me if true.

Jim G

My 2013 model year bike was purchased at the end of December 2018 with 8216 miles; it now has a few more miles on it. Never an indication that anything was wrong with it until this issue manifested itself. In all the reading I have done I have never heard of one going bad. As I stated earlier the ONLY indication that something might be amiss were the voltage readings. I bought a TPS off a wrecked bike and now all SEEMS to be OK. I have yet to put the PCV back on it and hook the MPS kill box back up; I am almost afraid to do that!

I still have error code 32 showing for the secondary TPS, and the check engine light stays on. The secondary throttle position sensor does not function at all, in any gear, or any throttle position, so I know it is bad as well. I hate to run my bike with the check engine light on, as it might mask another problem, but with flies out it shouldn't affect the way the bike runs at all. I'll have to think more about this one...

Well now I'm curious about it throwing a code.Did it?It should have,yes?If it did,it's supposed to be stored in there.Unless the ecu deletes stuff .IDK.

* Last updated by: Grn14 on 4/28/2019 @ 7:58 PM *

GRN14: The only code it threw was for the SECONDARY TPS. I replaced the PRIMARY TPS as it would actually affect the amount of fuel at various throttle positions, and read way high on voltage at zero throttle. I still need to calibrate it; I just installed in roughly the same orientation (rotation) as the original and fired the engine to test it.

BTW: something that just came to mind; I had almost forgotten about it. I stated earlier I bought the bike early in December; now I am wondering if it was stored in a barn or something. What I had neglected to mention was the half-pound of mouse nest that was removed from on top of the engine. Little buggers had chewed into the coil wire harness in a few spots, down to bare wires. No breaks, and I repaired it, but now I wonder what else they may have chewed on. I have inspected everything I can see with a powerful flashlight and my fingers, but matbe there is damage somewhere else.. Crazy tight above and behind the engine.

* Last updated by: redzx14racer on 4/28/2019 @ 8:14 PM *

Rook: WHY would the secondaries be open at idle in neutral??? The engine certainly does not need the extra air at idle in neutral! That would really puzzle me if true.
Jim G

red, did you loosen the secondary TPS? I heard those are apt to get out of adjustment if they move even a tiny bit. Sounds like you are aware of that.

also, could be your solenoid gear is stripped. Wiring it and starting the bike would cause the gears to jump teeth. You might even hear the teeth grinding as the flies open. If the solenoid motor turns but the flies don't, that would seem to be a likely reason you are getting a secondary TPS code.

Rook: I have removed and inspected the secondary TPS, and watched it & listened to it with the bike running. I hear no grinding noises, etc. coming from it, but can't figure out how to disassemble it for inspection. Have you ever had one apart? If so, how did you access the internals? I don't think I damaged it by wiring the flies open, as it was disconnected from the TB when I did that, to avoid just that issue. I just put a rubber cap over the end of the TB shaft so it wouldn't suck air. It is all re-assembled now, as I took the secondary throttle plates out altogether on the advice of others. I suppose it is the cause of the CE light, since it is likely a bad sensor. Thanks

Rook: I have removed and inspected the secondary TPS, and watched it & listened to it with the bike running. I hear no grinding noises, etc. coming from it, but can't figure out how to disassemble it for inspection. Have you ever had one apart? If so, how did you access the internals?

I have never removed the secondary solenoid but expect to do that some day. I recall it was a black plastic housing that looked as though it could be unbolted from it's mount on the T-body assembly.

The picture I have at step 8 here is the best secondary flies solenoid pic I can remember taking.

http://www.zx14ninjaforum.com/messages.cfm?threadid=62F83816-D56B-84E2-14E2834C9FFA4D60

As far as disassembling the solenoid, IDK if that is even possible. You probably just replace the whole deal if it goes bad.

There might be some way to trick the ECU into thinking the flies are working and clear the code.

Are you sure the lead connector is plugged into the T-bodies right around the corner from the TPSs?

Step 7 here:

http://zx14ninjaforum.com/messages.cfm?threadid=21729D08-1B78-59F6-024CE7E1806DDB0C

Rook: I checked that connection; it is secure. I have been reading up on this assembly. It seems that if it goes bad, you need to buy an entire throttle body assembly. Hard to believe, but no listing for parts anywhere that I can find.
Looks like I ride with a warning light; I am not electronically-gifted enough to try to trick the ECU into anything.

No Meter: First gen I could move the subthrottle sensor either way until the code turned off. Made a slight move then waited a few seconds or more until I saw no change. Moved it ever so slightly again, waited again, boom, light out. Second gen (w/02) and without meter, I would have to wait for 14 or more key cycles until the light goes out. Only your keyfob knows for sure.

With Meter: Set sensor to said range @ 0 throttle opening. Do not move painted screw settings on the opposite side of the throttle body-thru-shafts.
Throttle - Use grip to open throttle.
Subthrottle - Use your fingers to open the sub-shaft on left side of throttle body.

Gen1 0~WOT volts:
TPS - .02 ~ 4.8v
Sub - .02 ~ 4.8v

Gen2/3 0~WOT volts:
TPS - 0.63 ~ 3.96v
SUB - 0.42 ~ 4.34v

HUB: Thank you for the diagnostic info and tips! I am traveling on business this week, but will run these tests on Friday when I get back home and let you all know what I find. Appreciate your help!