Stuttering came back.....

[OB_NumbNuts]

Okay. Did about 400 miles today, some high speed stuff, 160mph indicated, after slowing down after one quickie, the stuttering came back. Stayed till I got home. Tried letting her cool down and ride again, still there. Lifted tank, checked voltages on everyting, all okay and in spec. blew through vaccuum line to regulator and IAPS. conected tube to APS and blew and sucked a bit. DIDN'T TOUCH SPARK PLUGS (hell, didn't even take air box off)

stuttering has nearly gone, but not quite.

So tomorrow I have an idea that a spark plug may have rattled loose, lowering compression in one / 2 cylinders (before they were not torqued right down)

Any ideas JC??

could one of the pressure sensors be blocked?? or sticking?? If I take the vaccuum line off the IAPS, bike stalls (supposed to) so it is operating.

If i suck on a tube attached to the APS revs increase and bike starts to run smoother.

Increasing TPS makes no difference (tried it in 0.05V increments up till when the revs die off)

Suggestions greatly appreciated. plug gap now 30 thou inch.

Thanks

Nuts

 

[AQUADIOSMED]

are you running stock??

If you have a pc-2 you may need to alter the setting "just" off idle";

check throttle bodies, may have build up around the buterflies, etc.;

get some "redline" injector cleaner, follow the directions, this seems to help;

good luck

 

[OB_NumbNuts]

Totally stock

No PCII

throttle bodies clean
Valve backs clean
Used Redline for 3 months. didn't help. stopped using it. Now use Winn's. Is better. ....it has to be something to do with what I played with today.

As Gasabusa said, the only sensor that affects light load under 4krpm running is the IAPS sensor......this must take a reading relative to the AP sensor...so one of these must be partially blocked or loose wire which breaks contact when hot, but then wouldn't this show a fault in LCD???

ponderous Nuts

 

[OB_bruce]

Acording to bigabusa or richard from TTs you will not be able to get rid of this stutter but he does suggest checking the fuel filters for deposits.
I recal having a big problem just after the 4000 mile service when it would hold back and then take off like a scalded cat took the dealer a very long time to sort out he was convinced that the bike was supposed to be like that I kept pointing out that I had riden it for over 4000 miles and therefore should be in a better position to judge.
They replaced the complete butterfly including fuel pump assy.rebalanced them then replaced the plugs and it ran fine all my bits were put on the demo bike this then ran fine turned out to be a fouled plug Suzuki say replace at 8000 miles this seems to be open to debate as mine went pear shaped after the 4000 mile service I replaced them with Splitfire plugs which seem to be working just fine.

 

[OB_Sonic Boom]

'ey Nuts, those Brit busas have the same emissions crap as we do in CA? Just wondering...

 

[OB_DaveD]

NN

Probably irrelevant, but you might like to know that G-Force, makers of my race cans, say that the CATs on the 'busas are of variable density from bike to bike, and this explains why some bikes have the stutter, and others don't.

If we accept that the reason is initial on-throttle lean-ness, as is popularly believed, then the worst "stutterers" probably have the least restrictive CATs.

This is probably why your bike and mine are so much faster than everone elses! HA HA HA

(this could start a riot!!!!)

Mine didn't stutter stock, but did when I added the cans. Some careful tweaking with a Yosh box has virtually eradicated it.

DD

 

[OB_bruce]

DaveD with all due respect that is a pile off bull **** as my bike still suffers from the stuter and I have had two differant original pipes and I am now running a Akro.full system which has no Cat at no time has the stuter ever gone away for any length of time like Numb Nuts has noticed it seams to come and go When the bike comes back from servicing it runs fine I have just fitted all long stacks in my air box and during the process fiddled around with the routing of the pipes and blew down them to check for blockages etc.. suprisingly the bike now runs fine with no sign of a stuter but I dont hold out much hope for it not coming back as I have been there seen that and got the T shirt.
On a differant point do your riders seats rub on the tank mine has since new and was getting on my nerves so I moaned at the dealer he bless his cotton socks replaced it with a YK2 one which fits loads better and it is a more comfy seat differant foam density or somthing but well worth upgrading to.

[This message has been edited by bruce (edited 13 August 2000).]

 

[OB_NumbNuts]

Bruce.

whip yer plugs out, gap them to 31 thou inch, reinstall and make sure they are torqued down hard!!

Re: rubbing seat. I have a Baglux tank harness. Problem eliminated (previous tank did rub, got some black 'tabs 'N spots' put 2 of those where it rubbed (tank replaced under waranty, different issue)

Re: cat and performance, I agree with Bruce, DaveD, bull!!

Problem,I think is either poor fueling, caused by blockage, or faulty sensor, or, as in my case, incorrectly gapped plugs and not tightened properly. Worked for me!!

Nuts

 

[OB_NumbNuts]

Sonic

No. We have the PAIR and the stock pipe cat. but thats it.

Bruce

I managed to get rid of it the other day. something I fiddled with under the tank sorted it out. Could be IAPS, APS, fuel Regulator, Vaccuum hoses, plugs. becasuse thats all I played with.
Was good for 2 days (800 miles). Came back yesterday. half sorted it last night,by blowing through Vaccuum lines, sucking and blowing IAP and AP sensors.
Stuttering not that bad, but still there. Gonna gap plugs at 31 thou inch today. see if that makes any difference.

Nuts

 

[OB_NumbNuts]

well, gapped plugs to 31thou inch

(2 were not correct torque, about 1/4 turn out...I torqued all properly (plus a bit more day before.........)

Put all back together

runs fine again. Must be the plugs!!

after I got an aerosol can of carb cleaner, bike running fast idle, squirted about 5 seconds in each TB and let it work its way throug then did next one. Did this 3 times. Got a bolt of suitable size, screwed into hole for PAIR connection. Put tube back on.

Runs like a dream. No backfire of popping, no surging.

Not quite as quick of the button, well doesn't feel quite as quick, put I have, over the past 3 days increased plug gap from 28thou th 31 thou so difference should be noticable. Not running any hotter, Fuel consumptions appears to be similar, if not better than before.

Will keep you all updated.

Nuts

 

[OB_DangerMouse]

Numbs UK bike have Cat's too!

 

[OB_NumbNuts]

Yep, where the pipes all meet and branch into 2 under the middle of bike, going rusty already, why do you say this.......

 

[OB_bruce]

Numb Nuts
Bought some new plugs standard NGk Rs and gapped them 0.8mm then went to remove old plugs plug one nice and tight plug two only hand tight plug three also hand tight plug four nice and tight could this be the stumble just loose plugs I tightened the new ones up to correct torque of 8 lbs/ft seems a little slack to me but what the hell removed even more usless junk from under the tank vacume pipes one way valve vacume accumulator and mitsibushi valve as these are no longer doing anything.
Runs lovely now but no wheelies in first and second are you running with the pink wire connected because mine only lifts the front wheel in third on the throttle think Suzuki have tamed first and second gear maps and let you have the lot in third gear onwards I could be wrong but seams to make sence to me.
Not bad though 167.2 BHP with two loose plugs.

 

[OB_NumbNuts]

I did mine up tight by feel. Bollocks to the torque setting if they keep coming loose.

Has the stuttering gone??

Mine wheelies end of first and end of second. You probably have another prob.....pink wire conected. (yes DaveP, I re soldered it back. Makes no difference (IMHO!!!)

checked your fuel filters?? there are 1 in tank, 1 in each injector, and 3 in pump (or is it 4 can't remember of hand, little one under regulator, big paper one, one right behind pump, is there another behind paper filter??????? will check L8R)

What other mods do you have??

Nuts

 

[OB_bruce]

Keep p*****g *ff l**k**g a* *h**e f*el f*l*er* *eem* l*ke a wh*le l** *f w*rk pry**g *ff hea* ****la**r* a*d hav**g ** pl*g *he f*el *a*k d*** k**w why **z*k* d*d *** p** a **e way valve l*ke my *ld *a*l Kawa*ak* GPZ1100B1 well ahead *f *he re** whe* *ha* *ame ***.
M*d* well ** da*e *hey ***l*de **mple*e rem*val *f PA*R *y**em rem*val *f a*rflap a*d a*r b*x *** ** ma**h f*l*er ***ake BM* f*l*er a*d all *he a*r flap *pera***g *y**em ha* **w bee* rem*ved *he *bl*ga**ry Akr*p*v** f*ll *y**em a*d * am ab*** ** **ar* a we*gh* *av**g ***r*e f*r *he b*ke mak**g *h**g* l*ke wheel *pa*er* *** *f ally. fa*r**g bra*ke** e**... re*** y** ***ld *have *ff a fa*r few p***d* d***g *h** m*gh* **pr*ve ha*dl**g b** w*ll *mpr*ve 1/4 m*le **me*.
al** *h**k**g ab*** a* ele**r** m***r**ed gear *h*f*er, *f *he*e pr*ve ** be a* fa** a* a* a*r *h*f*er *ha* **.

[This message has been edited by bruce (edited 17 August 2000).]

 

[OB_NumbNuts]

filters are actually quite easy!!
just remove the pump and mounting bracket as a whole (remove injector rail first) and it all comes out real easy.

If you do pull fuel lines off, just make sure you have the spring pushed well back and have a good grip of the pipe. Squeeze pipe to stop flow with left hand, put cap on tank with right. Easy.

Nuts

 

[OB_DaveD]

At least it was only second hand Bull!!

DD

 

[OB_bruce]

Sorry dave but I knew this could not be the reason for the low speed stumble or stutter that has been coming and going on my machine from new.
The dealer is allways blaming my mods such as the air box and filter swapping stacks etc.....
This I now know not to be the case as I have put it back to stock a few times and it still stumbles not nearly as bad mind.
I got a ride on the dealers demo bike and this was as sweet as a nut not a Numb one shame it was a naff colour Bronze and Silver yuk.

 

[OB_Dennis D.]

Sorry to hear stumble returned, but it sounds as though after regapping/tightening the plugs, your bike is running good again.

Strange. I am surprised this did the trick. I think it is still likely the fault of improper fuel air mixture control under influence of vacuum operated sensor (IAPS). Maybe the IAPS on some bikes are erradic or just not responsive enough to allow the ecm to compensate for small changes in vacuum pressure.

Does anyone know the specs for the IAPS electrical operating range? Is this info in the shop manual? If so, what is spec for IAPS electrical output (DCV) at idle? What is its sensitivity to vacuum changes?

Mine IAPS only changes about 150mv, 2.45 to 2.60V (does not seem to change any more beyond that point), at engine speeds where the stumble is most noticeable (1500-2000 rpm), from closed to slightly open TPS.

Does anyone know if this a normal response characteristic for the IAPS at low engine speeds?

 

[OB_bruce]

Filters are easy my *** !
Bloody nightmare of a job lost best part of a gallon of fuel what with the piss poor design by suzuki no stop **** and no non return vavle what idiots.
Having done this found that the dealer had been there before and instead of just nipping up screws had over tightened them to the point that you could not remove them without resorting to an impact screw driver and destroying the screw head thanks cresents.
Got it apart but the plastic bit which holds the filter in the pump housing would not come out with the pump motor?.
Finally got it out to find nothing much at all very clean just a few bits of dirt.
Then the fun bit all the O-rings had now swollen so none would go back where they came from.
Got the bike running again and I am afraid it is worse than ever wish I had left well alone.
Now thinking of replacing the Mickey Mouse Fuel pump pressure regulator and filter with my old Kawasaki one as this still works great after twenty years like to see this suzuki one match that.