Problem on the dyno

[Youkai]

Well, everywhere up to 100% throttle is great. On full throttle, the bike in the upper RPM's (8000-9000) acts like it hits the rev limiter. The throttle does not react until the revs return to idle. I watched the fuel pressure go where it is suppose to be at 100% throttle, back to idle pressure when this happens.

I have a GiPro w/TRE but never used the TRE. My tuner set it to the 5 setting and on the next run, the problem occured at 6000-7000 rpm's.

On the street, I tested the bike at full throttle in 3rd and fourth gear three to four times. Each time the bike didn't have any problems reaching 11,000rpm's. I still have the TRE on the 5 setting.

My tuner thinks its the throttle position sensor. Anybody have a clue what could cause this?

Thanks.

 

[Big Red]

I have seen this same problem-- several times-- ask Johnny Cheese for an expert opinion.  Hear are some of my questions: How much power is the bike's engine putting out and what kind of fuel delivery system are you using? Whose  P.C. map are you using? Is the waste gate working properly? How much boost and compression  does the engine have? Are you using a stock cam profile and/ or valve springs? I would remove the TRE from the bike; some people have problems with it---others don't though. Johnny Cheese makes the best de-restrictor.

 

[Johnnycheese]

yep VERY Good Questions!!!!!!.
also what size is the turbo.
is the dyno a loadcontrol dyno.(this is most important)

 

[GPW]

What plugs are you running. Had a similiar problem last week. Through in a set of NGK CR10E's and tightened the gap down to 20,0000ths and problem went away. Just a thought.

 

[Youkai]

Turbo is a Mitsubishi (spelling?) Super 16 G.

I think the dyno is a load control, it really bogged the bike down during the runs.

I am using a completely stock motor, PCIIIr with a base map from Hahn modified by my tuner.

The bike uses an external fuel pump from the kit, AC delco brand. I believe the wastegate is doing what it should, I didn't touch it during the install.

The bike before the turbo and with my bolt-ons at the time made 166rwhp on this dyno.
We are seeing a peak boost of 7psi and the plugs are NGK Iridium.

 

[Johnnycheese]

post a copy of the graph.
this may help the most with a/f if possible
also what gear is the pulls done in?
and what gearing does the bike have?

 

[Youkai]

My tuner said because he could not get a run on 100% throttle, he wouldn't get numbers/graphs.

He said the a/f is great until the bike acts like it hits a wall. He does his pulls in 3rd/4th and my gearing is 1 down in the front, stock rear.

 

[Johnnycheese]

he needs to do them in 5 or 6th and use the eddie current to load it and hold it at high rpms to see what is happening.
and what do you mean won't do 100% throttle?? maybe you need a real tuner

 

[black954]

i don't believe you are supposed to use iridium plugs in turbo applications. Also, you are supposed to install new plugs and shorten the gap like GPW said.

 

[Youkai]

At 100% throttle, the bike acts up so my tuner won't get numbers/graphs until I get this fixed. I will let him know about the 5th and 6th with the load.

As for the iridium plugs, thats the first I heard of this. But I know I told them the gap for the plugs from hahn's specs when they put in a fresh pair.

 

[GPW]

(black954 @ Sep. 10 2007,18:05) i don't believe you are supposed to use iridium plugs in turbo applications. Also, you are supposed to install new plugs and shorten the gap like GPW said.

+5

 

[Uncle Bob]

use a cheap single ground arm plug, reduce the gap to .022", and I bet it'll fix your prob

 

[GMbusa]

Just as a precaution. Check the ignition ring that bolts to the crankend under the stator cover. Check the keyway to make sure it hasn't broke. If the ring moves slightly, it will give off a hesitation and/or a false rpm ceiling.