problem seen on dyno





Milwaukee_Joe

Registered
ok this past weekend I dyno'd my bike it ran 146.7 rwhp. it was in milwukee @ ~750 ft above sea level (guess), and lots of humidity.
Now the problem I found was that my idle was moving all over the place. My air/fuel ratio came out perfect on the dyno, and the tech was saying any misfires, bad spark plugs, or any simple fixes would be detectable on the air/fuel ration map.
Now what is wrong...any ideas???
the tech suggested that the TPS might be off, but I'm waondering why my bike is producing such low hp, it should be making more.
help is appriciated.
joe
 

BADZXELEVEN

Registered
Why didn't the "Tech" check the TPS sensor for adjustment?
It takes about a minute.
Low HP.
Check compression and leakdown.
Is it running good?
Maybe the "tech" doesn't run the dyno well???
 

Milwaukee_Joe

Registered
it runs fine, except the idle is all over the place.
the reason he didn't check the TPS was because this was a open house day and they're were ~15 bikes behind me waiting to get dyno'd.
I tried adjusting the TPS last night and I don't think that's it, it was still moving everywhere.
 

mikeyusf

Registered
damn, well let me see if I can help you with my limited knowledge.

First, how many miles do you have on your bike? I ask this in case of any routine valve adjustments, air cleaner, sparkplug, or any other routine maintence part is needing adjusting or replacing. Look at the simple no-brainer parts first, like the air cleaner, spark plugs, wires, etc..

Second, question the dyno. When was the last time that Dyno was calibrated? Have you tried taking it to another dyno to match the numbers? I say this because dyno's are extremely expensive to calibrate, and most shops rarely do it. I've seen as much as 15+HP difference between dyno's !!

Now, lets look into the 3 basic components of combustion.. air, fuel, spark. Is then engine getting enough air? Is the fuel of good quality, and the fuel filter isnt clogged? Is it getting spark? Is the coil, wire, and spark plug working properly?

Now, lets consider drag and friction. What kind of oil are you running? Is it time for an oil change? I hate to nit-pick but particles in the oil cause excessive friction, which causes lack of horsepower. Check the oil. Also, when was the last time you cleaned you chain with WD-40, drove it 100 miles with just wd-40, and lubed it with a quality chain cleaner? Friction is the enemy!

To investigate the dyno, how does your rear tire look? The rear tire connecting with the dyno drum is what creates the numbers. If your rear tire is really bald, it could cause slipping and lack of "numbers"

This is the obvious stuff. Before tearing your engine apart, check all the simple obvious stuff first. It's also the cheapest and easiest to fix. Check all this out, and if it doesnt improve then we'll do some in-depth analysis


hope this helps

Mike
 

SierraFlyer

Registered
My guess is that people are not sure how to react to the idle wander problem and they are holding back. That one is strange. I might take a guess at it having just done the 1/5th turn mod and been messing around in there. The idle set screw is on the right side of the throttle body near the cam the push-pull cables attach to. The cam and its shaft through the throttle body are spring returned to rest against the idle set screw. If your cable is misadjusted and tight, it will not let the throttle return spring do its job. I had this problem when I first set up the 1/5th turn mod. Also if the return sring is broken or not attached the throtle can wander and the RPMs will rise and fall within the slack in your throttle cables. You would know this because the throttle would not return on its own. You would have to twist it closed. My question is if the idle is a different RPM each time you let off tbe throttle or is it that once the engine settles down the RPM wanders with no change in throttle position?

I don't think its the TPS. It is simply a variable resistor. If it changed resistance due to some damage, the ECU would control the engine to a new idle through fuel and timing. But it would be a stable new idle. If your bike is wandering around in RPM, it would imply the TPS is changing resistance just as much - not likely. On the other hand, if you are talking about each time you return the throttle to idle it is at a different but stable RPM, then it could be water or particles in the damaged TPS.

You might also check out your vaccuum lines for leaks especially if the engine has been worked on lately. Also check the electrical connections while you are at it. Loose or corroded connections can change the values of your sensors the ECU uses to calculate the fuel and timing. A small change is some of them can cause big changes in HP.

Last is the FI light on or are you getting any codes? The ECU is intelligent and can self-diagnose problems. It will tell you if a sensor is out of tollerance and which one(s) need attention. It will also tell you if the TPS is out of adjustment.

TPS is really easy to get codes and check the TPS. Do you have the switch?
 

MET

The Watcher
Registered
Sounds like air restriction some place. Open the tank and filter and see if you get any variation in the idle. if that does not change anything check for vaccuum and minor gas restriction. Your Hp is low but not that low that it is showing a big problem. check the simple things first.
 

Milwaukee_Joe

Registered
ok,
I know the air filter is good..just checked it
I have 5300 miles on my bike
I just put in new plugs (Iridium plugs)
I just did another oil change.
I regularly lube my chain, but have't cleaned it in a while.
The rear tire is new..Pirelli Diablo.
The Tps was ok, I tried to adjust it, but didn't solve the problem.
I adjusted the throttle cables (forward and return) and the fast idle. And they all have minor slack in them.
I figured that the dyno hadn't been calibrated properly, cause others had said it was low as well.
My major thing is why would the ilde be wandering all over the place?? I don't know, but since this is still under waranty I shall take it back to the geniouses and let them try to sort it out.
Any more questions and help is still appriciated.
Thanks to everyone who has already wrote in, if I missed something let me know...
Thanks
joe
 

jwcfbd

Administrator
Registered
My major thing is why would the ilde be wandering all over the place??  I don't know, but since this is still under waranty I shall take it back to the geniouses and let them try to sort it out.
Are you using a TRE mod? If so from what I have heard it will screw up your idle. People are putting a switch in line so they can bypass the resister at idle.
 

MET

The Watcher
Registered
My major thing is why would the ilde be wandering all over the place??  I don't know, but since this is still under waranty I shall take it back to the geniouses and let them try to sort it out.
Are you using a TRE mod?  If so from what I have heard it will screw up your idle.  People are putting a switch in line so they can bypass the resister at idle.
It will not go up and down however.
 

OB_VegasDude

Registered
If you have a Pc2 or 3 and you have the wrong plugs, this will cause your problem. This will also cause your gauges to stick...............put the stock plugs back in and try it......................I went through a lot problems before I found out the wrong plugs were put in...............
 

mikeyusf

Registered
I think vegas dood has a point. If you have any modifications to the bike, try returning to stock as much as possible.

I saw guy put a new aftermarket air filter, new exhaust, power commander, and a couple other engine mods and his horsepower actually went DOWN!

It was because nothing was calibrated to work together. He had to take his bike to a power commander specialist to redesign his entire fuel map in order to reap the benefits of his aftermarket parts.

If you have a TRE, PC, or some other aftermarket parts, try pulling them out and replacing them with stock to see if that helps.

When nothing works, always simplify and slowly build up.

If your bike is back to stock, and you've taken it to another dyno to cross-reference the numbers, then I would take it to the dealer for further investigation.

Keep us updated

Mik
 

Milwaukee_Joe

Registered
ok, the only mod that I have is the TRE, I'd be surprised if that was doing it though. Otherwise my bike is pure stock.
I'm gonna end up taking it in though, sometime soon...just to see what's up.
 

mikeyusf

Registered
the TRE does funny stuff to the busa. Everything I've read, yes it eliminates your top speed, but it also changes all your maps (1st through 6th) to 4th/5th gear, and you will idle higher because the bike doesnt know when it's in neutral. Take out the TRE and re-dyno it.

I hope you get it fixed soon dood, I've been racking my brain on what it could be. Get the bike back to stock and re-dyno it. If it's still low, drop it off.

Was this the first time you dyno'd the bike?

Mike
 

Milwaukee_Joe

Registered
yeah this was the first time that I dyno'd it, but I don't have a way to get it dyno'd for cheap, but if I take it in for service this would be part of it, due to the fact the guy at the dealer is the one who dyno'd it, and he is the one who told me to check it out.
 

mikeyusf

Registered
yea the reason why I asked if it was the first time you dyno'd the bike is because a mechinic one time gave me a really good tip when I started throwing thousands of dollars into my GSXR 750.

1) get the bike dyno'd at 2000 miles to ensure a good break in
2) dyno the bike after each and every single upgrade/modification you do. From changing sprockets, to full port and polishing heads, always re-dyno your bike to see if you went up or down
3) always dyno the bike at the same place, because dyno's are very rarely cailibrated
4) If you get a unusual dyno number, take it somewhere else for a second opinion. Dynos can sometimes be over 10 percent off!

Keep us updated

Mike
 




Latest Bikes

Forum statistics

Threads
172,058
Messages
3,075,881
Members
47,334
Latest member
KHobbs
Top