RX Problems Limited RPM untill let off throttle???

[RX1DERFULL]

I am running a 2003 RX-1 with a stage 1 MPI kit. I am running it on the asphalt and the engine seems to be limited to 8500 PRM untill I let the throttle off of the handle bar about 3\16 of an inch. After that all the RPM I want. I checked the TPS and it checks out fine.

Please help???

 

[RX1DERFULL]

In Addition

Just to add to my earlier post.

The problem only arose when I started running on ashphalt.
I was originally using stock clutching.
Only change made from the winter was adding a VDO tach.

I have tried:
4 heavier primary clutch springs as I originally thought that I had too much weight in the clutch.
I tried tightining the rear clutch as I thought perhaps the belt was dropping in the clutch.
I lightened the primary clutch weights by drilling out the rivets at the tip.
Nothing has worked other than backing off the throttle part way down the track.

The first time that I learned what was going on I was starting to get frustrated an decided to let off the throttle. As soon as I cracked it off of the handle bar, the sled took off. A noticeable increase in power. It actually overrevved up to 11000+ RPM but did not hit the limiter.

Anyway I am open to any comments or ideas. I feel that the problem is not in the clutching as regardless of what I changed in the clutchs, the sled was limited to 8500 RPM.
I was convinced that I was going to find a problem with the TPS but it check out fine when I checked it at room temperature. Perhaps it is only acting up when it gets warm.

 

[hlmrx1]

You say you checked the TPS, did you actually unhook it to tested or just used a meter or something?

 

[Need for Speed 2]

is it possible under load clutches are misaligned. broken mount or something.

 

[RX1DERFULL]

TPS and Clutches

I unhooked the TPS to check it. THe TPS was at room temperature and the procedure indicates, but I think that maybee it is acting up after the engine warms it up????

I have not checked the engine mounts, but will due so tonight. I will update on their condition late tonight or tomorrow.

Does anybody know what actually happens when the throttle is backed off the handle bar approximately 3/16 to 1/4 of a inch. I know that the position of the TPS changes. The position of the buterfly vales also changes. Does anything esle happen?? Is there a chanch that my main jet size is not correct? I know that they are stock size at 135.

Thanks for your suggestions thus far!

 

[monker]

Sounds like it could be a fuel issue? Check your throttle cable, and all the air/fuel lines that run from the carbs/fuel pump/intercooler. Watch for kinks or air leaks.

 

[RX1DERFULL]

Air Leaks

What happens when you get an air leak?

I will also check the air lines tonight. I will post my findings.

 

[monker]

Re: Air Leaks

What happens when you get an air leak?

I will also check the air lines tonight. I will post my findings.

The way the system works, the 'boost' pressurizes the float bowls to force more fuel in to the motor with the air. Off the top of my head I forget where the second line coming off of the intercooler goes. If the line is kinked, you won't be forcing enough fuel and be running lean. Also, if you don't have a good 'sealed' connection at the carbs you'll have the same problem.

You could also have the intercooler boots that aren't fully on. In this case you'll most likely be getting fuel, but not the boost through the carbs resulting in a rich condition.


I believe you said this is only has been happening since running on the asphalt. What have you changed since the winter? What was apart since it was working properly? Don't worry about jetting, when I ran the supercharger on the asphalt I used the same jetting from summer to winter.

 

[RX1DERFULL]

Air Leaks

Thank you for your insight Monker. I will let you all know what I find out.

I see you had some very impressive numbers on the ashphalt. Are you will to share some of your clutching secrets? How much boost were you running to go 9.78?

Did you run 10.61 on all motor?

Thanks again.

 

[RX1DERFULL]

Mounts and Air leaks.

The mounts are all good and solid.

I was no able to find any air leaks, but did not really have a good way to checks for a leak. What is the standard procedure? run engine at idle and spray on some soapy water, or does the engine have to e running at hight speed?

Please advise??

 

[RX1DERFULL]

Cut O-rings!

I decided to take apart my carbs to look for problems. I found three of the four packings on the aluminum tees that presurise the float bowls were cut / ripped.

I am not sure if they were leaking or not. Does anyone think that this could have been my problem?

 

[hlmrx1]

Pictures here would help. As for pressure testing I picked up a pluming cap and put an air chuck on it, then I remove my air filter and replace it to this device, hook up my compressor and crank the pressure until the boost gauge reads 10lbs or so. Then you can listen and spray soapy water around to see if there are any leaks. Seems to work.

 

[RX1DERFULL]

Leaks

Thank you for your help hmlrx1. I will try to make a set-up like that this week-end.

Everyone's help with solving this problem is greatly appriciated.

 

[hlmrx1]

Re: Leaks

Thank you for your help hmlrx1. I will try to make a set-up like that this week-end.

Everyone's help with solving this problem is greatly appriciated.

Your welcome, the way I did mine is to drill a hole in the cap, a little smaller than the air chuck, then heat up the air chuck with a torch until it's hot enough to melt the plastic, then screw it into cap and just hold it there until it cools. If it leaks you can unscrew it and use plumbing tape on the threads. If that doesn't work you may have to get a new cap and try again until you get it to work.

 

[monker]

Re: Cut O-rings!

I decided to take apart my carbs to look for problems. I found three of the four packings on the aluminum tees that presurise the float bowls were cut / ripped.

I am not sure if they were leaking or not. Does anyone think that this could have been my problem?

if the o-rings were in bad shape it could be. As the boost came up, you lost pressure in the floats and didn't get enough fuel. Wether this was the cause or not, it certainly didn't help.