Hi,
I have a issue that no one can put their finger on, can anyone help?

Iv just got my 2004 rx jdm 4 PORT and it perfect apart from a slight hesitation at high revs (between 6k and 7k) and then it pulls again upto 8k just before it hits the limiter.
Has anyone else had this issue or does anyone know a solutuon before I spend a load booking it into Mazda"

Iv put new coil packs on and it tidnt seem to make any difference.
Iv also fully serviced it and given it a week of spanking to burn off any build up in the tips incase it was that but still no different.
Iv also tested the oil catch tank for leakage as this can cause flat spots too but thats also fine.

The plugs and lead were changed a year ago so im sure they will be fine too.

Last night I sent my mate out in it ajust to see if it was in my head and he noticed it too.
Best way to describe it.... At 6k the engine tone changes (quieter) and the revs seem to slow a bit then the engine tone goes back to normal and picks up just under 7K.

Its litrally just for a split second so I dont know if its what these cars do but I cant imagine it from videos Iv seen on youtube.

p.s Its a 4 Port

 

Sounds like it your cat is going

 

^^ditto

 

i'm going to suggest you get it compression tested, esp it being a 4 port.

additionally, verifying the cat is still in good shape wouldn't hurt.

 

Well the cat has been gutted so it cant be that. il get a comression test carried out.
What figures should I be looking for?

 

Make sure all of your intake/vacuum hoses are properly connected and in good shape. Sounds like you are hitting a lean spot when your valves open up. Maybe PM Easy_E1 as he is BHR's resident 4-port/AT expert.

 

Iv dropped him a message, Hopefully shed some much needed light.
Iv checked all the vacume hoses at the back of the inlet extension and even zip tied them on so nice and tight.

 

Oh boy, cat can't be the problem--- I wish it was
Definitely do the compression check
Hopefully its nothing to costly. Keep us updated
Good Luck

 

Many of the 04-05 models are starting to see cracked/broken elbow fittings that connect to the OEM flex intake duct, too.

 

^........Ray, think this is more than likely due to the way people try to take those off not knowing how to do it properly until it's too late right? Or do you feel like it's just heat related fatigue on it's own?

 

Check the SSV valve. It opens around 6000 rpm. If you reach under the upper intake manifold, the plastic one, where it meets the lower intake manifold, aluminum, you'll see a vacuum model and a pivot arm.on the left side of the car. Sitting in the drivers seat of course. Not facing the front of the car. Turn the little arm on the manifold and make sure it moves freely.

 

I had a look at this on Wednesday when I had the upper plastic manifold off and it moves freely as I also hought this may be sticking or reacting slowly.
I un plugged the power to it and the feeling was very similar but boviously lasted from 6 to the red line.
I was thinking about jaming it open just to see if this could be a possible cause, I know it sounds crazy but im running out of options.

Also im having the compression checked tomorrw, what should the readings be when warm? (4 port)

 

If your between 125 psi and 95 psi your good. I don't have the exact numbers with me.
The small area of power loss makes it a little hard to get an accurate diagnosis.

 

try changing the plugs and wires... I change plugs around every 6 months....

then use this in a full tank of gas....

 

Iv just ordered some of that but interestingley I think I have made a break through.
I disconnected the power to the valve that opens at 6k and jammed it open.
I took it out and there was no flat spot, just smooth power.
Granted it did seem a bit slower on the whole as it was sucking in too much air.

Has anyone had any issues with these in the past?

 

Bg44k is very good stuff
Use it every 15k you'll feel the difference.