I tried to search for this issue but couldn't find anything with my chosen search terms...

My car runs great and the transition to secondary boost works the way it is supposed to. Except sometimes.

For example, if I am cruising @ 70 in 5th and downshift into 3rd and floor it, it seems that I get primary boost only. In other words, if the car is not allowed to accelerate through the transition point, secondary boost doesn't come into the picture.

Has anyone else had this issue and can offer pointers?

Thanks,
James

 

James,
Try changing the one way check valve behind the black vacuum box in front of the intake manifold. It's green in color. Be sure to note which way it's facing when you replace it, put the new one on backward and it won't work. Ray @ Malloy Mazda is a good source.

 

Thanks for the response and sorry for the late reply; I haven't been messing with the car lately and forgot I asked about this.

All the check valves on my car are those viton ones that Dale Clark has been selling. They have only about 1500 miles on them. I'm not saying that it's impossible that one could go bad, but because they are highly regarded it makes me think that is not the problem. Also, the one in question couldn't be backwards because the car did not behave like this from when they were installed up 'til now.

I will try to replace the viton one in the location you mentioned with the stock Mazda valve and see if that does anything. But I would like to hear of any other possible causes of this behavior, if there are any.

Thanks.

 

I doubt dale's check valves would have failed on you in 1500 miles. They are quite tough and durable . Next suspicion would be solenoids. Check the FAQ for sequential turbo troubleshooting once you read and understand how the sequential turbo system works, it's not hard to troubleshoot.

Matt

 

Is this:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/weird-boost-issue-341534/

similar to your problem?

 

...Following up with this thread...

One piece of info I left out is that I had been temporarily running without the filter on the MAP sensor. I've since installed a new filter from Malloy and this issue has disappeared. I can't exactly explain how a lack of the filter would cause this, but there it is. Car runs properly now.

 

Could you please elaborate more? what filter do you speak of? i have this same problem.

 

It's the small 'filter' that keeps vapors etc from getting to the MAP sensor.... But allowing pressure readings too..

I don't have a diagram or part number off hand, but it's the only filter of its kind on the FD, and needs to be reinstalled anytime the hose is removed...


J.