I'm still having boost problems.. After 4500rpm, I lose all boost. I don't feel any pull or hear the bov after that 4500. 0-4500, the car pulls very strong.
I've checked my vacume lines, and changed my turbo control (solenoid valve) because I found one nipple was broken. I thought that would be the problem, but it wasn't.

Since it boosts hard up to 4500rpm and the bov is very audible, but after 4500 rpm there's no more pull and the bov is not audible, is it possible for the wastegate on the secondary turbo to be stuck open? Has anyone ever heard of this happening?

 

If you aren't getting any secondary boost, try unplugging the CRV hose from the airbox (so it's venting to atmosphere) and listen as you get to 4500 rpms. If you are hearing air vented from your CRV after 4500 rpms, the CRV isn't closing (and you need to check the Charge Relief Solenoid).

 

Thanks for your input. Where is the charge relief solenoid located?

Also I want to add that, if I let off the pedal after 4500rpm (maybe around 6-6500) I hear a quick low winding/low whistle noise.. Almost sounds like air being sucked in or something.

 

Saner the charge relief solenoid is one thats not on the rack but sitting on top of it loosly. Check out the diagram I uploaded to my site.

http://plaza.ufl.edu/yanni25/vacuum_hose_diagram2.JPG

Let us know how to help you

 

Thanks, Surge. That diagram helps a lot!

 

Check for vacuum problems. Do WOT acceleration. Once tach needle passes 4500 rpm, get out of the throttle, and allow vacuum to build to 20 inches Hg. Then, back WOT. If boost comes back on, you have a vacuum problem. Could be vacuum chamber check valve, or vacuum chamber itself (full of oil, or cracked). Could also be a bad turbo control actuator. Good luck.

 

I also want to add that after 4500 rpm it goes from 11psi to 0psi.
SleepR1, I tried what you said. If I hit WOT, let off, then WOT again, it won't produce the same amount of boost until I let off for about 4 seconds. It only goes to about 4-5psi. Very weird. I also hear some sort of howling noise during that time
.
I figured I'd post every symptom I can recall. I'll have all weekend to check the vacuum lines and all your suggestions. Anymore ideas would be apreciated.
Thanks again.

 

I'm telling ya, vent the CRV to atmosphere and listen at around 4500 rpms and above. Most likely the CRV isn't closing which is venting all your boost.

 

Will do. I'll do that when I get home from work.

 

I also agree with Mahjik.
So, check the CRV and the hose.. also, make sure your secondary turbo pipe to the y-pipe is secure and not loosely connected.

 

Changed the CRV, but still having the same problem.. Anyone have any ideas?

 

Did you vent the CRV to see if it was closing? I wasn't saying the CRV was bad. It's controlled by a solenoid. If the solenoid has failed, it won't close the CRV, thus venting all your boost after transition.

If you vent the CRV, you'll hear whether it's closing or not and that will let you know if you need to remove the UIM to test the solenoid.

 

He tried a new CRV from my car and it still has the boost leak. Can you guys give some more tips I don't know my sequential as I never had it long.

yanni

 

Read my post above. If the CRV is staying open, then it's most likely a bad CR solenoid. Venting the CRV and listening for it after 4500 rpms will let you know if the CRV is closing or not.

You first need to verify if the CRV is actually closing or not. Once you verify that, it will let you know how to proceed.

 

It's kind of difficult to notice any rushing wind. My exhaust is kind of loud. If it's venting, will it be loud enough to really hear?

Anothing thing I just noticed.. If I gradually get on the throttle and go past 4500rpm, secondary boost works (sometimes). If I hammer it from the start, I never get secondary boost... I'm getting frustrated with this problem.

 

Absolutely as it will be pretty much ALL your boost.

 

Mahjik, I just vented the CRV but there is no sound of rushing air.. In fact, it almost seems like the turbo isn't spooling. It get's quieter.

During that time, if I go below 4500rpm, my primary turbo will not spool unless I push the clutch, let the rpms lower, then engage the clutch again. Even if I'm decelerating with the clutch engaged, then try to give it gas, the primary turbo won't spool. I must push in the clutch to somehow "reset".. I'm sure this is a bit confusing. Any help would be appreciated.

 

mine was doing the exact same thing in sequential, I have checked the lines numerous times. I finally just went non-sequential with them and got my boost back . Not happy with the lag though and plan on pulling the UIM off and doing the simplified sequential setup, test all solenoids, etc. If anyone figures your problem out, let me know- it will save me from having to do the whole thing from scratch .
joe

 

What a pain in the @$$, huh? I'd like to stick with sequential for now.. I want to find out what this problem is. Once I do, I'll definitely drop you a line.

 

Saner,

So, you are only getting primary boost sometimes and secondary rarely?

 

I'm having this exact same problem. Replaced a hose and I'm still having problems. I get up to 12 psi on the primary and then I just drop off the map

Sometimes 12-8-3 ...Sometimes 12- 3-3

 

if you get the funky "boooooooo" sound then it could be the same as this.

https://www.rx7club.com/showthread.p...+boost+problem

that's what's wrong with my car, or the exact symptom i should say. apparantly it's the solenoid (or something related to it, i physically can move the CCvalve without much effort so i know it's know stuck shut) controlling the charge control valve, the valve that seperates charge air from the primary and secondary turbo in the Y-pipe, and the valve staying closed. the secondary spools into a wall and the sound is probably it spinning backwards or something equally as horrible.

unfourtunatly the solenoid is under the rats nest, which so far has been enough from keeping me alone from fixing it.

 

Yeah, it is!!! If you haven't seen them, there are diagrams for a simplified sequential setup that allows you to get rid of a lot of the mess the car comes with stock for vac. lines and such. If you want, I can dig up a link to the diagram. When I redo mine, I will probably go that route- keep it simple .
Joe

 

Really? I'm ready to throw out what I don't need and keep sequentials. Post up! I need to go through all my hoses and see what's up. Would love to find and elminate "junk" I don't think Alabama will care

 

Here's the link. I'm sure there are plenty of others with it now too, but I found this one doing a google search for the vacuum diagram. http://www.turborx7.com/images/turbo...simplified.jpg

And here are other diagrams including the full setup-
http://www.turborx7.com/rx7vacuum.htm


Joe