How does one "properly" check the boost pattern in an auto? Do I (we) roll to 30-40 mph, put the tranny in "hold" position in drive (3rd gear),. and then go full throttle,.. or do we just leave the tranny in the "drive" position, go full throttle and allow it to change into the overdrive 4th gear? OR.....do we check the boost pattern while driving it on/at highway speeds, then go to full throttle? Your advise will be much appreciated. Thanks.

 

Do you have a boost gauge yet? If not you will need one to do this. Hold the tranny in 2nd or 3rd and let her rip.

 

Yep. Got the dual pillar pod going with autometer fuel pressure and boost gauge. But the boost gauge only shows boost (about 6-8) above 4500 when I go full throttle at highway speeds, that is...traveling 65mph and then "flooring it". When left on "hold" in 3rd, going bout 30-40 mph, the gauge flattens to zero above 4500 rpm.

 

My 93 automatic only boosts to about 5-6... i have yet to get it higher than that... and after the first turbo stops, it just goes to 0 and sits... i think my turbos are shot... the first turbo whines anyways.. thats a sign of bad bearings. anyone have opinions on that?

 

IMO its solenoid/vachose/vac chamber related. I'm not the expert on this so maybe someone else can chime in.

If you are only achieving 5-6 psi both primary and secondary, you probably have a small boost leak somewhere. If you read low psi 0-2 in both primary and secondary, you probably have a big boost leak.

If you achieve 5-6 psi, the the boost falls to 0 upon transition, there's something else wrong with your system. You're probably f-cking your turbos up going wot because you're not achieving the proper boost pattern. There's soemthing wrong with the system related to the secondary turbo. I suggest you do a search

 

First question: does your car blow smoke? If so, remove the intake, and front and rear inlet pipes leading to the turbo compressors. See if there is any axial play (front/back) in the turbo shaft (any at all means they're shot). Gently move them side/side and see if you can make the turbo touch against the housing. The turbos are probably fine on all accounts, and the noise is probably the boost leak.

Second, like POS7 said 9/10 times or more the issue is a leak or the control system. Go to http://www.autosportracetech.com/RX-...leshooting.htm and start working your way down the list.

1) Look for boost leaks in the rubber couplers and elbows. Remove them and inspect them like a hawk - leaks/tears sometimes only appear when you bend/look at them just the right way, and any visible leak is enough to kill boost.

2) Pull the crossover pipe, pressure chamber, and look for cracked/popped off vacuum hoses. If you don't find any, carefully remove the UIM and look deeper. If they are stock black hoses, be very careful handling them since they are stiff and make it easy to break the plastic solenoids they attach to.

3) Check that you have your precontrol and wastegate pills in place. Check that the precontrol and wastegate solenoids have their electrical connectors right (the white-dotted one goes on the driver's side).

4) Continue with the troubleshooting list. First be sure the primary is getting 8+ psi before worrying about the secondary transition (4500rpm+). Borrow a Mityvac vacuum pump from Autozone, or better yet buy their Silverline Plus kit which generates and measures pressure and vacuum with the flick of a switch. The cost of this kit can be paid for by accurately showing which components need replacement and which don't.

Dave

 

Dgeesaman covers alot of the good points.

Check the precontrol system with a fine tooth comb. This is often the reason why you never see secondary boost. My car was in at a Mazda dealership for the fuel pulsation dampner and they replaced some vac hoses. Well the Precontrol actuator was one of them and they never put a pill back in it so I never saw over 7 psi.

As far as the 10-8-10 check on an auto. I cruise up to 35, put it in hold and lay into it and watch the boost pattern. This is the easiest way because it takes awhile to get through all the transistions.

You can punch it in normal drive, but it will downshift you and you won't see your primary very long (Maybe not long enough to see full 10 before transistion) so using hold is better.