pistonlover

Hello,



I am fixing a friends car and need help. Background info: This car was brought in from Japan just over a year ago, the person who bought it sold it to my friend as partial payment on a company. It has been parked for about year. The fuel was changed and it was in pieces when I got it. I put it together and took it for a drive. It has NO boost till 3500 then builds .5 bar and then goes back to 0 instantly. I took it apart and there is no oil anywhere but the front turbo has minor side to side shaft play and VERY minor in and out shaft play. Anyone knwo what else might be going on? Anything I should be checking? When does the second turbo come on?



Thanks for the help guys

Ogpogo

I'm no expert, but it sounds like a blown apex seal messing with a turbine.

Signal 2

^Really? Exactly where in the hell did you come up with that?



To the OP

First check all your couplers and make sure you don't have a leak. First suspect is a soft coupler above the turbos to the cross-over. Boost leaks substantial enough to cause symptoms as you've described usually make noise. Since you didn't mentioned anything about it, it sounds like a sequential system issue. That could be sourced to any number of things. Here's a site to get you started and at least familiarize yourself...

http://www.autosportracetech.com/RX-7/rx7stuff.htm

Ogpogo

I think the way I started my sentence would be sufficient enough to answer that.

Signal 2

Your right, that was rude...appologies.

But understand that what you suggested was as likely a cause of his symtoms as low windshield washer fluid. "Broken apex seal" is also something that people who've never owned a rotary reflexively toss out because they heard it somewhere. The equivalent of me blaming everything that goes wrong with a piston engine on bad rings.

The OP's post suggests that it runs and idles normally (at least he didn't mention any issues in that regard), but won't build boost. The vast majority of boost issues will be in the sequential system..solenoids, actuators, check valves and lines. And the shaft play he describes is normal for used turbos and a seal belched out going through a turbine wheel is usually pretty obvious.

Speeder

If it was a broken apex seal the OP would definitely know it. I lost one at one time in another car & it was all I could do to make it home.



+1 on going through the hoses, control solenoids & actuators in the turbo system. Many pros will tell you that most of the time, it isn`t the turbos themselves that go bad, it is the systems that control them that start acting funny.

Speeder

Oops! Forgot to answer another question the OP had. The secondary should come in around 4500 RPMs. I call that one, the fun one!

JBs93FD

bad cats (restricted,melted) can cause some serious boost issues also when i first got my 7 it had a bad pre-cat and pre-control solenoid. like signal said mostlikly the control system, cats or chargepipe leaks!!!!

travis117

I'm not a 100%, but I think the secondary turbo starts to spool at 3500 rpm, then comes on service at 4500 rpm. There could be a seal or couling loose in the turbo outlet piping that holds until .5 bar, then leaks out all of the built up pressure.



My suggestion to pistonlover is that he goes ahead and converts to a single turbo. It replaces most of the components of the turbo system, so it should eliminate the problem as well as give you a healthy boost in performance over stock.