blackspade13

87 rx7 Tii
guage reads -20 at all times, and no set in the seat turbo action!! Also sounds like a bad manifold exhaust leak,(couldnt find one)
Already tried
checked wastegate and actuator (good from pressure test but no movement during rev)
checked cats
tested boost sensor ( no output reading)
checked turbo (spins smooth no play or damage)

could this be caused by the switching actuator?
or maybe turbo solenoid valve?

Help me out I am lost on where to go

-RotorDemon-

Post a video. I'll put in my .02

blackspade13

ok, ill have a vid up in a few mins

blackspade13

heres the video let me know if you need to see anything in particular, I appreciat the help!

satch

iTrader: (1)

Are you relying solely on the Boost Gauge as whether you are boosting or not? Are you driving the car to check for boost or are you just reving the engine while idling to create boost? And your video currently does not work.

RXSpeed16

iTrader: (41)

The gauge should move even while you rev it at idle. Either check the wiring for the gauge itself or install an aftermarket gauge that doesn't use obscure units.

blackspade13

I am not getting any boost while drivong either, not because the guage says im not bit because you cant feel it

RXSpeed16

iTrader: (41)

Well let's go over everything that needs to happen to make boost.

-Exhaust needs to drive turbo. Engine needs to be strong enough to run the turbo. Fix the pre-turbo exhaust leaks. Little cracks won't hurt, but gaping holes could do it.

-Wastegate needs to be shut. Disconnect the wastegate arm from the actuator and wire it closed. CAREFULLY drive the car to see if it makes boost.

-Turbo needs to make boost - Check turbo for play/damage.

-Intake piping needs to hold pressure. - Check for vacuum leaks and or test for a boost leak.

That's pretty much it as far as actually making boost. Getting it to run well is another story.

blackspade13

Ok on the wastegate, is it shut when the rod pulls in? Also the switching valve in the manifold pre-turbo, if this is stuck or not working would that cause not enough exhaust pressure to run the turbo? Thanks for your help man

RXSpeed16

iTrader: (41)

Before you try the test, get a boost gauge. The stock gauge is obviously not working and overboosting is the fastest way to brick an engine.

Yeah, the wastegate actuator pulls the wastegate closed. As you described.

The twin-scroll flapper won't restrict the exhaust flow enough to completely eliminate boost. It runs on vacuum, so it should flop open if the system isn't working right. If it were stuck closed, it would actually help you build boost in light load situations.

blackspade13

Ok ive got guages on the way should be here by saturday ... could that twin scroll flapper be loose causing the ex. leak type noise?

j9fd3s

iTrader: (3)

i've seen the S4 manifolds split down the center, i think unfortunately step 1, is to pull off the manifold/turbo and look for broken stuff/exhaust leaks.

wthdidusay82

iTrader: (15)

Taking it off was tough for me while on the car. How long should it take normally?

j9fd3s

iTrader: (3)

if you've never done it before and its got all the chinese fingercuff heatsheilds, a couple hours is about right

wthdidusay82

iTrader: (15)

Are the shields a necessity or do people keep them off after removing the Turbo to make taking it off easier if they need to?

I was planning on keeping mine on, but I was curious.

blackspade13

ok so I hooked up a boost guage to see what she is doing, -18 at idle -5 during rev and then 0 while driving at wot. My next step will be to pull the manifold of and figure out wtf is going on.

j9fd3s

iTrader: (3)

i like to run em, but sometimes the car doesn't come with any...

blackspade13

So i took the car out for a drive today and bam, all the sudden the tirbo is hitting 8 lbs of boost. Hmmmm i didnt change any thing but now its working...wtf

wthdidusay82

iTrader: (15)

Looks like your prayers have been answered.

blackspade13

**** I guess so, just drove it 950 miles and had no issues,... exept it does have the ever so popular 3800 rpm stu stu studder.. but theres plenty of write ups on grounding procedure to take care of that

katkaroto

Damn... my 7 is acting exactly like this too. Bought it that way. The turbo and waste gate are acting normal. I haven't pressurized my intake to verify if it's leaking.

While on the highway, boost does look like it starts to build in 4th gear... but only hits 0 vacuum, no boost.