Slipstream Steve

Hi rx7 club!

Im new to the rotary game, and am going to enjoy getting dirty. (My hands I mean )

Recently having brought an Rx7 FD 1993 (JDM import), (AND I absolutely LOVE IT) I decided to first take it to a Rotary Specialized Workshop in order to get it looked at to make sure it was running healthy.

Well, They called me back and It turns out it wasn't boosting correctly. So they started working on it, and countless hours later (Over a couple months, and a couple thousand dollars later) they were unable to fix the boosting issue.

The Car is barely able to get wastegate pressure. You really need to hammer it to get 5-7 psi.

SYMPTOMS
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Car struggles to make boost, no boost until around 4-5K rpm, and then its only 5-7 psi.

In Neutral, AT WOT, car wont make any postive boot pressure, until 5-6 k RPM, and then it climbs to about 4psi.


This is what the ROTARY WORKSHOP told me they checked / Replaced

*All vacuum Hoses replaced with silicone.
*Checked Solenoids - Tested with replacements
*Checked inter-cooler piping (No boost leaks)
*Tested Air bypass valve and Charge relief Valve.
*Inserted Pills for pills for Wastgate and Turbo Pre-Control Actuators.
*Tested another stock ECU

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So after getting the car back, I've started on my own troubleshooting, following this guide.
Troubleshooting

So Far I HAVE Checked
*The Pressure tank (Audible air sound when hose removed, and doesn't leak bubbles when holding pressure underwater)
*The Vacuum Tank (again, can hear air when hose removed) .
*Also checked one way valve for vacuum tank
*Tightened vacuum hoses around the two PILLS, to make sure they weren't being by-passed.
*Disconnected Double throttle actuator, and blocked the vacuum hose.
*Checked charge Control Valve Actuator. (After Idling, it opens and closes with key on-key off. Disconnecting Vacuum hose to it is NOT necessary, as it open and closes with just the key.)
*Also removed all inter-cooler piping, and doesn't seem like there's any cracks. (Cant hear any leaks either)

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Another thing I should mention, Is that the workshop claimed they let the turbos spool freely, and they made 15 psi boost, which he said indicated the inter-cooler system and turbos themselves were working correctly.

My question is, how did he test this? I would like to try it.

What else could cause such poor boosting?
What other tests can I try to pinpoint the issue?

Clutching at straws
Just want snails to work.

Slipstream Steve

obligatory photo!

rx 075

make sure your cat isnt blocked buddy.

Troclo

The twin turbo system is very complicated, read up on it and understand exactly what goes on and when! at 3000 rpms the 2nd turbo begins to spool but wents through the charge relieve valve, looks like the blow off but sits below it, at 4500 rpm this valve closes at the same time the flap in the y-pipe opens. Also at this time the flab in the exhaust manifold that opened at 3000 rpm to begin the spool of the 2nd turbo closes. Both vacuum and boost is used here to help a quick transition.

There could be many things wrong and it a very tricky puzzle to try and solve.

I like to use smoke (cigaret, I'm a non smoker so I get others to do it for me) to detect boost leaks.
Block off the exhaust and the inlet, blow smoke into one of the vacuum nipples on the
upper intake manifold, if you have a leak smoke will rise from it.

Remove the manifold and test ALL solenoid valves, make sure they all "click" when applied with 12v.
Also check all vacuum hoses are CORRECTLY mounted, most people with an IQ below 160 will **** something up here at least once, myself included!( there are 64 of those little ******* and 128 nipples)

It is said the is would be easier to build an atomic bomb than to build an sequential biturbo system.

This is probably true. Good luck.

jarr0d

[QUOTE-So they started working on it, and countless hours later (Over a couple months, and a couple thousand dollars later) they were unable to fix the boosting issue.]
where did u take the car

Troclo

And another thing.

there are 3 actuator arms below the turbos, you are going to have to get beneath the car,
one or more of them might have thrown the little ring that hold them attached to the pin of the
flap/door they control, any one these arms fall of the pin and your newclear device is fucked!

Slipstream Steve

All Right, I'll start to rip it all to pieces tomorrow. However, would it be a solenoid or even a blocked cat converter issue if its not even making waste-gate pressure consistently?

Or could solenoids still cause this problem?

And is there anyway to bypass the ecu control of the boost in order to let the primary turbo spool freely?

Slipstream Steve

The Waste-gate control actuator, Turbo Pre-control acutuator and Turbo control actuator right?

That reminds me - One of the tests I tried was take the car to neutral wot, then key off-key on, and check if the TURBO CONTROL ACTUATOR is closing and opening. IS it the rod that should be moving? Because mine was not.

Troclo

If all fails go non-sequential (or however that is spelled!)

yes, one faulty solenoid or wrongly attached hose could be your problem. Go beneath the car to start with though. if all three arms are on its off with the manifold.

if the cat is blocked the car will run crappy but still make lots of boost.

I find it interesting that the car makes some kind of boost at exactly 4500 rpm, this means that part of the system is working. its not that the car isn't making boost below 4500 rpm, is does but its wented through faulty solenoid/actuators.

The test you did should move the little arm on the y-pipe (there is a flap in the y-pipe that must stay closed until 4500 rpms), shoving you that you are able to contain vacuum. if not, turbo 1 will spill into turbo 2 and only be able to make boost when both go online at 4500 rpms.

DaleClark

iTrader: (55)

Going non-sequential won't get you anything. You're getting no primary boost. If you go non-sequential, you'll have even less than you have now.

First off, it's going to be nothing with the turbo control system. That's all there for the transition and getting the second turbo to work. You have NO boost.

So, think about it. What could it be?

- Intake air leak. If any of the hoses, gaskets, intercooler, intercooler pipes, etc. between the turbo outlet and the throttle body are leaking, you will get little to no boost. Best way to test is by pressure - pull the intakes off and use plastic bags and hose clamps to seal it off. Pull one of the vacuum lines going to the Y-pipe off, hook it to an air blow gun on an air compressor, crank the compressor down to 15psi or so, and pressurize. Look, listen, and feel for air leaks.

- Wastegate problem. If the wastegate flapper is stuck open, you're bypassing exhaust gas that needs to be there to spin the turbo up. That's not too hard to check under the car. You can also use compressed air to move the actuator, make sure it moves out and then sucks back in. If the turbine housing around the wastegate hole is severely cracked you'll lose exhaust inlet pressure around the wastegate door, this normally just reduces spool time.

- Restriction. Either clogged exhaust, clogged intake (I've seen shop rags stuck in an intercooler before), clogged airbox, turbo not spinning/siezed, etc.

- Engine issues. I doubt this, but severely worn plugs, plug wires installed wrong, blown engine....this could in theory contribute.

It could also be a combination of the above.

The turbo is a mechanical system, you spin one end of the wheel, it compresses air with the other end and crams it in the engine. Right now that's the level you're at, all the solenoids, check valves, etc. shouldn't be coming into play yet.

Dale

Rusty 13B

All the best sorting it - we can have a NZ rx not boosting!

Some good steers here from the team - I would look at replacing those factory check valves with viton ones. I got 4 off ebay...from this shop 'nettle air' - the diff in flow is huge.

http://www.ebay.com/itm/Pack-of-Four-4-1-8-Viton-Kynar-Standard-Check-Valves-Universal-/190758371689?pt=Boat_Parts_Accessories_Gear&hash=item2c6a15c169&vxp=mtr
Otherwise this trouble shooting guide has a good summary of things to work through.

Troubleshooting

I think you will sort it, it sounds mechanical over an electrical gremlin.

All the best, Rusty

Troclo

I still would like to point out that if the flap in the y-pipe is ajar boost can bleed from turbo 1 into turbo 2 until both go online at 4500 rpm.

Slipstream Steve

Ok, So a little update. I'll Just keep updating this thread as I go along, as I figure, why not?

The following I checked today.

ACTUATORS.
I put pressure on the waste-gate and the turbo pre-control actuators from the sides with the pills in the lines. Both rods moved out then sucked back in.
As far as I can tell, this is a healthy response.

As for the larger, turbo control actuator, the best I could do was move the rod with a pair of pliers to check it wasn't the jammed. This rod seems to be sprung out by default, but is able to pulled in fairly easily, before springing out again when released.

Charge control actuator pulls in during idle, and releases when car turns off.

INTER-COOLER PIPES.
I took off the off the plastic pipe that leads from the inter-cooler to the throttle body, and checked air pressure was coming out of the inter-cooler.
In neutral, with throttle applied, there's definitely some pressure coming out of the inter-cooler. Not enough to blow of my hand off the pipe or anything though. I expect this is normal as there's not much boost under light neutral load?

I also Sprayed soapy water all over the pipes, couplers, etc while car was running and cold, to check for bubbles. No bubbles formed. Unfortunately, I don't have a air compressor, so cant perform a full pressure test, yet. I will take it to a shop soon, and get them to check it.

ENGINE
My Compressions results are:
Even bounces of 115 on the front rotor and even bounces of 105 on the rear rotor.
Fair condition.

Spark plugs quickly go black, even after a clean.

Engine is all idling extremely rich, and after resetting the stock ecu, idle is lumpy and slightly erratic until the ecu adjusts itself.

My guess is bad o2 sensor.
I will replace with a BOSCH Universal.

Vacuum Hoses
I also pulled the manifold off, and did only a QUICK check the vacuum hoses. I did find one or two that had been squashed under the manifold, and some hoses mis-routed so I fixed that. Much of the emissions system is removed judging by missing solenoids (EGR, etc). I need to do a proper job of it, when the car can be apart for a few days.

I'll take the car out for a 3rd Gear WOT run, in an hour, and video the boost levels.

Slipstream Steve

Well, after my first real test, boost levels are even worse than I first thought. I Can still peak it at about 7psi, but it doesn't even hold 5psi reliably on a wot run. I was basing my earlier comments about my boost level or short bursts of wot, that makes the levels peak (with my cheapish boost gauge.) I will upload the video soon.

Slipstream Steve

So, Apparently,
It slowly builds pressure, where upon it seems to get a peak boost of 5 psi 3.5k rpm holds to 4k rpm.
After 4k Rpm, the boost falls and never recovers.
6k rpm is 0 psi of boost

Make sure you change to 1080pi, as otherwise boost gauge is impossible to read.
Its still very hard to read, but just remember that idle is about 17 in-hg vacuum
and peak boost I get is 5pi.

Heres a picture of my boost gauge.

Slipstream Steve

Great news!

Ended up doing the non-sequential mod, and now I am finally hitting boost properly for the first time.

Those solenoids were such a mission ...

Troclo

like I said! ;-) Now go drive the damn thing!!!