hi all, im fairly new to the site, ive been pottering about and getting info but havent really found anything to help me on my problem.
i will start from the beggining, i brought my 92 plate fd as a non runner, the problem was it was flooded which i sorted, the car now runs and starts fine. however when taken for a run i have no power, neither turbo spins up, and the car feels like its being strangled. if i put my foot down the boost gauge (taken of manifold) goes up to 0.5bar and when it reaches 4000rpm drops down to zero.
i have checked the leads and spark plugs all ar fine and i can not hear any air leaks and ive spayed some carb cleaner around the engine while running , all seems to be sound.
im hoping someone on here can share some expertise with me, basically i think its something restricting the turbos as neither are spooling at all.

many thanks and sorry for the long winded 1st post.

 

.5 bar means that the car is building boost, otherwise it would never get over 0, you are reaching roughly 7.5psi. The secondary turbo comes on above 4500rpm, so it sounds like you have a control system issue. The fast that you are reaching 7psi on the primary turbo sounds like someone has removed the restrictor pill from the wastegate line to troubleshoot "something" prior to you getting the car.

 

Are you in Norfolk va? If so send me a pm and I can take a look at it. It sounds like a vacuum hose issues and I be willing to help you out.

 

i wish mate, no im in england norfolk unfortunately, this forum seems to have a more wealthy knowledge base so i thought id try my luck with you guys. thanks for the offer though i wish i could take you up on the offer.
i was thinking it was vac hose, ive had the top inlet manifold off and this is what i had underneath.......

as you can see ive got a couple of blank pipes, this is a jap import so im not sure if it differs from the U.S specification car. whilst driving i cant hear no air leaks of any sort.
also, although the car reaches 0.5bar it seems guttless and doesnt pull at all.

thanks again for the help guys

 

hello mate, thanks for the input, although it reaches .5bar the turbo doesnt spool, and the car feels gutless it doesnt even feel as though the turbo is cutting in and i dont believe it is. im new to rx7's so i dont really understand how twin turbos work especially on a rotary, ive had a few turbo'd cars but none have been so complex. i understand the primary cuts in and builds boost for the secondary, but as far as i can make out even the primar turbo is not spooling up, the boost prssure is being read from the inlet manifold would that make any difference, should i try take boost pressure reading from another location?

cheers

 

Here you go. This should help. Vac Line diagram that is color coded for easier reading. It is located elsewhere here on the forum. Made by another member.
Also you may want to download copies of the factory service manual (FSM) as well as the wiring diagram. HERE Post # 11 is the money post...

 

If I was in your shoes, I would rip all the vacuum hoses out and replace them one by one fallowing that diagram.

 

that looks like one hell of a task, thanks very much for the diagram that looks like it could be very very helpfull, i will make a start on that tomorrow so expect me to ask for more help

 

Yes, it is quite a task. Key points, print out the diagram, and do ONE at a time. Get GOOD QUALITY line to replace the old ones. Don't buy cheap *** silicone hose or you will be doing this again in the not-so distant future.

On a side note, another possible issue to address... As you just purchased this car, I would replace the fuel filter as you do not know when it was replaced last. It also, is a large PITA to replace, but a necessary evil in preventative maintenance. Fuel starvation in boost... well, you do the math and implications of that... (hint= boom).

 

agree that it sounds like an issue with the turbo control system. at 4500 rpm when the secondary turbo comes online the charge control actuator opens up to allow the secondary turbos boost to go to the engine, and the crv(Charge relief valve) basically a blow off valve momentarily opens to smooth the transition, if your crv is bad it may be venting all the boost above 4500 rpm. below 4500 rpm the charge control actuator seals it off from the primary turbo so you would still make some boost before then.

 

Mate if your in Norfolk, england why not take it over to Andrew @ Jimmy's rx7's, You have a reputible builder on your doorstep.

I have to drive near 200 miles to my closest tuner.

 

yeah i know about jimmys mate, he is literally on my doorstep if i can avoid the costs id like to try and sort it out myself but im under the impression its a compresion issue, would the symptoms point towards bad compression at all?

 

im under the impression its a compression issue, if my compression was bad would the turbos still cut in? say if it was running on one rotor, would i still get full operation of the turbos, i understand it would run like a bag of poo but would the turbos be operational.
excuse my basic knowledge i bet you guys get these questions all the time, but im used to pistons and im basing my knowledge on that

 

Start simple. Have you checked to see if the catalytic converter (If you still have it equipped) has broken apart and blocking the exhaust stream?

 

im going to check some of these suggestions out thursday, starting with the cat, i will try and get a video up, turning the engine over with the spark plugs out to see what you guys think, im getting a steady choo..choo..choo..choo sound which im told suggests im getting compression which is my main worry.

 

Agree with the previous posts that suggest
1. The wastegate isn't controlled, that would lead to 0.5 bar in boost. If you are having boost the first turbo must be working.

2. That the crv is stuck open, that would blow off all boost above 4500 rpm and no leak would be seen as the air is recirculated into the airbox.

The crv blows off boost while the second turbo is prespooling. It is always open before the transition.

The hoses seen missing in your vacuum nest are for the EGR system, that is because you have a JDM car. The EGR solenoid is also missing. (AWS and pre-cat are also missing).

You could pull the errors codes (search the forum) to see if any wiring to the solenoid are bad.

 

A good thread if you want to understand the turbo system,
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-engine-so-damn-complicated-part-1-sequential-turbos-demystified-841821/

 

thats very good info thanks, i have tried pulling error codes by bridging TEN + Gnd and taking a reading via the FEN + BAT+ via multimeter with no luck, not getting any reading or blips. i was told to do it this way as its a jap import and has no engine light on dash.

 

Well I see three hoses heading into the LIM so you should have a solenoid for the CRV somewhere, and either the solenoid or the valve itself may be stuck open. If thats the case its a pretty easy fix.

Regarding checking the engine codes, that is for cars post '95 model year only, from 92-95 the CEL is in the dash.

My advice is get some foamy engine brite, a long weekend, and about 100' of silicone hose and go to town on that bad boy. If you car is actually a 92, then odds are against those hoses being in good shape.

 

FEN and BAT- <--MINUS or use the ground in the diagnostics connector.


I'm not completely sure when the car was sold in the US but I'm guessing 93-95. The USDM had a check engine light. JDM does not, I'm sure, I have a 1994 JDM. Post 95 there where no USDM and no CEL anywhere.

 

agreed on the above info USDM cars only had engine check light, and thanks for putting me right on the BAT- i shall be giving that a go tomorrow, ive got the car up for sale at the moment as spare or repair, if i can fix it i will be chuffed.

thanks for all the help and comments everybody, its appreciated very much