fatboy2k4

Hi everybody,
im the new kid on the block.I have seen the light and after a little looking around have bought a 93 import.it needed a little work but its coming along nicely.However i have bought a car which has developed the dreaded boost problems!!i have had a good look at it now and have replaced all the vacum hoses from the rats nest along with a good inspection of the boost pipes.it will pull all day long on halfish throttle but soon as you give it all the pedal it seems as it vents all the boost with a real loss of power.i dont think its dumping it down the waste gate because the exhaust note dosnt change,theres a wooshing and not a pisssss sound under the bonnet the second turbo is spinning up but the boost isnt getting where it should.
does anybody know what this problem is,or experianced a simular problem?
any advice would be so handy as i dont know anybody else who owns a rx7
and i figured if anyone would know it would be you guys.

many thanks
lee

dgeesaman

iTrader: (7)

The good news is boost problems are completely curable. The bad news is impatient people often don't survive the treatment ;o).

First, do you have a boost gauge installed? That will be important diagnostic info. What boost does it hit before and after 4500rpm under WOT?

Next, you need to figure out if you have vacuum and pressure being stored properly. A cracked tank, misrouted line, or bad check valve can cause this. If you don't have a Mityvac vacuum pump to perform the test, I recommend starting with the KOKO test. http://www.fd3s.net/boost_test.html Let us know what the results are: What boost does it hit in neutral? Does the CCA cycle? Does the TCA cycle?

Dave

s-thetikz

iTrader: (1)

are you in northhampton, MA ? if so i'm like five minutes away in amherst. lol.

fatboy2k4

hi again,the boost hits 6-7psi and when the second one comes in it spikes 10ish psi and then goes back to 6-7psi again and the power goes all flat.its a bit like driving a car when the clutch is sliping you kinda got to balance the throttle.i know 1 valve is charcol 2 way but are all the rest 1 way?the pressure tank near the inlet manifold and the vacum tank behind the steering pump are both ok.
i am in northampton uk are you uk or usa lol?

dgeesaman

iTrader: (7)

He's in Massachussetts (USA of course).

Anyway, all of the green/white or green/black check valves are supposed to be one-way. There is metal one that is one-way also.

The black one that leads to the boost sensor is only a filter, as far as I can tell.

I'd still like to see the results of a KOKO test. It can help to have the front end lifted to make the TCA action easier to see. It will verify check valves, actuators, lines, and solenoids all in one shot. From there you can start getting more specific.

Dave

fatboy2k4

thanks for that dave i will get on to doing those tests i have no idea where the metal check valve hangs out??but the g/w are all fine however one of the g/b valves is not working,its not the one from the pressure tank i think this one goes to the throttle control.could this be the problem?i have also just noticed that pedal has become notchy around the half throttle point...
lee

dgeesaman

iTrader: (7)

IIRC the other g/b valve goes to a hard pipe which branches to the vacuum tank. But it can be switched with a g/w one with no problems.

The metal valve connects to the purge control solenoid, which sits below the throttle cable wheel. It rarely fails and is not worth worrying about.

Dave

fatboy2k4

sorry its all gone quiet my end.had a bit of a moment with a craft knife at work saturday morning.on the mend now and hoping to be back under the bonnet this weekend.however i have looked for that metal check valve and cant see 1.there is 1 g/w + 1 charcol firewall side and 2 g/w + 2 g/b on the other side.O and 1 to the oil filler.

chinoflyer

iTrader: (1)

since you just replace your hose, did you forget to put the pills back it??

fatboy2k4

Hi there,
i replaced the hoses because this problem started.i was unaware the pills are inside the vacum hoses.i thought they were jets in the valves/solanoids etc..i guess this means i have a Whole new problem.Please could you tell were these pills are and what size the holes should be "in mm"and i will make some up as i have now discarded the old vacum lines!
"YOU ONLY LEARN BY MAKING MISTAKES"

dgeesaman

iTrader: (7)

Search for "boost pills".

As well, this site has a lot of info:
http://www.autosportracetech.com/RX-7/faqs.htm#Pills

Dave

fatboy2k4

thanks again gents you are being more than helpful.i would be up a certain creek without a paddle by now.any ideas on the notchie throttle body as this is another job to look at on the weekend?it seems as you hit the stop about half peddal if you only push lightly you need to push quite hard then it clicks and goes all the way?
thanks again
lee..

fatboy2k4

i have made the 2 pills today at work i have made them 10mm long 7mm thick with the correct holes in will they be ok? i dont know the external dimentions only the size of holes .062" / .058" and there location
lee..

dgeesaman

iTrader: (7)

I think the stock ones are about the size of a 5mm sphere - you might want to chamfer the edges 1mm and lube them with a touch of engine oil to be sure they can jam in there.

Do you have drills in that size at work?

Dave

fatboy2k4

hi dave,doing this sort of thing is no problem i work for the red bull F1 team.i have also been looking at another site rx7.voodoobox.net,this has a quite indepth guide to fault finding and pipe replacement. what do you think about my notchie throttle body?
thanks again lee..

dgeesaman

iTrader: (7)

If it does that with the throttle cable detached, just get a new TB. At least in the states they're easy to find. Mine's never failed on me, so I'm not sure except to take it out and look it over.

Dave

fatboy2k4

yer it does,rx7's are as rare as rocking horse s**t here.its hard to sorce parts from mazda dealers they dont want anything to do with them.i do know of a couple breaking for spares but im not realy into second hand parts they can be expensive and you dont know how long they will last!i will strip it down and have a look i take it there not like hand grenaids that explode bits everywhere
lee..

DaveW

Notchy throttle body could be due to carbon/varnish deposits at the throttle plates. Might just need cleaning. There have been a few threads on this...

fatboy2k4

thanks for that bud,i was kinda hoping on soming like that i come from a ford back ground "rs turbo/cosworth" these get a simular problem when you run over 2bar of boost.
lee..

fatboy2k4

hi again,
well another weekend under the bonnet and here are the results.
i got my hands on the 10 solidnoids under the inlet,air control vavle and a few check valves
which all came from a supposed good runner.i replaced the few vac hoses that were left and "inserted the 2 pills".
im sure everything is correctly plumbed and plugged in but it still wont run spot on.
WOT the second turbo doesnt want to come on line in 1-2 gear its a smooth pull all the way threw the revs with around 7ish psi.it gives that whooshing still but pulls better than before however the second turbo is as fearce as hell in 3rd it peaks about 13-14 psi its a bit splutery and with a limiter shortly after "i have only done this twice for diagnostic" feathering the peddal to regulate the load and boost its great in 3-4-5 gear.
P s, the TB was a zip tie head,the roller was just clipping it at half pedal

dgeesaman

iTrader: (7)

That's a big supposition. I strongly recommend getting/borrowing a Mityvac so you can do some real meaningful tests on the solenoids, and pick the best out of both bunches. As well, you can test the check valves.

Dave