danec020

I have been researching the forums a lot lately and reading up on FCD and turbo stuff tyring to fix a boost problem I've been dealign with. (Problem posted at the bottom with the ** for those interested)

I have a 88TII with these mods: TB Mod, No emissions, full racing beat exhaust (Dual), the home depot TID, and a cone filter, walbro fuel pump.

From what I read the TID makes roughly 2 more LBS of boost due to the increase of flow, and the exhaust 4lbs. So that is 6 added to the stock 7lbs? So I should be boosting anywhere from 10-13lbs of boost if those numbers are somewhat accurate. Is this without changing anything, because my stock guage is barely making it to 40Hgmm...(Sometimes stoping at 30-35ish)

If I need a FCD what are my options and what other routes could I go that might be more cost efficient or just better spent.

**My problem feels like fuel is getting cut after 4krpm, but I can still accelerate just lose a lot of power. Also sometimes my boost goes up to 40mmhg on the stock guage and then goes down quickly... Every now and then i hear poping sound like rapid backfire as if a intercooler hose was loose or something... I tried messing with the twin scroll, the TPS is adjusted and good, and cant find any vacuum leaks. The motor and turbo have been rebuilt as well..

If anyone has comments or suggestions on either the FCD or my problem it would be greatly appreciated.

Thanks
Dane

Funkspectrum

iTrader: (5)

yes....technically....

But rather than getting an FCD now, port the wastegate first. Even with an FCD, you're going to lean out at anything over 10psi on the stock fuel setup. I'd port the wastegate, see what you're boosting at...if it's under 8.5psi, there's no real need for an FCD. if you're boosting over 8.5, get an FCD...

I have an FCD and my engine never sees more than 7.5 psi, even though i have the same mods as you. I had the wastegate ported to eliminate boost creep...basically what you're dealing with right now. You should never pass 10psi on a stock fuel system. That leads to chewed apex seals and ****.

sossfc3s

yea i would get an fcd, it would make your fuel stay up with your boost a little better. you should get a fuel computer as well, hksfcon, safc, and make it run a little more rich if your running above 6 pounds to make sure you dont run lean. you dont need bigger injectors yet your 550 will handle the 7 to 10 pounds or boost range.

Carzy Driver

it does sound like you are leaning out when you pass 4k. what injectors do you have?

Funkspectrum

iTrader: (5)

regardless...if you open up the exhaust, boost creep becomes an issue...especially if you pulled all emissions...

Port the wastegate and go from there. if you want to get an FCD, do it. I have the Knight Sports one and I like it...

Carzy Driver

^^^^^^^^yeah that's a good start.^^^^

NZConvertible

Without a FCD you won't be getting 10-13psi, you'll be getting 8.6psi and no more. Your first mistake is permorming mods to a turbo car without buying a proper boost gauge first. You should not have installed any of those mods before installing one. You have no clue who much boost you're really running and that's just plain dangerous. Go and buy one NOW!

The only reason you need a FCD if if you want to exceed 8.6psi. If you don't, you'll need to port the wastegate extensively because with your mods you're almost certainly hitting fuel cut now and would be boosting too high if it wasn't there. If you do want more boost than that then you should still port the wastegate as you'll never get proper boost control without doing that. You'll obviously need a FCD too.

You should not be trying to accelerate under those conditions. Fuel cut kills one rotor entirely, so if you're hitting it you'd certainly know it, it's pretty violent.

danec020

Thanks for the replys guys, I am going to get a FCD for sure then.

NZConvertible: I need to get a boost gauge but right now I dont think i am even hitting stock boost. I just put this exhaust on 2 nights ago, and even before I put the exhaust on I was having this problem with the stock exhaust. The power loss I feel isnt violent so I geuss I am not getting cut of fuel, it is more just like the boost pushes you back in your seat then stops and excellerates but sounds weird and is slow. At first my Twin scroll was stuck closed cause it wasnt hooked up properly and now that I fixed it i seem to be able to accelerate fine in 1st and 2nd but in 3rd and up it does the same thing still... I was wondering if Timing can be a cause for this? The TPS is good, I havent got a timing light to double check the timing yet. I checked for boost leaks, intercooler leaks, and vacuum leaks and couldnt find any, I even pulled the UIM.

Thanks again guys,
Dane

MattB

Get an RTEK 1.7 chip. its only 20 bucks more than an FCD, and it not only has an FCD built in, but it allows 720cc injectors without an AFC, retards your timing after 9PSI so that you dont blow up, and if you flood it you just hold the pedal to the ground and itll unflood...so much better than an FCD.

BUT, it is still a good idea to port your wastegate and increase boost manually using an MBC of some kind.

http://www.pocketlogger.com

-Matt

danec020

But doesnt the Rtek REQUIRE you to use 720 injectors.. Not allow it? If I went that route I would need to buy the injectors I believe.

Thanks for the input though I will look into it.
Dane

NZConvertible

With those mods I'd be very surprised if this wasn't fuel cut but until you get a boost gauge it's very difficult to know for sure. Just make sure you get the gauge before the FCD. If it is fuel cut, you might suddenly find yourself with a lot more power caused by a lot more boost, right before it goes pop...

My DIY FCD cost ~$10...

You're correct for the Rtek 1.7, although you could get the 1.5 which does not need upgraded injectors.

danec020

I did what you said NZconvertible. I went and bought an autometer boost/vacuum guage from one of the local shops here. I t'ed it into the vacuum source on the back of the UIM. The results were just as expected plus some other wierd things.

The vacuum stayed at -15 when idling at 1500rpms. When I would boost it would show my PSI (usually around 5-7lbs) and then when i let off it would drop down to -20 for only a split second then bounce back to -15... I am assuming this is caused by pulling in air from somewhere after the AFM. Hopefully this is causing my high idle.

Some other strange things are in 1st and second I cannot get anything above 0lbs. Like it refuses to boost, it just loses power like I mentioned before but still accelerates. 3rd gear I can create about 5lbs, fourth I can make 7lbs, and in 5th gear I can make and hold 7lbs but still after 4krpm I still feel the loss of power.

Also I noticed if I would give it 30% throttle and get 2lbs or so of boost, it would hit 2lbs and then drop slowly down even if I accelerate more. I checked all my nipples, vacuum lines, and still no luck. I even sprayed starter fluid at all my vacuums to see if I could see a change in Vacuum or RPMs.

I have 4 geusses right now. One of my block off plates for emissions isnt sealing correctly even though i used gasket maker. The Metal fitting on the compressor side for the wastegate vacuum hose is leaking cause I know I could pull it out when I rebuilt the turbo, but I forced it back in and made sure it was tight. Or, maybe the dashpot or thermowax holes on the TB are leaking when I did the TB Mod. Finally last, my timing is off a little...

Well if you have any suggestions NZconvertible I would greatly appreciate it. I trust your advice and used a lot of your old threads in the past which never served me wrong =P. is -15 normal? or should it be -20? Also you were right the stock boost guage isnt even close to accurate, it detects boost later than the autometer and doesn't show accurately.

Thanks again guys,
Dane

danec020

Too late to edit, when i say -20 or 15 i mean 20inHg or 15inHg. Just to clear it up a little :P.

Dane

NZConvertible

Those numbers aren't too far off what you should expect (except idle should be 750rpm). 15inHg is normal for 750rpm but sounds too low for 1500rpm, possibly from a vac leak. The reason it drops to 20inHg on decel is because the higher rpm can draw a stronger vacuum.

If you're only getting 5-7psi with those mods you definitely have a problem (stock is 6.6psi). A loose fitting between the compressor outlet an TB is often the cause, but it could also be a tired turbo.

Buy the gasket from Mazda or cut one from a sheet of gasket paper. Sealants leave more room for "operator error"...

danec020

Thanks for the quick reply. Ok so I geuss tomorrow I will go ahead and pull my intercooler and UIM and check all vacuums again but this time I think I will add some more zip ties. I will check the compressor side of the turbo to see if the nipple for the wastegate is loose again, then I will get a timing light and check the timing...

I Was wondering if you had any feedback on why my idle is so high? 1500 rpms is not very desirable IMO... Is there something I could have done to mess it up by doing the TB Mod? The set screw with the 8mm bolt used to adjust the idle isnt even making contact with the throttle body linkage.. it has a good MM or so distance from it.. I cant even pull the cables closer to it, so I am pretty sure the plates are closed.. Plus if I remember correctly I didn't even have to mess with those plates when doing the mod.

Thanks again,
Dane

adrock3217

Something you may not know -

Theres *2* of those idle set screws. One on the front, in plain view, and also one on the BACK of the TB, near the firewall. What most people do, is while they have the TB off, they take out the stock short set screw..and replace it with a nice long one. Otherwise, adjusting it with the TB in-car is quite hard...

What I would plan to do, if I ever get around to it, is set the one in the back until it's not touching, and just have the front one be in full control :P


---- And, as far as "didn't have to mess with those plates", if you did the complete TB mod, you will have changed these plates very slighty. I don't even know how, but this is just what I've noticed + been told. You have to reset the idle set screws post-TB mod.

danec020

Well when I say TB Mod, I did Kevins way since I was using his emissions removal guide. On the site I dont see anything saying about repositions the plate.. Also if the set screw made contact with the throttle cable that would increase my idle correct? Since it would be opening up the plates more. Thanks for the suggestion though, I think I am going to go ahead and remove the TB To get a closer look at the plates and screws on it, maybe something else is hindering it from closing.

Dane

danec020

Umm looking at the Throttle body mod i noticed i am missing this Dashpot looking thing on the thermowax side.. Its in this picture and they never remove it. You can see its 2 gold screws on the top left, could this be whats causing my wierd idle.. What is it and what is its purpose?

http://www.fc3spro.com/TECH/HOWTO/TBM/tb08.jpg

NZConvertible

The throttle damper is there to stop the throttle closing too fast, which can upset the mixtures a bit. It's absense will not cause a high idle. If you do the TB mod wrong you can end up with a high idle speed. Reread this and make sure you've done it correctly.

http://fc3spro.com/TECH/HOWTO/TBM/tbm.html

rx7idgit

What hardware is going to be neccasary to install a boost gauge on these cars, I was reading this post and have been meaning to get one but don't know how difficult it is going to be to get it wired up.

danec020

It is relatively easy to install a boost guage. Just pick a good vacuum source and T the guage into it, and that is it. If you want the light to work then you will just need to choose a good power source for it, or make your own from the battery with a fuse wired in so it doesnt send too many amps.

As for the TB mod, I checked everything and everything is fine. The only thing I had wrong was I took off the Throttle damper. I found my problem though, or several small problems that probably added up to it. The cruise controll cable came out of its linkage and was stuck causing the throttle to be open a little bit. So when I removed it and set the TPS it was pretty good. Then it kept randomly not wanting the start so I electric taped some of my vacuum connections around the T and I taped the areas I tapped into the TID I made and it fired right up and now holds a 500rpm idle when cold, and then warms to about 800.

So all is good. The 4k problem was solved too with the same thing, but I am not too sure if it has any problems higher than that because when I hit 4k, I start getting close to 8lbs.. So I'll need to wait untill I install a FCD.

Now I just need to go to the store and buy all new vacuum hoses, zip ties and hose clamps and I will redo everything securely to make sure I have no more leaks. Thanks for the help everyone and I'm happy it is running better.

Only question I have left is, if I decide to set my boost to 10 or 12lbs, do I need to upgrade the secondaries? If not, then I can just get a FCD instead of RTEK. I dont want anymore power then what I have right now. Just trying to determine if I should get RTEK if I need 720s or if not just get the FCD.

Thanks,
Dane