88turbo

ok i did a custom cat back exhaust and took out the second cat.... only thing left is the cat in the down pipe....now when i get on the car will hesitate then kick in then hesitate the kick....i think its boost spike but im not sure any answers here?
thanks in advance
jeff

Scott 89t2

probably fuel cut. do you have a boost gauge? or a fuel cut defender?

88turbo

no niether....welll stock boost guage....but i figured it wouldnt fuel cut if it was all stock excpet fo the cat-back,test pipe, intake filter and hks turbo timer....none of those would actually cuase fule cut would they?

Scott 89t2

yes because without the cat you are hitting over 6-8 psi or whatever fuel cut is at.

first you thing you need is an aftermarket boost gauge. and then a FCD to prevent the cut off. then you need to make sure you have enouh fuel for the amount of boost you are seeing. shouldn't go over 8psi or so without adding some fuel.

88turbo

ok ive got a boost guage which line to i tap to get a good boost reading
and is it possible to take the injectors out of an 84-85 "7" cuz there 680 injectors

Rx7Nub

Is this possible?

NZConvertible

Pressure sensor line. Yes they'll drop right in, but you'll just run very rich and lose power. You need a fuel computer like an S-AFC to tune them to suit the stock ECU. Or get an aftermarket programmable ECU like a Haltech. You should look at upgrading the fuel pump first though, as that's the weak link, not the injectors. It doesn't matter how big the injectors are if the fuel pump can't push enough fuel through them.
BTW, the 84 injectors are 680cc/min, the 85's are 720.

Barwick

oh yeah, you'll hit fuel cut with that.

Get an aftermarket boost gauge like they're saying. Go to home depot and get a "T" (make sure you have the right size, drive the car over there and yank the pressure sensor line real quick) When you get back, plug it back in, and when you get home cut the line going to the pressure sensor (should be a black rubber line), plug the T into it, and then tee off of it towards the boost gauge line. Might take some fenagling to get it to the right size/type of line, but it'll work. I've actually got like 3 brass reducers going to mine, it's really wierd.

Ryde _Or_Die

Also with the FB injectors, they are low impedence. It depends the year(and what part of the year) your car was made as whether you have high or low impedence injectors yourself.

No7Yet

No, all GSL-SE injectors are 680s.

Brandon

Ryde _Or_Die

I thought the 720s were on the 12AT's? I don't see why they would use different injectors for the same car/engine/etc?

NZConvertible

That doesn't seem to be the general concensus here. Only from 82-83. They were 800's from 84-on. It would be very unlikely there are many 12AT injectors in the US, in either size.

No7Yet

General consensus or no, all USDM GSL-SE injectors are 680cc. Nothing else on the car changed between the two years, why would the injector size? Besides, I've seen flow tests report cars from injectors pulled from my friend's 85, and they're certainly 680s.

Now, as for the 12ATs, I have no idea. There are fewer 12ATs in the US than 20Bs, and those that are over here are most certainly not stock.

Brandon

yearrgh

Before you install FCD, check the vac lines on the front of the turbo that go to the waste gate actuator. If you broke one of those then your waste gate won't open and you will get uncontrolled boost which will cause fuel cut. That happened to me. It was fun while it lasted...

mrb63083

iTrader: (4)

The weather will help with the boost. Mine hit 14 the other night. Kinda scary.

NZConvertible

So where are all the 720's that people use from?

scathcart

Common aftermarket size.