hi all I found my boost problem..



When I bought that car, i was unable to push teh gaz because I always hit the feul cut. the stock gauge was always above 400 mmhg.



I do several test and found that the boost pipe wasn't in the right hole. so i inverse the boost pipe and now all work great.



now I have some question.



I boost 6PSI on my mechanical boost gauge. I thing for a TII 87 this is pretty well. The boost stay at 6 psi from 4000rpm to 7000 rpm it seam that i don't have any leak or problem with the turbo.



for the stock gauge. on idle, it was at -20 mmhg. When I boost at 6PSI, a see the stock gauge set to 1/2 to 2/3 of the gauge. (25-30 mmhg. is this correct ? because on my autometer, i never drop below 0 PSI.



I hook up my autometer to the rear pipe of the intercooler. I don't know if this is a good place but it seem to work well.



I dont feel the kick when the turbo goes on. I don't know how the stock turbo suppose to feel. so I don't know if this is normal.



I have a N/A cat and 2 n/a muffler. I don't know if this can be the source of why I don't feel the turbo.



I don't have a down pipe.



hope this is clear.......



chicoutimi

 

do you speak french? I see your from montreal.



If you want a more accurate reading from your autometer boost guage your going to need to hook it up after the throttle body.



exhaust makes a big difference on a TII, but it will also make your boost creep up to a higher pressure than it's set at. You will probably want to install a fuel cut defender to avoid hurting your engine by hitting fuel cut a lot.



14.2 psi = 1 bar = 100 mmhg



7.1 psi = .5 bar = 50 mmhg



5.7 psi = .4 bar = 40mmhg



so the highest your boost gauge can read is to 5.7 psi. if your reading 30 mmhg that's more like 4.3 psi.



Usually with stock exhaust and intake the turbo spools slower so you won't get much of a "seat of pants" feel of speed. That's why you don't leave it stock.

 

What boost?

 

ok.. I have a 88 13B n/a and now I just bought a TII 87.. this is why I'm talking of boost.



yes I'm a natural french speaking... this is why some time isn't easy to describe my problem clearly...



how you guy hook up the boost gauge. does exist a fitting that plug directly to the boost pipe ???



can some one have a picture of how the mechanical boost gauge is plugged ?



thanx



chicoutimi

 

wait i thought that if the fuel cut... then the engine was dead?

 

i'm pretty shure I didn't hit the cut fuel...The car rev smoothly



so i don't thig this is way i 'm boost only 30mmhg

 

Ok, The N/A exhaust pieces may be blocking some flow that may make it different. It may be a boost leak somewhere too.

 

is it normal to be at -200 mmhg when I idle (on my 87 TII)



chicoutimi

 

My stock boost gauge rests on the lower peg at idle. My Autometer shows about -17 vacuum. I'm guessing both readings are more or less normal.



Question: What vacuum reading is considered normal for an S4 T2 engine at idle?

 

On s4's the fuel cut hits only at fuel boost so that you dont over boost the engine. The fuel cut shutsdown fuel to the rear rotor only. max boost is 6.8 psi on 87-88 turbos. It sounds as if someone put a fuel cut defencer on the car for you.

Fuel Cut Out Switch* (86-92)





This switch is mandatory for any modifications that will be increasing boost. The computer is pre-programmed for shut down of fuel to the rear rotor at a boost of 8.6 PSI. The fuel cut out switch tells the computer that the boost is lower than it actually is.



HKS 'FCD' Fuel Cut Defencer (turbo)



The HKS FCD properly raises the factory fuel cut level on turbocharged vehicles to a safe and higher predetermined point. The electronic signal from the FCD prevents the triggering of fuel cut & engine diagnostic codes as boost levels are increased.The HKS FCD is an electronic device developed to properly raise the factory fuel cut level, on factory turbocharged vehicles, to a safe and higher predetermined point. As modifications such as intakes and exhausts are made to optimize engine performance along with utilizing a boost controller to further raise boost levels, the conservative factory fuel cut is often triggered by the higher boost levels which activates a fuel delivery cut off as a failsafe procedure. Symptoms of fuel cut are often expresses as hesitation, bogging, and/or illumination of diagnostic indicators. With the integration of HKS fuel controllers, or in certain cases where the factory fuel curves are very aggressive, an application specific amount of additional boost above factory preset levels can be accommodated. The electronic signal from the FCD will raise the fuel cut level to accommodate for the additional boost without triggering fuel cut and/or an engine diagnostic light. The FCD installation is designed as a simple integration on to the VPC/F-CON or factory ECU harness. RX-7 FC3S setting 2

I would go by the aftermarket boost gauge. I hope this helps. pm or e-mail me if you have any questions