10lbs w/o fcd wtf is goin on!!!
07-20-02, 10:43 AM
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10lbs w/o fcd wtf is goin on!!!
i decided to feel how it is on boostcut. so i took of my fcd.
since it was a very cold night i thought id be boostin something higher than 8.6lbs.. and so i did. at 4k i already hit 8 lbs and as soon as i hit red line on second gear.. (whoa) it was on 10lbs.. wtf is goin on.
. this is not normal. but cool.. can some one explain whats goin on.. my mod are on my sig. (nothin much to look at).
since it was a very cold night i thought id be boostin something higher than 8.6lbs.. and so i did. at 4k i already hit 8 lbs and as soon as i hit red line on second gear.. (whoa) it was on 10lbs.. wtf is goin on.
. this is not normal. but cool.. can some one explain whats goin on.. my mod are on my sig. (nothin much to look at).Last edited by ryandogg; 07-20-02 at 10:48 AM.
07-20-02, 11:38 AM
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I'd cast a suspicious eye on the aftermarket boost gauge, especially if it has the letters A___M___R in the name. What does the factory gauge read, approx, when the aftermarket gauge reads 10psi?????
07-20-02, 12:56 PM
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I had a similiar experience with my S5 turbo. I hit .8-.9 bar without an FCD. My boost gauge is an Apexi EL so I think its pretty accurate. It damn well better be for what I paid for it. Anyhow, I contributed mine to a boost spike. Needless to say I watch the gauge closely around redline now.
Last edited by turboGXL; 07-20-02 at 12:59 PM.
07-20-02, 03:06 PM
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Well I struck out with the autometer idea. Apexi does not spell A___M___R. Your probably right about the spike. Just wondered if your factory gauge is reading anything at all? No reading might mean the ECU isn't seeing the output of the boost/preassure sensor.
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07-20-02, 06:51 PM
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Originally posted by HAILERS
I'd cast a suspicious eye on the aftermarket boost gauge, especially if it has the letters A___M___R in the name. What does the factory gauge read, approx, when the aftermarket gauge reads 10psi?????
I'd cast a suspicious eye on the aftermarket boost gauge, especially if it has the letters A___M___R in the name. What does the factory gauge read, approx, when the aftermarket gauge reads 10psi?????
07-20-02, 06:53 PM
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Originally posted by Felix Wankel
When you unplugged the FCD, did you plug the boost sensor plug back into the boost sensor, or did you just unplug the FCD plug from the boost sensor?
When you unplugged the FCD, did you plug the boost sensor plug back into the boost sensor, or did you just unplug the FCD plug from the boost sensor?
07-20-02, 06:55 PM
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Originally posted by BlackRx7
why would you wanna see what your fuel cut feels like....no offense but hit the fuel cut harms your engine...
why would you wanna see what your fuel cut feels like....no offense but hit the fuel cut harms your engine...
07-20-02, 06:57 PM
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Originally posted by vosko
i would say previous owner had ecu reprogrammed ?
i would say previous owner had ecu reprogrammed ?
07-20-02, 07:35 PM
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Without FCd I wouldn't hit fuel cut to 11 psi on my S4, measured on the same line as the Map was installed on.. Hit it a couple of times, but you really had to keep in it deep to get it to cut..
FCD was added, and of course no more fuel cut..
I don't believe fuel cut harms motors.. Some people think ignition cut would be better, but remember fuel will still detonate without a spark from the plugs, so killing the ignition would not accomplish much except pump your turbo and 8 feet of exhaust pipe full of raw fuel and air, so when the ignition came back...BLAMMM.. yeah that would be safe..Max
FCD was added, and of course no more fuel cut..
I don't believe fuel cut harms motors.. Some people think ignition cut would be better, but remember fuel will still detonate without a spark from the plugs, so killing the ignition would not accomplish much except pump your turbo and 8 feet of exhaust pipe full of raw fuel and air, so when the ignition came back...BLAMMM.. yeah that would be safe..Max
07-20-02, 10:59 PM
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Originally posted by HAILERS
Well I struck out with the autometer idea. Apexi does not spell A___M___R. Your probably right about the spike. Just wondered if your factory gauge is reading anything at all? No reading might mean the ECU isn't seeing the output of the boost/preassure sensor.
Well I struck out with the autometer idea. Apexi does not spell A___M___R. Your probably right about the spike. Just wondered if your factory gauge is reading anything at all? No reading might mean the ECU isn't seeing the output of the boost/preassure sensor.
Vosko makes a good point... My ECU is used Jspec (N374). Its possible that my ECU has been modified by previous Japanese owner. My EEPROM has numbered labels all over it and does not look stock.
07-21-02, 04:31 PM
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the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
yes this is why you didn't hit fuel cut.
actually i found out this morning that the boost pressure line was disconnected off the sensor. no wonder i was gettin bouncin idle.. could this be the reason why i hit 10lbs..
07-21-02, 04:51 PM
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Can someone give a clear and concise explanation on why hitting fuel cut would damage your engine?
The way I see it fuel cut is just that - no more fuel at that moment initiated by the ecu when the boost parameters are correct to cause this. Engine is still rotating and the oil is still being injected into the rotor housing.
Determined by the ecu, fuel flow returns, engine has dropped in rpm and boost level dimished.
Where and how in this scenario does damage occur?
The way I see it fuel cut is just that - no more fuel at that moment initiated by the ecu when the boost parameters are correct to cause this. Engine is still rotating and the oil is still being injected into the rotor housing.
Determined by the ecu, fuel flow returns, engine has dropped in rpm and boost level dimished.
Where and how in this scenario does damage occur?
07-21-02, 05:17 PM
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Looking at the 87 fsm, I see that the boost gauge gets its input from a spliced wire off the output of the Boost/pressure sensor, and gets its ground from the same gang of wires that ground the airflow meter, tps etc. In other word independent of anything happening inside of the gauge cluster, which includes the oil pressure gauge. Oil pressure gauge seems to be a different issue.
Looking at the 89fsm ECU outputs on www.fc3s.org, the input from the Boost/pressure sensor is pin 2H. Thats if you wanted to see if its getting there from the boost/pressure sensor. Must be though since you hit fuel cut.
I've seen posts by Ted and maybe NZCONVERTIBLE, that when you hit fuel cut, no matter how fast the fuel is cut, it will run lean for a moment. The gist of it, I think, is that the mechanics of the fuel delivery are not instant on and off. I'm am a turbo novice and it might be showing.
Looking at the 89fsm ECU outputs on www.fc3s.org, the input from the Boost/pressure sensor is pin 2H. Thats if you wanted to see if its getting there from the boost/pressure sensor. Must be though since you hit fuel cut.
I've seen posts by Ted and maybe NZCONVERTIBLE, that when you hit fuel cut, no matter how fast the fuel is cut, it will run lean for a moment. The gist of it, I think, is that the mechanics of the fuel delivery are not instant on and off. I'm am a turbo novice and it might be showing.
07-21-02, 06:31 PM
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I could see it if fuel cut meant a reduction in injector pulse width, but being that its turning the injectors off completely, worries of leaning it are completley unfounded IMHO... That was the days before soft touch ignition control was incorporated into ecu's and soft touch ignition cut may still no be enough to reduce turbine speed and therefore boost, but as I said previous just cutting the ignition is a bad idea, and fuel will still detonate with out spark at high boost levels..Max
07-21-02, 06:35 PM
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Ted and I discussed this a while ago after I asked the same question. I couldn't see how it caused engine damage, and I'm still not 100% sure, but Ted managed to kill an engine by bouncing it off the fuel cut, and it's hard to argue with that... 
07-21-02, 08:22 PM
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Originally posted by Scott 89t2
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
07-21-02, 09:02 PM
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Originally posted by Scott 89t2
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
yes this is why you didn't hit fuel cut.
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
yes this is why you didn't hit fuel cut.
07-21-02, 09:06 PM
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Originally posted by ryandogg
"what if i put a checkvalve on the pressure sensor line..im guessin this will act as a fcd. wouldnt it.. "
"what if i put a checkvalve on the pressure sensor line..im guessin this will act as a fcd. wouldnt it.. "
07-21-02, 09:08 PM
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Originally posted by Scott 89t2
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
the j-spec ecus are different. even if it was stock it would still have a higer fuel cut then US ones.
07-21-02, 09:31 PM
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I thought a FCD is acually a bad thing to buy, because when your running higher boost you need more fuel, but the ECU is only sending the engine Enough fuel for stock boost levels. Wouldn't fuel cut off be better remideed by a Haltech ECU and largers injectors, and fuel pump? (if running high enough boost injectors and pump are needed)
Someone please clarify the details of this set-up for me.
Someone please clarify the details of this set-up for me.
07-21-02, 09:43 PM
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Originally posted by TriTurboGen3 RX-7
I thought a FCD is acually a bad thing to buy, because when your running higher boost you need more fuel, but the ECU is only sending the engine Enough fuel for stock boost levels. Wouldn't fuel cut off be better remideed by a Haltech ECU and largers injectors, and fuel pump? (if running high enough boost injectors and pump are needed)
Someone please clarify the details of this set-up for me.
I thought a FCD is acually a bad thing to buy, because when your running higher boost you need more fuel, but the ECU is only sending the engine Enough fuel for stock boost levels. Wouldn't fuel cut off be better remideed by a Haltech ECU and largers injectors, and fuel pump? (if running high enough boost injectors and pump are needed)
Someone please clarify the details of this set-up for me.