loss of power after 4500 rpms in 4th gear??
08-30-09, 01:24 PM
#1
loss of power after 4500 rpms in 4th gear??
ok well its just like the title states...
car is '88 tii
after car has been at operating temp I decided to get on it. all gears seemed fine under full throttle until 4th. after about 4500-5000 the car acts like its cutting spark. so I changed the plugs and wires that did nothing. so I'm thinking it might be fuel related. it has a brand new walbro 255 and new fuel filter. the other thing is it could be fuel injectors?? I'm not sure what is going on but if you can imagine full throttle and hit those rpms then it cuts power then gets back into it and cuts again. by that time I just get off the throttle and just go easy.
thanks,
~Andrew
car is '88 tii
after car has been at operating temp I decided to get on it. all gears seemed fine under full throttle until 4th. after about 4500-5000 the car acts like its cutting spark. so I changed the plugs and wires that did nothing. so I'm thinking it might be fuel related. it has a brand new walbro 255 and new fuel filter. the other thing is it could be fuel injectors?? I'm not sure what is going on but if you can imagine full throttle and hit those rpms then it cuts power then gets back into it and cuts again. by that time I just get off the throttle and just go easy.
thanks,
~Andrew
08-30-09, 02:31 PM
#4
YAY! No more smoke!
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I see by your sig that you have a Corksport 3 inch downpipe.
Did you port your wastegate?
Do you have a fuel cut defenser? (goes between boost sensor and wiring harness)
If not, then DON'T boost in high gears till you do. You WILL lose your motor. With the larger downpipe, the turbo will become more efficient. The stock wastegate (especially the S4 turbo's) can't maintain consistent boost in high load. The higher the gear, the larger the load at any given RPM. This produces boost creep. Your pressure will spike after the wastegate has been overcome.
This is bad news because the stock ECU cuts fuel to the rear rotor after ~8psi. Pretty much death to the rear rotor. This is where the FCD comes in. It tricks the ECU into thinking the boost pressure is lower than it is. Keeps it from fuel cutting.
So pretty much the bottom line is:
Pull your turbo and port the wastegate and buy a FCD.
-Blake
Did you port your wastegate?
Do you have a fuel cut defenser? (goes between boost sensor and wiring harness)
If not, then DON'T boost in high gears till you do. You WILL lose your motor. With the larger downpipe, the turbo will become more efficient. The stock wastegate (especially the S4 turbo's) can't maintain consistent boost in high load. The higher the gear, the larger the load at any given RPM. This produces boost creep. Your pressure will spike after the wastegate has been overcome.
This is bad news because the stock ECU cuts fuel to the rear rotor after ~8psi. Pretty much death to the rear rotor. This is where the FCD comes in. It tricks the ECU into thinking the boost pressure is lower than it is. Keeps it from fuel cutting.
So pretty much the bottom line is:
Pull your turbo and port the wastegate and buy a FCD.
-Blake
08-30-09, 02:55 PM
#5
ok well now I'm pretty worried about my engine! I just swapped in this engine and i have been going real easy on it and ive only driven it hard twice. once on the freeway and the other in the city. i live 2 miles from work so it never gets to operating temp for me to beat on it. I hope its ok. where can I get this fcd?
08-30-09, 03:24 PM
#6
Now With 10th AE Fun!
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You can get an FCD usually in the classifieds, but Racing Beat and a few other companies sell them as well. I would recommend getting your wastegate ported instead so you can just run stock boost until you can get a nice aftermarket ECU and some injectors. Even with an FCD you will still boost creep and can still blow your engine.
08-30-09, 03:27 PM
#7
so do you think my engine is ok? i mean i just spent like $2gs getting this thing close to how i want it. and the last thing i need is a blown engine again.
So tell me if this would be a good idea: port wastegate, get bigger fuel injectors and fcd? or just the first two and no fcd?
So tell me if this would be a good idea: port wastegate, get bigger fuel injectors and fcd? or just the first two and no fcd?
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08-30-09, 04:31 PM
#8
YAY! No more smoke!
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The stock ecu lacks the ability to compensate for larger injectors. You'll run insanely rich. If this is the route you wish to go though, your easiest bet is an Rtek. This voids the need for a FCD. Also ads a few little changes which are nice. Either way though, FCD or Rtek + larger injectors, please port your wastegate. Save your motor. Good luck!
08-08-10, 09:48 PM
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Theres a few Rtek 1.7 ecu's for sale in the classified right now. The 1.7 includes the fuel cut defender and is set up for 720cc injectors, and it does some other cool stuff. You can get the rteks for like $100 used. A good, cheap, and safe upgrade.
pocketlogger.com more info on the Rtek
pocketlogger.com more info on the Rtek
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