severe power loss problem...help please

[neo_s13]

Ok I have a 90' fastback with 5 speed M/T and KA24E. 1st and 2nd gear hold to 6000 rpm with no hesitation, however 3rd, 4th, and 5th DO NOT! The engine will spin to about 4000 rpm in 3rd and 4th and only about 3500 in 5th before it shuts down. It feels like something has cut off my fuel supply or almost like the clutch has been depressed even though it hasnt been touched.

I'm stumped. This little problem has resulted in a 19.7 in the 1/4 mile and thats just emberassing(sp?)

Does anyone have any ideas? Any help would be greatly appreciated.

Neo

[azn_juvenil3]

could be fuel pump?

[seanman]

yeah fuel pump probably, maybe injectors? could have a leak in fuel delivery too

[neo_s13]

Ill check the pump and injectors tomorrow when I get to work ( I work at a repair shop/performance shop, I'm just an oil&tire guy so i get no respect from the other guys , but thats a differnet story) but i find it odd that it does it in only the top 3 gears. Ill let everybody know what I find out when I get home tomorrow. Also thanks for the fast responces.

[neo_s13]

Ok all 4 of my injectors read 14.5 Ohms of resistance (spec is 10-15..so my injectors are definatly healthy) but I couldnt get anyone to tell me how to test the fuel pump (they really dont like me at work). Can anyone tell me how to test my pump?

[Clearalbino]

My car is doing the same thing but its in every gear. I check the ecu and its reading a fuel injection problem and knock sensor. I'm guessing its the fuel pump because everything else that I've check looks good.

[FliMSiCaL]

change your fuel filter before you go after the pump, if its clogged, it will cause these issues.

[Jiggyfry]

If the ecu gives a knock sensor code, will the check engine light come on?Possible to have the code and no MIL light?

[Fahaka]

maf?

[S13FASTBACKSR]

maf possible but he would be running rich.if your ecu throws a senses a code the check engine light will not come on (unless you are in the diagnostic mode) when you are checking your ecu for a code the l.e.d. will blink a series of flashes and the check engine light (should) blink simotaneously with the l.e.d.

neos13 i say check your ecu for codes first

[neo_s13]

Definatly not the fuel filter. I changed it today and its still doing it, next stop ECU and MAF.

[S13FASTBACKSR]

ya like i said i dont think its the maf because you havent said you are running rich..if you are its very likely..check for maf voltage and unplug it as well and try reving your engine past 2000rpm or 2500rpm (around there) if it goes past you have a bad maf..also turn your key on and you will see a l.e.d. come on, on the back of your ecu. then start your engine. if that l.e.d. stays on you have a bad ecu..if it goes off then shut the engine off turn the key back on and check for codes.

[neo_s13]

Its not the MAF because the engine would barely start unless i held the gas to the floor...and wouldnt wrap up past 2200 rpm.

Now for the noobie question. Where is the ECU located in the car? And how do I check for codes?

I dont have much experience with the wiring/computer in the car so i need help.

[S13FASTBACKSR]

ecu is in the inside of the car on the passenger side. it is down towards the floormat. the ecu will be on the right of where the passengers put their feet. you have to remove that panel.

also to check for codes you must turn the key on and you will see on l.e.d. on the back of the ecu along with a tiny screw. remember you must have the key on for the l.e.d. to come on and you will also be in diagnostic mode. turn the screw fully clockwise and hold for atleast 2seconds. then turn it back fully counterclockwise and you will see a series of flashes. it will be the first flash followed by a pause then another flash followed by a pause then another flash followed by a pause then a fourth flash followed by a very very quick pause then the fifth flash followed by a very very quick pause then the sixth flash and it will stop...that is a code 33 ( you must take the # of flashes from the regular pauses and put them with the # of flashes followed by very very quick pauses) see what i mean?

also remember if you start your engine that l.e.d. should go off. if it doesnt you have a bad ecu itself.

[pr240sx]

Rev limiterDisconnect the 3 middle conectors under the trannyand rev your engine (and blow it) to the sky!!

[neo_s13]

ok its blinking 3short flashes, pause, 4 shorts, pause, 5 shorts,pause, 1 long, pause, 2 long

so would that be a 32? or somethign else?

[neo_s13]

Ok nvm I searched the ECU codes and found out how to read them...it read 5 reds and 5 greens( 55:no malfunctions detected). Do you think I have bad transmission speed sensors like pr240sx said?

Also i dont know if this will be of any significance or not but my spedometer has been really unreliable lately, sometimes it will read, some times it wont, and most of the time its way off (unless my car can do 80mph in 2nd gear at 3000rpm ). Do you think this may be part of the problem? Or just another nuissance? I know the vehicle speed sensor needs changed bc thats what controls the speedometer right? and I do need a correct speedometer.

Im running out of ideas and no one at my work knows nissans, they finally broke down and tried to help me but cant.

[S13FASTBACKSR]

yes that is very possible that it is rev limiter..plus the speed sensor is on the transmission so its kind of wierd how both could be bad..i say go with that it sounds like a good guess

[Dattebayo]

There is no "3rd gear sensor".

Therer is only top position (4th), overdrive (5th), and reverse sensors.

I think it could be as simple as replacing you spark plugs and checking your power transistor for spark. Sometimes when the engine is at high RPM and under load and the spark is weak, the air flowing in the cylinder can blow the spark out.

[KA24Power]

hey, sorry i don't know whats wrong with your car, but i'm a bit of a noob and was wondering why the gear would affect the rpms? if it were an engine problem wouldn't the problem be constant? seems to me that if your spark wasn't delivering properly, it would lose power in ever gear.

just trying to understand! sorry!

[neo_s13]

There is no "3rd gear sensor".

Therer is only top position (4th), overdrive (5th), and reverse sensors.

I think it could be as simple as replacing you spark plugs and checking your power transistor for spark. Sometimes when the engine is at high RPM and under load and the spark is weak, the air flowing in the cylinder can blow the spark out.

Brand new DENSO Iridium plugs so I know that shouldnt be it, but what of this transistor of which you speak? That is plausable. Where is it located and how can I check it?