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ka24e headache.. please help meeeee


drastic520

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Well after much much pulling of what lil hair i have left on my head and checking everything a few times, i cant seem to figure out why my ka just wont run right. it starts well and then after hitting the throttle, it just bogs and backfires. sometimes it even dies. i replaced the 280z fuel pump with a brand new walbro so i know the pump is ok. has anyone had the same issue???? here is a quick video of what it does. any insight will be greatly appreciated. need to get it running so i can get my roadster next!!!!

 

http://www.youtube.com/watch?v=ew-AXzQ_96Q

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What ecu you using? Try downloading a consult program and plug into the ecu, and see on the consult program whats happening when u get on it. If you were in washington id come buy and help ya out. It almost sounds like its in some kind of limp mode. Clean all the sensors really good as well. Did u put the maf on the right direction ;)

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maf is in the right direction, checked all sensors and the all ohm out within specs so far. i am using the fsm for the donor car. i have not checked the coil yet. guess ill add that to my list. i do have a broken ficd but i believe that only kicks in when the a/c is turned on, so i have not worried much about it. and ive noticed that when i unplug my temp sensor, it idles smoother than with it on. but thats also hit and miss. it does it whenever the hell it feels like. ugh....

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What ecu you using? Try downloading a consult program and plug into the ecu, and see on the consult program whats happening when u get on it. If you were in washington id come buy and help ya out. It almost sounds like its in some kind of limp mode. Clean all the sensors really good as well. Did u put the maf on the right direction ;)

 

i have a motor from an 89 240sx and the ecu is from a 90 auto 240sx. the one the the number 11 on it. i do know that there was a tsb for the car where they added a intake air temp sensor and lowered the compression on the motor. wonder if the ecu has to be from the same year car?

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TPS? Are ur Fuel Injector's working properly? I've had this problem before, it had to do with my fuel if i remember right. ... Is your maph is good?.......

 

fuel injectors check out well. the tps/idle switch did come back with a weird reading on the negative side. gonna try and locate one and see what happens too. while at it, i will borrow a mass air from a friend to double check.

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i have a motor from an 89 240sx and the ecu is from a 90 auto 240sx. the one the the number 11 on it. i do know that there was a tsb for the car where they added a intake air temp sensor and lowered the compression on the motor. wonder if the ecu has to be from the same year car?

 

Only the first 4 months of the 240sx had the 9:1 compression motor. After 10 '88 they were all 8.5

 

The following are NON CALIFORNIA ECUs...

 

A11-A42G41

C11-B08G54 are the two ECUs for the high compression '89 motor with automatic tranny

 

A11-B03G49

A11-B16G03

A11-B16G12 are the ECUs for the 8.5 compression '89 motors with automatic tranny

 

 

 

A11-B16G03

A11-B16G12

A11-B16G17

A11-B99G54 are the ECUs for the 8.5 compression '90 motors with automatic tranny.

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i notice your opening the throttle body the whole way in your video...

 

you can hear it loose velocity when you open the throttle, then it pops..

 

kinda sounds like it doesnt know how much air is coming in to compensate with fuel...

 

my guess is the TPS is off or bad, and when you open the throttle all the way, it doesnt know what to do. the MAF sees all this air going past it, but the throttle sensor isnt playing along letting the ECU know to give more fuel..

 

but then again, i dont know a thing about EFI, so i could be wrong..

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Like my dad always said the car needs a full tune up before it can be properly diagnosed. That includes cleaning the MAF. I would cap off the breather from the valve cover as well. Cap in on the intake side. That's un-metered air. How does it run with the MAF unplugged? If shittier than you have some vacuum leaks if better you have some bad inputs. That's where I start.

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well according to the tsb from nissan, engine numbers from ka24-012039 have the lower comp and the air intake temp sensor. my engine number is 028825w so i guess i have the lower comp one. and my ecu is a11b16g12 so it should work with mine. but i dont see an air temp plug. fml...........

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The air temp sensor does absolutley nothing trust me ive messed with 2 and neither have affected a obd1 system. I struggled with my ka forever trying to diagnose idle problems. go back to square one. Make sure your tps is set correct, from exp dont pay super close attention to the voltage number from it, what you really want to be adjusting is the idle switch built into it ( the plug that points right at the radiator) make sure it is working and raising in resistance as you increase throttle. if it just stays at zero ohms the whole the ecu will still think the car is still at idle. also pressurize your intake and check for vaccum leaks make sure your timing is set correct (with the tps unplugged) Its all pretty simple really you just gotta pay attention and check the small things. also make sure your fuel lines are hooked up right and you have fuel pressure. check pressure on the return.

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I'd lean towards the ECU being not correct, but the thing still should run. The problem is resetting things to base conditions are hard because it's not running right, and harder because the ECU may not allow for the correct set procedure.

 

Like the Stanza ECU in the D21. Same motor, different manifolds/parts. Couldn't set the idle with the Stanza ECU in, the IAC valve couldn't compensate for the differences between the two.

 

Assuming you changed nothing and the motor was running, I'd try and find an earlier ECU to start with, then see how she runs. Even if you can borrow one from a buddy for test purposes.

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