swap problem , weird

[le_ryan]

Well i just had my 89 auto Ka24e swaped for a 95/96 5spd DE.It was done "profesionally" by a shop.Took it home, but that night,PROBLEM. Start it up and sounds fine off the start, but then when comeing down from the start idle, it starts missing and dies.start it back up, again same thing, sounds good for 2-3 seconds, but starts to die so i try to hold the rpm at 2-3K and cant even get it to stay steady.Its just all over the place then, and eventually comes all the way down and dies.Details:parts used:95/96 kade , 5spd transmission , ecu into 89 240sxshop had the same problem earlyer that day but thought they fixed it with a "main relay box"Its got spark its got fuel because it sounds good when i start it.help.....what do you think? Im too far from the shop to have them fix it so im trying to locat the problem myself..

[turboboost]

maybe the ecu?

[amolao]

I dont think the main relay box is the culprit....sounds like you are loosing or missing signals somewhere. How is the wiring ??? any questionables splices.....??? I would check wiring and try to get some codes or viceversa...

[le_ryan]

possibly, but they said the ecu they put in is definatly good..i guess the only way to chech if it went bad is to swap out another..any other suggestions?

[turboboost]

i think the ecu off the 1989-94 are different than the 1995-96...so maybe that could be it

[le_ryan]

I dont think the main relay box is the culprit....sounds like you are loosing or missing signals somewhere. How is the wiring ??? any questionables splices.....??? I would check wiring and try to get some codes or viceversa...

The wireing seems good, but their is a new relay fuse that has a wire dipped into the eng. cont. fuse in the fuse box in the passenger side bay...its just wedged in there with the fuse..

[le_ryan]

i think the ecu off the 1989-94 are different than the 1995-96...so maybe that could be it

its a 95/96 ecu..well im off work now and my computer is down at home, so ill be back tomarrow with more info. thanx for all the help guys!!

[amolao]

The fuse mod dont sound right, If this is a "professional" shop I'm pretty sure they installed the right ECU for the engine....

[Skinsk]

My car had a similar problem a while ago. My injectors wern't working correctly. you could try an injector ballance test after testing fuel flow/pressure after the filter, and pressure regulator. you could check spark that should be easy. I believe the resistance for the primary coil is .7 ohms. although my coils resistance is 1.4, but it still works... I hope this helps.

[Philsnotfalling]

I have the same swap I went from a 90 sohc auto to a 95 dohc 5spd in my 90 hatch. check the idle air control valve vaccum line coming from the intake. I had similar problem and the ecu would throw code 25 and it was just from a kinked vaccum line. also check ground contacts. also my car would die from the coolant temp sensor... there are two in front of the upper intake manifold. the two wire plug is for the ecu, they're cheap from nissan, I think I paid like 15 or so bucks for that. to test that a scan tool really helps, but doing this swap you'll need to have a 95 diagnostic plug. three or four green wires and a black wire... needs to be wire directy to the ecu and a 12v source for one of the green wires.

[574-240sx]

Check for vacuum leaks and make sure the vacuum system is correctly routed.

[le_ryan]

Ok, corrections, the motor/transmission are 95, the wireing and ECU are 92, some of the emisions has been deleted.When i unplug the MAFS it runs and holds idle at around 1500.so im guessing thats the problem.......how do i check voltage on the MAFS?i do have an ohms meter.

[amolao]

Hopefully they only deleted emission components that are not going to affect your car performance. THe MAFS might be the problem for what you are saying, I dont remember how the testing goes for it. Check the FSM for details, is going to help you troubleshoot the wiring/engine if anything else arises.

[le_ryan]

crap, im at work, cant down load anything to this computer, and my computer at home is toast.anyone know how to check the mafs with an ohms meter?

[S13FASTBACKSR]

to check in ohms you just need a volt meter that has different testing settings such as voltage, resistance and ohms..put it in the ohm section not sure which one i think 20k but you try them all..however I dont even know what the mafs should read in ohms why dont you do voltage? the black/white wire should be 12v power and the white wire should be 5v while the black is ground. also check your tps voltage could be a bad tps..voltage on that should be i believe .45 to .55 volts at idle and 4.5volts at w.o.t. if you can do that...also check for a vacuum leak somewhere and you should really check your ecu for codes

[le_ryan]

^^ thanx man, ill try the wires when i get home, all i have now at work is the mafs unit itself and my multi meter.is there a way to just check the mafs by using the prongs in the plug in.?

[S13FASTBACKSR]

you have the maf unit? or the mafs (connector with wires)? im guessing you have the maf. if thats the case i dont believe there is a way to check it. the 12v signal comes from the ecu to the maf and the 5v goes from the maf to the ecu (i believe) so you might be able to test the 12v and 5v by touching the power needle on your multi meter to the 5v pin and the other to a car battery ..it jumps it..same for the 12v but im not too sure about this so dont do it because i dont want you to short anything out..just wait till you get home and then let us know

[le_ryan]

yeah just the maf i guess, big metal cilinder with a four prong plugin on a box on top? i belive its a 92 maf, i think 91 and up look the same right.?well i just found one at the junk yard ill just pick it up and swap out to see if anything changes.thanx for the help guys.

[S13FASTBACKSR]

well before you buy the one at the junkyard just put the one you have right now on and test the voltage..12v power and 5v the other obviously a ground. it will save you a little money if this ends up not being the problem..also you can hook up your maf but unplug it and try to rev past 2000rpm or 2500rpm ..you shouldnt be able to because your ecu would be in limp mode..if you can however you have a bad maf

[le_ryan]

yeah when i unpluged it, i couldnt get past 2-2500, i anticepated that, but wasnt sure what it ment (broke or not).when checking the wires, i have to break the plastic wrap on the wire and probe it there, right? one probe to the wire, one probe to the frame?and this is all done with the key in the "on" position but not running right?

[le_ryan]

one more thing, after cleaning the spark plugs and spraying throttle body cleaner on the mafs, i actually got it to hold rpm at around 1500 with the mafs pluged in. But when i touched the gass it would bog down, kinda like a reverse effect , give it gas and it drops the rpms.So im definatly banking on the mafs being bad, good hunch?

[turboboost]

i think im haveing the same problem you have....like i would step on it and the car would choke...and my idle is at 1500rpms....but the funny thing on mine is that when the check engine light is on the car revs fine..but the check engine light goes off it starts to do the same thing..but my car runs fine cuz i disconnected the tps sensor ......and the car runs fine...but the check engine light stays on of course.......and the problem is that i cant smog it if the check engine light is on.....i checked all the vacums lines and all...but they are right........i changed the mafs...from another 240 that i have but still same problem.......oh btw i recently put the motor in.....too....ka24e....

[S13FASTBACKSR]

are you guys burning rich? because if you arent then your maf is not bad..by the way yes that is how you check the voltage on your maf...im thinking a bad iacv have you guys checked into that yet or has it been mentioned on here? to clean it take out the idle adjustment screw and spray carb cleaner in there and if you have an air compressor hit the inside of the iacv the best you can with that. try that and let us know..also if that doesnt work it is still possible you have a bad iacv..sometimes cleaning it works sometimes it doesnt

[turboboost]

hummmm..im a try that!!! carb cleaner you say?

[S13FASTBACKSR]

yes carb cleaner to clean your iacv. just pull out the screw and spray it in there also helps if you have a air compressor to hit the inside with air throught that hole. and when i cleaned it i put a piece of wood on it and hit the wood with a hammer to knock built up carbon loose (by the way...lots and lots of carb cleaner..not more than a whole can but a lot)

[le_ryan]

weird, the problem is gone after the new mafs and premium gas..bad gas?anyway, i seafoamed the system and raised the idle a little with the screw, it holding steady at 1000.i got a new O2 and it seems to be doing pretty well, ill be doing a tuneup as well.Thanx for all the help guys I LOVE NICO

[Philsnotfalling]

240 gas tanks thatsit around for awhile seem to be bad about rusting. pull the sending unit off and look in the tank see if you have black gunk and or rust. mine did.

[rollingindiana]

Well i just had my 89 auto Ka24e swaped for a 95/96 5spd DE.It was done "profesionally" by a shop.Took it home, but that night,PROBLEM. Start it up and sounds fine off the start, but then when comeing down from the start idle, it starts missing and dies.start it back up, again same thing, sounds good for 2-3 seconds, but starts to die so i try to hold the rpm at 2-3K and cant even get it to stay steady.Its just all over the place then, and eventually comes all the way down and dies.Details:parts used:95/96 kade , 5spd transmission , ecu into 89 240sxshop had the same problem earlyer that day but thought they fixed it with a "main relay box"Its got spark its got fuel because it sounds good when i start it.help.....what do you think? Im too far from the shop to have them fix it so im trying to locat the problem myself..

what shop do you go to im not to far from chicago?