KA24E speed issue

[nis720]

I have been driving my 720 for some time now... but I havent really had time to work on it (other projects).

Symptoms - Cannot rev past 3.5K RPM in 5th gear... it almost seems like the ignition cuts out. I tried adjusting the TPS (which was off) and it helped with starting the truck up, but not completely. Truck runs strong all thru the gears and as of late I find myself abusing the power.

This weekend I raced a few times and was able to rev past 3.5k RPM in all gears except 5th.

Does the transmission 5th gear sensor need to be hooked up? I really want to get past 90MPH. Any suggestions?

[jimmy726]

You have one of the nastiest motors ive ever seen. I have a 1993 ka24e in my hardbody and you just motivated me to have an engine that looks as good as yours

[nis720]

You have one of the nastiest motors ive ever seen. I have a 1993 ka24e in my hardbody and you just motivated me to have an engine that looks as good as yours

Thanks man.


Last night my electric fan controler took a dump.... now the fan stay on all the time.... so now I have one more thing to work on. :mad:

Update.... from what I have found online regarding the TPS adjustement. The FSM shows it should be between .4 - .5 volts closed and 4.0v fully open. I had previously adjusted it to .45v. Last night I set it to .4v and it helped startup when engine is warm but did not solve my issue with the ignition cutting out at 3.5k in 5th gear. When is cuts out it stays that way till it gets down to 3k RPM. She definetely runs smoother.

[alabama_lowlife]

for the record, i haven't done any research into this nor do i claim to be an expert.

do you have an electronic speed sensor installed in the tranny and is it hooked up? i can't remember exactly which aspects, but i know the TPI motor in my truck references the speed sensor for some functions. if it's not installed, maybe this one is the same? just throwing it out there as something to think about.

[nis720]

Well the electric fan controller seems to be workign fine.... I messed with the adjustment and now it's back to normal.

alabama - that's what I was thinking. But on our engine there is a 5th gear sensor (which I don't have connected.... nor the reverse). If anyone has the wiring info for the sensor... since it has 2 wires. One for the ECU but the other I'm not sure. I know on the Reverse sensor I need to connect one to ignition and the other to the wire for the reverse bulbs.

[alabama_lowlife]

so i guess yours is the cable speedo? none of my wiring stuff (95 pu, 94 path, 97 pu) has info on the cable speedo, all of the stuff 94 and up is electronic.

[yeti_'87HB]

hey, is that distributor vacuum advance or electronic, i had a KA on a previous HB, but i can't remember. it sounds to me like you may have an timing advance problem, possibly in conjunction with your 5th gear sensor not connected

[nismopu]

I never had the 5th gear sensor hooked up in my KA swapped 620 and I know several others who don't either. I think your issue lies elsewhere.

[ridin4life]

nis720 do u have a stock ecu is it chipped is wat im asking. if not i would put a chip in it and see if that solves the issue.do u have the speedo hooked up. the ecu cuts out at 115 on the 240sx. i would get the consult board and check the codes on it

[burrsg101]

its exactly what it feels like, a fuel cut. one of the gay things most cars have on them called a top speed limiter. for whatever reason nissan apparently decided to make it 90 on the hbs. that sucks becuase i have yet to hit it in my pathy and ive buried the speedo and had to be doing at least 120.:D

[JsD21HB]

ive never hit it, i got a mechanical spedo though there is no speed sensor so there is no way the thing to know how fast its going inturn making it impossibe to hit fuel cut unless i hit 6750rpm haha.
let us know if u figure it out.
btw hes got a 720 with a ka24e swap.

[turtlehead]

what ecu are you using?

a little more info on your setup?

[JsD21HB]

uh 93 hb 240 intake swap auto tranny, 89 auto 240sx ecu but before ne of that i didnt hit speed limiter either and that was bone stock like right when i got the truck had 76000 on the odometer 5 years ago.

[nis720]

I have a stock 240sx ECU (number 10 to be exact), I also have a spare 240sx ECU but it's for automatic and it does the same thing.

It seems more like a timing issue... the ignition is what cuts off at 3.5K (only in 5th gear) and will cut back on when it gets exactly below 3K.

Should I look into swapping the TPS and MAF sensors?

[yeti_'87HB]

like i said, a timing advance problem. look at your ditributor, if its electronic advance, check all the connections in the circuit, if its vacuum, check the lines and mechanical parts in the cap

[nismopu]

Ok, which wires didn't you hook up from the 240sx ecu? If it was a dizzy problem his truck would have a rough idle from being to far retarded. The dizzy offers plenty of advance which is mostly controlled by the ecu. The injectors and ignitor would not be firing if the dizzy wires were messed up. peace.

[turtlehead]

uh 93 hb 240 intake swap auto tranny, 89 auto 240sx ecu but before ne of that i didnt hit speed limiter either and that was bone stock like right when i got the truck had 76000 on the odometer 5 years ago.

I have a stock 240sx ECU (number 10 to be exact), I also have a spare 240sx ECU but it's for automatic and it does the same thing.

It seems more like a timing issue... the ignition is what cuts off at 3.5K (only in 5th gear) and will cut back on when it gets exactly below 3K.

Should I look into swapping the TPS and MAF sensors?


well then i can confirm its not a speed cut, 240sx automatic does not have a speed limiter.

[nis720]

I'm using the truck distributer (electric) and the plug matches perfectly. Also using the 240sx engine harness. I will try playing with the timing.

I will also try to get a video of the engine reving (while parked) and one while driving thru the gears past 3.5K.

[nismopu]

I'm using the truck distributer (electric) and the plug matches perfectly. Also using the 240sx engine harness. I will try playing with the timing.

I will also try to get a video of the engine reving (while parked) and one while driving thru the gears past 3.5K.

So, the complete harness is being used? Nothing is missing from it at all? I have a couple of spare MAFs floating around if ya wanna try em? peace.

[beebani]

It's the ECU, the #10 ECU does this for some reason. My truck did the same thing, I switched it out for a #11 and it works like a champ!

[JsD21HB]

yeah i think mines an 11 too but i cant remember.

[nis720]

So, the complete harness is being used? Nothing is missing from it at all? I have a couple of spare MAFs floating around if ya wanna try em? peace.

Only things not connected (plugs still there) is the air temp sensor near MAF sensor and the silenoids for EGR, and SVC.

I looked at the ECU today and checked the JWT ECU Chart. Anyone know what's the compression ratio on the truck block?

My current ECU shows for a 240sx with 8:6:1

http://i35.photobucket.com/albums/d193/nis720/nis720/IMG_0198a.jpg

The spare (which did the same thing last time I tried it) shows 9:1:1

http://i35.photobucket.com/albums/d193/nis720/nis720/IMG_0199a.jpg

Anyone have the long numbers on the #11 ECU?

[JsD21HB]

the only ka24e with the higher compression is the earily 89 240sx the have a tsb that explains what the changed. also the add of a intake temp sensor the 9:1 had none.

[nis720]

BTW both are for 89' 240sx with manual transmissions....

[nismopu]

just went looking through some of mt old pics during the KA 620 install and it appears i used a number 11 ECU as well. hmmm.

[beebani]

Yeah, Jeff and Frank had the same problems with several of the #10's. He's the one who told me about it.

[turtlehead]

Anyone have the long numbers on the #11 ECU?


i have a #11 sitting here in my living room. lol. what do you want off it?

A11-B16 G03

[nis720]

I will be picking up a #11 ECU tomorrow.... Well see if that works... but I'm still curious if the 5th gear sensor is the culprit (using the 5 spd ECU)

[lowrolnhardbody]

Hey Man I had the same problem... I know this sounds a little odd but man got back and check your coil... make sure its not cracked or anything.. I had the problem for ever and replaced everything to do with the fireing.. plugs,wires, etc.. Mine would rev out and then just cut out.. if you held it to the flow sometimes when it cuts out it would buck like crazy like it was trying but just could not get it going.. yeah man check out coil.. funny thing is I had it happen on my old nap z too.. the exhaust coil went bad.. and it did the samn thing too...

[nis720]

I didn't get the #11 ECU but Spencer (from Nico) had a #15 which is also an auto ECU. That was definetely the problem... now I was able to rev past 3.5 RPM.

[nis720]

Here's the pic with the full number for the #15 ECU for future refference.

http://i35.photobucket.com/albums/d193/nis720/nis720/IMG_0204a.jpg

[beebani]

Yeah, it's the craziest thing, me and a friend of mine have done tons of research and have nothing that explains why the infamous #10 ecu does what it does. I beat my head against a wall for a long time before I figured out that's what it was.

Just remember, the auto ecu's don't have a rev limiter (so I've been told) so keep an eye on it.;)

[nis720]

I'm back to square one.... last night I decided to drive my truck (haven't driven it since saturday when I picked up the #15 ECU). Now I have a whole new problem. I set the timing with the new ECU (different for some reason) and when I drive the truck it seems to lack power on the low end. It doesn't pick up till after 2.5K RPM and run like a champ on the high end.

So since the truck is my daily driver I reinstalled the #10 ECU and set the timing and fixed the low end issue..

I now have to see about getting the #11 ECU.

[turtlehead]

ill send you a 11 for 25 shipped.

[nis720]

ill send you a 11 for 25 shipped.

I'll let you know... the guy that provided this one will try and exchange it for a #11 ECU..

I've been messing with the timing and TPS adjustment... it seems to be drivable now but has some issues with hesitation if I hit the gas too hard and slight surging at low RPM cruising speed.

I think I'm getting somewhere with the FSM and have some ideas on what to test.

[91nissan94]

sounds exactly how mine was doing before I adjusted my tps. I have the truck ecu and the don't have the air temp sensor hooked up and have had no problems. maybe if you have an extra tps around or can test to make sure it is good.

[nis720]

sounds exactly how mine was doing before I adjusted my tps. I have the truck ecu and the don't have the air temp sensor hooked up and have had no problems. maybe if you have an extra tps around or can test to make sure it is good.

I already swapped the TPS and still same result. I'm starting to suspect the silenoid next to the PCV on the upper plenum... I will have to take it off my spare intake.

[beebani]

Did you put the #11 ecu on yet?

[nis720]

ill send you a 11 for 25 shipped.

Do you still have that ECU... my guy is lagging it... and I've been to busy to hunt him down. send me a PM or email me at nis720@hotmail.com