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View Full Version : Idle and Drivability issues (i searched)


sileight_04
03-28-2008, 01:13 AM
Let me first start by apologizing if this is something that has been brought up before. I did use the search to the best of my search abilities and also have read a couple hundred pages into the tech section with no luck. =(

first off this is my 3rd 240sx, this one being a 93 KA24DE. I purchased it from the original owners. This is the only one that has had a KA in it for more than a few weeks, so my knowledge of the ka is not plentiful. The original owners did have the motor rebuilt a little over 10k ago with receipts.

Now on to the issue(s).
1. The car refuses to idle decently, seemed as if it was suffering from a dirty iac and was in need of a tune up and maybe a missfire. it fluctuates and like to stay about 1k for a while. it seems to also throw timing around a lot. I cleaned the Iac and replaced the plugs, wires, rotor and cap, as well as your other tune up items. It still idles terribly.

2. here is the part that i can't even begin to wrap my head around... It starts up and idles (bad, but it idles and drives) While driving or just free reving, it will just drop the revs and then try to go back up and then drop them again and so on and so on all while still having the throttle applied. this usually happens after driving the car around for 10-15 minutes and/or normally between 2k-5k rpm. It doesn't always happen in a certain amount of time but does every time the car is driven. it is bad enough to where it becomes un drivable. I have no idea what it could be, it didn't happen for the first day or two after the car was bought and the stuff listed above was done after it all started. I have thought of it maybe being off on ignition timing so i restabbed the distributor, still happens. checked to see if injectors are clicking away and when pulled create a stumble. has spark.

I am really at a loss of what to do, Ive read through the FSM rigorously with no positive outcome pertaining to this. I would greatly appreciate any and all help! if this has been brought up and you know where its at, point me in the right direction. Please help me out as best you guys can.

Thank you for your time,
Jonathan

sileight_04
03-30-2008, 01:56 AM
Anyone? Any suggestions or theory's at all? someone please help, I'm stumped.

s13drob
03-30-2008, 02:11 AM
maybe a dirty/bad maf

playastarkz123
03-30-2008, 07:27 PM
^ beat me to it.

also try checking the wire connections to your maf, they maybe loose or just bad....I had a similar problem with my sr. I swapped out the maf for z32 one and the car idles and drives perfectly now

darkslide
03-30-2008, 07:57 PM
how well did u clean out the iac?? kinda sounds like it has a tps problem, i had a veryyyy similar problem on my civic, it gave a tps code but ending up being the ecu that was bad.. GL =]

KA-T_240
03-30-2008, 08:07 PM
disconnect your maf, if it runs fine, then clean the maf.

Z U L8R
03-30-2008, 08:45 PM
i also concur on the maf, that's where i would start as well.

other possible culprits could be leaky injector o-ring, tps, ignitor ie distributor itself. in that order i would test per fsm diagnostic to deduce driveability problem......or you could take your car and put it on our steady stay mustang dyno and we can check everything at any given rpm with the correct load on the vehicle to simulate it in actual driving conditions......then after we fix it we can run the 1/4 mile on it and get your actual time within xx.x_ ( +1/-1 a hundredth) of a second hahaha.

(sorry i'm psyched about our dyno we just got @@!! it's kick ass!) :D


Dave =]

silpena
03-30-2008, 08:50 PM
ur dizzy may be off. I had the problem where it would flutter even after cleaning and replacing everything. Try re setting it to tdc and set the distributor at 1 and re time it. Can't hurt to try. My other guess could be a bad ground or tps.

sileight_04
03-30-2008, 11:44 PM
thanks everyone for the input, It is really appreciated! im going to check some of those things tomorrow and see what comes up. thanks again

cronux
03-31-2008, 03:47 PM
oh, and this may be rediculous, but check to make sure your battery terminals are attached firmly. as if the positive is loose, it can lose connection, and cause a wierd crazy drop in rev's and then back up. just something else to check.

menace89
03-31-2008, 06:14 PM
ohh ohhh lol i got a 93 240sx and it starter happening about the idle shit...it took me 4 days 2 find out..and i finaly got it fixed...i dont noe if is the same on all cars....but ok here it comes...i hope this helps u....first i change my spark plugs...then my cap and rotor...then clean the MAF sensor...then the car was the same....i was getting pissed every sec...but wen i change the fuel filter the car got better...my idle was soo good in 2 days or 1 day...u noe u have 2 wait until your filter gets used 2 it and all that....just change the fuel filter and give it 1 day or drive it for 20 just 2 make the fuel filter get use 2 it.....aight...hit me back if u got any questions
Pz

grachman
03-31-2008, 07:47 PM
If you still have the air injection valve, disconnect the rubber hose that goes from canister to fuel filter box. You can leave it that way with no problem. just plug the resulting hole in air filter box.

landins13
03-31-2008, 09:57 PM
if youre still having trouble. go here http://www.240edge.com/manuals/91-94_240sx/ec.pdf
start on page 33 of the section that comes up and work your way down, you should be able to narrow your problem down and fix it.