S13 KA24E Running Rough and Cutting Out

[Gokussj5okazu]

Hello everyone! I've been around a while reading, researching, etc, just never posted. I've had my S13 for about 2 years now, but it's always had some problems.

Right after I first got it, I pulled the engine and trans for a rebuild and removed all of the smog equipment. Well ever since, it has had a sporadic miss and stutter at idle (1000RPM), and a very bad popping/backfiring when going from hard acceleration to deceleration. Also, when freewheeling, it would pop and stutter.

2 Weeks ago, I took the MAF and AAC valve off, and cleaned them both with carb cleaner. I got out a lot of carbon and crap, but I also noticed the inside of my intake was oily. Not heavy, but it definitely had a light coat of oil.

I dried it all out and put it back together. It ran like shit, and used a ridiculous amount of gas. I let it sit for a few days without driving. Some fellow on the 240SX Forums suggested that I had toasted my MAF with the carb cleaner, so I was prepared for the worst.

Last Tuesday, after sitting for about 2 days, I fired it back up to see what I could figure out. It ran better than ever before, though it still did have a slight miss. I took a trip around town to make sure it was running well, and made a stop to pick up a bottle of injector cleaner, for shits and giggles. This seemed to clear up a lot of the hesitation I always had, but the miss was still there!!

Drove it back and forth to work for a few days, then decided to try and set the idle where it should be. You can see where I did this, and hear some of the missfire in this video.

http://i19.photobucket.com/albums/b159/gokussj5okazu/Projects/240sx/th_SettingIdle.jpg (http://s19.photobucket.com/albums/b159/gokussj5okazu/Projects/240sx/?action=view&current=SettingIdle.mp4)


Everything seemed ok up until tonight. There was still a missfire, but it was better than it had been. Well today when driving to work, it cut out on me a few times while going down the highway. Just a short sputter, at no particular RPM. I didn't think much of it, figured I might have gotten some bad gas or something. However, when I got off from work, it was absolute shit. This video speaks for itself.


http://i19.photobucket.com/albums/b159/gokussj5okazu/Projects/240sx/th_RunningRough.jpg (http://s19.photobucket.com/albums/b159/gokussj5okazu/Projects/240sx/?action=view&current=RunningRough.mp4)


Basically, the idle was low, like around 500RPM for the most part, but was bouncing like crazy. It kept sputtering, missing, etc. The drive home was much worse, lots of cutting out, stalling, and it died a few times at stops, and even once while coasting.


Any ideas would be extremely appreciated!

[Gokussj5okazu]

Anyone with suggestions?

I fired it up today, and it was still running terrible of course. While it was running I unplugged the MAF, and it did pick up the idle and smooth out a bit. I did this a couple times to confirm, and it did smooth out every time.

Bad MAF afterall?

[jdm213]

have u possibly checked ur fuel pump and filter maybe hesistating for fuel and u definatley have a MAF problem i would try another MAF to see if it runs smoother whith the connector on rather than unplugging it

[Gokussj5okazu]

Thanks for the suggestions. I took a good thorough look at the MAF, and found a break in the ground wire. Fixed that, and it's back to running ok-ish.

I used the ECU diagnostics to determine that there's no codes, all sensors seem to be working properly, and it does enter closed loop above 1500RPM. It runs very well above, say, 2K now, but I still have the bad miss at idle.

Does a leaking or restricted injector sound plausible? I do notice though, that when it's missing very badly, it smells very rich.

[Hardie]

If its only at idle there is a good chance it is your IACV.

[JDMRIDDAZ]

Thanks for the suggestions. I took a good thorough look at the MAF, and found a break in the ground wire. Fixed that, and it's back to running ok-ish.

I used the ECU diagnostics to determine that there's no codes, all sensors seem to be working properly, and it does enter closed loop above 1500RPM. It runs very well above, say, 2K now, but I still have the bad miss at idle.

Does a leaking or restricted injector sound plausible? I do notice though, that when it's missing very badly, it smells very rich.

hey the resons ur not getting codes r because its voltage to sensors
or fuel issues dirty injectors or bad gas because these cars have steel tanks
if i were u check output voltages of eccs relay
relay wires r
blk/wht=12v ignition
red/blk=ground
x2 red=12v to injectors and ecu
and voltages to the engine harness....
iacv selinoid
ignition coil
etc....u can find these corressponding wire guide in frsports sr wiring guide
also make sure fuel pump is also getting 12v at blk/yellow at pump
ive fixed this on at least 50+240sx here..89-94
and 9 time outa 10 its voltage or age that make bad voltage issues

[Gokussj5okazu]

Thanks for the suggestions. I'll check the voltages going to everything just to be sure. I know the voltages to the MAF and ECT sensors are ok, as I checked the last night.

I have a new issue now though. It was running relatively fine last night, but when I took off this morning, it was running absolutely terrible.

When I first start it, it doesn't maintain a high idle at all, immediately dropping to ~800RPM. Then it will idle search back and forth between 500 and 1000 or so, and actually died on me twice this morning while idling.

If I rev it up a little, around 1500, it putts and drops off randomly. Sometimes it's every second, some times it's ok for a bit.

Then, the last part of the problem it that it will not rev above 2500RPM, AT ALL. It doesn't bounce there like it would at a rev limited, but when it hits 2500, it cuts out, but bounces to 3000, then back to just below 2500.

This thing is getting really frustrating, especially since it was running pretty damn good last night!

[kennedy8383]

You said the car misfire then you have a problem within the engine bay..

It could be a bad wire, ignition coil or other part of the ignition system, a fowled spark plug, vacuum leak at the intake port, bad injector, or low cylinder compression (bad rings or warped or burned valves). A cylinder needs three things to fire, proper fuel mixture, proper spark and sufficent compression. If any one of those are not present, you will get a misfire. Car need to be check up again..

[Gokussj5okazu]

Thanks everyone for the help so far. I found that I had another broken wire going to the MAF so I repinned the connector and got that all fixed. That fixed the bogging and RPM limit, but the miss is still there.

Well today I decided to check my timing. Now ever since I built the motor, Ive known the dizzy was 180 out, so i just swapped the wires. Well I pulled the timing cover today, and the cam is good. Dead on TDC .

However, if I align the dizzy rotor at #1, the crank pully shows 40* advanced!!! I don't understand How it's running that far out...