240 running really rich

[mofeel]

Hey guys i got a problem with my 91 240sx, its running very rich and throwing code 12 for the maf sensor. But i dont wanna blow money on a new or used one and it not fix it. also noticed it has a different plug on the maf then whats supposed to be on it. Its also not wanting to rev past 4,000 rpm.

Here is a vid i took of the car running (not the best quality but it works)

http://s742.photobucket.com/albums/x...afilter=videos

Any ideas?

[compactfean]

Us the maf has a good power source, has a good ground, than there is something wrong with the maf. You might be able to fix it but no guaranties.
http://www.youtube.com/watch?v=V1ap7MSk ... ata_player

[mofeel]

yea im going to take it apart and check it out.

[biggie]

First thing to do, make sure its the correct plug/maf for the car/engine/ecu.

[mofeel]

heres a update on what i just done to the car. i just picked up a maf and a plug and hooked them up. ran a little different then before so i decided to reset the ecu by taking cables off the battery. going to wait a few hours and try it out. ill let yall know the outcome. but i did find out the maf was the wrong one. it was a nissan maf but it said hitachi on it and was a 3 prong. no idea what vehicle it goes to tho

[mofeel]

hooked the battery back up now the car barely runs, hesitating rpms between 0-500, hit the gas and it dies. with or without the maf hooked up. and i smell gas like crazy from the motor. any ideas

[moso]

First thing to do, make sure its the correct plug/maf for the car/engine/ecu.

I totally agree. Is this car a new acquisition? have you checked the ecu to make sure its the correct one for your ka, removed the cover and checked if its stock inside?

[mofeel]

Yea i jus got the car bout a month ago. And its been running hella rich the whole time. Im also smelling a little bit of gas in the oil as well

[moso]

in that case i would.... check the ecu, see if its stock. generally look over the wiring for any "modifications". pull the fuel rail, with injectors and fuel lines attached and key on to see if your injectors are leaking, then crank to check spray pattern (bring a towel and fire extinguisher, injectors are made to make fuel burn easily). change the oil, change the oil, change the oil, fuel in oil is very bad. check the ecu for codes following the procedure outlined in the fsm and go from there.

[mofeel]

Thanks moso, but what kind of mods should i look for?

[moso]

Spliced wires, cut wires, excessive amounts of electrical tape, zip tied wiring harnesses, ect ect.... really a stock 240 with a ka24de shouldnt have any "extra" wiring. the stock wires should be run to the stock locations....colors matching. to be honest it sounds like you have a leaky injector but i would still look over the ecu and ecu wiring harness to make sure everything is still connected.

[mofeel]

Ok ill check everything out in the ecu. All the wires are correct goin to all the components in the engine bay. Ill take a pic of the ecu also and post it to see if you can catch something that i wont. Since ive not went thru one yet

[moso]

to see if the ecu is chipped you will need to remove the cover, when looking at the ecu board the "chip" will be on a daughter card that is added in to the ecu on the opposite side of the wire plug, it is soldered into two rows of pin holes that are not used at the factory. if you look inside and there are two strips of silver dots opposite the wire plug with nothing attached to them, the ecu is likely stock. also note the ecu number and post it, it should be something like A11-B44 G70.

[mofeel]

Here are pics of the ecu. Doesnt look messed up to me.





I did go through for codes it brought up the maf again and now the knock sensor. I guess since its not firing. Will check the injectors out tomorrow. The fuel pump is kicking on tho

[moso]

yea that ecu is stock and is for your car/motor/trans combo. I would start looking for leaks in the intake system. its likely that your getting unmetered air in your intake system and its throwing the mix outta whack. the ecu is sensing a lean knock and is blaming the maf for not metering the air properly. just my $0.02.

[mofeel]

Yea it has got me stumped big time. But as soon as i wake up in the morning im goin to check for spark and fuel. Do you think i couldve put the ecu into a limp mode when i unhooked the battery cables? It ran before i done that

[compactfean]

Have you checked your fuses?

[mofeel]

Which would i check?

[compactfean]

Mainly all the ones under the hood

[mofeel]

I checked all fuses and they are good. Checked power to everything and they are getting power. Ill check the plugwires for spark tmrrw and see if the injectors are spraying as well

[mofeel]

sorry it took so long but it is getting spark like its supposed to and is running still ( the plugs were fouled out thats why it wouldnt start) but its still running rich and has a idle of 2k. i put a new fpr and all new injectors with o rings. didnt help at all, other than my spark plugs are only getting black on the tips now and not the full plug that screws in. Also done a comp check and on a cold crank here are the numbers

1-150
2-148
3-160
4-161

so my compression is good. also feeling alot of air coming from in between the first and second injector. any ideas?

[moso]

....so my compression is good. also feeling alot of air coming from in between the first and second injector. any ideas?

you may have an intake leak, what are the hoses and vac lines like that run under your intake manifold? are your injectors seated properly into your intake? your very high idle suggests that the motor cannot control how much air is entering the motor at idle.

[mofeel]

right. i havent actually gotten the top of the intake off yet. been trying to talk myself into doing it since there arent many at "how to's" on how to do the removal.

[moso]

the whole thing comes off as a unit, you cant really take the top off without taking off the bottom with it.

[mofeel]

Ok i got the intake and exhaust manifolds changed. Along with a new cap, plugs and wires. Just throwing the maf code now. But it will rev to redline with it plugged in.

When i drive it 1st and 2nd gear cruise itll start jerking. But if i lay into it its fine til 3rd gear at around 3500rpm.

But if i unplug the maf it runs and idles like its supposed to. But if i rev it it cuts out.

So should i try another maf perhaps?

P.s. i checked fuel pressure and it was right on the money.

[moso]

240sx mafs have been known to break the solder joints inside the unit. It may be worth it to pry off the plastic cover and check the leads.

[mofeel]

K ill check them out

[mofeel]

I took the plastic piece and pried the copper tin looking piece. It was kinda black on one side and the actual circuit board was corroded. I sprayed it with maf and brake cleaner and didnt help any. Even took a wire brush to it and cleaned off as much as possible. So it looks like i need to find a good working maf.