No power

[youngmanvr4]

I haven't set the timimg to 20 yet. I'll do that as soon as I can find my timing light.

I'll get a new fuel filter since they're like $5 bucks at AutoZone.

Do you think I should check the vacuum pressure or whatever the right term would be?

If the 02 sensor wasn't working would that mess it up? I think it is but you never know.

It was idling really really bad today. I'm not sure yet. It was really cold today but even after it warmed up it still idled rough and acted like it was going to stall...it almost did a couple of time. But this was the worse its been.

I haven't cleaned the inside of the MAF yet. I'm trying to think of anything else I haven't done?

[deviousKA]

Sounds ecu related to me, especially since the ecu was changed, and hasnt run properly since.

Make sure the ecu harness connector is tightened down all the way, and that both edges of the connector are pushed in. This ecu connector is notorious for not making proper connection unless it is fully seated.

After you check that, start your car back up and run it for a while. Shut it down and run the codes. If you do not get a code 55 (all good), continue to suspect ecu issue. The ecu may be from a california model in a federal car (or vice versa), or something similar. The ecus themselves rarely have a problem unless wires were shorted or have gotten wet.

Make sure that you are checking the codes properly, if your not getting a code 55, or other problem codes, continue until you do.

[DjPantsSpecR]

what a guy, devious even took the time to read thye entire post and notice something we hadnt already....

bad idle problems are hard to find, but if it happens after youve already stopped adn its idles for about ten seconds, then im fairly sure its vacuum related, but then again i have this problem occasionally on my rebuilt motor, adn i cant find it just yet....

deviousKA, im gonna assume you dont need my 95 ecu, but if the offer still stands it still is free

[youngmanvr4]

Ok so code 55 is a good code? I'm not sure how to check codes.

[deviousKA]

Unbolt your ecu from your kickpanel and lay it on your floor, with harness connected. Look at the side of the ecu that has the the diagnostic light and there will be a knob to select the diagnostic mode. Turn this knob fully clockwise with a screwdriver until the diagnostic light flashes 3 times. After it flashes 3 times, turn it back fully counterclockwise. The ecu diagnostic light should now blink with your codes.

5 long blinks, 5 short blinks = code 55 (no problem codes)

Do this with your key on after you have let the car run for a bit so that the ecu has a chance to pick up and potential problems. In other words, dont try it right after you have removed your battery connection, otherwise it wouldnt have the chance to pick anything up.

If your not getting any flashing codes out of it, continue until you do. If you get a code besides 55, write it down and reference to the fsm.

DjPantsSpecR, I wouldnt mind taking that ecu off your hands for hack purposes (daughterboard design). Thing is, I wouldnt want to take it for free, and I dont really have the time I used to have for this stuff. I am out of state this month, when I get back to my place I might hit you up with an offer/trade. I cant think about it much right now.

[youngmanvr4]

Well I ran the car and drove it for about 10 minutes. Then turned the knob fully clockwise but it didn't not flash at all. So I waited for about 10 seconds and the turned back counter clockwise and got code 12. Thats the only thing I got. If I read right on the FSM thats Mass Air Flow sensor circuit. I know thats the code I got becuase I let it repeat about 20 times to make sure. I even redid it by turning the knob clockwise, then back (the light would just stay on when I did this), then clockwise about 5 seconds then back counter clockwise and get the same code (12). Did I do anything wrong? Anything else I can do?

The MAF hasness seems loose and if you look at the harness it only has 3 copper/silver pieces that you can see as to the 4 holes of them that there is (the MAF has 4 also but the harness only has 3 wires that you can see looking in it).

I have a couple pics I just took to show you.

[deviousKA]

You did it right, I forgot that some of the de ecus do not have selectable mode 1 2 3 4 or 5, and the knob is for code reading only.

The maf harness connection is correct, 3 wires only. The connection looks clean, so what I would suggest you do is measure the output voltage of the maf at idle. You need to get a voltmeter and measure between the black wire and the white wire at idle (not to be confused with the black wire w/white stripe, dont mess with that one). The black is ground, and the white wire should put out .9-1.5v at idle. With the engine off, key on, the maf should put out around .8-.9v

BTW, the maf connector should be plugged in when you do this, probe the back side of the connector with voltmeter. And just so you know, the black wire w/white stripe going to maf is direct 12v feed, which also feeds the ecu 12v.

[youngmanvr4]

With the key on, engine off it showed .80 then it went down to .60 then .40 it would go down all the way to .28 and stay there. We saw it show .80 two times. We tried turning the key off for 10 seconds then turning it back on and it still did the same thing. .80, going down to 0.28. It would only stay on 0.80 for less than a second right when I turn the key on. Then we started it at idle it went right to 1.61. I cycled just alittle by maybe .01-.03 up or down...but not much. It pretty well stayed at 1.61. Something funny that happened is when we pressed down harder on the harness it would idle a little better. Just having the ends of the volt-o-meter lightly sitting on the harness (not applying much pressure) it would idle sorta rough like it has been.

Also when I was driving it today I would slow down or come to a stop it would almost die. In would words before I would even stop or coming right to a stop to would almost die...but I would save it everytime.

[youngmanvr4]

I did a little looking on the FSM and they say the output voltage at idle should be like 1.0-1.5 on the MAF. So now I'm again confused and dont know what to do to get my power lol. I'm going to try to see if I can get anymore codes today. But its 20 outside right now with a wind chill of about 10 with snow starting to come ice on the ground thats been there since monday and the snow thats already there lol. But hey...I just want my power...I'll do anything.

[youngmanvr4]

Well I just got back from driving it and it wasn't good. I started out driving it around town and all was good. Then I got out on the highway and it felt almost better then it ever has been before. So I got about 2 miles away from town on my little turn around spot. About 100 ft. from the turn round the car studders...it was starving for fuel it sounded like. So I drove the 2 miles back to town and I didn't think I was going to make it. I would get a couple fires then it would just sound like it died then the would fire a couple more times. It did this all the way back home. So I pulled in and started to pull some codes. I first got code 12 (Mass Air Flow circuit code) and thats all. Then I turned the knob back and redid it. Then I got code 55. So I redid it acouple of more times and still got code 55. Its running worse then it ever has and now I'm getting code 55. Whats up now?

I feel like its starving for fuel but I'm not sure why its doing this. Help!!!!!!!!!!!!!

[deviousKA]

Take a small pick and try bending in the female pins of your maf connector. Make sure the connection attaches well and does not wiggle around if possible. Continue to check codes, if your getting 55 and its still a pig, start diagnosing your fuel system.

[youngmanvr4]

If I do have to start diagnosing my fuel system where do I start with that and what all has to be done? I'll try bending the pins tomorrow.

[deviousKA]

fuel pressure, you need a fuel pressure gauge and a T fitting on your feed line.

Thats what I would check next, that is of course if the ignition components look ok (plugs, wires, cap, rotor).

Replace/swap the maf if everything is checking out, saving the most expensive option for last.

[youngmanvr4]

I already check the fuel pressure. At idle it showed high. It showed 42 at idle and 41-43 at higher rpm and it would go down to about 39 at deaccleration. What do these numbers mean? (Like is anything bad by these numbers)

[youngmanvr4]

I tried bending the male and female pins and it didn't help at all. I did try pushing down on the connector and after it did it didn't wiggle as much (normal amount, like all the others). So unless the wires are crap (I hope not) then that means I have a bad MAF? I mean I can just get a good used one on here for $35 and if that doesn't fix the problem then I can just sell it. That would fine out if it bad or not. The only thing I dont get is I can rev past 2.5k rpm. I can rev way past that. It just doesn't make since.

I tried pulling codes again and the only thing I got was 55. So I dont know whats up now.

I did drive it today and good thing is I didn't get the starving problem I had last night. But I still want to figure out why it was doing that. Do you think that something went really screwy with the MAF and it started throwing some weird readings so the ECU starved the engine for fuel for some reason?

[deviousKA]

If your maf is sending the ecu the improper voltage, the ecu will provide fueling/spark as if it were at a different airflow. The ecu relies on the maf to tell it how much air is coming in, it wouldnt pick up an improper voltage unless it was way out of the 0-5v range (or disconnected).

The voltage readings you were getting out of it seemed to be ok at a few points, but it should have raised more in voltage when you rev'd it.

It could be something else, but that is why the ecu might not show a code even if the maf is faulty. You were getting the code before because the connection was breaking, most likely.

[youngmanvr4]

So what that given info what do you think the problem is?

*Note* I didn't try revving the engine as I was testing the voltage. So I dont know what the voltage is when revving. Only with the key on and at idle. I forgot to test it when revving. Should I do that?

[deviousKA]

Ah, right, I see now that you tested it at idle.

Voltage seems good, check your fuel pressure and get the ignition checked out.

[youngmanvr4]

At idle it showed high. It showed 42 at idle and 41-43 at higher rpm and it would go down to about 39 at deaccleration.

This doesn't seem right to me. Could I have a bad FPR?

The only other things it could be that I can think of it could be is: set timing to 20 (I know its off right now), Check out TPS output signal (adjust if wrong), Check out coolant temp output signal. I'll check the spark plugs but I'm just about 100% sure thats not the problem. Other then that I cant think of anything.

I hope its one of those things.


Modified by youngmanvr4 at 9:03 PM 12/4/2005

[youngmanvr4]

Well good news. I have power...and how boy I have lots of it.

Now I bet your wondering what I did to fix it. Lets just a spark plug wires. We were getting ready to do the timimg and we decided to pull the spark plugs. Just FYI they were all ok. The number 2 cylinder spark plug wire does need to be replace sometime. As I'm doing it I'm just going to get all number plugs and wires.

So here was the problem. You all can luagh becuase I still am. It was something you guys told me to check first but it was something that Justin said should be ok. The firing order of the wires. When I was pulling the spark plug wires out I traced the wires to make sure they where all hooked up the right ones. #1 ok. #2 is in #3. #3 is in #2. #4 ok. So heres how it happened. When we picked up the engine all the spark plug wires were hanging out. My dad saw this and thinking like any car guy he nor I didn't wanted anything to fall in the spark plug hole going down the road. So he put the wires back in. I was looking at something else when he put them in and wasn't watching. It was dark and almost no light. So he put the first plug in right, but second and third he put in backwards and forth was right. So when we put the engine in the spark plug wires were already in there so I didn't think anything of it. So needless to say cylinder 2 and 3 had never fired since I've owned it lol. I was running on only 2 cylinders. What a goof. So thats the story. But I tell you what, it feels really good now. Its really quick. I'm in love. Now I only need my SSauto chrome dual exhuast and I'll be set. The idle is smooth and it doesn't stall or try to stall when coming to a stop. Thanks everyone that helped me out. And a big thanks to Dj and Gabe (deviousKA). I now know the car inside and out. I think I can fix anything on that car now lol. Now you all can laugh your heads off like me

Moral of the story: One happy 240sx owner!!!!!

[deviousKA]

Sounds good, glad you got it worked out. Get that base timing set if you havent already, important.

[InsanityInc]

In fact, with 11:1 CR, he may need to retard his timing a bit, or at least verify that his knock sensor is working very well.

[youngmanvr4]

Yea its at about 18 or so right now. I figure hey if its running good as it is right now why mess with anymore?

[DjPantsSpecR]

hey awesome to hear man, i'm definately jealous....

its a damn shame we were all too stupid to talk all day about ignition adn the like, but never say anything about checking plugs.... thats why we need more noobs answering questions, they woulda got it.

however 240s are all about learning and learning only happens from mistakes. so tell your dad to learn! just kiddin, have fun man

[mackdaddy240]

LOL, Cant believe it was inproper firing order the whole time! Well I'm glad you finally got it running right, be careful though if your only running 91 make sure the timing is not to advanced it does detonate when it gets hot. Should be safe in this freakin 10 degree weather!! But dont feel to bad, after I installed new plugs in my sr20 I forgot to plug in the coil pack by the firewal so I drove my car for almost 2 days on 3 cylinders wondering why it was running crappy. Then I remembered to check the coil wires and duh. maybe I'll get a chance to race my old engine someday

PS dont by XS exhaust systems! they're **** I bought a header from them and it started leaking on a weld right in the middle that you cant get to practically since day 1. I trust obx more then XS honestly. My friend has a turbo ka and he bought XS headers for it, they leaked around the gasket, and cracked, so just thought I'd let u know to be careful.But its good to hear it finally runs right and it was someing simple and FREE to fix.