Engine problems...

[scyan]

Hey guys, once again I’ll have to refer to you guys and hope you can give me a hand on a small problem I have. Recently I cleaned my MAF and I’ve been having a rough idle since. I cleaned it with some intake cleaner I got at Canadian Tire. I changed the spark plugs recently too. So, on to my problem. Last night when I started my car, it revved up to about 3k and then died on me… I restarted and it went very very low and then stabilized at around 650 700 rpm like usual. Also the engine misses a lot in the lower rev range. At higher rev speeds it’s ok but it doesnt seem really eager to rev up. It seems to die at high rpm… Anyone can give me a hand ?

Scy

[Silvia007]

I don't know if this will help but replace the braided wire behind the motor on the driver side. It's heavily braided with a plug in type connector that connects to a metal plate bolted to the chasis and the other end is connected to the block. Replace if you haven't, I've done it and it solved lots of small kinks in the motor at low RPM. I just used some 12 gauge wire. I suggest just do it, it can only help.

[GodDrivesA240sx]

hmm..well maybe you caused the maf sensor plug/harness to come disconnected a little, when you were cleaning it, and it's not making a good reading. Try moving it around and make sure it's plugged in all the way.

[scyan]

I noticed the braided line is unconnected. I know that because I changed the valve cover gasket last week and the last one that changed it left it between the block and the gasket so it was leaking there. It was unplugged and inside the valve cover. I took it out but didnt know where it was supposed to go so I left it hanging... maybe i`ll try an locate that plate you're talking about.. should it be easy to see ?

thanks

[Silvia007]

Yeah, it's quite easy to see, if you follow the right edge of the valve cover along the top all the way to the firewall/wall where the brake lines are, it should be right below the brake lines bolted in place with a 10mm bolt. It's pretty critical coz if your engine isn't getting enough ground, your sparks will be weak and that's one of the main paths for proper engine grounding and can cause lots of engine problems.

[scyan]

wow, I did lots of mechanics myself... but this one, thanks Makes a lot of sense.. I `ll look into it today and let you guys know.

Also my transmission seems to get harder to shift, I dunno why, It feels like it`s stuck in molasse or something... I`ll try changing the oil.. I can feel the synchros when I shift but they dont crunch... kinda hard feeling to describe.. Might have something to do with my firlfriend learning to drive 5spd.. hehe

Scy

[onosqv]

Hey scyan, I've been having kinda a prob like yours. I've just cleaned my MAF last month and replaced the distrib cap, rotor, spark wires, and plugs last week. I still get a problem when going from a stop light tho. Once I tap the gas, the car hesitates, the RPMs go waaayyyy down and sometimes it fluctuates. Then After long enuf, It finally jumps and goes. It's a pretty scary feeling when I'm trying to make a right turn and trying to beat traffic comin down and my car is like half way in the lane hesitating! . I was wondering if you guys had any suggestions on my prob. Could it be the grounding wire too? thanks a lot guys.

O yea, if it is, do I have to buy a special wire, like a certain type from an auto place? or just any 12 gauge wire will do?

[GoofyATX240]

By any chance do your RPMS come close to dropping to 0 when your stopping or stepping on the clutch sometimes??Some of that hesitation could be with the IAA valve the deal that the IAC and AIC i think all hook into it.Try cleaning it sometimes helps.

[Silvia007]

Well, my 91 240sx (auto) would hesitate then die every time I stop at the stop light or stop sign. I replaced the grounding wire with negative battery wire and everything worked fine, on my 93 240sx, I didn't have the same problem but just changed it anyway and you could tell the car ran much much smoother. Like I said before, I would recommend just changing even if it seems like it's not going to do anything. I recommend 12 gauge as the minimum size.

[240FeVeR]

Intake/throttle body cleaners are very oily. You do not use this to clean your MAF sensor. The MAF sensor is very sensitive. You may think you're doing it a favor by cleaning it, but if you use intake cleaner, you're probably making it more dirty than it was originally.

Take the maf unit out and clean it with a q-tip and rubbing alcohol. This is an effective and proper way to clean it.

[onosqv]

Cool, I'll check the valves and the wire out.

Silvia007, can you give me some instructions/details on changing this wire by myself? I'm not very mechanically inclined . Where would I even find this wire? Is this something I would be able to do myself? Sorry for the stupid questions, I swear I'll learn how to maintain my own car sooner or later .

240Fever, the dood who cleaned my MAF used a qtip and rubbing alcohol . I want to do it myself but I'm afraid I'll do more harm than good.

Thanks guys.

[Silvia007]

Brokeas240sx... hey man, don't sweat it, we all start somewhere.

Well, it's quite simple, I prepared a photo, let me know if this helps. Copy the link and paste it into a new browser window.

http://www.angelfire.com/mn/Isamu/carstuff/ins.jpg

As I said earlier, from the center of your valve cover, look to the right where it curves down to form the edge where the the sparkplug holders are bolted down. From there, go all way way towards the firewall (towards the rear of the car) where all the brake lines are and in that area, you'll notice a finely braided wire probably green from corrosion as it is copper. The part that goes into the wall is held in place with a plastic peice that you can squeeze to release it from the braket it's clipped to. The other end is bolted to the engine head right below the valve cover towards the end of the motor (where transmission and engine meet). Take out that wire and construct one like I have in the photo. Put that in place. It would be nice if you could take off the braket that's bolted into the wall so that it's clear of any rust. Use like a metal brush or sand paper to clear the rust by where the wire is plugged into and where the bolt is used to hold the bracket to the wall. When that's done, use die-electric grease (You can pick this up at any auto parts store such as napa, checkers, pep boys) on the braket so that it will be more resistant to rust. After that, hook everything up and you're done.

[scyan]

Hey, I think I put the finger on something today, Remember I had some engine missing problems, well I changed the grounding wire and now I found out something else. It seems the engine isn't missing at all when it's cold. Anyone can give me tips on this ? What should I be looking for if engine goes well when cold ? But misses when warm...

thnsScy

[Silvia007]

well... what are your plugs heat ratings. I have a friend who owns a 2002 WRX and when he put in some high heat (stands a higher temp which I think means it runs colder) and his motor misfires when it's at normal operating temp. He took it to the dealer and it took them 3+ weeks to find that his plugs are running too cold so it misfires. That's the last ounce of knowledge or info I can dig up in my head so I suppose it's worth considering.

[scyan]

I didnt even know that the plug temperature could actually produce a misfire. I'll have to take a look into this. How do I find it out ? Is it like the last digit of the plug number ?

Anyone else has any other info on an cold engine running fine but then when it warms up it turns ugly.. hehe

Scy

[onosqv]

hey silvia007, great picture! , I was able to make the ground wire, but I couldn't get that bolt on the engine to loosen . I tried for 1 hr and it just wouldn't budge. I'm gonna try to get a better ratchet or something because i had to use the "screwdriver like" version and a wrench to try to get it out, maybe that's why. My 1/2 inch socket won't fit onto the ratchet so maybe I have to get a different extension.

Scyan, I think my car misfires much more when it is warm too, very good observation . I don't really know why this is either, but someone told me they had a similar problem (on his celica) and it was either is head gasket (or something) or his fuel filter, he doesn't really remember what he changed, just that he had the problem.

My car has seem to stop doing it, at least today . All I did was take my spark plug wires out and put them back in when I was trying to loosen that bolt hold the ground wire to the engine.

My problem is erratic though, sometimes it happens sometimes it doesn't. I put it into neutral & (drive w/ brake parked) and revved it like crazy trying to get it to go crazy so my buddy could check it out, but it seemed to be fine yesterday (don't know if that has anything to do with anything).

I have a temporary fix for your misfiring problem though . What I do when it starts acting up at stop lights is throw it into neutral, then rev it up to like 2000 or 3000 rpms before the light turns green (check our cross traffic light) and put it into drive again when it's below 2000. This helps out ALOT with that RPM dropping thing. So until we find a solution for your and probably my prob, I guess that's all I can suggest .

P.S. just out of complete curiousity for anyone: If you take that ash tray out in the middle of the car, there are a few wires running back and forth. For some reason, if I move them just right, My car door locks would lock or unlock or get stuck in between. Do I have bad wiring? thanks.