240 misfiring, please help me

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

ok, so i went to get my oil change, on the way home, my car started going goofy, the rpm's would jump all over the place while i tried to accel, or after shifting, so i went back to the mechanic, they said its definately misfiring, i changed my plugs to bosch spark 4's a week ago, i added engine cleaner to my oil a few days ago, and i also added fuel system cleaner to my tank today, at about half full, then filled up afterwards, so im assuming its an injector? how do i tell if its bad? i've been told to use a multimeter, and how can i tell if a used injector is good withough being able to test it in a running car? thanks in advance

P.S. my car's got 123k on it, and i doubt its had an injector job

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

if it were my car i would start by throwing the bosch plugs in the trash and getting some NGK's . and recheck it. but if you wanna check your injectors take your dvom set it on ohms and check all your injectors. the exact reading is really not important but that they are all about the same. you do this with the car off and injectors unplugged. if all those readings are good. check you wires cap and rotor.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

thx for responding, im going to get NGK's when i find a decent price on em, the stores want a good 12-13 for em, so, but if anything, i can put my old ones in, those are ngk R's 9are those stock?) im gonna go get some junkyard injectors while i wait for a new one to come in

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

check your injectors first dont just assume they are bad.ngk's are stock and damn good ones at that.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

ok, so i checked all the injectors, all of em read 11.5 on the 200 ohm setting. i changed the plugs back to the ngk's. i let the car warm up fully and then reved it a bit, still same reading. all the sparks have the same coloring and all. what would i look for in the rotor/cap/wires?

also, the injectors are clicking pretty loud, especially around the #3 cyl area, also it possibly doesnt rev as freely

ok, new update.... i left the car out and the sun warmed it up a lot, i started it, same thing, not as sever as the other day, but still misfiring

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

electrically your injectors are ok. visually look inside your cap for corbon tracking is it the original nissan cap or is it aftermarket? the aftermarket caps made in italy are junk. i re read your first post and your update to the last post. on the first i noticed you had the oil change and it began afterward. check your oil level if its to high your crank shaft could be slamin into the oil. on the update post temp seems to make a difference. so check your coolant temp sensor for corrosion in the connector and take a ohms reading on it.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

well, the car was pretty hot when i went to get my oil change, but i dunno. the cap looks fine. here's one thing that mihgt be a possibility.... i pured some engine cleaner into teh fuel tank after i filled up a bit, but i put in a bit too much, so i added some more gas to mix it better, is it possible that cause it? it happened the same day. i got home, out the injector cleaner in, got my oil change, started driving, and boom, it started misfiring

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

no the fuel additive shouldn't have any effect on it other then a possible ping on accel due to the very high octane that stuff has

Post by **p00t** » Fri Jul 18, 2003 2:08 pm

ive heard bad things about oil additives, be careful.

i used valvoline fuel treatment in my car in my last tank of gas, it definately affects your car a bit. i poured a whole bottle in and filled up. the bottle says recommended for 20 gal. my tank is 16 gal. It would miss periodically, so i did a bit of spirited back road driving and used up as much gas left as possible. filled the tank with new fresh gas... symptoms gone.

did you put the whole bottle in? i really think you and me need to pay attention to how many gallons the whole bottle treats :pface . also i strictly use 93 octane Mobil gas, which has a certain amount of detergents in it already. I guess it was a detergent overdose eh? maybe the same with you?

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

how can a bad temp sensor cause misfiring? im gonna try checking the injectors after the car stars missing, maybe that'll turn something up. any other reasons that it would misfire? plugs are good, so is the distributor. also, the misfire symptoms would only really show when i gave it gas up until i reved it kinda high, then it would go away, but still feel kinda slowish

Post by **InitialDGuy** » Fri Jul 18, 2003 2:08 pm

From what I was told, if the coolant temp sensor is faulty, it could cause the ECU to have the injectors dump to much fuel into the combustion chamber. This is what I thought was causing my car to run terrible. The sensor turned out to be faulty, but it was actually a bad fuel injector that was causing most of my problems (Although having a bad temp sensor probably didn't help). If you want to check yours, be sure that you check the one with the red ECU-type connector, and not the smaller one with the single prong black connector. The sensor in question is the left and larger of the two. I am sure that NISTECH will correct me if I am wrong though. Guy certainly knows what he is talking about.

According to the FAQ, you can test it with a digital volt/ohms meter (Thats what I did) 68 Degrees 2.1-3.0 ohms, 122 Degrees 0.68-1.00 ohms, and 176 Degrees 0.30-0.33 ohms.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

yea, the car seems fine now, been running good for hte past 2 days, no crazy tach needle dances or nothing, no lossof power, except for bad timing, but yea, im gonna check out that temp sensor, i think it may be messing with my ecu... thanks, post back later

Post by **[Zero-S]** » Fri Jul 18, 2003 2:08 pm

wow look our cars must be joined at the hip cuz mine just started doing this too.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

ok, so it happened again... the car started misfiring. after driving for a while, aprox 10-11 miles, normal driving, it started again. it feels very jump and it lurches so much, but only under accel, when i have the gas at a constant just to maintain the average 40 mph, it doesnt do that. would it be possible for my TB to be fluttering or something like that?

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

is there any oil or moisture in your spark plug wells? did you check your intake boot for any cracks? check your air flow harness too. try wiggling the harness at the back of the engine.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

is it possible for aninjector to go bad when the engine gets warmed up? the guy at NAPA said something about a hot soak condition but didnt bother to tell me waht that means

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

yes electronics are sensetive to temp. check your injector resistance with the engine warmed up.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

i checked the injectors when it started backfiring/mispiring, wahtever its doing, and they all read 11.5 again, even with the engine hot and thats right after i parked, so not that, trying to find the temp sensor (chiltons drawing is kidna bad)

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

front of the intake manifold near the coolant bleeder screw. 2 wire rectangular sensor red or yellow sensor

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

did you check your air flow harness,and for moisture or oil in your plug wells? and your intake boot?

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

i havent done that yet, i read the codes off the ecu finally, it gave me a 95, meaning the crank position sensor, could that be doing it?

edit: this it what it says in the faq's on 240sx.org Crank P/S (OBD) Cog 95 EC-174

there is another one, which i didnt get: Crank Position Sensor (OBD) 82 EC-167

i called up a dealership parts dept. and they said that one cps is the distributor and another one is a magnetic thingy in the bellhousing, andi have no idea which. also, there's a nice $400 price differance

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

the one on the bell housing is the cheaper one the one in the distributor is the expensive one. yes this will cause the problem your having. pull your cap off remove the rotor. undo the 2 screws in the gold plate lift the plate off and "VISUALLY" look at the silver wheel with all the little notches in it. all those holes should be clear of any debris,including spider webs, if there is ANY foriegn material on it it will screw up the ecu's abiltiy to properly moniter the position of the crankshaft. I am going to try and get to the site you mentioned and see if those codes are converted to OBDII codes i use and not the blinking light codes i dont mess with.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

ok, so i checked the wheel, its clear. could it be the smaller magnetic one, or could the distributor sensor going bad when it gets hot?

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

the site was no help to me so i dont know for sure which sensor it is referring to. and i will not have access to the fsm till next monday on vacation this week. yes it could be but if it was having that kinda prob i would think the car would just flat out die.have you done any clutch or trany work on it lately?

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

nope, no trans work, it doesn that even if its in neutral

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

well you have narrowed it to the cause of the problem. but not sure which one it is. with out a service manual it will be hard to determine which it is the code reffers to. you wouldnt happen to have a dso would you? you could look at signals from both and see which one has an inconsistant signal. if you dont have one dont even think of buying it to check this .they are more then both those parts combined and the labor a shop would charge you to replace them. I know i have one.

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

i went to the junkyard, but no s14's there, so i could get a diff distributor, and a new one costs around $500, i got $460 from courtesy nissan, im gonna go see a mechanic tomorrow maybe, see waht he can tell me, but i dont know, my friend had a crank position sensor issue on his sebring, the car would run but it would go in reverse (i'd just die, and it wold die sometimes on start up and accel from a stop), but my car only does this when it gets warmed up, so that boggles me

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

ok, so i got the code translated by Nismo_freak and here it is:

P1336 (OBDII Designated Consult Code)

Crankshaft Position Sensor

- The chipping of the flywheel (or drive plate gear tooth aka cog for an auto) is detected by the PCM (ECU).

Possible Causes - Harness- Sensor- Flywheel (Drive Plate)

The CPS is located on the transmission housing, facing the teeth of the flywheel or flex plate.

Testing the Sensor:1. Pull Sensor2. Inspect of Visable Damage3. Measure Resistance Between Terminals on the Sensor

Resistance should be 167-204 Ohms @ 68 deg. Fahrenheit.

the thing is, i noticed that when i shift in the lwoer gears, the car tends to jump lightly twice adn then it drives smoothly, i was told its probobly because of hot spots on my flywheel. maybe thats creating some of the problem?

Post by **NISTECH** » Fri Jul 18, 2003 2:08 pm

did you check the sensor as indicated by nismo?

Post by **matt4pl** » Fri Jul 18, 2003 2:08 pm

no, havent had the time yet, but i will today probobly

240 misfiring, please help me

240 misfiring, please help me

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