240 loses all power once hot

[elvis240sx]

ok, the car is a sohc 240sx.

changed the fuel pump last week, car ran beautifully for 3 days. also, new timing chain, plugs, plug wires about 3 weeks ago.

im driving back to school from home, which is about a 3 hour drive. drove the car for an hour, and took a break to eat. drove for another hour, and had to get off of the thruway. when i took off after the toll booth, the car had lots of problems. when i stepped on it, the car felt like it did a nose dive and the engine sounded like it stopped completely. it was jerking back and the exhaust sounded like the car was underwater and slowly drowning. i couldnt gain speed at all, probably took 30 seconds to hit 50mph. the weird thing, was that the rpms seemed to stay right where they should be.

i shut the car off, looked around and didnt see anything obvious, and started it back up after about 1.5 minutes and it ran great again, for like 20 minutes. continued to happen. each time i shut the car off, it would run fine but the amount of time if ran well for got shorter and shorter.

we finally made it back to school after a long time, and i had it checked out. the guys said my timing was way off and they fixed it. took the car out today and it ran better than ever for about 45 minutes, then started doing the same thing. im not sure what to check, it seems weird that it takes so long for the problem to happen, then clear up if the car is off for literally one minute. any help is appreciated!

[NISTECH]

check your wiring harness along the valve cover with the car idling push down on it and move it forward and back see if it makes the idle stumble. you could have cat back up too but it should show it self alot sooner then 45mins. check your air flow harness wiggle it too see if it effects idle quality.

[elvis240sx]

ok heres what happened.

pulled the cat off the car, perfectly clear.

they pulled the codes from the ecu and got code 13 which is engine temp sensor. i just replaced the coolant temp sensor the day before. are they both the same thing, or is there a different sensor which its saying is bad?

the bad code was deleted from the ecu, and i took the car out again. after about 20 minutes the problem came back just as bad as before.

what else should i be looking at? we have comfirmed that the problem is: once the car is driven for about 5 minutes, whenever the rpms go over 3500 during load it will get a huge amount of fuel and not be able to handle it all. the car bogs and sputters, but once you get up to speed and the rpms are lower (around 3000 or lower) it runs fine except for going up hills.

any help is appreciated, i really need this car by friday! guidance is any direction would be great

[elvis240sx]

ok i just took the mafs off of my friend sohc 240 and put it on my car. it idled a little better, but still had the same problem. checked the ground power for the maf harness and they were good. the output volts was around 1.4 to 1.5 v. this helps narrow it down but im still lost here!

[NISTECH]

did you check the harness along the valve cover yet??\ the temp sensor the code ifs for has a 2 wire yellow or red connector

[elvis240sx]

ok i wiggled all the harnesses and nothing helped. put in new o2 sensor and it didnt help. disconnected the battery, waited a couple minutes, didnt work either. we are out of ideas here. anything i should look at that im overlooking here? i guess its too late to get it fixed for the weekend but it would be nice if i could at least fix it soon. also tried a new tps and that didnt fix the problem.

[NISTECH]

check your rubber flex boot to the throttle body look between the folds for a split in the boot. the time and heat factor involved though strikes my curiosity. I have seen this type of behavior from the coil on altimas but never on a 240. the noted conditions as to when it happens and the decrease in longevity each time you restart it is the biggest charicteristic. also distributor caps made in italy seem to cause all kinds of problems for any nissan so look at that too.

[elvis240sx]

OK put on new distributer cap and rotor since they actually were pretty worn and dirty. Threw on a new coil just for the hell of it because we are stumped! The car fines and idles better than it ever has, it just wont work under load. It still smells like its running rich and when it is acting up under load has kind of a funny burnt smell. Any more ideas?

[p00t]

do you still get the temp sensor code? it has to be it.... engine wouldnt mistake that for another problem. What was the reason you replaced the temp sensor in the first place? its possible you hooked it up wrong, its the wrong part, or its faulty.

If you had a mechanic do all this dont trust it to be done exactly right.

[NISTECH]

it sounds like it is loading up as if it has restricted exhaust. if you have some where you can drive it straight pipe to the higher rpm you can determine if you have something going wrong in your exhaust. when you took your cat off you said it was clear..did you mean there was nothing in it? when you run this car with out a cat or muffler it is gonna be hella loud so be prepared. also if this reveals nothing hook up a fuel gauge and rig it so you can see it when driving when it acts up check the pressure. also if you havent checked your boot yet do so.

[kevy8up]

hmmm...could this be an AIV problem?

[elvis240sx]

Ok I pulled the codes in diagnostic mode today, and it threw code 21: missing signal in primary ignition coil. the coil was in fact just replaced 3 days ago. do i have some bad wiring leading to the coil? or do i need to unhook the battery and let the computer get cleaned out? What should the wires leading to the coil have for voltages and which one is ground? thanks

[elvis240sx]

I have access to alldatapro here at school and spent spent some time searching around today. I found a test for what they call the "power transister". it is the bracket that the coil sits in and has a three wire connecter running to it. to test this, youre supposed to check for continuity with a DVOM between certain pins on this bracket. if the continuity doesnt exist where it should, the power transister is said to be bad. i unplugged the harness and tested for continuity but couldnt get any no matter what i did. can i assume that this is my problem? how much does this cost and where would i get one from? thanks

[NISTECH]

yes that would be your prob . that would be the decrease in time charicteristic of electronics as they warm up. dealer is probably the only place you can get it.

[elvis240sx]

what is that part called by nissan then? and how much am i looked at paying? thanks for your help

[NISTECH]

"power transistor" not sure on the price. if you have alldata you can look it up under the main page for labor . if it lists the labor time it also may have the part number and the approximate cost. some times its hard to find those parts in that section though. so be prepared to be there awhile searching.

[elvis240sx]

ok thanks nistech. nissan dealer where i go to school wanted around $150 for it, and said they needed the production date off of the door to order it. i assume i could just get one of these off of a sohc 240 and replace it? im thinking of looking at a junkyard or buying it from someone who swapped in a sr. thanks for your help, i hope this solves my problem!

[elvis240sx]

ok my dad went to the junkyard to find this part and they told him one off of a sentra would work. my chip says prw-1, but the one he got says prw-2 on it. will this still work? the coil looks identical, and the chip looks just slightly different shape and a different color, can i assume this will work? or will it just screw up my coil? the only reason i am asking is because he has to ship it to me since im not as home right now, otherwise i would try it. thanks

[NISTECH]

I wouldnt attempt to use it if it is different. not sure what the differences are but I am guessing the resistances might be different or the gating for the transistor may be layed out a little different. I wouldnt chance it.

[elvis240sx]

this chip didnt fix the problem. car still throws the code 21 ignition problem. is this a distributor problem? how do i test the distributor? i think the crank angle sensor is part of this as well? what should i do to see if this is the problem

[elvis240sx]

i also disconnected the negative battery cable and waited 5 mins to clear everything out, didnt help. should i delete this ignition code and see what happens?

[NISTECH]

that code is generated from the primary signal to the coil. and the 120 degree signal from the crank angle sensor in the distributor. do a good check for corrosion.

[elvis240sx]

ok the car smells like gas when it is running. at idle, i held my hand in front of the tailpipe and could feel the moisture, which smelled extremely like gas. ive been going through gas very very quickly lately, even just around town trying to fix the car. could the fuel pump i bought possibly be bad? someone mentioned something about the regulator in the pump could be the problem? it seems like the car gets way more fuel than it should. the idle is at a solid 2k, and wont go down no matter how much i adjust the tps or idle adjust screw

[NISTECH]

your not burning all the fuel going into the cyl. when raw fuel goes by the o2 it does not detect it as rich the sensor measures oxygen in the exhuast not fuel so if the fuel does not burn in the combustion chamber oxygen is not displaced as it would in a normal burn so the o2 precieves this as a lean condition and the ecm will add more fuel to try and bring the O2 down. hence the use of heavy amounts of fuel. you have an ignition problem did you get the right power transistor or did you use one from the sentra? You need to resolve your primary igntion code first then chase your fuel usage problem if it still exist after you address the spark problem which is most likely causeing the unburned fuel problem.