[jacjm]

misfire diagnosis and no start/hard start??

Can someone try to post a checklist (most likely to least likely) of ALL the causes of the hard start/no start problem ?? is ANYONE up to this? i am on my third fuel pump (2nd was a WALBRO). - 2nd fuel canister assembly, 2nd fuel pressure regulator (at the fuel rail), replaced the crank and cam sensors (x1), added my own check valve before the fuel rail, and yet the car is in my driveway and will NOT start!! all of these "fixes" usually last about 6 months, and then back to the same thing,,,2002 sentra GXE (1.8 l) is junk. it only has 95,000 miles, but has been doing it since 64K miles, when i foolishly bought it. yeah, it throws codes, but i have read them so many times, and they are usually different, that i don't even remember them. last one was a generic "misfire cylinder3". could the charcoal canister (and related emission garbage with it) be a cause ?? i know i have seen them codes occasionally, and that is one area i haven't fooled with. i am at my wit's end,,,i can't believe it could be more than 2 things happening at the same time, over and over. there HAS TO BE a root cause. HELLLLLP !!

 

[i68k]

the checklist is the fsm (factory service manual), you can download it around here somewhere for free, which covers the most common problems.

for your misfire, the ecu is detecting a misfire on cylinder 3, it could be circumstance from evap issues, or it could be a bad coil, sparks, crank sensor, etc. you could clear the code, if you get another misfire, and its on cylinder 3, you know where the problem is. if you dont clear the code, the next misfire maybe just random/multiple misfire.

most likely your evap issue, your 'related emission garbage', is what is causing your no start or hard start. with an evap code, youll know where to look. without evap codes, youll need to use a smoke machine to isolate the problem. your charcoal canister and sensors are only a portion of the entire evap system. because of various definitions of hard start and no start, it would be better to describe you situation. does the motor crank over? do you hear your fuel pump prime? does it misfire while cranking? does it start and stumble then stall? does the motor lose idle once it starts? etc

 

[jacjm]

wow that was fast! thanks for trying to help, i don't know what else to do,,
it started out as a hard start, progressed to no start. it turns over fine, and is always just about to start. it actually does start about 1 out of every 15-20 tries (after seriously long cranking times). i can't use it as a work vehicle because i don't know when/if it will start. last time i drove it, it started right up (has been since i put the check-valve in about 2 months ago) and drove fine until it started with a misfire, and sputter, shaking, cel flashing. but now, it is back to its' old ways, no start again. i checked the codes and got the canister evap, purge solenoid, vacuum cut valve, bypass valve, etc.,,all that "garbage". cleared them, drove it, cel started flashing and that is when the cyl3 misfire showed up, and the emission codes disappeared (for now) . i didn't drive it for a coupla days, (no start),, and i got it started this morning, let it run and the cel light came on--i am gonna go check it now. (11:46 AM) it seems whenever i get something "fixed" (or so i think), the actual problem that is causing everything shows back up- could be 2 months, or 6 months. i believe that i have some intermittent problem, and after i throw more parts at it, is when the actual problem lets it run good for a while. gonna check vac lines, too. i bought a used canister w/all the solenoids and sensors. i am gonna clean it up and bench test everything to install it and see if that helps. guess i will get an extra coil pack, too. the plugs were replaced at about 80,000 miles. i sure do hate throwing parts at a car, and hoping it works.

 

[jacjm]

OK, back to P0303, cylinder 3 misfire (i already switched the #2 and #3 coil packs, so the problem DID NOT follow w/the coil pack). could a clogged catalytic cause this crap ?? how about the IAC valve?. i cleared the code and tried starting it. after about 10 seconds of cranking, i gave the gas pedal half-throttle, and it started, with a strong smell of gas, this time. ---took it down the road. started mis-firing, and cel flashing, brought it back. read the code(s), P0303. now, my reader is a pretty high$$ reader, and the circles for the EGR, O2S, EVAP and CAT were flashing on it. any idea why ?? if there were problems in these areas, why don't i get a PRIMARY CODE ?? is a P0303 a default code?? (it DID say generic). that wouldn't/doesn't make sense. the computer is useless if that is all you get.

 

[i68k]

p0303 is generic, because many cars a p0303 means a misfire on cylinder 3
p0300 is random/multiple misfire

if your engine light starts flashing, its most likely related to something electrical, maybe not coilpack since you switched it. how are your spark plugs? 80k is a long time for normal spark plugs, i change my iridiums at around that mileage, so regular sparks may not last that long. so i would pull the plug and take a look, check the gap as well, but do not re-gap the plugs. it may be flooding cylinder 3, so giving it throttle just helps it fire up, you shouldnt need to use the throttle to startup. also, bad ecu do happen is funny ways, so i wouldnt leave it out of the question, but rather a last resort, the qg18 have the common ecu rusting issue.

with your engine misfiring, sputtering, and shaking, its most likely just misfire related. however, it could be electrical. make sure theres no oil on the coilpack connector or something, everything is clicked into place. i would start there, also just double check your battery terminals for tightness, check your battery voltage motor on&off, hopefully your battery amperage is still good from all the starting, get someone to jump the battery if its dying.

usually vac lines will get you evap codes, or a bouncing idle. o2s should just run really rich. if you smell gas, most likely your fuel pump/assembly etc is good, but i would double check the injector and stuff on cylinder 3 for leakage. usually an injector works or it doesnt from failure or clog. a clogged cat wouldnt make cylinder 3 continuously misfire, it would be random cylinder, o2 sensor, or cat code. same goes for the egr and iacv, they may be dirty, but dont always replicate the same cylinder misfire.

 

[jacjm]

i changed the plugs at about 80K miles, i am now at 95K, so the plugs have about 15K on them. i am gonna pull #3 anyway, and see if it is OK. i did a home DIY injector cleaning not too long ago. but i can pull #3 no problem. well you seem pretty sure it is electrical, right ?? at least that gives me a place to start. where is the ECU, so i can look at it, too. the battery terminals could use a cleaning, but i didn't want to disconnect it and have it trying to re-learn while i am already dealing with the start problem, and now mis-fire. i definitely hear the fuel pump prime, that has become second-nature now, after all the trouble i have had with it, too. last time i checked fuel pressure, it was good, but my "chinese (harbor) freight" pressure gauge quit (junk, too). i don't think it is fuel related, except maybe the #3 injector. i believe i will finally get to the actual problem, but i prefer to not stand back and shotgun parts and $$ at it. i need to find out where the ecu is, in case it is rusting away (?? how does THAT happen??) thanks for your help. having someone else working with me keeps me from dumping it in a river!!

 

[i68k]

a misfire is most likely electrical/ignition related, since it was detected by the ecu, however, it doesnt point to a specific problem or bad sensor, it is rather 'generic' code.

the ecu is under the hood, at the passenger side top of the firewall. you should see large groups of wires going into it. i would check this last, so you dont mess with wiring that you dont have to, unless you know what youre doing. i would check your spark plug and injector prior, along with your battery issue.

if your battery terminals are corroded, its sign of bad connection to the terminals, you should fix this issue, clean everything up and make sure you get better contact, remove all the corrosion and tighten so you cannot move the terminals with your hand, yanking on them enough to shake the car. make sure you ground to bare metal, reground it if you need to. many sensors are voltage related, its possible any random sensor could lose voltage and cause a misfire. you wont have to do any relearns, just take the key out of the ignition before disconnecting the battery, you may just lose your radio presets.

 

[jacjm]

OK, sounds like a plan. i just "fixed" a bad ground on my 95 taurus, and it cleared up some minor glitches. taurus's are famous for bad grounds. i also read a post about a guy with a start problem, and he said there is a common "rubbing" spot on the engine to ecu harness. i don't have the kind of luck to find something that easy to fix, but i need to look, anyway. i could care less about the radio. i WILL track this problem down, the big Q is how long, and how much ?? the sad part of all this: i sold a 2000 GXE (250,000 MILES, ran great), to get this. i did have problems w/the old one, but it would always start and go. the body was falling apart, but it went from point A to point B consistently.

 

[i68k]

the common battery ground is behind the drivers headlight, on the sidewall. there are grounds all over the place under the hood, usually a bunch near/on the timing covers. im not sure exactly on the location of the rubbing spots, but they are common among nissans. usually you can find them while the car is idling, while your are flexing/moving the wiring waiting for the car to stumble.

 

[jacjm]

OK, i have the main ground cable out (battery-body-engine). everything is dirty and corroded. hopefully this is at least part of any of the problems. the battery has always worked like a champ!! (guess that's next to fail). when i first went out this AM, i started it (STILL had to give it a little gas) and it actually started. with no CEL. It idled fine, then started stumbling. never turned on the CEL, tho. so now, i am grinding/scratching off paint and shining up where the ground goes. guess i will look at cyl#3 in a while.
put the main ground cable back- with everything clean, shiny and tight. it seems to be starting easier, lately (except for the half-throttle). guess the "problem gods" are gonna work WITH me, for a little while. so from a cold start, it idled fine at about 1400 rpm's, after warming up a bit, as it started idling down THAT is when the misfire/stumbling shows up. ring any bells ?? i am gonna go put some good gas in it, and see if the CEL light shows up.

 

[i68k]

the misfire codes will clear themselves if no misfire are detected. if your battery terminals were corroded, that may have been your issue, hopefully you got a nice ground contact now. corrosion on the terminals is sign of bad/insufficient contact, which could potential not supply adequate voltage to any eletrical components. potentially, a bad battery ground, will cause coilpacks to ground, when the coil can no longer ground, it will ground thru the ecu, rendering the ecu useless.

make sure your oil and coolant levels are good before you drive. take it for a drive, the ecu maybe correcting stored values, so it might stumble here and there, but not consistently stumble/shake. since you may still have something going on in cylinder 3, when the ses light comes on, pull the code asap. if the ses light is flashing, stop driving. its possible something wrong in cylinder 3 is making you startup at half throttle, hopefully your cam&crank sensors are working properly. you shouldnt need to use the thottle to startup the motor. it maybe possible that you have a bad headgasket thats leaking near cylinder 3, one way to tell is to pull the spark plug and see if theres oil or coolant on the top of the piston, otherwise youd need a compression test, then a leakdown test.

 

[jacjm]

OK,,,I GOT IT !!, AND, in my defense, i DO have too much on my mind. when i pulled the #3 spark plug, it looked WAY WORSE than just 15K miles. it was my OLDER (2000) SENTRA i changed the plugs in, before i sold it and got this one- sheesh, i am an idiot. so i put in NGK IRIDIUM series something-or-other ($9.00 per) and voila, no more misfire. no CEL, for now. runs like a virgin on prom night.
AND, I believe the hard-starting was partly due to the cruddy grounds, unless it just "happens" to be that i am on the "good" spot of my intermittent problem. may be the car repair gods are on my side, for a little while. at any rate, i have a lot of shiny grounds.
still have more to clean up, tho. and other little things. i will post back when/if the hard starting problem returns. thanks for your help and support, i68k. you seem to know your way around cars pretty good.

 

[i68k]

glad i could be of assistance, your new iridiums should last you a long time, at least double the normals life of regular spark plugs. feel free to create a new thread for your other issues

 

[jacjm]

this thread should probably have the title changed. it deals more with the misfire than the hard start.

 

[jacjm]

OK, after all this,,,,,i am back to running like doo-doo. code P0300, random misfire. i have a high-dollar code reader, and it also has the little evap circle flashing. wtf ?? is that all i get to work with ?? computer is worthless if that is all it tells me. just for ****s and giggles, i added 20 ounces of techron 3 fuel system cleaner, but it seems to have had no effect. what is it with these cars ?? it only has 94k and change. somebody help !!

 

[i68k]

not sure what code reader you have, or what the flashing circle means. if you had just previously cleared the codes, that evap system may not be 'ready'.

p0300 is random or multiple misfire, many misfires on one cylinder or multiple cylinders misfiring. do you feel the motor misfiring? say when you start it up when its really cold out? did you clear your misfire code last time? if you didnt, the next misfire will change from say cylinder 3 to a random/multiple misfire on the next misfire. does it have a steady misfire, or is it rather random? i know you moved around coilpacks, but have you changed your cam & crank sensors recently? these are common problems, and can cause random misfiring. how is your idle when the car is warm? hopefully your not getting oil in your cylinder 3 again, i would take a look and make sure theres no oil on the spark plug or coil pack. if theres oil on your piston, you have internal issues like bad headgasket, or fried oil rings.

EDIT: make sure you are installing/removing spark plugs when your motor is cold. you can use a little anti-seize on the threads as well, dont want one getting stuck.

 

[jacjm]

EQUUS INNOVA 3140 code reader, i forget exactly what it cost, but it was up around $200. it has too many features, really. extras complicate the simple things.
IF i get the car started, you DEFINITELY can feel the miss. it is steady at low RPM's, but seems to even out at higher RPM's. all the coil packs are back in their original positions, with the new iridium plugs. cylinders (piston tops) were clean. i never had oil in cylinder 3. dealer changed cam and crank sensors 8 or 10K miles ago. why am i not getting a more definitive code ?? i don't need an ECU to tell me there is a mis-fire,,,

 

[i68k]

cam and crank sensors are known to miss signals, which can cause a misfire. if its misfiring steady right from a cold start, its possible some wires are loose or you have failing coilpacks. coilpacks tend to only last 100k miles, maybe one or more is kicking out on you. when they start failing, its usually noticeable on very cold starts, they will misfire for 5-10 seconds before they start working, possibly youve past these beginning stages of coilpack failure. if this is your case, you either need new coilpacks, or you need to rebuild them. as long as your ignitor works, i believe you can rebuild them with new springs and capacitors.

i would clear your p0300 random misfire, once you clear this just check your ses light right away, it maybe a p0303 or something which can narrow down the problem, possibly get another ses code all together. backtracking, do you still have to 'half-throttle' to start the motor? have you done all 3 relearns in order successively (drive-by-wire only), maybe something didnt hold there? you did check your battery voltage motor on & off when you checked your terminals yes? any smoke coming from the tailpipe, black, blue, white, etc? hopefully you dont have a bad headgasket, or bad ecu.

 

[jacjm]

yes, i still give it gas (sometimes pumping furiously) to finally get it started. that is what leads me to believe it is fuel-related. then, a big puff of white smoke out the exhaust (unburnt fuel??). i haven't done any re-learns, guess i gotta research what that is all about. dec 24th i put sunoco 93 in it, and went on a long drive. it drives pretty good at about 55mph and up, as long as you are steady on the gas pedal, but if you let off for any reason, you can still feel the miss (sometimes bucking and sputtering, too). the starter is on its way out, now. too much cranking. haven't done any voltage testing yet. i can't find any time w/the holidays, and working so much (six 10's and an 8). plus, my girls car needs brakes-doing that today (merry xmas!). i will be able to look at it again later tonight. i will try to do what you suggest, but i can't take it apart too much, because i am gonna attempt to use it to go to work tomorrow, thru new years-i have no choice. thanks for all of your input, i will keep this post advised, and Merry Christmas to you and all of yours!

 

[jacjm]

i forgot--do you think water in the gas could be a factor ?? (my girl consistently used the "junk" cheapo gas). i think i will pick up a "noid" light, to see if the injectors are getting a signal (i think it is called that), unless there is another way to see if they are working properly. i had them apart in the summer, but never bench-tested them-only tried to clean them up. what are your thoughts on the IAC valve, and the EGR being too dirty ??