02SE6MT

Ok, so i bought a longblock and heads and assembled per fsm and started it up and it has a misfire on cyl 5. i let the engine run while i pulled the coils and cyl 5 is the only one which doesnt cause a stumble ( i tried multiple coils). I tried checking the basic culprits such as the Injectors (was firing so i moved it to another cyl just in case), Coil/Plug, and then assumed it was possibly a bad valve job so i checked the compression which came out to 160+. Im on the verge of thinking the chain skipped a tooth bc of no oil press in the tensioners when i first started it. So, i put the motor at TDC for cyl 1 and checked the cam alignment and it looks to be spot on. I know the 2 cams are tied together with a secondary chain so i dont think they would be off in relation to each other but rather would both be off by a smidge in relation to the crank. but the lobes which are supposed to be down when at tdc are not cockeyed but perpendicular to the tappets which implies to me that the timing is still where its supposed to be. Does anyone have any experience/recommendations i could try out. I have resorted to checking harness for any broken connections and it looks so far as everything is checking out.

Thank you for any replies, i have an exam tomorrow and work tonight so i may be delayed on the response but i assure you any input (constructive) is appreciated

phatboislim

iTrader: (27)

have you ever just tried replacing the that plugs into the coilpack?

02SE6MT

ya, i tried one of my older plugs which werent even that old. I also grounded it outside of the motor and its getting spark. but the combustion chamber may be different.

one thing i was wondering is i have a small exhaust leak after the rear cat (not the precats) so my primary o2s should be getting a good reading but im not sure if that would cause some other issues. Does the 2002 have an egr system?

02SE6MT

could the timing be off by such a small amount that the compression passes but still misfires? Man im ready to get this thing going. The last motor bit the dust and ive been working on and off limited by paychecks since NOVEMBER, im so ready to drive it again. i could post the aftermath of 2 pistons falling apart and a rod exiting the block later in the thread just for kicks, im not on my home comp now tho. Thanks again for any replies

Amave

yeah i would say timing is off. usually a misfire in one cylinder with all the other related components being fine is a telltale sign.

as soon as i read the thread title w/o entering i knew it was timing related.

remove the timing cover, and turn the crank pulley untill all of your timing marks are where they are supposed to be and i'm sure you will see one cam being off one tooth.
as long as it isnt off by more than one tooth, no long term engine damage will result.


i have seen timing belts being replaced and the belt being off 3 teeth and bend valves


good luck op, let us know what you found

02SE6MT

Thank you for your input, ill pull the timing cover and check everything out. is there any way to avoid it skipping if i were to re-time it? i dont see how you would prime the tensioners or how you would go about keeping it where you put it when you crank it. do you kind of just have to pray and crank the key?

Amave

usually when you time the engine and get everything back together, you DO NOT start it with the key under no circumstances!!! Doing so can potentially bend valves, and turning it by hand is a good indicator if valves hit pistons ...so if you feel hard resistance , you back off and go back and check timing

after you get everything timed, you use a wrench to turn the crank pulley bolt by hand and after you turn the crank ONCE you check to make sure the timing maks are spot on.

after that you turn the crank a few more times and recheck , you make aure the marks are spot on again.


then to be safe, you leave the coil packs out and use the starter to crank but not start to prime the tensioners.

after a few times of oing that you should be good to go

chain timed correctly and tensioners primed correctly you shouldnt have a problem

02SE6MT

ya i turned it over a few times to make sure all valves were clear. i did notice that as i turned the engine over the marks wouldnt come match up again as it rolled over one complete revolution, but the cams were in the right spots just the colored links were off. I assumed it was because they were for reference on getting it installed but would not maintain a 1:1 ratio as the engine turned a few times. ill def pull the ignition and give it a crank before actually starting it.

Amave

looks like you may have found your problem

good luck and def. let us know what you found and if you can take pics of what you found for posterity

ampire

iTrader: (12)

It takes a couple turns before the indicators will line up even though everything will return to TDC position. The important thing is that the cams are in the proper positioning.

Also, I found that when I did my 3.5 hybrid, it was easy to be off by a tiny bit beyond TDC when setting timing, especially considering indicators on the water pump cover versus oil pump, which resulted in some issues when I turned it over a few times. A tiny bit off could be a full tooth, especially where the crank sprocket meets the chain indicator.

Are your tensioners primed nicely?

02SE6MT

ok so i pulled the timing cover and took some pics, im really at a loss for words. It looks spot on... let me know what you guys think about this and can anyone offer any suggestions to solve this misfire on cylinder 5. Thank you for any replies and help in advance.




ive checked coils, plugs, harness, compression, and injectors.. im not sure where to turn now. The fact that its only one cyl makes me think its not sensor related

*Im gonna check for an intake leak as soon as I get it back together

02SE6MT

anyone have any suggestions?

sontakke

You said you have compression on cyl 5. You also said that cyl 5 is NOT contributing i.e. when you removed the coil from cyl 5, engine speed did NOT change.

So you definitely have either plug not firing or fuel injector not opening. If you have already swapped the plug, coil and injector on the cylinder, then the only thing wrong is the primary side. Follow the ignition signal and/or fuel injector signal all the way to ECM. There are bunch of nice tools available which will make this job lot less painful but simple and cheap DMM will do.

If you can put the long block yourself, you certainly have the capability to resolve this! Hell, half the guys here can't even change their own plugs :-)

BigLou55

iTrader: (6)

I think phat is referring to the coil boot not the plug itself, it seems like you took it as the spark plug maybe.

ampire

iTrader: (12)

Your timing looks perfect in those pictures posted.

I agree with sontakke's suggestion, you either are not receiving fuel or spark. Also, send stevenmax a pm. I think he is in Austin, TX.

02SE6MT

k, ill check the harness, i have a voltmeter ive been using to check the injectors and coils themselves. But cyl 5 is the only one with multiple coils and having swapped plugs that continues to misfire. I think after knowing the timing is good im going to put it back together and go over the little things with a fine tooth comb. Id like to let it run and see what codes it throws. before i disassembled the timing it threw a p0021 (same bank as the misfire). But i did not check for an intake leak (bc it was only on one cyl and i made the mistake of assuming) so i hope i dont have to kick myself in the a** for that.

I bought 6 new plugs and threw them all in, when i saw the misfire the first thing i did was check the plug outside of the motor and cranked and saw it got spark, but i changed the plug and coil to a front bank to see if the misfire would follow them. I then did the same thing with the Injector after confirming it would at least fire. I have heard some funky things about injectors though : / , despite my actions the msfire stayed on the same cyl. I am not sure it does it all of the time, i can tell when it starts and it seams when the car is first turned on it may be firing. I notice after less than a minute the fuel system on the rear bank goes into close loop while the front bank stays open and by then the misfire has begun.
** i noticed while removing the oil pan for the 2 bolts (i never saw in the fsm BTW) in the timing cover and i saw some gskes sealer had been sucked to the oil pump screen. now, i didnt run the car very long, and ive heard of the restore crap making your sensors go haywire. but the P0021 kinda hints at lack of oil pressure (iirc but usually both p0011 and p0021 simultaneously) or if it got disintegrated and has any properties which would cause similar effects as that restore crud.

ampire

iTrader: (12)

If you are seeing some gasket sealer on the oil pump screen, you might have used too much RTV. Don't think it would cause a misfire though.

02SE6MT

ya i think i got a little rtv happy, i should have finger tightened the bolts and waited an hour for it harden and then tighten

ampire

iTrader: (12)

I don't know if thats necessary, just use less RTV The stuff is the devil. If you use too much it can clog the filter screen and cause oil pressure problems, resulting in spun bearings, and other catastrophic problems.

Amave

im at a loss for words if all the timing marks are dead one.

strange but by any chance have you had any misifires on #5 before?

you said you bought a longblock and then swapped heads out, by any chance did you check for power at the #5 harness on the coil & injecotr connectors?

02SE6MT

well the car hasnt had any misfire problems at all since ive owned it (2007). the harness remained in the car while i swapped the engine, lower im and fuel rails/injectors. i did keep the timing components (chain/sprockets) and upper im from my old engine (im debating getting a new chain but dont know if it could cause a misfire). i did make sure i had spark and the injectors were firing. i changed plugs and coils on that cyl as well.

Amave

thats what makes it so confusing


based on what you tested it should NOT be misfiring

02SE6MT

Maybe intake leak? thats the ONLY thing i havent checked, but i bought a complete engine gasket kit so theyre all new
I checked the timing ring but only inspected the alignment after installation through the sensor hole i wonder if the mark for cyl 5 has something wrong with it? i have no idea. a local mech says crank or cam sensors but that would cause random misfires, im pretty sure : /

also, does this car have 2 crank pos sensors, one behind the oil pan and one for the flywheel timing ring? i thought the first was an oil pressure sensor

02SE6MT

im gonna put it back together and run it and see if im getting the same results. if anyone has any ideas feel free to throw them my way. i do realize the room for suggestions is limited since spark, compression, timing and fuel have been checked lol. I also tried a maf sensor from my step brothers 02 to no avail. Again ive checked the engine grounds and most of the harness for shorts and have not come upon anything yet.

And thanks again to the .org, ive been a member of yota, and acura forums and this one stands apart.

sontakke

I wonder if your EGR is causing the trouble?

02SE6MT

ya i was wondering if the 02s had an egr system or if it was just cali spec maybe?. reason being is i had an exhaust leak because i reused washers and only really bolted up the cats to the y, and had the main cat and resonator barely bolted up. but that was because i found out the local place didnt have the exhaust gaskets. I was under the impression it didnt have egr. i would not be surprised if im wrong, but i looked in the fsm and saw nothing for it and nothing solid on googling it for the 2002 max.

02SE6MT

would a bad valve job cause a misfire? i pulled the vc and set the cams to check the tolerances visually until i can get a feeler gauge. i did notice one of the tappets or buckets whichever the term would have enough clearance to freely spin while the other tappet for the same cylinder, (the other of the 2 exhaust valves) was tight and would not spin and i doubt id be able to get a feeler gauge in between the cam and tappet at all...

sorry if thats confusing if i need to re-explain i will

*but the thing is, with our heads if one cylinder was messed up enough to misfire others should be as well... my thoughts are we only have a limited number of tappet selection and im pretty sure they didnt order any from nissan. so if 2 tappets/valves are off / misplaced the chances are many more are. Its South Austin Machine shop, i have heard good reviews from some local mechs here.
At the same time, when i got my heads back the one they "worked" by "adjusting" (or juggling/moving around tappets/valves) the had mixed up the lettered cam brackets and i had to change that back to spec.(they had just vatted/pressure check the other head).

02SE6MT

ok, so i pulled the entire head and decided to inspect the valve job this machine shop had done and despite my words at the shop they still decided to shim an intake valve on cyl 5. So they kept the factory retainer but didnt clip it in and set it on top of the shim. this leaves a huge space in between the valve stem and the nipple on the underside of the tappet. my question is, will the shim & clips push the valve or will they slide down the valve compressing the spring, until the tappet hits the valve and begins opening it?

ill post some pics later

02SE6MT

So i cannot seem to find a camera for what seems to be the first time in my life. so heres paint , i want you to see what they have managed lol. the one thing i pay someone to do... There is only one valve (intake on cyl 5) that has this "adjustment". And sorry, tappet/bucket = lifter my bad
I will get pictures

02SE6MT

So my dad took it before i got home this afternoon so i couldnt grab pics but he said he got one. The shop is repairing it for free and getting me a new head gasket. he thinks they didnt see the factory retainer (guess it got stuck in the lifter bc i got the head disassembled w/no clips in valves) so they put one on and then the lifter (clearance must have been tight as hell). He says he will make it right and i hear from some locals he will do a decent job . Thanks for the help to all who posted. hopefully itll be on the road soon.

Amave

so the problem was the #5 valve was missing a retainer?

sontakke

And does it explain good compression?

02SE6MT

no, there was a shim below the retainer, leaving a gap between the lifter nipple and valve stem. the diagram shows their retainer in green, underneath the factory purple one.

02SE6MT

ya intake valve not opening very much will have minimal effects at ~300 rpm (cranking speed). The valve sealed, just barely opened.