alright so its been a while since ive been stumped on something...i mean this has me really stupmed...heres the deal...its a 2000 dx with a bone stock d16y7...car came to me with a blown headgasket and out of timing...all has been fixed...now heres the deal...car starts and idles fine...all 4 pistons fire drives fine...after car heats up cyl 2 and 3 start to missfire....plugs also come out black!!...so i know i got fuel but no spark...but then again when i pull out the wire and ground it it has spark...i haved changed and checked wires....cap...swapped injectors and plugs to see if it was fuel...plugs...only thing i havent swapped becuase i dont have another one is dizzy...but i dont think its the dizzy...im almost starting to think it could be something internal related to the blown head gasket and over heating...im going to swap a dizzy but like i said i dont think its that...comp test hasnt been done also going to do that tom...what else u guys think it could be???...car gets cel for cyl 2 and 3 missfire...which is code 72 and 73 i believe...so lmk what u guys think...im pooped with this missfire

 

also when i pull out number 2 and 3 plug they are black like i said...but i mean black...threads plug everything black....it would have to be running rich as hell to get like that....u guys think it could be a rich missfire??...too much gas a stock injector???...but i dont see why it would run ok when cold and then poop out when heated up

 

Only idea I got is did you change the rotor at the same time as the cap? I had 2 and 4 misfires changed plugs, cap and rotor and it went away.

 

And if we see who can figure this out, then what happens?

 

The fouled plugs (black plugs) may be causing the misfire. Find out what is fouling the plugs, and you may cure the misfire.

If the plugs had a black carbon deposit, it is running rich or bad spark. The coil output could be low, etc.

 

if u figure it out u get a e-cookie!!!...flavor of ur choice...lol....well i did change the rotor when i did the cap...it could be low spark output from coil but why only when hot???...and why only 2 and 3??....the plugs on 2 and 3 were toast!!...so obvioisly its rich or low spark....just cant figure out what...ohhh well...ill keep checking tom

 

injectors sticking open maybe. was the head pressure tested for any internal cracks to be found. how did the valves look when the head was off.

 

Is your battery light on?

 

head wasnt tested...valves looked great actually which is why i didnt get it machined or checked...head looked really good...i cleaned it up rotated the cam to check all the valves...adjusted valve lash...which was also pretty dead on...i mean head really looked good...i also thought stuck injector but i swapped them out and swapped injector plugs with one another and it stayed being cyl 2 and 3 thats missfire

 

No E-Cookie for me bump to the smart people. Unless the fuel filter comes through.

Come on fuel filter, you can do it!

 

no batt light...why do u ask though???...ive never seen it on for a missfire...only when a alternator either goes bad...belt brakes....or plug gets loose or faulty...

 

lol...do u still want a e-cookie???...maybe we can make something happen

 

No candy from strangers thank you very much.

 

funny that it starts to miss after it warms up. maybe the ecu got fried during the repair. always make sure key is in off position when unpluging things. and when the ecu goes into closed loop the injectors stay on? whats the gap of the plugs? did you try unplugging the ect sensor?

 

Check the injector pulse width. Check compression. It is much easier to diagnose when the car is right in front of you. But, then again, that usually means I'm at work and that is bad. So, nevermind.

 

well...i can check the injector pulse witdh but again why only when warmed up??....and about the key on the off position i take it one step further...whenever unplugging stuff and what not i always disconnect the batt...i learned that the hard way when i first started my career...lol...well i guess tom is another day...im thinking maybe coil..actually i dont know what to think anymore...lol

 

also i havent tried unplugging the engine coolant temp sensor...i was thinking the same thing about the injectors but like i said i swapped and switched..so if its gas related more then likely ecu...but i doubt it...car was supposebly running ok before it blew the headgasket and went out of timing...i thought about bent valves but they looked good when i checked...i if it was so slightly bent that u couldnt tell by eye the motor wouldnt run like this...sure u might have a slight tick and loss of power but thats about it....my friend bent 6 valves on his k24/k20 and they were so slightly bent that it didnt even tick...he just noticed a ever so slight loss of power...imagine he ran and daily drove the car like that for months before we cracked it open and found out...

 

comp. test results?
try when cold and when operating temp./problem is occuring
did u check the head and block for warping? it's not going to be the coil or ign. module. i would try a known good dist. but i bet thats not going to be it. I'm thinking it has to do with heat expansion. not going to be plugs, wires, cap or rotor.

 

I know you said you adjusted the valves but it sounds like they are too tight and staying slightly open when hot.

 

valve adjustment its not...thats for sure...im also thinking heat expansion...block was checked with straight edge...it was ok...everything seemed gravy...im almost sure its gas or spark due to how fouled the plugs are and what not...when u start the car and its cold u can pull the plug wires and see thats 2 and 3 are firing...idle changes obviously...when warmed up nothing...i dont think its internal related...i dont know...comp and leakdown test tom after that its dizzy and ecu

 

 

The reason I said check injector pulse width is because you suspect a rich condition. This would help diagnose any ecu related issues. Since the problem is with 2 cylinders only.

 

well performee comp test today and wow...number 3 wont even start to build comp...it wont even pass zero...i guess motor is toast...i just dont see how a light headgasket failure would cuase this though...i mean if it was 10 20 psi under i would understand...but to not even start to build comp...i dont know...

 

Valve seals????

 

dont know...im thinking more along the line of deck...maybe valves...just also noticed car if blowing bubbles and steam into overflow and radiator....so i know it has to be either head didnt seat right as in deck...or something else up top...