Weird mis-firing and backfiring problem?!?

[kaotik]

This is the second time it has done this, the first time was a while ago but this morning i went to start it and it struggled to turn over and just let out a big BOOM. Cranked it again and it started. Now its misfiring badly and i changed the spark plugs and leads not too long ago, definatley not long enough to be due for another set.

what could the problem be? coilpacks? timing?

anyone had a similar problem?

 

[CLuTZ]

I'd be checking your sparkplugs again, and tell us what you see!

 

[SIVART]

it might be rare but mine is the same sometimes but it the factory ecu plug pops out just enough to through out a missfiring issue

I put a cable tie there and its much better now

 

[GVR40]

if it went boom and then started ok after that with a bit of misfiring i would be doing a compression test, sounds like a bent or burnt out valve to me

 

[Benny]

+1.

My old GSR did exactly the same thing.
Was running fine, then suddenly crank crank crank...pop pop....bang...pop...pop

burt (dead) exhasut valves = 0psi compression in all fours.

 

[GVR40]

i was lucky it was only 1 valve on mine so i could still drive when you get up in the revs it seems to smooth out a little, but it wont pull all the way through, mine happened on the drag strip

 

[kaotik]

ok i just checked the plugs, seemed fine, lil bit of carbon deposits but thats to be expected, gave the points a bit of a clean with some sand paper and blew em out.
I also did a compression test, 130-150 PSI
SO i put it back together, started it and it now purrs...what the...?

its got me baffled, the first time it did it, it just poped and then started and run fine, this time it misfired afterwards.

we'll see how it goes now anyway

 

[rob323]

my j spec vr4, every now and then, when the wind is blowing from a particular direction and you have you leg cocked a certain way, will give a cough when you start it and run on 3 cylinders for about 20 seconds and then clear itself up. I have checked everything that I can think of without success and I just live with it now.

 

[GVR40]

maybe carbon buildup on the valves, put some flash lube in the tank the next couple of times you fill up, may help it a little and you will get a little bit better fuel mileage

 

[JAP63]

my j spec vr4, every now and then, when the wind is blowing from a particular direction and you have you leg cocked a certain way, will give a cough when you start it and run on 3 cylinders for about 20 seconds and then clear itself up. I have checked everything that I can think of without success and I just live with it now.

I beleive this is a leaking injector

 

[VR-4Squid]

ok i just checked the plugs, seemed fine, lil bit of carbon deposits but thats to be expected, gave the points a bit of a clean with some sand paper and blew em out.
I also did a compression test, 130-150 PSI
SO i put it back together, started it and it now purrs...what the...?

its got me baffled, the first time it did it, it just poped and then started and run fine, this time it misfired afterwards.

we'll see how it goes now anyway

could simply be a plug lead that wasn't sitting tightly on the plug?

 

[rob323]

I beleive this is a leaking injector

Keep guessing, had them checked for exactly that reason. But my car would do it even when the car was hot and you only shut it off for 5 minutes to go to a shop. Not enough time for a leaky injector to leak enough fuel to foul a plug.

 

[GVR40]

bad connection on a coil pack, signs of wear on the ignitor

 

[265T]

my j spec vr4, every now and then, when the wind is blowing from a particular direction and you have you leg cocked a certain way, will give a cough when you start it and run on 3 cylinders for about 20 seconds and then clear itself up. I have checked everything that I can think of without success and I just live with it now.

my j spec does exactly the same thing

usually does it about once a month when i go to start it after work