im new to honda forums and i need some help. i have a 99 accord 3.0 and its having a misfiring problem. once the engine is fully warmed up and i shut it off for a couple minutes, it will idle roughly and the about 10-15 seconds later it will idle where its suppose to. It stalled on me 3 times during the last 3 months. when the engine sits for about 10-20 mins when fully warmed up it will idle more rougher and can possibly stall. Also, when its in the single digits outside it will misfire on cold start for a few mins until it gets warmed up. its a hit or miss when it happens. i just replaced the cap and rotor and it didnt help whats so ever. spark plugs are fine and same thing with the plug wires. any advice?

 

Do you have the Check Engine Light on? If yes, go to Autozone or other auto parts and have codes (Pnnnn) read. Post actual codes, not what clerk tells you they mean.

Are you losing any coolant? Coolant in the cylinders from faulty head gasket will cause brief engine miss on a warm startup and could cause stalling.

good luck

 

Many of the early 6th gen v6 had/have an issue with heat soak.......car is warm/normal op temp....shut the car off for 15 to 30 minutes....re-start and you get a "stumble/rough" idle, sometimes a CEL, sometimes you can hold the gas down and clear it out.

Seems to show up more in the cold when winter blend gas is being sold.

Now if this is also happening from a stone cold start you could have another issue or two different issues.

 

There is no engine light on. I replaced the cap and rotor and it didnt help. A couple weeks back I went to autozone and it through some p300 code at me and it said random misfire detected. Then I went back couple days later to get a print out of the codes and the misfire code wasn't there anymore but the 420 code was still there. The cars been acting up like this for 3 months now and there's still no engine light coming on

 

I am not losing any coolant. Well at least I haven't noticed at all. If I was losing coolant I'm sure it would of been drained out by now. (3 months) which is the length I had the car for

 

Just to be clear here the car only does misfire when its extremely cold. Not warm. And when it doesn't misfire then its constantly idling roughly when I start it on a warm engine. As long as its not freezing out the car will start up real easy on a cold start. I have some videos of what the car does but idk how to post it on here

 

I'm still a bit confused....I'm the slow one so it is not you.

Cold start in very low temps and the issue happens.

Warm re-start (normal op temp, shut the car off for 15~20 minutes, then re-start) and the issue happens.

Try to cycle the key to "on"/pos II for a few seconds before starting the car and see what happens.

 

Looking at the Troubleshooting by Symptoms chart in shop manual suggests to inspect for intake air leaks, poor ignition wires/spark plugs (how do you know they are fine?), and adjust idle speed.

If you intend to DIY, a shop manual from automanualsource.com for $22 is essential.

good luck

 

I always start my car that way. I tryed starting it right away and I tryed turning it to on position for a few seconds and then starting. Still the same outcome. On a sub zero cold start, the engine chokes and you see a cloud of white smoke come out of exhaust. As the engine try's to warm up you can see the rpm gauge bounce up and down like it wants to stall. So I usually hold the gas pedal down at about 2k rpm for a couple mins. When I take foot off gas pedal it idles where it suppose to..

 

My friend checked spark plugs and said they were fine. Plugs were ok to