...I've been searching but cant seem to find the exact reply I am looking for... I recently installed my OBX V2 headers, Running O2 Sims on my 2003 SE. Now it seems that when I am at idle (at a stop light/car was etc...) the car idle will get rough. when it starts, if I lightly rev the engine the idle goes back to normal for a few more moments. If I let the idle get bad, the check engine light will start to blink and I will get a multiple cylinder misfire code... The car has 78K on it. Is it possible that I have a bad coil or 2? Other than at idle the car runs awesome, and performs great. No complaints... This issue is just stumping me...



8/17/2011
UPDATE

I had the car out and stopped at my mechanics. We let the car idle until the CEL started flashing. We pulled the codes and all we got was a P300 (random misfire). We were unable to get any other ones.

while the car was still idling we started to try and figure out if it was a coil, and if so, which one. We started to pull the plug (one at a time) off each coil to see if the car would change idle. The front 3 were showing to be good. When we pulled the plug for the coil that is under the intake manifold (drivers side) NOTHING different happened. engine still ran like poo. WE FOUND A WINNER (loser)!!! So now we will replace all 3 coils in the rear (for good measure) and replace all the spark plugs in the car. Hope that solves my issues!

 

You could do an idle re-learn procedure and see if that helps.
However the blinking CEL means that one cylinder is misfiring. You should be able to pull the codes and it will tell you which cylinder. Remember P300 is the multiple cylinder misfire and P301-P306 is the codes for the cylinders. So if you have a P300 stored and P301, P301 is bank one,cylinder 1.

Possible causes for misfire include ( this is from the fsm )

Improper spark plug
Insufficient compression
Incorrect fuel pressure
The injector circuit is open or shorted
Injectors
Intake air leak
The ignition secondary circuit is open
or shorted
Lack of fuel
Drive plate or flywheel
Heated oxygen sensor 1
Incorrect PCV hose connectio

 

It happened to me after I installed my headers as well. Turns out one of the IM bolt was loose and causing air leak. Check and make sure all bolts are tighten and relearn idle if neccessary.

 

Could be related to the IACV.

 

He has a vq35 not a vq30 so the iacv is way different.

Check for leaks first like people have said. Make sure everything is plugged in.

 

BUMP... Update in 1st post

 

All 3 rear coil packs and what... 2 to 3 labor hours? That's gonna hurt.

Glad you found your problem. If one of my rears went bad, I'd probably replace all 3 as well. So far I've only lost 2 coils, and both were in front.

 

Labor will cost me almost nothing, since the family is a close friend with the mechanic. so labor will cost me $100 or so.

This way I will replace all 3 rear coils, 6 plugs and the gaskets. I'll deal with the front coils later when needed (and I'll have 2 spare coils. for future use)

 

The UIM will be off the car... use that opportunity, and savings in labor costs, for some phenolic spacers.

 

Glad to hear you found the issue. Hopefully new coils will fix it

 

You're referring to THESE ones right here?

 

Yes sir, exactly that. I don't recall reading anywhere that you had them.

If it's a fresh idea for you, then my job here is done.

 

Fresh idea it is... I think I'll go for it (even though i drive a 4AT)

 

Transmission is irrelevant. Gains are the same, although observations are often described in terms of changes perceived in various gears and RPM's.

 

well, we'll see what happens. Order just placed!

 

There in stock? Hmmm......

 

Way to hijack a thread....did you bother to read the stickies at the top or the FAQ?

 

$345 later, I ordered what I need from the stealership....


3 OEM Coils
6 Spark plugs
Intake Manifold Gasket

Plus I have the spacer kit



Next week will be the tear down!

 

You bought the spacers? Nice!

 

Let me know if you have any questions about the NWP Spacer install.

 

Did you happen to extend your primary O2 sensors? If so, did you extend the sensor wires, or the harness wires? I ask because I was having the exact same issue (rough idle, blinking SES light, random misfire code) after installing my Cattman headers.

I extended my primaries on the sensor side but found out later through research that it's not a good idea. I recently ordered new O2 sensors and extended the harness wires this time. That was last week and since then, the rough idle and blinking SES are gone.

I still need to scan for codes, I will see if I still have the random misfire code but hopefully it's gone.

 

Will do... We are planning on doing the install at the end of next week.

 

Right now I have the sensor wires extended. Honestly I never thought about extending the harness instead. I will look into that, thanks for the idea.

 

when i installed my headers my crankshaft positioning sensor went .. car wouldnt go over 2500 rpms and after i swapped in a new one it runs great

 

Glad to see you found your problem...If this is your first time changing the spark plugs as well.Check to see if your rear has oil in your plugs. Thats wut happened to my max and ended up changing the valve covers as well.

 

From what I understand the sensor wires are shielded and very sensitive so you really don't want to mess with them or it will affect the signal to the ECU and give you problems. You are going to need to buy new primary O2 sensors and extend the copper wires on the harness side. I'm guessing that will solve your problems.

 

Just an update from post #21, Today I ran an emissions test and I passed! No more multiple misfire or any other codes!

Just to give you a little more background, I have been trying to get my car to pass emissions ever since I installed my headers 3 months ago! It has been nothing but a headache. Everything I did to try to get it to pass was not working. I was about ready to just give it away for $3k but I'm glad I found the problem and it was a simple fix.

I'm almost 100% positive you just need to get new primary O2 sensors and make sure this time you extend the harness. You don't need new coils