I installed my longtubes this weekend, and it seems like ever since my car has a horrible miss. I thought i heard it miss before i did the header install, but was unsure. Anyways, I've put new plugs(gapped to factory specs,) new plug wires, and reinstalled my rear O2's. So now i hav no clue what it is. Under WOT it runs good, but jsut accelerating at about half throttle to can hear it missing in the exhaust note. I hooked it up on our scanner at work and it shows to be missing at every cylinder, its just a random missfire that just shows up everywhere. Its also running really rich. only thing i took off during the header install that had anything to do with wires were the coil pack and o2's. I didnt damage any wires installing the headers. IDK WTF IT IS, AND STARTING TO **** ME OFF!

Devin

 

One of the things that can cause that is if the plug wires are touching the LT's or if they are very close to touching them.

Make sure none of them are, best way to get them off of a LT if it is touching is to rotate the wire at the coil until it moves off the LT.

 

YEah, i made sure that theyre not touching. Tehres only one that i know thats touching, and that can't be helped as the dirction of the plug wires jsut happens to go towards the header. I think its Cylinder #3 that the plug wire is touching. after the isntall i jsut unplugged my rear O2's and took them off the car because i thought tehy wer turned off when i got my tune. So i reinstalled them, thinkin that'd fix it, and its still doing it. I daily drive this, so i need to get it fixed ASAP.

Devin

 

YOu can't have any of the wires touching, it will start a problem with the entire system. Once electricity arcs, it goes further than a few inches. There's always a way to get the wires off the pipes. Even if you need to use a wire to keep it from touching, do it.

Did you try to twist the wire where the boot goes onto the coil?

 

Yeah, its just the angle of the spark plug and where the number 1 cylinder primary comes out of the head. hmm... i'll go try to get it to stay off the header.

Devin

 

nope, i pulled that away from the ehader and still nothing helped. I also tested all my coil packs to make sure they were working with taht little light that goes between the sparkplug and plug wire and they all are working with a steady beat, no missing. I cleaned the MAF sensor too to make sure that had nothing to dow ith it. So could it be a fuel issue? It is smelling extra rich! Maybe O2's? Crank sensor? Idk what it could be. I'm goin to let the guys at work do a full diagnostic on it to see what they think.

Devin

 

did you check the shielding around the front o2 sensors? when i did mine, it actually melted 2 of the wires together and made my car run like poop. might have been because i spliced in some extensions and didn't get it covered all the way, but it's something you can check.

took me a couple used sensors before i figured it out.

 

Very well could be the Crank Shaft Position sensor, that thing when its failing causes all kinds of wierd stuff. 02's cause all kinds of wired stuff too.

OBDII scan is the only thing that'll tell you. I've had both, bad and failing 02's and a failing CSP sensor, niether showed an SES light. Only thing that found it was the real dealership type OBDII scanner. Not the little orange scanners at Advance Auto.

 

Yeah, i actually work at a shop with a good $5K OBDII scanner, haha. So yeah, i guess i'll just let them look at it tomorrow at work, give them something to do.

I was looking around on the site, and thats what i was thinking either the crank sensor, cam sensor, or O2's, but i'll find out more bout that tomorrow. I'll keep things up to speed as they are figured out.

Devin

 

I had a similar problem and it turned out to be a cracked sparked plug, check for that maybe?

 

they're brand new spark plugs, and after install of them it was still doing the same thing. I don't even have 50 miles on the new plugs yet.

Devin

 

Could be the crank sensor as mentioned before, but also had a car acting just like this the other day and it turned up to be a frayed wire on the back of the motor.

 

OBDII scan at the dealership. Not the little orange junk scanner at Advance Auto, it doesn't pick up some of the problems with our cars.

 

yeah, we have a mastertech obdII scan tool, a solus scan tool, and a verus(sp??) scan tool with a touch screen off the Snap-on truck(that thing was expensive, almost $10K i beleive, but could be wrong.) we could to go drive it around. I'm a try switch some O2 sensors around and see what it does.

Devin

 

so all those scanners showed nothing?

If the 02 sensors were not working properly, the OBDII would show it, as long as its read correctly.

 

well on the way home, it startin missing BADLY. It didn't like to idle, and was backfiring like crazy and finally set a codeit was for O2 sensor bank 1 sensor 1, so i bought 2 O2's to replace both fronts. After replacing the O2's it stopped backfiring and stuff, and has gone back to just a slight miss again. wtf?? $200 gone, and its still messing up. MAybe a MAF? IDK anymore.

Devin

 

Not neccassarily, reset the PCM. Not the 30 minute thing, just unhook the positive battery terminal and tap it a few times on the positive battery terminal to get it to spark. Then re-connect it. Start the engine and go for a drive.

And I hope you inspected the hell out of the wires.

**Don't ask me why that procedure should be done with the battery.....a builder that replaced bad 02 sensors and wires in my car once did this and I drove away 100% perfect again. He said thats how you reset a PCM***

 

if you dont have them,then id say you need a set of wire protectors. also, my maf made my motor run rich because the sensor was coated with oil from my k&n filter! after cleaning it ran fine. with long tubes i also went with corvette o2s. they run hotter you wont need o2 extensions.

 

just start the car when its dark out with no lights under the hood u should see your problem if not u know your wires r good

 

I did that after installing the plugs with no arcing found.

I'll reset the PCM tomorrow after i get to work, i wanna check the codes out that are still on. Make sure it didn't set a code for something else.

**I also heard about the terminal thing, a buddy told me about it the other night. I usually jsut unplug the negative terminal and turn the ket over a few times.**