Installed long-tube headers

**My00Z28** · 03-25-2011, 07:20 AM

ok so i started on these at like 6pm and ended at 4am!!! OMG!!! well we removed egr and air.... replaced the motor mounts with poly mounts and installed my headers and new plugs... and today got a custom 3in ory installed well driving it around i noticed it is missing alittle bit but doesn't throw a code, i installed new NGK tr55 plugs used dielectric grease everything clicked in good ect.... what could be wrong?

**Danger731** · 03-25-2011, 07:46 AM

if it was missing the ses light would flash. give it time for the comp to learn.

**mike171562** · 03-25-2011, 08:12 AM

could be a crack in one of the plugs.

**My00Z28** · 03-25-2011, 08:24 AM

More info the computer was frosted so its tuned... and the computer was installed before the headers, does the pcm need to learn the header flow even tho its tuned... and wouldn't it throw a code if the plug was cracked?

***SMWS6TA*** · 03-25-2011, 08:45 AM

Yes PCM needs a little bit of time to re learn. A cracked plug may or may not throw a code. All depends on how bad the crack is. Did you hear 2 clicks when you installed the wires? How old are the wires? Are you reusing the OEM? If so that may be where the problem is.

**My00Z28** · 03-25-2011, 09:05 AM

Heard 2 clicks on all coil side and plug side... wires r original... I think. All plugs are gapped to .055... idels perfect only misses when I jump on it but its not always consistent.

**02Sweet** · 03-25-2011, 09:44 AM

I would REALLY inspect those wires. Think about when you jump on it the motor moves. Plugs could get close enough to the headers to arc? Just a thought. Doubt its the plugs though. Did you pull any codes?

**My00Z28** · 03-25-2011, 10:38 AM

My car doesn't throw a single code but if it matters I can rev it up to 6k rpm with no problems only when there is a load on the motor that it misses

**02Sweet** · 03-25-2011, 11:32 AM

Originally Posted by My00Z28

My car doesn't throw a single code but if it matters I can rev it up to 6k rpm with no problems only when there is a load on the motor that it misses

Hmmm....tough one. Injector wires clipped in all the way???

***SMWS6TA*** · 03-25-2011, 11:43 AM

Check your pcv hose. Make sure you have no vacuum leaks.

Check coils - make sure WH are connected correctly. If one is not entirely connected when the motor has a load on it it moves thus moving the wire. I'm just grasping at straws here on this on but it's a possibility.

I would be getting new MSD wires. It is quite possible that the new plugs are putting a higher demand and the wires are starting to short out.

Check your O2's are hooked up properly too.

**karpetcm** · 03-25-2011, 01:07 PM

If you've checked all that i would check your tune. Mine would miss and was a unique situation. I had to send it back and get it re tuned and it was perfect afterwards. Mine like yours wouldnt do it all the time either.

**My00Z28** · 03-25-2011, 06:43 PM

Originally Posted by SMWS6TA

Check your pcv hose. Make sure you have no vacuum leaks.

Check coils - make sure WH are connected correctly. If one is not entirely connected when the motor has a load on it it moves thus moving the wire. I'm just grasping at straws here on this on but it's a possibility.

I would be getting new MSD wires. It is quite possible that the new plugs are putting a higher demand and the wires are starting to short out.

Check your O2's are hooked up properly too.

my PCV hose i know has a tiny hole in it but it never affected the car before i put some electrical tape over it to plug it.... ill need to look at the coils again but i know the o2s are correct... i also removed my AIR which went to a vacuum controlled regulator type deal but i left that like open thinking it was turned off.... you think that could be my problem?

Originally Posted by karpetcm

If you've checked all that i would check your tune. Mine would miss and was a unique situation. I had to send it back and get it re tuned and it was perfect afterwards. Mine like yours wouldnt do it all the time either.

i just cant believe it would be the tune i ran the car before the header install with the tune and after i installed the headers it started missing...

**My00Z28** · 03-25-2011, 06:54 PM

THIS LINE!!!!

http://www.ls1.com/forums/showthread.php?t=130641

**My00Z28** · 03-25-2011, 09:02 PM

Also more info we broke the coolant temp sensor but it still reads on my cluster could this cause a problem?

**JunkyardZ** · 03-26-2011, 01:17 PM

I'd take that AIR thing off and plug the vacuum line, thats what most do. that way you know it isn't letting air in. most of the time a miss under load like you describe is ignition related and won't always set a code at first which can be a pain. If car is an auto you can put it in gear with one foot on the brake and give it some gas to make it miss and have someone look carefully at the plugs/wires to make sure there is no arcing going on. Otherwards, you may need a scanner that can read misfires and that will tell you which cylinder is doing it. After doing my headers I installed some taylor race wires and they caused a miss while the car sat and idled, went to NAPA and bought a set and they have been fine for a year now.

**My00Z28** · 03-26-2011, 02:58 PM

Ya I have a feeling it is the wires at least I hope but is it normal for it to maybe get worse? Ill be picking up some wires probably Friday when I get paid...

**Too Fast** · 03-26-2011, 03:37 PM

This is a classic example of, "I just put some headers on and now it has an occasional misfire. What is the problem?" 95% of the people will later report that it was a spark plug/wire issue. I would take them all off (plug wires), and re-install them all, and see if you fix it.

**black2kSS** · 03-27-2011, 02:01 AM

this sounds very ignition related. a miss under load is the most common symptom of a wire being bad. if it was a coil it would be much worse if not constant. Also the vacuum line that is in your picture comes off an electronic solinoid for the AIR system, its only open when the PCM tells it to open. it would still be smart to plug it tho. wires should fix your problem

**My00Z28** · 03-27-2011, 06:08 PM

installed new wires and it did not fix the problem i found out i am throwing a code but my SES light is not lit... P0300 random multipal cylinder misfire.... reading 10 inhg when the code was set checked most of spark plugs all look the same... is it a vacuum leak?

**My00Z28** · 03-27-2011, 09:04 PM

Haha ok so I reset my pcm removed my new wires and removed the stupid metal wire protector things plugged everything back up and the car is running great now lmao thanks for everyones help.......