BrianLS1

I can't figure out the problem guys..I'm lost like a baseball in tall grass..I thought it may be the stock wires that were causing my car to miss but I bought new plugs and wires and installed them and it still misses..my passenger side 02 went bad so I replaced it and it's still missing..the car runs like a beast but it's missing on and off..I've autotaped it a few times since the hooker longtube install and it will miss sometimes at idle and sometimes at wot..it will have only 2 misfires then 20 misfires all at different times..sometimes at stop light and sometimes while driving regular..my 02's are like .97 and ltrims at like -10.5 at idle so it's running extremly rich..I don't know if running extremly rich like I am can cause it to miss or not..and another question, can not having any backpressure cause it to misfire, I don't think it would be I'm willing to try anything so I'll cap it the cutout up and see if that helps..I need some ideas fast cause the bad thing is I'm not very patient with things like this so if I don't figure it out soon the stock manifolds will be going back on and I'll start troubleshooting from there..car never missed once until header install and I autotaped it right before installing them..a local club(kyfbodies) get the track this weekend and I'd love to get a few runs in to see how much the headers have helped but I'm not driving the car at all until I figure out how to rid the misfires.. appreciate any help <img border="0" title="" alt="[Sad]" src="gr_sad.gif" /> Oh, and by the way, I have the ceramic coated hooker longtubes into 3 inch y-pipe going to 3 inch collector through 3 inch cutout

<small>[ October 17, 2002, 12:40 AM: Message edited by: BrianLS1 ]</small>

sited12

Had the same thing happen with my hooker LTs. Just found out today that two plug wires wiggled loose. Also the day i put the headers on it missed do to a leak with the EGR. Had the EGR problem at the beginning of the summer too. Go simple and make sure you cant hear of feel air being sucked in aroud the EGR tube if you have one. And make sure the plug wires are on really good at the top and the bottom. And if all else fails maybe you broke a plug. I broke 3 during my install so it is possibly you got atleast 1.
<img border="0" alt="[Camaro]" title="" src="graemlins/camaro.gif" />

BrianLS1

Thanks for the quick reply..the plugs were ok and I've checked the wires off and on too many times but I'll be sure and check the egr first thing in the morning..hopefully if I'm lucky it's something like that and I can find it but who knows..anybody else with ideas to try..and an answer to the running rich and backpressure problem? thanks!

NoGo

iTrader: (2)

Here are some things that you may want to look at.

First off, are you setting any SES codes?

Bad O2: You may have an exhaust leak exposing the O2 to fresh air. This will falsy indicate a lean condition and cause the car to incorrectly add fuel for a percieved lean condition. This will cause your car to run exceptionally rich. Another indicator of an exhaust leak is a large split between your O2's (ie one indicates -2, the other indicates +21) Look at your connections after the collector (collector to Y connection), and the O2 bung itself. If you have a leak at your head-header connection it will tick like a biaatch.

Vacuum Leak: As stated by SITED12 you may have a vacuum leak pulling in excess air. This will typically cause a lean condition, but is also a big contributor to misfires.

Ignition: Being you replaced all of the plugs and wires, you may want to start looking at your coil packs. Loose connections? The coil packs are side specific. Did you put them back on their original side (this will usually stop the car from running at all, but you never know).

Plugs: Also, what kind of plug are you running. If it is the Bosch +4, I have heard of people having problems even getting their cars to run with those things. Try a platinum-type factory plug if you are using a funky aftermarket special.

Boofed Sensor: You may have damaged a sensor when installing your hooker LT's which is causing the car to go into "Limp Home" mode.... or as us tech-geeks call it "Volumetric Efficiency Referencing". Basically, you have smacked/cracked/short-circuited something that contributes to the normal a/f calculations. The sensors that you should be interested in: MAP (located back of intake), Cyl Head Temp (located driver side head), MAF (you should know this one), IAT (you should know this one too), O2 Sensor (you already know).
These faults usually set an SES code. Limp home mode will make your car run excessively rich and backfire.
Check the wires and plugs to these sensors. What you are looking for is a loose connection or exposed wire.

Good Luck,
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

NoGo

iTrader: (2)

Backpressure will have nothing to do with your running rich. The installation of the headers has moved your O2 sensors and changed the diameter of your exhuast. These changes to your exhaust will cause the O2's percieved reading to be altered slightly. This may result in a slightly richer or leaner condition than what was seen prior to the header installation.

Backpressure will have an effect on backfires. Being you have less of it now the new free flowing exhaust will push out hot fuel enriched air (because you are running pig rich) which once it comes in contact with the outside air may combust. This "problem" becomes excessively apparent once the CATs are removed, and even rich conditions that are induced during normal operation (ie quick decelleration) will begin to cause backfires.

Your car should still run with the headers though with no problems.

BrianLS1

NoGo..I greatly appreciate the big reply..ok lets see what there is left to check..I have checked the coil packs and they're on right..tightened all the header bolts and no leaking there..I have ngk tr55's and I have them gapped at .50 like my other ones where so they're right..as sited12 said, I need to check egr for leak..and I definately need to take the time to go over every wire to make sure I haven't damaged one because my car very well may be in limp mode(wasn't aware our cars have this) cause it's running rich, smoking like a frieght train, and backfiring like crazy..it's not throwing no ses light for anything which is making it difficult but hopefully, I can put it in my buddies garage after work tonight and find the problem..again, thanks for the replies sited12 and NoGo <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

Chad00ws6

Hey Brian I just did the exact same install two weeks ago and I had a misfire that I could not track down either. I would get new plugs just incase you did crack one (could be a crack you can't see) have you A-tapped it again to see if it is the same cylinder that keeps missing? That will be easier to track down then.
Mine was actually a plug to the fuel injector on #2 that was not tight and was causing the miss. I didn't find this though until I checked everything else. I guess we hit it knocking it loose during the install. I swapped wires, I swapped coils, I even pulled the valve cover and pulled the pushrods and checked the valve springs. I hope you find it. Did you use the front O2's and leave the backs out? I capped all of the air tubes and EGR spots on the headers too. Remember it cant be the headers themselves so keep us posted and check all connections on everything.

Batmobile/SS

iTrader: (1)

Unfortunately you can't rule out the headers themselves as a cause for a leak causing A/F problems. Hopefully you pre-checked them for no missed weld spots (In the dark by shining a flashlight through the tubes/collector you should see no light). I had no less than 5 "bad" areas on my first set of Hookers and had to send them back. One hole at the collector to pipes was big enough to run a 16 gauge wire through it.

sited12

If the headers are leaking you would be able to clearly hear it though. So i am not really focusing on the headers themselves. Do you hear a pop coming from under the car like it is at the collector or is it from the engine. If you autotap it and its the same cyl giving you trouble then it is probably an ignition problem. If its multiple cyl and just random then i vote for the vacuum leak. Oh another problem is with the EGR if you bent the tube moving it around during the install that is your problem. It will get pinched if you bend it just the slightest bit. Thats how i had my problem during the free EGR mod. That seems like a good bet

Street Racer

iTrader: (65)

Hmmm I saw a similar thing happen to a buddies car. It turned out to be where the 02 wires were extended from he didnt put the heat shrink stuff around them individually and the connectors were bare touching each other <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
I have also seen were people extend the wires for the 02's and cross some of the wires to the 02's <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Slowhawk

iTrader: (12)

I got an engine light by just not having the engine tuned right.Ran rich and everything.Just installed a MAFT and richened base.Code went away for good.