Headers installed, stuttering issues now

**tu8i1o7** · 02-14-2011

This past weekend i got my speed daddy headers in, installed, and welded my hi flow cat in. On the first start up it took quite a few cranks to get it to start up. After it started up it was idling fine. I tried to rev it up a little and as soon as I pressed the gas it started to stutter like it was misfiring. The aeroforce didn't detect any misfires and I had no codes. If i feather the trottle it will throttle up fine, but any more it will "miss" all through the rpm range. Same thing happens when i try to drive it, hesitation at all rpms but idle. Another odd thing is when i get above ~3500 rpm the vacuum line hooked up to the MAP sensor comes off and is the only time i throw a code which is P0068. Other then that no codes.

I checked the plugs and wires and they all seem fine. I looked around for any disconnected wires, and everything was good. I cleaned the MAF and throttle body. And while installing the headers i broke the EVAP purge solenoid, but I wouldn't think that would cause this problem, I have the part on order.

this car is a 2005 comp g that has a s1x cam, 3.5 pulley, intense pcm, fwi, 180 stat, zzp wires and autolite 104s (that were both installed less than a month ago), and now sd headers with hi flow cat. Thanks in advance for and advice given.

**ChrisJ** · 02-15-2011

I have an 02 L67 with the Mods listed below. The day I installed my headers the car went into limp mode when I started it up. Meaning it would not rev above 4k RPM. It was running super lean had to adjust the fuel tables with HPTuners. I want to say it popped a fuse when it did it.

Hope that helps.

**SlowNA06** · 02-15-2011

What configuration is your tune for?

**gtpinsc** · 02-15-2011

re check everything ..trace all vac lines and make sure none broke or came loose. re-check wires. check plugs and make sure u didnt break any.. etc etc

**BillBoost37** · 02-15-2011

TU...A broken evap soleniod is likely a huge vacuum leak. Make sure you plug the line to the throttle body until the new valve is in. See if that helps. Otherwise I'd assume you hurt a plug or two..but that's less likely being tha tyou mentioned the evap.

Chris..do you mean revving it in park or neutral? That's a factory safety feature, not a limp mode. There is no limp mode that allows you to rev less.

**TheOtherNick** · 02-15-2011

yup sounds like a big vac leak.

**ChrisJ** · 02-15-2011

Chris..do you mean revving it in park or neutral?

neutral drive or driving.

**starscream5000** · 02-15-2011

I had the same problem, even broke the EVAP soleniod just like you did, lol. Turned out I cracked two plugs (one I noticed and fixed before the first startup). The second plug I couldn't tell anything was physically wrong with it until it snapped in two... New plugs in it and it drives just fine.

**tu8i1o7** · 02-15-2011

Thanks everyone for quick replys. Earlier today I disconnected the MAF and it idled fine, but when it reved up it bogged down like it was stalling. once again if I feathered the throttle it reved up fine. Took it out for a drive and drove fine, but when i took my foot off the gas it wanted to die again. It didnt stutter during acceleration, would this be a sign of a bad MAF? I'll probably get new plugs just in case. And i've checked everything over multiple times. And still waiting on that damn solenoid haha.

**99GPGTP** · 02-15-2011

when i installed my sd headers i coverd my a** and removed my plugs so that i didnt break them.
im will billboost37, a huge vac leak will cause it. but it sounds to me like u may have cracked a few plugs also. you did extend the rear o2 sensor correct????

**SilvaMan61** · 02-15-2011

sounds like a vac leak. i'd listen to Mr.Boost

**BillBoost37** · 02-16-2011

Plug your maf back in and please do your wallet a favor, stop trying to diagnose stuff that you didn't touch. This is something you touched/broke. You know you have a vacuum leak, it acts like a vacuum leak, it smells like a vacuum leak.... I'm gonna say...most likely ..it's a vacuum leak. Unplugging the maf put you on the table which runs rich etc. That's way it seemed a little better for a bit.

Chris..next time you want to free rev past 4K punch yourself in the nuts. The only good that'll come from that is learning how to swap a motor. I'm thinking you don't want to do that.

**tu8i1o7** · 02-16-2011

Thanks to everyone, I got it fixed today. Went and picked up the evap solenoid and some new plugs just in case. put the solenoid on, still ran crappy. So on to the plugs, where under further inspection there was a hairline crack on 2 plugs (looks like you and I are the same starscream haha).

I really need to be thanking you bill, you sure know your stuff. I might just have to buy you a beverage or two if you ever make it down to NC haha. I usually don't throw my wallet at the problem. But with a newborn and working long hours. It didn't leave much time to troubleshoot. I'm not at all new to the 3800, ive had a 99 since i was 16, and now my 2005. Been in mechanics for a while too. Im a helicopter mechanic in the Marines, so you know I deffinately mess some stuff up LOL. But once again thanks everyone and sorry for sounding n00bish.

**BillBoost37** · 02-17-2011

Chris...we've all done it.. That's why I was a little harsh.. you needed to refocus.

Am I the only guy that always pulls plugs to put headers in? We don't have a lot of room....why not give yourself as much as possible?

**starscream5000** · 02-17-2011

I'd rather leave the plugs in and not risk foreign debris getting into the motor.

To me, the cost of replacing somes plugs is better than needing to replace a motor as a worst case scenario.

**BillBoost37** · 02-17-2011

What foreign debris are you throwing at your motor while you put headers on? There isn't much that's getting into a plug hole to begin with.. and..there's little that can hurt your motor that you'd be putting near/in the plug hole.