Recently installed a Vortech V-3, T-trim supercharger kit from A&A (w/ 60 lb injectors) + longtube headers and a ported throttle body into a 2004 Z06. Since starting her up, I have been getting the P0300 code. I have replaced all sparkplugs a second time as well as changing the sparkplug wires again. Also tested each coil with a timing/strobe light and all seem to be good. When I hook up a scanner, it sporadically states P0301 (and always shows P0300, just like the DIC) but I’ve check & rechecked cylinder #1 and it seems fine. When I listen to the engine while the car is running, it seems the misfiring occurs on Bank 2 (can hear the actually misses); this was also evident with the strobe light when I was testing coils as there was a slight miss on cylinders #4 and #6. Also, I noticed a strong gas smell and when actually smelling each exhaust tip, I can smell it from only the passenger side exhaust tip, though I do have an X-pipe which is probably crossing the gases. Also, the freeze frame data from my scanner is showing the following for P0301:
STFT B1 0
LFTT B1 25%
STFT B2 0
LTFT B2 4.6-6.2%
Why the large variance between Bank 1 and Bank 2? Oh, I have also replaced the O2 sensor in Bank 2 (passenger side) but it hasn’t changed a thing.

While the car is running, the scanner displays the following “live data”:
O2S B1 S1 (V) 0.445
STFT B1 S1 (%) 0
O2S B1 S2 (V) 0.445
STFT B1 S2 (%) N/A (rear O2s removed)

O2S B2 S1 (V) 0.21
STFT B2 S1 (%) 0
O2S B2 S2 (V) 0.445
STFT B2 S2 (%) N/A (rear O2s removed)
Again, why the discrepancy between O2 sensor#1 in B1 and B2???

Can anyone point me in the right direction? I feel like banging my head against the wall with all the problems I have been having with this install. Thanks to everyone!

P.S. – Also have HPTuners so I can post data if needed.

 

Vacuum leak from vacuum line, cracked intake, improperly torqued intake, compromised seal, fouled plugs, bad plug wires, cracked plug, bad ignition coil connection or voltage, exhaust leak upstream from the 02, injector not plugged in or firing. These are some of the things that might cause your issue. Basically anything that can throw any extra air down the driver side exhaust. You can disable LTFT's and just watch the STFT's. Go to OL&CL under fuel control and look at the dropdown on the right. Select disable.
Sounds like the misfire is causing your trouble. Fix that and your troubles should disappear. You can swap plugs, wires, exchange coil packs with the passenger side, check your grounds, verify all injectors are plugged in.

 

Pull the plugs on that side. It should tell you which cylinder is missing. Then check the valvetrain on that one. If all looks good maybe swap injectors with another cylinder to rule those out.


I chased a problem 1 time for a long time before I finally pulled the plugs out and saw the gap was zero. Guess I wasn't paying close enough attention installing them.

 

P0300 Engine Misfire Detected

Did you get your O2 sensors crossed during the header install? I've done that, the car runs bad and the fuel trim adjusts the wrong bank. That could be your issue.

 

broken spring or rocker

 

Thanks, everyone! Will check all of these on Thursday (next time I get time to work on the car) and post my findings. Will go back to step one & check every little thing once again. I just get this feeling I'm missing something simple and when I find it, it'll be like, "Doh"!!!

If I was better at HPTuners, I'm sure there's a way to set a config file & then scan all the parameters that might be affected to narrow down the problem. Caulk it up to being one frustrating learning experience.

 

Here's what I've done so far:
1) swapped sparkplugs, wires & coils from Bank 1 to Bank 2 (measured resistance in each sparkplug wire as well....all ok, each approx 44.5 ohms)
2) checked O2 & injector fuses...they're ok
3) retorqued manifold to 89 in/lbs
4) retorqued headers to 18 ft/lbs
5) checked that all injector connections were fully connected
6) checked vacuum at idle....very steady 17 in/Hg

Scanned her again while running and all problems that were there before ARE STILL PRESENT. Still misfiring on cylinder #1. I looked at the injector harness for Bank 1 when I was checking each injector connection and it looked fine but I will recheck it again due to posts I have read about it rubbing/chaffing and shorting some of the injector wires.

The only other things it can be at this point is:
a) bad injector - I will swap #1 injector this afternoon
b) busted valve....PITA because I have Katech valve covers and believe I have to remove alternator to remove Bank 1 valve cover to check springs/rocker.

In addition, when looking at my scan (those who have HPTuners can go to http://www.hptuners.com/forum/showth...318#post189318), I think my engine has 2 problems. The misfire issue stated above & also a bad Bank 1 O2 sensor or bad connectors to this sensor. I don't think this would have affected my misfire issue since during warmup I was still in Open Loop but it would lead to problems once warmed up....which I haven't done yet since I haven't let her run long enough due to the misfires/backfires.

One last thing......when I swapped the plugs, Bank 2 plugs all looked fine. Bank 1 cylinder #3 and #7 plugs had soot/carbon buildup BUT I WAS GETTING A P0301 (misfire on #1 cylinder). Plugs from cylinders #1 and #5 looked clean. Does this make sense to anyone?

 

Looked at your log. Cyl 1 has a major problem, but you have random misfires on most cylinders. What plugs with what gap?

You said this all started after the blower install? Do you think you had a tuning mishap? Possible ring issues? You can force fuel trims off and open loop with your vcm controls. I would troubleshoot in this mode.

Broken valvespring(s) is sounding very likely as well.

 

Hi, User,name.

I am running the NGK TR6 (part # 4177) plugs gapped at .035". It could be tuning....don't really know. I am using a "basetune" supplied by the vendor of the SC kit (A&A).

I just finshed swapping the #1 and #3 injectors & rechecked the injector harness again for binds, pinches, chaffing or pinched wires. Looks ok so I will be trying to run her again & scan.

 

I doubt that baseline tune caused issues. It should be nice and rich up top. I'd pull the valve covers before messing with anything else at this point.

 

I just swapped injectors.....#1 for #3 and problem still persists on #1 so now I am going to pull the valve cover to check the springs. Katech valve cover PITA to pull.

"User name"....I think you are right with the valve spring. When I first finished the install, I had a problem with the car immediately going to 4000+ rpm every time I started it (you can scan my user name 'padler' for my posts dealing with these issues). It turned out to be a blown "burst panel" in the bottom of my FAST intake but it took a while to find. The FAST intake has been removed & the stock LS-6 intake was put back in its place. I am wondering now if the few startups I did where the engine immediately went to 4000 rpm might have broke a valve spring (or worn rings - yikes!!!).

Here is a link to the new scan with the injector swap
http://www.hptuners.com/forum/showth...712#post189712
Can be compared to the prior scan with injectors still in place & I think it is pretty much the same.

Can someone who is expereinced at reading these please chime in? User name, any more ideas would be appreciated. Thank you.

 

The log indicates you will likely find something on mechanical on cyl #1 imo. You already replaced the plug/wire/injector. It could be something with the wiring harness, but to only affect 1 cylinder it isn't that likely. Just have a look.

 

.....and #1 springs are ok????????? I feel like I'm on crazy pills! What can it be? Now either do a compression test (maybe screwed up #1 rings when car rpm shot up to 4000 rpm when I had bad intake manifold installed....though really didn't let it run that long when this happened)

OR

do some testing of Bank 1 injection harness.

ANY ADVICE? PLEASE.

 

If I did a compression check of the engine, wouldn't damaged rings have shown by fouling the plug on #1 with oil? When I pulled out the #1 plug, she was squeaky-clean, like brand-new clean. Granted, I only have a few minutes of running the engine between idle and 2,500 rpm while the car is on jackstands in my garage but all the plugs on the other side of the engine (Bank 2) came out of with a very slight tannish/brownish color. Meanwhile, #1 and #5 plugs looked brand-new while #3 and #7 plugs were carbon-fouled. Something is definfitely going on with Bank 1 but I just haven't found it yet.

Again, here's what I've checked:
1) sparkplug - NGK TR6 gapped to .035"....tried 3 different plugs in #1, all with same misfire.
2) plug wires - tried 3 different wires...measured resistance in each and only showing 44.5 ohms of resistance so wires are ok.
3) coil - swapped coils around twice, check coils with timing light & they're all good.
4) vacuum - steady at 17.5 in-Hg at idle so no air leak.
5) retorqued manifold
6) retorqued headers
7) pulled valve cover on Bank 1 and checked springs and rocker arm - all ok.
8) checked wiring harness for Bank 1 and it is intact - no chaffing, rubbing or splitting.

 

Trace it back to what was changed that caused the problem. Everything was fine before the A&A install? Problem started immediately after?

If so I would go back through everything you touched. It's likely with valvetrain or ignition related. Swapping coil packs is another idea. I would also swap pushrods and springs between 2 cylinders and/or get seat pressure checked on a few. You will need stronger valvesprings/pushrods anyway so you could just install those before moving forward. While you are in there check for bent valves/pushrods.

 

I had a similar problem but it was only one cylinder. The wire to the injector was broken internally. The wire looked fine but I guess I put too much pressure on while pulling the intake and broke the wire but not the insulation. I found the break by probing the wire upstream to the plug with an ohm meter. I purchased a new plug with the wire attached from Napa and soldiered it in. Problem gone. Another quick way to see which cylinder is miss firing is to use a water spray bottle and spray the header; the cool tube is the problem. Another way is to use a laser temp gun and read the temps.