aaronware76

iTrader: (2)

Fellas, I had my stock block pulled and a forged iron Thompson 5.7 installed so I can really push my Huron speed V3 kit. Got everything fired up, got a cylinder misfire CEL,check engine light. Some wires were making contact with the manifolds. Swapped out any burnt wires, put protective sleeves on all of them, moved some coils around, CEL gone. Went to my tuner for a break in tune, CEL comes on intermittently for cylinder misfire bank 1. It goes away, he keeps tuning. It pops up and goes away a few more times while tuning.
I pick up the car, no CEL, but the idle is TERRIBLE and cold start up is super lean for the first minute then goes into a normal range. Drives fine, no boost. Keeping it under 4K for 500mi break in.
A day and a half, 80 miles later, CEL comes on. P0332, knock sensor 2 low circuit input bank 2. Surprising, I would have thought cylinder misfire. WTF?
I ask my tuner, he says it's mechanical. Knock sensors are bad from the swap over from the old motor. I ask my mechanic, he says no way. It's a tuning issue. It's adjusted to sensitive. He says the misfire is increasing knock and the sensor can't pull enough timing out. WTF...
So.... where the hell do I go from here? Any thoughts would be greatly appreciated.

transam69230

iTrader: (49)

All the plug wires on? coil packs plugged in tight ? Loose ground wire on the back of the head?

What plug wires? MSD wires are garbage.

I haven't had knock sensors in years. I would run without them personally, or at least unplug them and see if you are still having issues.

neverstop

can always put some unleaded race gas in there to make sure it's not real knock also. the cold start thing makes me think the tune is not good

sbcgenII

iTrader: (1)

Tune shouldn't be off on cold start. If it is fine after it warms the O2s are correcting for it. If you have a scanner reset the fuel trims start it up and watch what they do.

Find new tuner and mechanic.

The BallSS

iTrader: (9)

Lean at first start up is a tune issue.
On cold start my AFR is at 12.5 and as the engine warms it leans out to 14.6 so to start out lean tells me the tune is off.

aaronware76

iTrader: (2)

Oh I know the tune is off. My wideband is reading a 20-22:1 afr at cold start up for approximately the first minute then it fattens up into a normal range. My question with the knock sensor fault though is are they bad and does that need to be corrected with new knock sensors or is there something in the tune way out of wack that is triggering the check engine light for the knock sensor code? So do I go after my tuner, basically hunt down a new one, to correct the issue all in the tune or do I need to mechanically fix and replace the knock sensors first then retune? Or let's back up a little bit, am I having a misfire still that isn't throwing a misfire code anymore and is somehow throwing a knock sensor code?

ddnspider

iTrader: (26)

A misfire and code for knock sensors is hardly a tuning issue. You need the motor to be mechanically sound or any tuning he did was a bandaid. Figure out the misfire and knock sensor issue first. Then have it turned. Do the logs show knock?

jordoza777

iTrader: (2)

random misfire code could be tune . Misfire on only one cylinder is mechanical almost always. The knock sensor code you have is electrical. That is not tune related. Do you have a shitty tune yes because of the lean on start up but you are chasing multiple issues. Fix your knock sensor issue. Install one new plug. Swap coils 1 and 5. Swap injectors 1 and 3. If no more misfire plug was the answer. If it starts missing on 5 coil is bad. If it starts missing on 3 its the injector. Get a better tune or a more complete tune.

turbotruck2007

Well said ..

silversweetZ

iTrader: (11)

For the knock sensor I would look under the intake. I pinched those wires twice on the vent tubes and was getting similar codes if I remember right. As for the rest of the tune these guys are spot on...find a better tuner

RealQuick

iTrader: (14)

and to add, if the misfire stays in the one cylinder the whole time, pull the valve covers and check your rocker arms.

mightyquickz28

iTrader: (8)

Do you have the tune in HPTuners format you can send? I can compare it to some other turbo tunes and see if anything is glaringly off.

ddnspider

iTrader: (26)

Misfire being a tune is highly unlikely. I've seen cars idle at 10:1 all the way to 18:1 and not misfire.