Well I got the motor back in the car and everything buttoned up. I fired it up last night. It sounds good. However, to ruin my excitement I was presented with a misfire code of po300 and my aeroforce gauges are showing random misfires in all cylinders.

These misfires are why I pulled the engine out in the first place suspecting something was wrong with the engine. I have new plugs and new wires. So now I get to chase these misfires

I calibrated my wideband before starting it. It was showing 15.5-16.0 idling. On the way home I'm going to get a new wideband sensor and 2 new front 02 sensors. As well as borrow a fuel pressure gauge to check the pressure on the rail. Will the misfires and lean a/f at idle hurt anything while I get this figured out? I don't plan on driving the car or giving it any rpm until I figure it out. I'm also going to pick up 5 gallons of fresh 93 octane today and throw that in too. Gas is low and has been sitting for 2 months. Same gas I had when the misfires started.

Open to any suggestions. So far my guess is 02 sensors, bad gas, maf or fuel pump. Am I way off base?

 

Wow, I can't believe none of the tuners have responded to this.
I could be wrong, but I thought random misfire codes were common with aftermarket camshafts. That being said, I am sure Ed will stop by and post his opinion.
I think all you need is a good tune, though. We have done numerous cam swaps on the local GTOs, some of them resulting in the misfire codes, some of them not. In every case, though, there was nothing really wrong, and a tune took care of it.

 

The problem is the misfire table. It's hard to explain but basically Ed sent me a tune file with some adjustments to help me keep the car from downshifting on the dyno to load it up better for tuning the spray. I sent him my base tune file and he edited from there. When I got the file from him I compared it to my file and it appeared nothing was changed but the tranny settings for the downshift issue. I didn't think to look at the diagnostics section..

So in a nutshell I started using that tune as a base tune. It makes sense because I didn't get the misfires until after the dyno that day. So I went back and looked at my original tune before that day and the misfire settings are NOT stock. So I just need to modify the settings back and I should be good to go. Not sure if this makes sense.

I would be pissed that I pulled the motor for nothing if we didn't find the cracked flex plate, busted up timing chain, bad pulley, worn bearings and wearing rings. In the end now the motor is built for spray so I'll have a little more insurance so I don't have to worry about the rings.

So tonight I'll load the file and fire it up and see what I get. But I'm 99.75% sure that's the issue. Especially since it makes sense. I'm waiting on an adapter that should be here today or tomorrow for the new 100mm maf. Have to tweak the exhaust a little to fit better and then on to tuning.

 

Hmmm, I thought I modified your tune for the lock up. The tune you sent me this morning had stock misfire tables. They're not stock no more........

 

Yeah I just figured it out this morning on the way to work. The tune I sent you originally to modify lockup had the misfire tables modified. Not sure where yet without looking at every tune, but somewhere in the crossfire I got the misfire tables mixed up and it ended back to stock. No biggie as this is a very easy fix. Just copy and paste. I wouldn't have figured it out if you wouldn't have sent the file this morning for me to compare. Thanks!

 

Just drove it for the first time. All good. I noticed with the 160 degree stat it runs at 167-171 at hwy speeds. When idling it will get into the 190s up to 198 before it starts coming back down.

Is 160sih running temp too cold?

I noticed the trans output shaft is spinning 1000 rpms faster than the engine rpm at low rpm/speed. I checked and I have too much fluid in the tranny. Will that cause the converter to slip?

 

Shawn,

I just changed the oil Amsoil 15w40. I pulled the plugs, coils and fuel pump relay and did a compression test. Engine was cold with the throttle open. Each cylinder cranked 5 times. Has only been driven to work and back twice.

1) 195/196 2) 185/190
3) 203/197 4) 176/176
5) 235/230 6) 191/188
7) 193/193 8) 183/180

Why the huge variance? The old 416 was ~180 on every cylinder even before broken in. I realize the nitrous rings are different but shouldn't it already be broken in from the dyno? Based on the internals/compression what kind of compression should I see? Don't even know what the compression ratio is.

 

dude,just run the motor-there is nothing wrong with it.i have no idea what the cylinder pressure should be-i don't do compression tests unless there is something wrong.it takes up to 30 hrs of hard running to fully seat in the rings-the rings in this motor are much harder than the old rings and will take longer to seat in.

 

Just being precautious man. Always do this, did it with the 416 too. Just do everything in my power to make sure it's 100% before tuning. Just never seen that much variance. Figured after the dyno it would already be broken in. So after running it hard a bit there could be more power in it? Maybe after a couple pulls on the jug it will tighten up.

 

with the hard rings it does take a while,and yes there is probably some more power-usually as they lossen up a little they make a little more power.it needs some good hard running to get everything where it needs to be-take it to the track and makes some passes.

 

With any luck I'll make some passes this coming Sat.

 

so.....the rumor is 550rwhp and 522tq.how about a dyno sheet.

 

First pull was 538 spinning the hell out of the 17" Hoosier DRs. We heated them up and a couple pulls later got 550/522. The last pull with the car hot was 545/520. That's the sheet I have.

I'm still doublechecking everything and making sure it's dialed in. I'm going back on the dyno tomorrow so if all goes well I'll post up the sheets. I was waiting until we got the nitrous pulls 100% before I posted.

I'm going to the 1/8th mile tonight for some shakedown passes. Then on to the

 

First pull was 538 spinning the hell out of the 17" Hoosier DRs. We heated them up and a couple pulls later got 550/522. The last pull with the car hot was 545/520. That's the sheet I have.

I'm still doublechecking everything and making sure it's dialed in. I'm going back on the dyno tomorrow so if all goes well I'll post up the sheets. I was waiting until we got the nitrous pulls 100% before I posted.

I'm going to the 1/8th mile tonight for some shakedown passes. Then on to the 1/4 mile tomorrow. We hit the full 150 shot on the street from 58 mph and let me tell you it was dirty. Motor pulls strong. I'm running 15w40 amsoil and so far does not burn any or smoke. Just like the old 416. The car drives awesome. I drove it to work on my 15" drag setup today. I'll be running on those for the first time tonight. I'm extremly happy with the car so far...the only thing I have my radar on is that my wb says the car is rich on the street. That's why I'm going back to the dyno tomorrow to try another wideband. Tomorrow will be a different dyno than the one I used Wednesday.

 

Congrats man . Looks like your up about 50 hp over the 418

 

Amsoil???????

 

Got a few shakedown passes in on motor tonight.

1.48
6.75@101.90 with 120lbs more in the car than normal

I have a little more tweaking to do before I spray it. I think it has a 6.65@103 in it

Shawn - I noticed in the logs that parts of the run the car only has like 35psi oil pressure at 6500. Is that ok? I was always told that you wanted 10psi for every 1,000 rpms. Car has plenty of oil, I checked.

 

Got a couple passes in on motor tonight. I'm extremely happy with the motor. I'm still working out some issues on the nitrous so no passes on the bottle tonight.

1.44
4.27
6.66@102.52
10.44@130.48

All Motor GTO. Raceweight was 3520. Done on a 275/60/15 Hoosier drag radial. I'll post a video of the run, although it looks pretty tame, and dyno sheets in the next day or two.

 

Nice numbers!!!

 

Congrats again. ITs really movin out now. I cant wait to see how it runs in the fall.