2000 C2500 Project

[EJ_74]

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I apologize for the dust on the valve covers, it's from all the pollen lately.

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I removed and capped off the air intake resonators. Cleans up the engine bay and it sounds a little louder now. You can hear more of the wooshing sound when opening the throttle, not the same as a quadrajet but still cool.

 

[SNCTMPL]

Looks good, how’s the 383?

 

[EJ_74]

Looks good, how’s the 383?

Thanks. It's definitely better than the worn out 350. I had a few problems at first, low oil pressure and transmission not shifting. Both were because of brand new, faulty sensors. I thought Standard Motor products was supposed to be a decent brand. And then I had to pull the upper plenum back off because my metering body gasket was leaking. But all is fine now. Runs good, just need to finish breaking it in. Feels strong, I want to see what it's like on the highway. Curious about the gas mileage too.

 

[SNCTMPL]

Well that sucks about the sensors, but it happens, more than it should these days. I’ve used Standard before with good luck. I’ll bet you’re going to dig the 383, keep us posted.

 

[EJ_74]

My new exhaust has been noisy since I first installed it. Found one of the clamps before the muffler was not sealing well. The muffler itself was leaking between the body and pipe entrance. And the intermediate flange had blown the gasket out. The clamped-on tailpipe did not want to come off the muffler so I had to pull everything from the flange back as one piece.

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Gap between the pipes. I tried putting the clamp in different positions but it still leaked.

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Welded it together. I'm still learning, this is only my third time using a welder. I also added some beads to the muffler where the pipes go in. But I left the clamps to hopefully make disassembly easier when I get ready to put duals on it. I used two gaskets at the flange last time but I guess that wasn't enough. Used a lot of high temp RTV and one gasket this time. Leaks are gone now, sounds much better. I still want to do duals though after I decide on mufflers and find a good exhaust shop.

Yesterday was the truck's birthday (turned 24). I took it on the highway and finished the last 80 miles of the engine break in. The stroker seems pretty strong, it'll cruise and accelerate in 4th with little throttle pressure. Changed the oil, using synthetic now.

 

[EJ_74]

I've been driving this but haven't done much to it lately. Seemed to run ok but wondered how much better it would be with a tune. Got a mail order PCM from Black Bear a couple weeks ago. After installing, it started spark knocking a lot under load. Checked a few things, nothing obvious. Replaced the plugs, cap, and rotor because they were not high quality and pinging improved but was still there. There was a little oil on one of the plugs so I checked compression against another cylinder and they were similar. Hopefully it's just because the engine is new and still breaking in. Engine is supposed to be 9.1:1 compression suitable for 87 octane. Tuned for 87 as well. But 175-185psi seemed kind of high so I tried 93 in it. Spark knock went away. But then I got a CEL for bank 2 long term fuel trim too rich. Cleared it and it came back. Contacted BB for advice, they said they didn't do a whole lot to the fuel trims so it's probably not because of the tune and it could be a faulty MAF. I replaced it and it seems to have fixed the issue.

I don't know a whole lot about computer controls but a few things seem odd to me.
The short term fuel trims are about the same between the banks, but the long terms are -8 and -14%. I don't know if this is an acceptable difference or if something is going on with that bank.
I don't have any misfire codes but while watching live data with the scan tool I can see that cylinders 2, 3, and 4 are getting 10-40 counts per cycle at idle. It's been doing this ever since I put the engine in. Changed plugs, wires, cap, rotor, no change. Seems to have less misfires when cold and more when hot.
The rear O2s were disabled in the tune but are still connected and display data on the scan tool. One of them fluctuates up and down a lot more than the other.

It runs great, no driveability issues. I want it to be healthy, but since I'm not getting any codes not sure if I should mess with it.