95 Z28 has more power with MAF unplugged seems to miss or bog down in closed loop operation. It behaves nicely all day with the MAF unplugged. I have attached csv from SCAN9495 It seems like Bank2 is adding more fuel compared to Bank1.

Any ideas of what to look for?

 

Lack of punctuation leaves your post unclear. Are you saying the engine runs poorly with the MAF sensor connected, and runs better with it disconnected?

I'll download the file, but seems to be a lot of these requests lately. There's a backlog at this point.

 

Sorry about the confusion. Yes, it runs poorly with the MAF sensor connected, and better with it disconnected.

Don't bother looking at the log, I found a loose bolt on the header. I tightened it, but the gasket is damaged and it still leaks. I will replace the gaskets and see how it goes.

Thanks,

Jim

 

Was it the passenger side header with the leak? That's the side w/ the elevated LTFT.

 

Yes, the passenger side was leaking.

 

Looked at it anyway.

Is the problem new, or long term? Did you make any changes to the engine immediately before the problem started?

You've got large additions of fuel on both banks in the heavy load cells, not just on the passenger side.

You have a significant amount of knock retard when you roll into the throttle, enough to sense a loss of power at large throttle openings. Based on the O2 sensor readings, doesn't seem to go lean in power enrichment (PE) mode (recognizing the accuracy limits of narrow-band O2 sensors at ~12:1/A/F ratio). Even without the throttle application there is often a background of a fractional amount of knock retard.

Shows DTC 48, but appears that your log was done with the MAF connected, and DTC 48 is a stored code from previously unplugging ?

Did you have the PCM tuned for the cam? What 1.6 rockers are you using - full rollers? Do you have an LT4 knock module?

 

The problem should be considered long term.

When I got the vehicle, it had two blown head gaskets. I pulled the motor, took the block, crank, and heads to the machine shop. Cylinders were ok with just a hone. The crank needed to be ground. Installed new valves, seats, springs and rockers.
I reassembled the engine; installed rings, bearings, cam...

The DTC48 is from a previous operation with the MAF unplugged.

I have not yet gotten a tune for this cam and assorted changes. I wanted to get it mechanically sound before attempting a tune. The rockers are Comp CCA-1418-16 magnum roller tip rockers.

The knock sensor is the original.

 

The Magnums are only roller tip, not full rollers. The "knock module" is not the same as the "knock sensor". The LT4 knock module (plugs into the PCM) filters out noise from the LT4's full roller rockers, to prevent false knock retard. Probably not an issue with roller tips.

Without a tune, and resolving the problem with the high LTFT's and knock retard, I wouldn't be hammering it cold, in open loop. With 30% throttle it went into power enrichment (PE) mode, peaked at 9-deg knock retard, and poured excess fuel into the engine, particularly on the right bank, with the 153 LTFT (20% extra fuel) in Cell 18. After you drove it for a while in closed loop (learning enabled) the right side LTFT in Cell 18 dropped to 142. But the PCM was using Cell 15 LTFT's in PE mode, and right bank was 148. Hopefully correcting the exhaust leak fixed some of this.