AdsoYo

I recently had a shop install a brand new 383 LT1 with new opti, sensors and gaskets except for the header gaskets. The engine has about 3000 miles on it and after fixing a number of issues I've come to this one.

My scanmaster reads the rBL at 108 under cruise and light acceleration. As I accelerate harder the value increases. 115 under moderate acceleration, 120 if I press the pedal a little farther. If I hold that level of acceleration the rBL won't fall, it stays the same. If I reset the PCM, the rBL will quickly fall to 108 under cruise and light acceleration as the PCM relearns. If I'm idling or coasting, the rBL is up around 144-150. No codes. Tune is pcmforless but will get it dyno'd July 11th.

I haven't seen LBL go below 122. While idling or coasting, it goes up around 140.

It runs great, although I notice it retards the timing under load on the highway (going up a hill for example) but I assume that's just the engines different torque curve. It's gone as high as 9 degrees though!

I didn't find any vacuum hose leaks. Fuel injector cleaner didn't fix it. I was thinking of having the fuel injectors tested. Also look at the spark plugs, check the header for leaks. Someone recommended swapping fuel injectors from one side to the other but I'm hoping I can just have them tested.

Any ideas as to what could be pegging my rBL value? Anything I missed? Thanks.

Injuneer

Have you checked the right O2 sensor and the wiring? Use your Scanmaster to watch the right O2 sensor under various operating conditions. When you see the 108 RBL, switch to the RIN and see what that is doing. Is it varying near 128 (slightly above and slightly below), or is is also taking a dive well below 128?

It isn't likely its a vacuum leak. That would elevated the block learns. Ditto with exhaust leaks and misfires. They elevated the BL's.

Check the vacuum line to the fuel pressure regulator. If the regulator is leaking, the fuel ends up on the right side of the manifold. Pull the rails, pressure the fuel system, and look for leaking injectors.

As far as the knock retard, not sure what you mean by "I assume that's just the engines different torque curve. " Correctly tuned, you shouldn't see any knock retard at all. If you are "lugging" it up the hill, the EGR would normally activate, and EGR reduces the need for knock retard in that situation. Do you still have the EGR system working? What grade fuel are you using? What is the elevation where you live?

AdsoYo

Thanks Injuneer, I'll do your recommendations asap.

I do have EGR, I had the shop put a brand new valve on. I haven't paid attention to it in the scanmaster to see how its working.

I'm back in Washington State using 92 octane at about 1100 ft.

AdsoYo

I just cruised around to get some readings.

LBL was lower than I remember at 118. LIN would alternate between 124 and 131. O2L was varying normally.

rBL was at 108. rIN would alternate between 116 and 123. O2R was varying normally.

I held the throttle at a harder level of acceleration to get different BL values since the PCM hasn't learned them yet and both banks would drop after a few seconds, LBL to just below 120 and rBL to 108.

Injuneer

Swap the O2 sensors side to side. See if the problem follows the sensor. That would confirm a faulty O2 sensor. If the problem stays on the right side, you have to start looking for things that affect only one side of the engine.

AdsoYo

The fuel pressure regulator was good to go, no leaks of any any kind, held fuel pressure. Swapping O2's didn't change anything. I took it to my usual shop and had them test the injectors. They said they were fine and that they were unable to set any codes. Their suspicion is the tune at this point. I knew pcmforless could realistically achieve a only a ballpark tune but rBL pegged at 108 and the constant knock retard seem amateur. I guess I'll find out for sure on dyno day.

Injuneer

Why would the "tune" affect only one bank of the engine?

AdsoYo

I don't know, are you saying it's not a possibility? The mechanics said their computer showed the engine was operating within normal boundaries and the injectors and fpr were fine, I'm not sure what's left in the equation.

Also since you asked about the egr, I watched it while cruising on the highway. If I held the throttle in an attempt to activate the egr, it would rapidly bounce between 00 and 12. The longest it did that was about 3 minutes, then I couldn't hold the throttle anymore because of traffic. The valve is brand new, everything else is off the old engine.

I appreciate the help Injuneer, thank you.

AdsoYo

Still having issues with the fuel. The car has been dyno'd so the fuel trims are higher but there's still about a 10 point split. There are plenty of other issues I'm dealing with too...

I have a datamaster file in .uni and .csv

I'm sucking at setting up an FTP so I was wondering if I could email it to who ever will take it and tell me wtf is going on?

I'm using a speed density tune right now because of a MAF issue, so there aren't any MAF values in these files.

AdsoYo

As far as Injuneer's recommendations, I pulled the vacuum line to the fuel pressure regulator while the car was running and it was dry, no leaks. I pulled the fuel rail and pressured the system and there were no leaking injectors. I swapped one sides injectors to the other and the problem didn't follow the injectors. After I did the swap, the car didn't show any knock retard for about 2 days though, and it's been a constant problem of mine since the engine was installed. I also swapped O2 sensors from side to side and the problem didn't follow the O2's either. The EGR is also working properly.

AdsoYo

ttt

AdsoYo

ttt

Injuneer

Under light load/cruise, what is the right O2 sensor reading?

AdsoYo

There's a section in my data log where I hold a steady 35mph for a while and the O2 reading varies. The O2's are hundreds of mV's apart more often than they are close together. One side is never higher or lower more than the other it seems, they both spike and plummet just as much as the other, but not at the same time.

Injuneer

Each bank of the engine is controlled independantly. They are not linked, so they will not have the same readings, or even close in closed loop.

For the BLM to drop to 108, the O2 volts have to be high, or the INT's are having to pull out even more fuel to keep the voltage where it belongs. What are the short terms reading under those cruise conditions?