DataMaster Log File - Anyone willing to look and help troubleshoot?

[meissen]

Something's off on my dad's car but we can't quite put our finger on what it is. At 3,000+ rpms the car has a miss or a shutter. It's not throwing any codes. The long term fuel trims seem off.

AutoLog_001.uni

[Fox Slaughter]

Do you have the tune from the PCM?

Stock setup?

My god! LEAN! LEAN!

Left Bank:
Cell 0 No hits,
Cell 1 No hits.
Cell 2 143.5
Cell 3 133.2
Cell 4 141.0
Cell 5 134.5
Cell 6 132.5
Cell 7 128.2
Cell 8 130.5
Cell 9 130.2
Cell 10 130.0
Cell 11 128.4
Cell 12 No hits.
Cell 13 No hits.
Cell 14 128.2
Cell 15 128.0
Cell 16 153.3
Cell 17 151.0
Cell 18 138.1
Cell 19 No hits.

AVERAGES.

You don't even wanna see the Right Bank.

If its true, hes going to be buring valves in no time.

[JoeliusZ28]

I dont have software on my laptop yet but ill try to get that done this weekend so i can take a look

[98blackbeauty]

Do you have the tune from the PCM?

Stock setup?

My god! LEAN! LEAN!

Left Bank:
Cell 0 No hits,
Cell 1 No hits.
Cell 2 143.5
Cell 3 133.2
Cell 4 141.0
Cell 5 134.5
Cell 6 132.5
Cell 7 128.2
Cell 8 130.5
Cell 9 130.2
Cell 10 130.0
Cell 11 128.4
Cell 12 No hits.
Cell 13 No hits.
Cell 14 128.2
Cell 15 128.0
Cell 16 153.3
Cell 17 151.0
Cell 18 138.1
Cell 19 No hits.

AVERAGES.

You don't even wanna see the Right Bank.

If its true, hes going to be buring valves in no time.

what is right bank doing? and what does no hits mean in a cell.

[meissen]

Now I know it's lean, but I'm curious to what extent. I mean a stock tune isn't 14 afr the whole time, nor should it be, so I would expect it to be a little lean, right? But is this "way lean"? It's not throwing any codes for being too lean.

[Fox Slaughter]

The right bank is even worse.

128 translates to 14.7 for stoichiometric. So by being say at 140. Thats 6% off. So since >128 means rich and >128 means lean you would need to increase fuel by %6. (It will get you in the right area, still need to tune, datalog tune more for accuracy).

No hits means the car never entered into that cell. The cells are made by certain airflows and RPM scales.

The codes are 64 Right o2 Lean, 65 Right O2 Rich. 45 Left o2 Lean, 46 Left o2 Lean. Why they aren't throwing I don't know. It could be because its a OBD1. Don't know.

[Fox Slaughter]

Right Bank:
Cell 0 No hits,
Cell 1 No hits.
Cell 2 151.5
Cell 3 143.4
Cell 4 154.0
Cell 5 146.8
Cell 6 146.7
Cell 7 136.8
Cell 8 141.0
Cell 9 133.8
Cell 10 143.6
Cell 11 143.7
Cell 12 No hits.
Cell 13 No hits.
Cell 14 131.3
Cell 15 136.4
Cell 16 159.9
Cell 17 154.7
Cell 18 153.8
Cell 19 No hits.

AVERAGES.

From the factory cars are tuned to run slightly rich at WOT. This is because running slightly rich is safer than running lean. To rich though and it will cause cylinder wash, foul plugs, and detonation.

What are the modifications done to the car? Or is it stock?

[98blackbeauty]

car is basically stock except for long tube headers, an egr and air delete

[Fox Slaughter]

Has the car had a tune to remove the AIR and EGR?

Did this just start happening?

[meissen]

It's tuned to get rid of the egr and air pump codes.

[Fox Slaughter]

There is a spot where it hit 10.3 degrees of spark retard.

Right at 3550rpm.

[meissen]

FWIW, looks like it's definitely not the tune. We have a spare PCM so I found a LT1 file for a stock 95 Trans Am M6 and uploaded the stock tune to the spare PCM. Didn't change anything, still very lean. That reaffirms that whatever is going on is mechanical (exhaust manifold leak, leak in the intake manifold, etc). Somewhere too much air is getting in.

[JoeliusZ28]

FWIW, looks like it's definitely not the tune. We have a spare PCM so I found a LT1 file for a stock 95 Trans Am M6 and uploaded the stock tune to the spare PCM. Didn't change anything, still very lean. That reaffirms that whatever is going on is mechanical (exhaust manifold leak, leak in the intake manifold, etc). Somewhere too much air is getting in.

Yep start looking for vacuum leaks... Although a vacuum leak usually gives you a high idle too. Is it some kind of valve that is only leaking at high rpm?

[meissen]

Yeah not sure. We do hear chattering like the rockers are loose but my dad says he's adjusted and readjusted the rockers like 5 times and yet the chatter still seems to be there after a heat cycle.

[Fox Slaughter]

Hm. Take a piece of newspaper or some thin paper and hold it up to the exhaust and if you feel it suck in, you have an exhaust leak. Could be air getting in after the head, or in my case burned exhaust valve.