Deenasty

Hello all. First off this is what is going on. Only at idle, the drivers side (left bank) o2 sensor states the car is running lean Sterm 160-170 blm, Lterm 160. Passenger side is Sterm125-133 blm Lterm 139. I have a y pipe from a 1996, so it has locations for four o2's, although my car only runs with two being that its a 1995. In place of the driverside rear o2, I have a wideband o2 sensor, and on the left side(passenger), just a plug. Being that the right side regular o2 states its running lean 160-170 blm, the wideband 02 states 13.1-13.4 AF, so if indeed the car is running lean, the o2 is doing its job and correcting the lean condition. Keep in mind the o2's are brand new. I have looked for exhaust leaks, none are present. I dont know what else to do as far as fixing this situation. Thank You BTW I have logs and all for anyone who cares to view. Thank You once again...

OBE1 95Z28

What throttle body are you running. I've read post where aftermarket TB's don't have the "breather hole" that feed the cylinders during idle, causing uneven blms. If you look at the stock TB, there's a hole through the TB that assists the IAC.

Deenasty

Its a 58mm BBK..

Deenasty

Here are the Pictures of the spark plugs on bank 1:

plug 1


plug 3


plug 5


plug 7

MentalCaseOne

Get a digital meter from Radio Shack.... an inexpensive one will do. Then measure the internal resistor of those spark plugs. I have replaced spark plugs that looked just like those and Just two weeks ago I decided to measure them. The good ones had a resistance of less than 5 K ohms.. or Five thousand ohms. The bad ones were clocking in at over 40 K ohms.


I have replaced those NGKs three times this year already and I have less than 10 k miles. I dont know what my problem is at this moment.

Marvin

Deenasty

how do you measure them, positive on the resistor, negative on what?

Injuneer

This is a VERY confusing statement:
I'm assuming you meant to type right side (passenger)???? But fiurst you say the drivers side has the 160/170 STerm, and then you say the passenger side is running lean 160-170BLM. Confusing as he!!.

Might want to retype your data using:

Bank 1 = left side = driver's side = Cyls 1/3/5/7

Bank 2 = right side = passenger side = Cyls 2/4/6/8

The combination of the O2 sensors and the PCM are NOT doing their job. If they were, the wide band on the drivers side would be reading 14.7:1 at idle and part load. Appears you may have a "false" lean, and the PCM is adding fuel the driver's side doesn't need. Looking at the plugs, one is running fine and maybe a little lean, the other three are running excessively rich. That tells you that a problem on one cylinder may be causing the lean condition and causing the PCM to screw the other 3 up.

What do the passenger (right side) plugs look like?

What do the BLM's for the rest of the cells look like?

Have you tried swapping the wide band over to the passenger side to see how it is running?

How does the drivers side show up on the wide band at lther than idle conditions?

These are just random questions, because its really not clear to me which bank has which BLM's.

Deenasty

Im sorry. Now that I read it over, my post was horrible. Bank 1 is running Lterm 160 Sterm 145-160. Bank 2 is running Lterm 149 Sterm 128-132. The wideband on bank 1 side is showing 11.8-12.0 at idle, but clears up upon acceleration or cruising speeds. This is only occuring at idle. I have checked the plugs on the passanger side, and they looked pretty black, with grey tips. So it could be that they were overloaded in the past, and now starting to clear up. I have not put the wideband on bank 2, but I will try that and see what happens. I also do believe that a false lean condition is present due to the amount of overlap this camshaft has, 24 degrees. If this is the case, what is a remedy for it, PE idle?

1racerdude

24* isn't much overlap at all.Your problem lies somewhere else.Your cam was built to retain compression and is pretty short.
Most cam's I use have 30*-35*@50 and 70*-75+* at seat. The plugs in my builds don't get richer as they go from front to back.I have seen this with a Victor carb manifold that have a fuel distribution problem that is inherent with them and a carb.
Look at the other side and see if they are doing the same thing. If they are ya need to figure out why it's lean in the front cyl and getting richer the farther ya go back.

Deenasty

yea Larry I checked the otherside, and this is not occuring on that side. The o2 on bank two is reading fine. Its just bank one I am having a problem with. And there is no exhaust leaks on bank 1 side...

1racerdude

For some reason ya ain't getting the right fuel to the front two and too much to the back two.
Vacuum leak,intake gasket,valve adj,don't know.

Deenasty

could mis-adjusted valves cause this?

1racerdude

Intake valves to tight is a vacuum leak not to mention the other things it would cause.
Not saying that's it,but it could be.