y5e06

I have a poor running bone stock LT1 engine, especially at part throttle w/ warm engine. I used datamaster on the PCM. When warmed up and cruising at steady part throttle (10%) I get a long term BLM (LTerm Counts) of 149 on the right and 126 on the left. injector duty cycle and pusle width appear to correlate to the BLM's, right side DC and BPS is ~10% higher than the left. I looks as if the right side is running very lean. O2 milivolts seem to swing in the expected ranges. during cruise my spark retard ranges from 0.4 to 0.7 and jumping up to 1.7 at one particular change of throttle possition (slight acceleration).
Under heavy acceleration I get three spikes of spark retard, two corresponding to the auto tranny shifting. At WOT the retard is as much as 9.0 degrees. yes I know this is way too much. right side lean condition causing detonation and therefore spark retard?
MAP pressure and TPS volts/% also appear to vary in the expected, correct ranges.
A few other things I've noticed: IAC is 48 at idle, 62-64 at cruise, and 81-90 at WOT. EGR duty cycle is 0 at idle and WOT (normal, right?) but 99.6% at cruise. Charcoal canister purge is also 100% at cruise. I checked these values against my Z28 under similar conditions: IAC 21 at idle, 48 at cruise, 66 at WOT; both BLM's 108 (rich) at cruise; EDR DC 0.0 at all times; CCP DC 0 at idle and WOT, 21-42 at cruise; at WOT left 02 ranges 866-900mV and right ranges 790-950mV, at idle and cruise they range about the same.
I checked the EGR by pressing on the diaphram, it almost stalled, which is normal. I don't have any engine codes of any kind. However at idle I did not feel any vacuum at the EGR from the vacuum line from the solenoid. I reved the throttle in park and still did not feel any vacuum. However there is vacuum at the line from the intake to the solenoid. Is this normal or is the EGR solenoid bad?
Does it sound like I have a bad EGR solenoid? bad right 02 sensor? bad injector not fully opening on the right bank causing lean conditions?
I tried posting my datamaster files on a webserver but they never download correctly when I do this. If anyone wants to look at them I can email it too you. How do I verify the solenoid or 02 sensors are healthy?

The right is running lean so I'm assuming its not a spark/ignition issue or a bad cylinder with bad compression. I would those issues would cause rich condition by not thorougly igniting the mix. I am planning on swapping injectors from left to right and right to left to see if the conditions change sides. If it does, then probably injectors. If not then maybe its the injector wiring harness, connectors, or maybe not injectors at all. I have not gotten any codes indicating a misfire or bad cylinder.

anyone have similar experiences? any good ideas?

Injuneer

Can we assume that since you are comparing the "problem" engine to the 94 Z28, that you are in fact talking about a problem with the 1993 Corvette? It gets a little confusing when you talk about:

"at WOT left 02 ranges 866-900mV and right ranges 790-950mV, at idle and cruise they range about the same. "

Is that for the problematic Corvette, or are you indicating data for the 94 Z28?

Your EGR solenoid is "normal". Its purpose is to block the vacuum from the intake manifold, until the PCM tells it to open. Then is pulse width modulates, cycling rapidly to achieve the proper vacuum level in the EGR diaphragm to produce the required degree of opening. No vacuum in the line from the solenoid to the EGR valve is "normal" at idle.

You will not get any misfire codes or "bad cylinder". Your cars are both OBD-I and there is no misfire detection provided in OBD-I.

Your problem is obviously on the right/passenger/bank 2 side with the 149 BLM. The left/dirvers/bank 1 side seems to be perfectly normal with a 126 BLM. By the way.... what Cell are you taking the BLM's from? There are 18 Cells, and it helps to have as many of them as possible to track down possible causes. As a minimum, get Cell 16 (idle) a low load cell, like 01-04, a moderate load cell like 08 - 10, and the max load/max rpm Cell 15.

Your 149 BLM "may" indicate a "false" lean. It can be reacting to incorrect data from the O2 sensor, either a fualty sensor, a misfire or an exhaust leak before the O2 sensor. Any of these will cause the PCM to elevate the long term corrections and over-fuel the affected bank. The fact that the peak O2 mV's on the right side is 50mV above the left side would indicate this is a possibility.

And.... your right side is not actually "running lean". It would be running lean, IF the PCM was not increasing the BLM on the right side to 149 to add the extra fuel. But it is adding the fuel, and since the BLM is not max'd out (160) it appears to have it corrected. Unless of course the O2 sensor is providing the wrong info because it is faulty, or seeing "false" excess O2 from a misifre or an exhaust leak.

To rule out the O2 sensor, swap them from side to side and see if the problem follows the sensor (sensor problem) or stays on the right side (wiring or misfire, etc.)

y5e06

yeah, I should have indicated which car. Actually it is for a '94 Caprice 9C1, so it is very similiar to the z28. I don't hear any tell tale sounds of an exhuast leak from the right side between the 02 sensor and manifold, but I'll pay more attention I go play with the car. I do notice a different exhaust note on the right , more of a putter or chugging sound i.e. unhealthy running and not necessarily leak. It could be though.
at idle w/ cell 16 I have BLM's 115 left, and 134 right.
cruising at 10% TPS its cell 10 BLM's 126/149
throttle 7.5%, cell 6 BLM's 125/142.
at very light throttle 2%, cell 2 BLM's 116/136.
at full throttle 100%, cell 15 BLM's 139/153.
decellerating with 0% throttle after a WOT run cell 17 BLM's 120/134.
I didn't realize the importance of the different cells, this is my first time using the software. There is definately a difference between the sites.
Also I just noticed I ran the logging as an F-body in stead of the correct B-body, but seeing as how they are nearly identical, sensor wise etc, the results should be the same.
I will try swapping the 02 sensors and injectors (independently of course) from side to side. with a misfire, ignition component replacement is probably on the list of things as well.
thanks for the input!
This software is awesome! Eventually I'll learn the tuning aspect w/ LT1 Edit or tuner cat.