sonman

Aloha to everyone! First time Camaro owner, I have a 95 Z28. Bought it 5 years ago w/ 150k miles on it. Owned a 79 Trans Am back in the '80s. Recently my Z was down for a few months, but with the help of a friend, whose also a good mechanic, he got it running again, which began w/ replacing the starter. Like dominos the problems began to compound, one thing, one part after another failed and needed replacing and so began my expensive saga to keep my car running. So generates the list as follows replaced: opti, rotor, plugs & wires, egr valve, fuel pressure reg, map sensor, maf sensor, low coolant sensor, injector orings, opti harness wire, single cat, iac valve, 1le intake elbow, radiator w/ new antifreeze, engine flush, new oil & filter, flush pwr steering, new fluid, flush brakes, new fluid, drain trans, new filter & fluid, serpetine belt, high pressure ac hose, r134 refridgerant, vacume hoses, yet to install is ac expansion block valve. So right now my two big issues are the transmission and the ac. Put ac on hold, tranmission more important, it's slipping, not sure but no 3rd or 4th gear, if driving real slow 1st & 2nd gear is felt but at WOT it high revs and acts like it's in neutral. HELP!!!!

Injuneer

Welcome to CamaroZ28.com !!!

Gotta love these LT1's. Glad to see you had the commitment to bring yours back to life.

Scan the PCM for codes. There are codes for the 4L60E that do not turn on the SES light. If that fails, post the specifics of the trans problem on the "Drivetrain" forum. We have an experienced 4L60E rebuilder who drops in about once a week and offers advice.

Good luck!

95 Z/28 LT1

Welcome to the board! Be sure to use the search feature as there are a lot of threads out there that may be of help to you in diagnosis of the trans issues and much more 'fun' stuff with the good ol' LT1's.

TedH

Welcome to the board. Please send some spare sunshine to Maine.

Chevy Cust Svc

sonman,

Welcome to the forum! Thanks for being here. We're unable to provide technical advice but if you have any other questions, feel free to send us a PM anytime.

William R.
Chevrolet Customer Care

GaryDoug

Hey Sonny, I sent Fred the scan log file you sent me, so that it won't be absolutely necessary to post it in this topic.

Gary

Injuneer

As noted, took a look at it, but need some more time. I have a day off Friday and plan to look at it in more detail. I didn't draw the connection between"Sonny" and the new member.

Injuneer

Looking at your original post, and then at the data log, it appears your main issue is the tranmission, and the data log doesn't seem to indicate any trans codes. As far as the transmission problems, I would recommend posting the details of the trans problems on the "Drivetrain" forum. We have an experienced transmission rebuilder, who drops in once a week or so, and helps people out. I knoe nothing about automatice transmission.

Looking at the data log, some things look good:

-engine idle speed appear to be very stable, with minimum departure from the programmed value.

-TPS closed throttle volts correct

-system voltage healthy

-MAP appears close to normal, but see comment below.

-MAF appears close to normal, but see comment below.


Some things look questionable:

-IAC counts at idle are very low. This could indicate a small vacuum leak. The MAP is slightly higher than I would expect, and the mass air flow grams/second are maybe a bit toward the low side, but not much. Would appear to be a very minor leak.

-Left bank (driver's side) of the engine has very high long term fuel corrections, right bank is dead on at 128. Problem is mainly in the idle cell (16) where you have a 146/128 L/R. As the cell numbers increase, appears the L/R differences disappear.

I notice that in your list of parts replacements, you did no mention the O2 sensors. Might be a good idea to replace, if you don't know the age/miles on them. The range of the left O2 sensor seems "dampened" compared to the right bank. Even when the throttle closes and the PCM cuts off fuel, the left O2 sensor is a bit higher than the right bank.

The other things that can cause the PCM to add fuel on one side would be an exhaust leak before the O2 sensor, or misfires. But those problems would normally show up in cells other than idle as well. A misfire at idle would make the MAP readings unstable, and they are as steady as a rock.

-You have two instances of significant knock retard (9+-degrees). In both cases the throttle was opened quickly, and the EVAP system was showing 100% duty cycle. In both cases the left O2 sensor shows a lean reading for a few cells on either side of the knock retard, but that may be the result of a very low sampling rate on the data log (1.0 - 1.15 frames per second). You may be able to get a better idea of what is go9ing on with a higher sampling rate.

Not sure what I can add. If you feel the engine is not running well, let me know what the symptoms are. Is there any evidence of spark plug fouling on the left bank, which would indicate the 146 BLM is the result of a "false lean" condition?

GaryDoug

Some, but not all, of the transmission trouble codes are available in the engine section scan. The engine section items are the only things saved to the datalog file. To see all the codes in the transmission DTC window, you have to enable the transmission section. The only way to log that is to write down the list or to take a screenshot of the transmission tab while it is or has scanned.