1995 S10 4.3 vortec Zr2 Issues

Ok, this is a 2 part question. Does the speed sensor affect the way my automatic transmission shifts if its bad?

And 2nd, When i drive for a while like a few miles lets say 5 miles when i stop and turn it off and get out i smell fuel very strong from my fuel tank area. Im sure thats not a normal thing. I only smeel it after driving it for sometime though. it doesnt smell like 1st thing in morning when its been setting.

Thanks

Speed sensor directly affects transmission shift points.

Is the check engine light on? If so, what DTC's are in memory?

Which connector is under the dash for the OBD system?

http://i561.photobucket.com/albums/ss58/cwhook/Diagconnectors.jpg

No check engine light and it looks like i have the obdII type port. The transmission doesnt slip or anything and the fluid smells good (not burnt) its just that it will quickly shift back and forth between 2nd 3rd gears just for a second or 2 kinda like it confused or something.

A transmission is sort of like a computer... if you put junk in, you're gonna get junk out. If the engine is not running correctly, the transmission will not shift correctly. Don't misunderstand me here, there may be a problem with the transmission, but make sure the engine is running correctly first. How many miles since the last tune up with AC Delco parts? (aftermarket stuff doesn't cut it in these vehicles.) Have you checked fuel pressure and leakdown? Again, these engines are very fussy when it comes to fuel pressure too.

Ok after i read your reply i started thinking about the CEL so i oulled out the gauge set and sure anough the CEL was burnt out so i replaced it and its lit up, so i went to auto zone to get the codes read and they said i couldnt check the codes unless i went to dealer because its 1995 with obd2 port. So here is my question.

Can i not jump some connectors in the port to make the light blink the codes? And couldnt I go buy a 1997 computer that would work on my 1995 and then be able to read codes thru a computer reader? Arent 1995-97 all compatable?

Thanks

95 was a change-over year for OBD systems on GM S & T body vehicles. Most have OBDI, (top connector in post #2). Some have OBD1.5, (bottom connector) which is what you have. There are very few late 95's with OBDII. OBD1.5 requires a scan tool capable of communicating with it. Autozone, Advance, and most other auto parts stores, use a cheapie code reader, not the required scan tool. No way to jump pins or swap ECM's, best to take it to a shop with the proper scan tool.

a guess a benefit of having the funny OBD 1.5 system is that a full scan from a good shop or dealer will also reveal any trans codes that are stored...

I bought an autoxray scanner with all the cables that can be bought for it. It turned out that all i needed was the obd2 cable. I plugged it in and it gave a code about my evap solenoid, i replaced it and then i reset the code. No other codes were in it. So now back to the question. I have no CEL or SEL so what could be causing the intermittemnt shifting. I also noticed that it switching between 3rd and OD not 2nd and 3rd. Also when i run the engine for a few miles and get it good and warmed up/hot the idle is high and erratic when i stop and put it in park it will go between 1k and 1800 rpm, but when i switch the engine off and then start it right back up its normal again.

Im starting to think its the ECM bad.

Dial in to the VSS, (not the ABS wheel speed sensors) and drive it, watch for smooth speeds. If you can graph it on your scan tool, you'll be able to see if/when it acts up.

My autoxray doesnt have that option. Its just a reader, cant tell it where to read. I t just looks for codes.