What Should I Look At
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
What Should I Look At
The 95 I recently bought has an issue that I'm looking for thoughts about. It has the LT1 and today it was running like it had a miss. A couple of times when i gave it full throttle to see how it ran as RPM's increased it would hit 3000 and start breaking up and go no higher. At some point I SES light, but once that happened it started running normal and fan started running in addition to idle RPM higher. I tried to pull code with my scanner and it connects and recognizes car but scanner shows an internal error.
I have FSM for my 91 L98 but not for 95. Any thoughts?
I have FSM for my 91 L98 but not for 95. Any thoughts?
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Here's the howto on the paperclip: https://tech.corvettecentral.com/201...trouble-codes/
The FSM can be acquired from Rockauto for $20, it's listed in the "Literature" section at the bottom.
Best of luck!
The FSM can be acquired from Rockauto for $20, it's listed in the "Literature" section at the bottom.
Best of luck!
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
Would an Opti issue actually cause a SES light?
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
I would, but I can't physically get into a position to paperclip the terminals. I'm thinking it may be a vacuum leak and/or a MAP sensor. So I don't throw parts at it I'm trying to figure out why my scanner isn't properly reading.to point me in right direction.
Would an Opti issue actually cause a SES light?
Would an Opti issue actually cause a SES light?
To use a "scanner" for codes instead of the paperclip, as well as to check live data and even reprogram the computer if you so desire, you'll need a $50 cable and free software.
Cable: http://aldlcable.com/products/aldlobd2u.asp
Software: http://fbodytech.com/eehack-2/download-eehack/
Good luck!
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
If I had to guess, I would say the reason is because you saw the connector, thought it was OBDII, plugged a common OBDII scanner in, and are wondering why it won't connect. The reason is because only the 1996 is OBDII. The 1994 and 1995 have an OBDII-shaped connector but do not actually speak OBDII.
To use a "scanner" for codes instead of the paperclip, as well as to check live data and even reprogram the computer if you so desire, you'll need a $50 cable and free software.
Cable: http://aldlcable.com/products/aldlobd2u.asp
Software: http://fbodytech.com/eehack-2/download-eehack/
Good luck!
To use a "scanner" for codes instead of the paperclip, as well as to check live data and even reprogram the computer if you so desire, you'll need a $50 cable and free software.
Cable: http://aldlcable.com/products/aldlobd2u.asp
Software: http://fbodytech.com/eehack-2/download-eehack/
Good luck!
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
Could a oxygen sensor going bad cause an on and off SES light? I know it can cause rough/missing running. I'm betting mine has the original sensor and with over 80k it seems like it should be replaced regardless of what my issue turns out to be.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
O2 won't cause " breaking up" it also won't fail only over 3k.
Opti can set codes.
Breaking up usually is some kind of ignition or spark problem. SFI losing injector is more of a "chuggle" a you feel it but it's not sharp or bucking. Low fuel pressure will feel a lose of power possible lean back fires. Hole in boot between throttle body and maf sensor can also cause rough running.
Opti can set codes.
Breaking up usually is some kind of ignition or spark problem. SFI losing injector is more of a "chuggle" a you feel it but it's not sharp or bucking. Low fuel pressure will feel a lose of power possible lean back fires. Hole in boot between throttle body and maf sensor can also cause rough running.
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Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
I still stand behind my statement. I believe your scanner cannot actually talk to the car.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
I didn't write it clearly enough, it works on both I and II because not only have I used it on my 91 but also on a few of my current newer vehicles.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Ah, well if it works on the '91, then it'll work on the '95. Or should, anyway. My apologies.
Perhaps you could find someone to contort and do the paperclip for you? Or unbolt the one 7mm bolt holding the OBD plug on and pull it up to a position where it's easier to access?
It's just not good to start throwing parts at a problem or making blind guesses when the computer is clearly trying to tell you what's wrong.
Perhaps you could find someone to contort and do the paperclip for you? Or unbolt the one 7mm bolt holding the OBD plug on and pull it up to a position where it's easier to access?
It's just not good to start throwing parts at a problem or making blind guesses when the computer is clearly trying to tell you what's wrong.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
error before completing.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
The parts stores use OBD2 scanners because OBD2 has generic base codes. OBD1 requires specific software and connectors making impractical to read OBD1 codes. GM used 16 pin OBD2 style connector on all models with flash programming even before OBD2.
Last edited by Kevova; Oct 30, 2020 at 04:29 PM.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
I was finally able to get codes. Showed voltage issues with MAP and TPS and showed oxygen sensor issue. I replaced MAP and TPS. It now seems to idle smooth in closed loop and engine pulls strong through RPMs. I did get a SES again and fan comes on when light comes on. Would an oxygen sensor cause fan to come on? Still appears to run normally except for fan coming on.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
If the O2 circuit is totally shorted or open, to the point where closed loop operation becomes impossible, I suppose that could cause limp mode to kick in. The O2 sensor wiring on our cars is in a very precarious spot, and has clips that clip onto special mounts. If the wires aren't clipped in properly, they can very easily end up touching the exhaust, which will melt straight through them.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,796
Likes: 579
From: Mays Landing, NJ
Just posting update to my problem. Replacing the MAP and TPS did improve things, but still had an intermittent SES pointing to left 02 sensor so had it replaced and so far car is running great. Thanks to all that responded to the tread.
