I have 95 vette. When i bought shortly after that there was a coolant leak - fixed it. Then again but in different place - fixed it. After that it was idling rough. I replaced DISTRIBUTOR CAP AND ROTOR. Then replaced all spark plug wires. That seemed to be the problem. It was ok.

One day i was driving did quick acceleration and then stopped on red light and engine started to wibble a little. I restarted the car but still nothing.

Did checked all the spark plug wires then checked distributor cap and rotor - seems fine. I sprayed contact cleaner in it ( hepled last time.) This time didn't help. I was looking for a hole in seals.. Replaced cover seals - still rough idle. Went to Chevy service - they told - don't bother it is nothing, if it does not eat up more fuel than usual - no worries! Drive the car as it is now. We had older vett with same problem and couldn't fix it.

It starts to wibble only when it gets hot or if I'll do about 5 rpm and after that it will idle rough. But when you start the car it is normal and then after like 25-50 seconds it would start idling like misfire or something.

I couldn't find the problem so I was driving the car and still was looking for a problem - cleaned all the wires and connections and insulated and taped all wires that go to sensors.

After a while I was driving on a highway and smelled burned oil when i arrived to my friend. I was mostly driving whiting the city area. So oil was leaking on the pan and strong wind form driving was splashing it all over the bottom of the car and some oil got on exhaust pipes. That is how i noticed that. So i was looking for an oil leak. Couldn't find it. I figured that is the problem - why it is idles rough i have a hole in a seal and air gets in the engine and it idles rough... But it wasn't a problem. I figured that the leak somewhere behind the water pump and distributor, that's why i could see oil spills on belts and the back side of the hood. I ordered seals. I was driving fir 2-3 days and my water pump started to leak too. I ordered those parts as well - figured that makes no sense to fix this part and then go and take water pump off again when i'll get my seals for water pump. So i was driving it to a short distances. And then i went to pick up my seals finally, had to get on to a highway. And while i was driving my RPM got higher suddenly and then my 4th gear disappeared. I stopped the car. Checked the engine, oil leaks was minimal water pump was not leaking that bad - it was only dripping a little. Engine temp was fine tranny temp was fine. I checked oil levels in engine and tranny - was fine. But my 3-4 gears disappeared. I went to the chevy service - asked them to check my tranny and give me a print out of error codes. They said Yes we will... They charged me a lot of $$$ and told me to wash the engine and replace seals, clean all sensor connector. Probably there is a short and tranny does know what to do. Basiccaly I paid for advice only.
I did replaced all seals, bought new water pump, cleaned all connectors and cleaned distributor inside with contact cleaner.
Now:
Rough idle when hot, no oil leaks, but still no 3-4 shift.

I was looking for trouble codes from chevy dealer, but they told me that my car is 95 it is a hybrid and there is no such tool to see trouble codes and i just need to replace tranny $$$$$$$.

I don't know how to find a problem without scan tool. My dad has some kind of a scan device that you attach to a OBD-II and it shows what is going on when you drive, but it works on his Volvo, not on my vett. It just don't read anything. says: NO DATA.

I was looking for an answers everywhere.. One guy told me that it could be a sort somewhere or loose ground.
I did checked all grounds and retightened ground wires from tranny to body. I even bought some wires and did direct connect from tranny to engine and to the body.. nothing still no 3-4.

Then i figured maybe it is solenoids, dropped the pan - checked solenoids with 12 battery - they do their job. I installed one new one anyway, it was kinda loose and other one had oil under pressure when i pulled it out.

Now i'm thinking could it be Opti ( i changed only cap and rotor ), could it be intake valve position sensor, or just short in the system somewhere. How would i find it without scan tool???

I'm thinking that it could be short somewhere since.. when i was replacing oil pan i broke oil level sensor. So i just disconnected the wire and it would show me low oil only when i start the car in the morning. When i restart it again immediately light would disappear.
No check engine light.

Symptoms:
1. Rough idle when hot.
2. 2-3 3-4 does not shift.
3. Sometimes when accelerate suddenly it would just drop rpm to 1000 and then would restore it back to desired rpm.
4. No check engine light.
5. Sometimes tranny doesn't know what to do, wouldn't shift to 2nd gear from 1st. Have to drop gas pedal and hit again.
6. Replaced Distributor cap and rotor ( before oil and coolant leak though )

Please help!!!! Chevy dealers and services are no help at all.. Already spent a lot of $$$, could've buy needed parts..

Any suggestions?
Need help, please!

 

look up LT1 edit, they have a cable that will help you get the codes off the car. your car like my 2 cars ( 95 vette and 95 z28 ) have the obd 2 connection, but all the codes and sensors are for and obd 1. the cable comes with a usb connection on the other end so you can hook it up to your labtop. the software has a 26 time trail version that will help you get the codes off. as far as the rought idle I can't help you there, mine just started to act like that so I'll be tearing into it this weekend. hope this helps.

 

Just got the cable and vett doesn't give any codes at all. DTC OK; DATA OK but i have no 3 and 4th gear and Rough idle is still present. What could it be?

Could it be MAss Air Flow or OptiSpark for rough idle?
What coild it be for Tranny? How do i find out exactly what happened with a car through DataMaster?

I have graph and everyhting. I have file. It shows that is shift to 3 and 4 and solenoids go from 0 to I and backwards.

I was looking at MassAirFlow graph it doesn't show ideal mixture every time sometimes is shows slightly rich or lean mixtures.

How do i find out if it is Opti? I was reading in posts before they were looking at low voltage somewhere, but where?