At first, the check engine light would come on and do would what it does in this video.

http://webpages.acs.ttu.edu/blincoln/bad.AVI

Then it would go away for a few minutes, then come back. Now it is there constantly.

Ill post a link to how it runs when it is normal, once I find a fast host (and more space)

BTW when it runs bad, it runs smooth. It just has WAY less power, less RPM, and struggles to keep constant. I checked for codes and it did not display any.


Edit:
Heres a link to how it runs when it is fine:

ftp://68.1.231.79/good.AVI

 

Open the hood and check the engine. If it is there, you are fine.

Get a code scanner otherwise we don't know what the code is.

 

If the light is on there has to be a code.

 

Is there a way to check for codes while the light is actually on and the engine running?

Im not kidding.... You ground both of the two terminals up at the top right, right?
According to thirdgen.org at least.

I ground the two, check engine light stays on for like 10 seconds, then finally blinks 12 over and over. Never anything new.

 

Dudes, I just tried it again.
I turn the key, check engine light stays on for 1 minute. I wait patiently. Suddenly, I hear a click under the hood and the electric fans come on, and the engine light starts to blink code 12 about 8 times. Then the click happens, the fans shutoff, and Im back to a constant check engine light. About 20 seconds later, the fans come back on, and the light blinks again... over and over...

 

try adding 1 litre of oil to the engine and see if it goes out

 

- 11:30am
Started Camaro.

Idle at 1000rpm for 30 seconds.

Check engine light comes on and RPMS took a nose dive to 200rpm but to quickly move to 500rpm. Check engine light stays
on for 10 seconds with the motor surging between 500-600rpm.

Turned vehicle off and drove truck to work.


- 12:30pm
Left work early to work on Camaro.

Started vehicle, idle at 1000rpm for 20 seconds, then surge to constant 500rpm with check engine light for 10 seconds,
then back to normal. Turned off vehicle.


- 1:00pm
Started car. Ran for 3 minutes and never saw a problem.


- 1:30pm
Started car, immediately displays SES light and surges from 500-600rpm. SES light and surging problem does not go away.


Note: After each test I check for SES codes. Each time only code 12 is displayed.

 

Light comes on and no code. Could be a number of things causing a problem but they're all a guess. Why nothing sets a code though has me baffled.

Bad computer?
Knock sensor or wiring retarding the timing (grounding out)?
Fuel pressure too high?

You may have to put the engine on a scan tool.

Is there any way a mechanical fault, too much fuel etc, cause it to run like that setting the light on but not set a fault?

Try disconnecting the battery for a couple of minutes then try it all again.

You'll need to get a code while the fault is active. If the light goes out you'll never get a flash code for an inactive fault. Start the car up and when it starts to run rough and the light comes on, jump the data link connector to get the flash code.

 

I wasnt sure if it was possible to pull codes (paperclip trick) while the car was still running. I just didnt want to mess something up.

Is this method ok on all OBD?

 

All GM OBD1 vehicles can display codes with the paper clip method, but each manufacturer is different. For example I think Chrysler has you cycle the key a few times. But anyway, a scanner would be very helpful in a situation like this to get some koeo and koer readings.

 

Thanks, I rented a scanner today. Found no codes set. Tried to go into monitor mode, but it wouldnt let me (said it needed to be "upgraded" or something). Tried to clear the codes via the scanner and it told me vehicle not responding, but tried that on my truck and worked fine (I guess the camaro communications are one way only?).

I kind of like this scanner tool though. If it would let me monitor sensors and voltage readings then I would buy one asap (I think its like 150 bucks). But if I have to hand over extra $$$ for that feature, that sucks.

 

What car are we dealing with? Is this for the Z?

 

Im working with both vehicles.
Although the truck is pretty much done.

But Im referring to the camaro right now.

This morning I started it up (before WALKING to work ) and got the hesitation immediately. In fact it didnt even want to stay running. All the other times I had it started, it would idle inbetween 500-600rpm. This time it would take an absolute dive to death unless I kept it floored.

Incidently, the engine light didnt come on (only flickered for 1/5 of a second) during the whole ordeal.

So after work I went and got that scan tool. Plugged it in and turned the key. No codes stored.
So, I started it up and it ran perfect. Drove it around town, and no problems whatsoever.
I mean, Im glad and all it's driving better now, but damn I want to know what the hell was going on before.

I can keep the tool for another day, so I guess all I can do is just fill up on gas and just keep driving around until it happens again.

http://webpages.acs.ttu.edu/blincoln/bad.AVI

 

I suspect the light comes on just when it is sputtering just as it does when the engine is off. Maybe the air temp sensor is out of whack? I suspect this because it works in the afternoon and doesn't in the morning? Also check the TPS. With the KOEO see what the TPS reading is on the scanner. Slowly depress the pedal and see if there is a dead spot in the TPS voltage.

 

Code 33
"MAP sensor too high"

This after REPLACING THE DAMN BATTERIES IN THE SCANNER.

Interesting enough - I noticed when I took it out on the highway that the speedometer would fall to 0 when the engine light came on.

Voltage problems?