Need help!! 98 LS1 in a 68 Camaro running bad when at temp

[68rsss]

drove my project car for the first time today and everything worked great until the motor got up to temperature.

It would hardly run once up to temperature. WTF? My tuner just downloaded a quick program removing the VATS and some other stuff earlier during build, could something he did be causeing me problems?

I dont have a temp sensor installed yet. My harness was sent with a two wire and whats on my motor takes a 3 wire. I did splice in the colors yelow - yellow and brown - brown leaving a green un used?

I also dont have the speed sensor plug connected on the tailshaft, same reason as above.

And my pcv valve tube got damaged. valve cover breathers are filtered but no pcv right now.



when I started it up to pull the car out the passenger side tail pipe was puffing black smoke but not the drivers.


Any help would be great,
Thanks in advance!!

[dhutton]

You might also try posting this over in the conversions forum on ls1tech.com

Don

[WS6]

definitely get that temp sensor hooked up and working, it's very important.

What about your forward O2 sensors? Are they installed, working, and you're not running open header?

[68rsss]

You might also try posting this over in the conversions forum on ls1tech.com

Don

I did thanks,

[68rsss]

definitely get that temp sensor hooked up and working, it's very important.

What about your forward O2 sensors? Are they installed, working, and you're not running open header?

When i ordered my harness i asked for a 98 and I think they got a little confussed. I will track down a 99+ temp sensor in the morning. Checker said they had one in town but apparently they couldnt find it when i went to get it today. Napa should have one.

Not running open headers, o2 sensor could be bad but I dont know how to check myself. My check engine light is one right now.

[Boulder69]

You really do need the temp sensor if it is the one for the PCM.

My LT1 had a similar problem last year. Ran OK until it warmed up and went into closed loop. Black smoke, stumbling, etc. Turns out it was bad O2 sensors. Quick swap out and all was good.

As the engine warms up the PCM doesn't use the O2s. I think LS motors are the same.

[68rsss]

You really do need the temp sensor if it is the one for the PCM.

My LT1 had a similar problem last year. Ran OK until it warmed up and went into closed loop. Black smoke, stumbling, etc. Turns out it was bad O2 sensors. Quick swap out and all was good.

As the engine warms up the PCM doesn't use the O2s. I think LS motors are the same.

New temp sensor just came in and I have two extra o2 sensors since my harness only required two.

I will try the temp sensor and then the other two o2 sensors and let you know.

Thanks for your help!

[68rsss]

Tried a new temp sensor but that didn't work. I think its an O2 sensor failure. Will take it in tomorrow and find out whats happening.

Thanks

[junkman]

You may want to get a scanner and make sure the coolant temp is reading right to the pcm. The car will not run worth a crap with out the coolant temp. It will be extremely rich once the motor warms up. Seems like it shows -38 degrees to the pcm if it is not hooked up. Usually after the first startup, you will have to hold it to the floor to get it started back up, and even then it probably won't idle. The air intake temp sender is important as well. If it isn't hooked up you'll be running very rich as well.