I found a loose cable after changing sparkplugs and cables on my -91 Z28.
After i changed the cables and sparkplugs the engine doesn`t run as smooth as before when the engine is coold ..??
The engine runs as it should when it reaches the normal temp.
Is it possible that the cable has something to do with it,where should i connect the loose contact??
/Rogg

 

On the left, in the filter runners, is your IAT (Intake Air Temperature) sensor.
On the right, peeking from under the TPI upper plenum, is the connector for the IAT. It needs to be plugged into the engine harness. The other plug is in the vicinity. Search for it, it should be there, maybe a little farther back.

The IAT sensor tells the ECM the temperature of the incoming air and it influences the mixture greatly. If it is disconnected, it could easily cause engine trouble when cold or hot.

Find the plug, reconnect it and see if cold starts improve.

Hope this helps.
Lou

 

Thanks Lou for the reply..
ivè added a picture change...
The green marked plugg goes under the TPI and i think it`s called Manifold air intake..
Is there a one more plugg for the IAT further back..?
/Rogg

 

Oh, so the wires from the green marked connector go under the plenum and are hooked up to the original IAT sensor? That would be the factory setup and you can leave it as is.
The other wire whose ends you marked in orange is an extension for the same IAT (MAT) sensor which has been relocated to the front air filter runner. I am not sure why your car is wired up that way.

You can unplug the green-circled connection and plug in the orange-circled plug (to switch to the fwd-mounted sensor) and see if that improves your cold starts.

Lou

 

Yepp that`s exacly what i meant..
I will try to switch them and see what happens..
Thanks again!!
/Rogg

 

Rogg, do you remember unplugging the green or orange connectors during the work on your engine?

 

That`s the problem..i don`t recall unplugging it..
So that`s why ivè search for a second plugg to connect the "orange marked" cable..
But maybe i connected the "green marked" cable (if it has been unplugged during the work) without thinking,because it was the same colour as the other one..
Tomorrow i will switch cables to see if it runs smoother..
/Rogg

 

Found it!!
The "greenmarkt" plugg was not properly connected because the lock on the plugg did not tighten the seal so it was full of dirt..i cleaned it and the code 23 was gone and the engine runs as it should..
Thanks for the help.
/Rogg

 

Great, glad you found it and fixed it!
You should have said "code 23" in the beginning, that points straight to a bad connection to the IAT/MAT sensor.

Thanks for following up with your solution, it always helps others who find your thread in the future.

Btw, hope Sweden is not too cold this summer.
Lou

 

Great trouble shooting.