Ok working with my 81 Turbo T/A. 1st generation ECM. Recently replaced my ecm. It was cooked. Car runs better. Next I put a carb that was rebuilt for me by Jet Performance. Car ran even better as my old carb had some issues. Now I'm trying to get my dwell and rich idle set up. All the sensors are new. I mean all of them. So during open loop ,car starts right up and runs decent. Dwell stays in low to mid 30's. Soon as closed loop kicks in dwell jumps to 55-58 and stays there. Therefore car runs real rich at idle. Adjusting the IAB does nothing. TPS checks out .42 as per my service manual. The mixture/idle screws are 5 turns out. Now I have a OTC scanner hooked up so I can read what the computer is seeing. It reads the dwell,TPS,idle, etc... No codes are coming up. Now the thing that is throwing me off is the CTS. If I go by scanner it's only reading at half temp. Meaning if the gauge in the car reads 200* then the scanner shows 100* yet the computer is in closed loop. So I thought that the computer still thought the car was colder than it is and dumping fuel in. Maybe not though. Checked all connections at the sensor and ECM and they are good.

So I wonder if the computer is really getting the proper reading for the temp. Any way I can confirm that?? After all it does go into closed loop which would indicate that the temp is close to what it needs. The whole deal is killing me cause I want to be able to adjust the dwell so it will idle properly . Also with all of this after the car has run for awhile I get a hot start issue. Like the tiiming is to advanced and tends to not want to start without alot of cranking and some stumbling. I'm almost sure it's realted to my other issue. My timing is right on the money. Any ideas? That that temp sensor thing is really throwing me off.

 

Have you tried replacing the sensor? If you could find the specifications for that sensor you can probably check it with a multimeter. Finally, are you sure the thermostat is closing properly?

 

yeah you should be able to check that sensor with a d.v.o.m. and as far as i know the computer uses exhaust temp and coolant temp before it goes into closed loop. good luck

 

This is the second sensor in two days. So yes it has been replaced. Thermostat works as it should.

 

Ok a little update. For the coolant temp it's just how this particular scanner reads it. Tested on my GTA and it did the same thing. I finally got the dwell to come around spec , but the mixture/air screws are about 2 TURNS OUT!! Any more than that and the dewll shoots back up.That seems a little to thin to me. This was the only level I could adjust the IAB to get what I needed, but I sware it still runs rich. Little color out of the tailpipe. Still seem to have a hot start issue. Car was running for about 1/2 hour at idle , so it was pretty warm. It may have been just to hot. Still should have atleast turned over. Only get a couple of cranks and acts like battery is dead.