Ok. I learned something today though... Did not know there was any screw on these.

Idea: The coolant temperature sensor. We've had very cold (-10F) weather here and the Blazer, which I was almost convinced was fixed, is no longer idling at all.

Which brings me to the idea of the CTS. Could explain intermittant low and high idle errors... I believe the IAC is functioning properly or I dont think it would ever idle properly... So what is sending it the wrong signal? CTS fits in my mind but I don't know. Had a TBI 350 with a bad CTS and it had irregular symptoms like this...

 

After the vehicle sits for 8 to 10 hours, before starting the engine, connect a scan tool and compare the IAT, (Inlet Air Temp) sensor, ECT, (Engine Coolant Temp) sensor and ambient temperature, all 3 readings should be with 2 or 3 degrees of each other. Post your results.

 

Is there any way to do it without a scan tool? The guy here in town is not exactly a rocket scientist, seeing as he couldn't find anything wrong with it and still charged me $45 to put the scanner on it...

Just out of curiosity, how much does one like that cost?

 

Hello i have a 1995 with the same engine and problem did all the checks i could and same issues as you it going in shop this week or next if i find out what is causing mine i will let you know and you can see if it is the same as your

 

You can probe each sensor with a digital volt/ohm meter but, probing circuits requires piercing the insulation on the wires, not a good idea. There are some decent scan tools on the market that will access a limited amount of streaming data. Actron makes some models for under $200, not professional quality by any means, but they will access the basics. In most cases they're are good enough for the "DIYer". Bi-directional scan tools start around $4K and you can spend upwards of $10K for some of them. That kinda gives you an idea of the capability level of the less expensive "DIY" models. The more you spend, the more it will do.

 

Tested the voltage of the Coolant temp sensor and the intake air temp sensor today.

.018 volts at each... so either they're good, or both bad. the ambient temperature at the time I tested them was ~34F.


It seems to be running rich the last few times I started it (noticable black smoke)

I'm stumped as hell. What are the chances if I could find a scanner and post all the data up that you or someone else on here could spot the problem? As it is I think I know more about it then the supposed mechanics around here...

 

no way.
take off the connector at ect. Turn key on - measure for 5v between two wire sockets, not to frame.

Then measure resistance between the two contacts in ect


Then measure resistance to block in turn. Should be infinite resistance to block - more than 1 Megohm

 

Thanks

 

Someone cheated on my blazer. They cut an access panel in the floor just above the fuel pump =P

 

Wow... and it's honestly not that bad of a tank to drop... Not like the Ford pickups that have it right over the axle...