Hello everyone I am a new member. I was giving a 99 blazer from a friend. The blazer had a blown 4.3 vortex.

We found out the motor had blown gaskets. Mileage was around 143k and the vehicle sat for several years. We changed the gaskets, replaced the spider, distributor with new cap with plugs and wires. New alternator and water pump.

The car was running great. Been driving it for about a week. My temp gauge started to bounce around with no other issues. The next day the car had a hard cold start. Once it warmed up a little, the car runs decent. Threw a P117 code. I changed the temp sensor and replaced the pigtail for it. I also changed the air temp sensor that was locate after the airflow sensor.

Car still has hard cold start and gauge still doesn’t work properly. Just wondering if I missed another sensor. Should I use AcDelco parts only. I am ready for some things going bad since it is old. Can the pigtail be hooked up backwards. At least it passed smog before this issue so I can drive it. Just want it to run properly.

Thank you for any help and sorry if this question has been asked before.

 

You may want to check the wiring for these sensors for pinched, chafed wiring.

 

I will check the wiring but it is covered with some wire covering. I moved some wires around to see if I could get the gauge to jump around but no luck. I’m sure it’s something simple and stupid. I’ll keep looking.

 

this may seem like a stupid question but you did top off the coolant and bleed the system right? air bubbles moving around the sensor will cause gauge weirdness.

As far as it running roughly, what gaskets were replaced, what type of injection spider did you use, and is the upper intake sealed up properly.

 

Not sure on what spider, it was bought at Oreilys. The gaskets for the heads and others for the top end. I did too it off but no bleeding the air out. I took the cap off the radiator and let the engine run for a few.

 

headgaskets eh
You did a compression check?, checked for a cracked head or two?
honestly im running out of ideas that are not mechanical damage//