Could CTS be culprit here?

[Jkpowers]

Okso I recently picked up an 84 crossfire on trade and have been working hard to tune it up and get it running right as the last owner appareantly lacked a brain. 100k miles and still had original plugs lol

Anyways when I took apart the intake to balance the TB's I noticed the vacuum system off of front TB was not hooked up properly so naturally I hooked it back up while balancing the TB's and car ran like crap for weeks after.

I thougt I had done something wrong then was reading on here bout people having EGR problems. Nonetheless I plugged it back up and poof, running better than ever(hence the balance TBs and everything else back to normal)

I wanna get the car RIGHT so I replaced EGR valve AND solenoid(found a great used one at pull n pay)

Anyways the car seems to run amazing until it heats up all the way.

Here is my thinking and any input here would be greatly appreciated.

Ever since I've owned the car the COolant temperature on dash works when it wants. I've verified that it is accurate when working but when not working just reads 299.(used heat gun at local shop that tried to fix coolant temperature in 1st place but they said there was nothing they could do to fix readout)

Itd be great to always have an accurate readout but really I just want the EGR working correctly all the time. Anybody think replacing the CTS could be my cure all?
ive located and bought a replacement CTS but it looks near impossible to replace? Any suggestions?

 

[ex-x-fire]

There are several coolant sensors, one for the gauge (drivers side head), one for the fan (pass. side head), & one for the ecm (front intake).
If the one in the intake is acting funny it'll make your car run bad, usually rich. I like to replace it w/ the newer style sensor & connector. Get one off of a 87 up tbi truck at the junkyard. The oem style is very troublesome.

 

[Jkpowers]

Sorry about the delayed response... Both your posts were very helpful

I have yet to pull any codes off of it as I'm not too familiar with the OBDI systems...
Ive been looking into this and pretty sure Ill end up getting a laptop cable so I can do it on the fly

But anyways I got two things accomplished on the car and it running 10x better already without even replacing a sensor.

My connection on the sensor on drivers side block was just full of 30 years of grime and oil so some silicone spray and wire brush did the trick and presto my coolant temperture gauge inside the car works perfect now. Could that make the car run better just having the gauge inside the car working properly?

Also was reading a thread on here about vacuum leaks from the TBs and just thought I'd check and sure enough I tightened a vacuum leak out of them... Gonna rebuild them this weekend as I just got the kit from Sorenson and then Ill be bumping the fuel pressure up with the tool from DCS as well.

 

[boomdriver]

Sorry about the delayed response... Both your posts were very helpful

I have yet to pull any codes off of it as I'm not too familiar with the OBDI systems...
Ive been looking into this and pretty sure Ill end up getting a laptop cable so I can do it on the fly

But anyways I got two things accomplished on the car and it running 10x better already without even replacing a sensor.

My connection on the sensor on drivers side block was just full of 30 years of grime and oil so some silicone spray and wire brush did the trick and presto my coolant temperture gauge inside the car works perfect now. Could that make the car run better just having the gauge inside the car working properly? Only if you messed with a sensor that sent input to the ECM. The car has a different temp sensor or switch for the dash gauge ECM and fan circuit. The one you fixed was for the gauge (whichever it was, there are 3).

Also was reading a thread on here about vacuum leaks from the TBs and just thought I'd check and sure enough I tightened a vacuum leak out of them... Gonna rebuild them this weekend as I just got the kit from Sorenson and then Ill be bumping the fuel pressure up with the tool from DCS as well.

You're heading the right direction.
You found the most likely reason there are other problems...electrical connections. These C4 wire harnesses are junk. Plain & simple. There was some critisism from the NTSB (gov office that oversees domestic auto production) regarding the cheesy wire used in 80s and 90s Corvettes. Undersized and it lacked insulation that would stand up to the min gov standard for aging and durability. These wires often shrink back exposing bare wire and allow "cross-over" signals and grounding. PITA. The harness splices are amazingly stupid....simple crimp on with NO real insulation...just some black tape and this allows the wire to rot and the crimp fails and you have odd electrical issues...Laziness at GM.
Your Corvette electrical control is based on Ground Path Completion, NOT power path/route. Power route is always present. Its the grounds that get broken or completed to operate everything. Sensor input to the ECM comes from delicate resistance values that are adversely effected by crud, corrosion and rotten wire. Ground connections to frame are CRITICAL and must be in good shape. Look over your oil filter for a stack of small black wires...thats you most important set of grounds. The big one on the battery is not half as important as those little ones...they do all the work for controls and sensors.

Look at the power source contacts. Trace the smaller HOT wires off the battery post. There are MANY hot wires that are "always hot" or "always ON" and they do NOT go thru the fuse panel. They will have fusable links under the battery. Check those connections. Poor contact in wire on a Corvette means poor communication to and from the ECM...the brains of the car. Look to Flea-Bay for a 84CF FSM (used set) for about $75. Best investment you will EVER make.