I got the rough running fixed...it helps to have the spark plug wires in the right order (I had them backwards [sm=headbang.gif]). Anywho...in the process of fixing that problem, my engine temperature gauge stopped working. Sometimes it will show one bar...sometimes three bars...and sometimes nothing (I have the digital instrument cluster). I drove around for about a half an hour in mixed driving (freeway up to 70mph, and stop-and-go on city streets), so I know it was up to normal operating temperature. Any thoughts??? Also, yesterday my muffler rusted through, so I don't know if that will affect anything (other than sounding like a bad harley).

 

I dont know what year your vehicle is but my sensor was located on the left side of the head, right near the plugs. Check your sensor wire

 

first of all just a piece of advice, put your vehicle info in your signature. go to My Profile up at the top and you can do all that in case you didnt know.
now the problem. if your temp guage is working sporadically then i would check your cable first. i've never done that but i would think thats the easiest thing to check, and thats usually the best way to do things if you dont know exactly whats wrong. check the cable make sure its intact, had a speedo cable melt on me once, and also check your connection at both ends. then i would check your temp sending unit, that should be what the cable plugs into on the engine end. if its not either of those then check your thermostat. if you follow the top hose off your radiator then the place where it meets the engine block is what you want to take off to get to the t-stat. once you take that off, it should be 2 bolts, then you can just take it out. i dont know how to tell oreven if you can tell if ones gone bad visually but its pretty cheap to replace.
if its not any of those then i have no idea. but some of the more knowledgeable members can help you out. and as far as the muffler holes i dont think that will have any effect on your specific problem, however you're gonna wanna get that fixed ASAP as it can cause a lot of other serious problems. also, and this may sound stupid, but are you sure its getting up to operating temp? i helped my bro change out an engine in his jeep. we got it in and started it and the guages would show it overheating in under 5 min, but we could stick our fingers in the radiator. turns out the t-stat whas upside down, no coolant was flowing.
hope this helps.

 

Sorry for not having my info on...now, Several days ago I fixed a miss-fire with new plugs, wires and cap & rotor. Up until that point the engine temp gauge worked flawlessly. Now as described before, it works spuraticly...if at all. Is the sensor on the drivers side or passenger side? (there are sensors on both sides and i don't know what the other one is for) And I dont think it would be the thermostat...since it was working perfectly just a few days ago. Anywho...I'll check the wire and see if anything happens. I'll keep everyone posted!

 

im sorry i mispoke. i just looked back at some old posts to get some clarification and if it comes to it you want to check the sending unit, or sender, located in the drivers side cylinder head not the sensor. the sensor sends info to the computer, the sender sends info to the gauges.
oh and dont worry bout the sig info, took me a lil while too.

 

computer sensor are usually 2 or 3 wire sensors. The one on the left head if it only has one wire, it is a sender that resistance changes with temp change grounding through the body of the sender. Quick check : if only one wire sender, turn key on disconect wire note temp guage then ground to engine block guage should go to the compete opposite. If this occurs your wire up to guage is good. You most likely damaged the sender and or the wire connection, most likely a poor connection that has moved when you moved the plug wires.