over heating issues/ misfiring

[djhah]

ok so i have been having lots of problems with the g. i have been misfiring started as misfire on cylinder 4 (code p0304) i changed the plug wires coil packs it drove fine for about a month then it threw code p0300 (random multi. misfire). so i swapped back to the old coils it went back to the code p0304 (so i assumed it was bad coils) then after a couple days it went back to the p0300 code. so i took her to the shop to get further diagnostics ran, the came to the conclusion that it was the crank position sensor so i changed it. the problem is not as bad but it still persist. as i was test driving it it started overheating, i pulled into a gas station let it sit for several hours before i tried to check anything out. i came back and was putting coolant in it (as it was low) and heard it coming back out on the ground. i found it was the hose to the throttle body busted fixed it drove it home let it sit overnight and today i tried to drive it again and it started over heating again as i was driving, but at a stand still the temp. went back down i have done a check and no coolant leaks any more just the over heating and the misfire. what could cause this please help me.....

[allrice4g64]

is the car going through coolant? seems to me when ur driving coolant isnt circulating through the block. the engine gets hotter when its under a load when its just ideling maybe there is enough coolant to cool the engine down but not enough when driving. could be leaking into cylinders, bad headgasket,cracked head?? maybe when the coolant gets low the computer doesnt know to go into open loop because the 02 sensors are trigger to work based on the engine temp. so leaking coolant equals false reading from the coolant temp sensor thus causing your 02 sensors not to work properly causing your fuel trims to be way off causing a misfire. could be a possibility but any other input about my speculation would help to diagnose this.

[djhah]

i have been brain storming this afternoon while at work and i think that possbly the theristat maybe seized up only half open so that when driving the coolant is not circulating properly so when at a stop it is able to flow correctly, i am going to pull it out tomorrow and check it out. as for the misfire i am lost...!? but if any other ideas they are welcome, or if you think my therory is missing somethink please let me know i am at a loss.

[djhah]

well the misfire has gotten better although its not fixed it is better. as far as the over heating is concered i still dont trust long trips but it is a little better i think the coolant level was just to low from where the hose busted on me friday (i put some in it but i dont think i added enough). i dont think the head gasket is blown or i have a cracked head due to the fact that i have no water in my oil or oil on my plugs, and compresion test is good. once i figure out these bugs i will be happy.

[djhah]

So my car is only having issues upon start up now, if i run it for awhile the turn it off (run into a store etc.) Then when i restart it i have to give it a little pedal to keep it running for the first couple seconds then it runs fine. Once again i am lost?

[01blackG]

Its been a while since I have been in here or had to work on my car. But for the problem when your car is cold..........our cars do have a set up that will allow them to run rich for a while until warmed up. My car has some high miles and every so often I get the same issue when the car first starts up. I have noticed when it does happen a rich smell from the exaust, which I know in return will cause running issues. You might want to look at fixes regarding cold start up issues.

[Trevs56]

i wonder if u have a bad injector? as far as ur coolant was concerned if u were able to crack open the radiator cap while the car was on u should observe to see if the coolant was moving. that would indicate ur water pump might have an issue. if it wasnt moving at all ur water pump was bad.

[djhah]

I have a new waterpump it got replaced when i did the timming belt. A couple months ago. I need to check the injectors it runs fine sometimes and a small amount of the time it misfires.