Overheating, missfire and flashing CEL...HELP!!!
04-30-2014, 01:42 PM
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Overheating, missfire and flashing CEL...HELP!!! Yesterday I was driving, slowed down to take a right turn, and when I went to give it gas, very little power and seemed to have a hesitation, like it was running hot, but the temp gauge was showing fine. A little way on, maybe 60 yards or so, the CEL started to flash and it felt like a bad misfire. Came to a stop sign, and idled, felt it was going to die but didn't. When I pulled away, hesitation, misfire (no backfire), and little power. A couple of times it seemed to smooth out, power came back, but for just a few seconds before acting up again. As I pulled into my driveway, I could smell coolant, and noticed a little steam coming out from the hood. Not a lot, but some. It never died or back fired, and the temp gauge never showed hot. Whats going on? Oh, it's a 2001 Z28, 124,000 miles. The only engine mods I have are headers, exhaust, SLP air lid.
Update....Just went out to start it, it fired right up, no miss, no flashing CEL. But also, no coolant. It was so low it wouldn't even read on the stick, I'm assuming it was low to begin with, and it blew the rest out when it boiled. Looking at the engine, I can tell it was spraying out from under the cap. I was aware of a slight coolant leak the car had, and it's been awhile since I checked the fluid level. But as I said, the temp never read hot. Bad sensor? And would an overheating car throw a CEL? Cause the CEL to flash?
Update....Just went out to start it, it fired right up, no miss, no flashing CEL. But also, no coolant. It was so low it wouldn't even read on the stick, I'm assuming it was low to begin with, and it blew the rest out when it boiled. Looking at the engine, I can tell it was spraying out from under the cap. I was aware of a slight coolant leak the car had, and it's been awhile since I checked the fluid level. But as I said, the temp never read hot. Bad sensor? And would an overheating car throw a CEL? Cause the CEL to flash?
Last edited by Bmar15; 04-30-2014 at 02:09 PM. Reason: Update
05-01-2014, 01:27 AM
#2
CEL flashing is a misfire occurring, all things considered i would guess head or head gasket. it would be one hell of a coincidence that they would be 2 separate concerns that just decided to act up at the same time. head gasket or head cracked concerns can act funny. ive seen over heats to running perfect with unexplained coolant loss. here is my 98SS 427. no overheat and ran fine. unexplained coolant loss has been explained. cyl 3&5 ingesting coolant.
good luck with your concern.
good luck with your concern.
05-02-2014, 04:58 PM
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I thought it may be a blown head gasket as well, but I don't see any coolant in my oil, and no oil in my coolant. There is no tell-tell white smoke or liquid coming from my exhaust, or any other head gasket syptoms. I took it for a short drive earlier today and it ran/idled fine for a few minutes then started to misfire again. Does that still sound like a blown head gasket? I haven't pulled the plugs yet to look at their condition. Can a overheated motor ruin them?
05-02-2014, 06:36 PM
#4
blown head gaskets are funny sometimes. oil and coolant mixing or white smoke from tail pipe are obvious signs. depending on how the gasket blew will determine what concern you will have and believe me there are many weird concerns caused by a head gasket. one of the best ways to tell is by using a Co2 combustion leak tester, basically it sniffs your coolant for combustion gases.
your spark plug will get fouled if it is a blown head gasket ( kind of hard to burn coolant efficiently). you can buy a descent test kit off of amazon for about $60. you do not want to overheat that engine much because the heads will crack fairly quickly.
your spark plug will get fouled if it is a blown head gasket ( kind of hard to burn coolant efficiently). you can buy a descent test kit off of amazon for about $60. you do not want to overheat that engine much because the heads will crack fairly quickly.
05-02-2014, 09:11 PM
#6
have you taken the radiator cap off and looked in the radiator to see the actual level. i just realized you have been checking the overflow bottle dipstick. as far as any other concerns that may cause you problem can be as simple as a bad radiator cap. if the cap is bad it will keep dumping fluid into the overflow everytime the coolant heats up and expands. with a bad radiator cap coolant will prematurely heat up because the cap is supposed to hold pressure in thus raising the boiling point of water from 100 deg F to 300deg F approx. so its possible that u may coincidentally have a normal misfire and a bad radiator cap. which would explain coolant steam. i hope its just a cap and a spark plug but without me physically looking at the car i can only speculate.
05-02-2014, 09:16 PM
#7
by the way i have the UVIEW 560000 combustion leak detector kit. fairly easy to use, get car warmed up with radiator cap off, make sure level is no higher than a couple inches from top of radiator. fill both chambers with the blue liquid to fill lines. set the tester over the radiator opening and pump the tester a couple times. if that top chamber turns yellow game over. if it stays blue look for some of the other things we discussed.