3400 Misfire and temp increase - HG?

[bszopi]

On the way back from our vacation (on the 16hr straight trip), the SES light came on, and blinked about 4hrs from home. I checked all the fluids and all levels seemed fine. The temp hovered between 1/2 and 3/4, but I thought that it may just be due to constantly driving for 12hrs+, plus driving in a very hilly area where it was constantly downshift (sometimes jumping to 4k+ RPMs) just to attempt to maintain speed. I got it home, and took it over to the parts store to get the code read - Cyl #1 Misfire. Ok, so causes could be spark plug, wire, or possibly head gasket.

My wife had to work on Sunday, so she drove it in then with no problems (SES light was off). I was thinking it was just temporary thing, especially since the light FLASHED, didn't stay on constant (never seen that before). She drove it some today as well, with no problems - until about 5 min ago. Just got a call said the light came on again and is flashing, and the temperature is getting up to the 3/4 mark. Its 95 degrees here, with a heat index of like 110, so I'm sure its running a little hotter than normal. But it still worries me, obviously.

Thoughts? I guess I need to probably start with a compression test, as well as look at the plug and wire. And seriously, why did it need to be a back cylinder?!?!

[Tbay99Venture]

I just had a head gasket problem last March. There was no check engine light, but the temperature would slowly increase above normal, then start rising to the top of the arc and fall back to normal and resume the process. These were short city drives and the needle excursions got worse. The exhaust only had a faint hint of steam smoke, but a compression test did show a big difference with the #2 cylinder.

Anyway, with warm weather we run the a/c and the fans stay on so the needle is usually only 2 or 3 widths above the lower range of the arc. Without a/c it can get almost halfway up the scale before the fans come on. Hope that helps your diagnosis.

[bszopi]

Talked to my wife today and she says the SES light comes on when she gets up to speeds above 55mph. At that point, it sounds like it starts to drive like crap (i haven't had a chance to drive it yet). I'm going to drive into it this afternoon hopefully and see if I can figure anything out.

Are there any sounds typical of a bad HG? When we got home Saturday night, I popped the hood and listened, and I heard a sound that didn't seem normal, but not sure I can describe it. I'll have to listen again today and see if its still there or not.

[Tbay99Venture]

Talked to my wife today and she says the SES light comes on when she gets up to speeds above 55mph. At that point, it sounds like it starts to drive like crap (i haven't had a chance to drive it yet). I'm going to drive into it this afternoon hopefully and see if I can figure anything out.

Are there any sounds typical of a bad HG? When we got home Saturday night, I popped the hood and listened, and I heard a sound that didn't seem normal, but not sure I can describe it. I'll have to listen again today and see if its still there or not.

Our case didn't make any different sounds. Couldn't really get above 45MPH for where we were driving so I didn't notice any performance difference. I've seen it mentioned a few times on this forum to crank with the radiator cap off and see if the water gushes out, then remove spark plugs to isolate the cylinder, but I had already dealt with our gasket by then.

What I did find is that the funny head bolt with the unthreaded extension to support the engine mount bracket on the passenger side came off much easier than any other. (And that was the cylinder with low compression.) I really couldn't see much of a problem by looking at the gasket, block or head. Fresh bolts and gaskets and we've been fine since. (FL -> Nova Scotia and back, through PA & VA mountain country as well last week but temp stayed nice and cool.)

[BLADE]

Thats strang that it didnt have any lean or rich codes with the misfire. I would get a coolant test strip to cheak for exhaust gas in coolant or are you losing coolant Mine in the past had a random misfire turned out to be fuel pressure reg but a cylinder specific misfire could be plugs, wires, coil

[bszopi]

Ok, so I got a chance to mess with it tonight. First off, let me just say that the engine is staying unusually warm, at least to me. After sitting for ~3hrs in the evening, I was still burning myself on the UIM while trying to access the back of the engine. I ended up having to put a towel over the UIM so I could work on it. Anyway, here is what I now know...

• Compression on #1 cylinder was tested twice. First time was 135psi, second time was 150psi. Perhaps a little low, but that doesn't seem to indicate a bad HG.
• When trying to get the plug boot off, the internal connector came off. Was able to replace it for free thanks to a lifetime warranty. WOOT!
• Plug appearred to be a light grey in color, and dry.
• The sound it is making sounds like a toy train - a puff puff sounds, in sync with RPMs
• After getting it back together, I took it out for a drive. The SES light only appears to come on >60mph, and when accellerating (usually >3k rpms). After slowing down for a short amount of time, the light turns off.
• When accellerating on the highway, it struggles to get up to 70mph, even with a downshift to ~4700RPM
• Coolant levels are normal
• Engine is running hot as well... between the 1/2 and 3/4 mark (fluctuating) with the AC on

[mickaz]

is the any signs of exhaust pressure in the coolant?

[bszopi]

(time to feel like a noob...)

is the any signs of exhaust pressure in the coolant?

How would I check this, and what could cause it?

[Tbay99Venture]

I think "exhaust pressure" is supposed to mean compression. Maybe I'm being dense but I think he's saying what I said in post #4. I found at least one place here where I've seen it: http://60degreev6.com/forum/showthre...l=1#post420464

Though it doesn't sound like a HG to me anymore. Coolant loss in my case went from not noticeable to considerable. BUT the recovery tank level didn't go down, removing the radiator cap was the way to find it. (The low coolant sensor on this vehicle gives lots of false alarms so we usually ignore it.)

[bszopi]

Yesterday afternoon, when I first started looking at it, the recovery tank was full, but I decided to check the radiator anyway. As soon as I got the cap off, water started pouring out of the radiator. I immediatly thought that the coolant system was getting pressurized. Then I looked at the recovery tank and noticed it was emptying. The recovery tank is actually above the radiator and drains down into the radiator. Brillant design...

[mickaz]

i had the same problem and it was an HG. the gasket was holding pressure when cold but as soon as the car heated up, it was passing through the fire ring.

[Tbay99Venture]

How common is a coolant leak to the intake passages but not yet into the engine? (Trying to understand the low performance, but that doesn't answer the temperature issue.) You might get your LIM gasket replacement site article yet

[mickaz]

How common is a coolant leak to the intake passages but not yet into the engine? (Trying to understand the low performance, but that doesn't answer the temperature issue.) You might get your LIM gasket replacement site article yet

since there is more pressure on the cylinder side of the leak, cooland will be forced out of the radiator cap or the pressure tank. you might see some coolant burning but if its a very small leak it will be hardly noticeable.

since coolant is pushed out the radiator it will have a harder time cooling the engine depending on the leak it can take days or minutes to happen, in my case it was minutes lol

you will not get a noticeable low compression with a compression tool. ( since you need to do it cold, then again depending on the size of the leak.

if some coolant does get into the engine it will be so small that it will not be enough to be seen. ( a clean spark plug or cylinder)

and performance wise, well you get the idea. air + gas + coolant = shitty acceleration.

So this was how my HG was blown. Internally but only to a water passage to cylinder.

Oh and if you did drive like this, a while Do both the headgasket, as you will have put a Big strain on them because of the high temperature of the gasses.

[bszopi]

I did the following, as stated in the linked thread:

Take the radiator cap off, unplug the coil packs and turn the engine over. If there is coolant spewing out like mad, it's a head gasket.

I cranked it over a couple times and no coolant came out, so I think that rules out the head gasket completely then? I really have no urge to replace it right now...

[bszopi]

Could a clog in the coolant system cause the above to occur? When I took off the radiator cap the other day, there was some pretty good "growth"" on and around the relief spring. Just thinking if something like that started to clog the coolant passages, a cylinder could heat up in a hurry and possibly cause misfires. And the fact that the engine gets up to halfway almost instantly. I mean, its been close to 100* here for the past few days, so its going to take longer for it to cool down, but I don't think it should be taking as long as it is.