Team Camaro Tech banner
1 - 14 of 14 Posts

·
Registered
Joined
·
797 Posts
Discussion Starter · #1 ·
I drove my Camaro last night for the first time in a while. The last time I drove it-no pinging or signs of detonation. This was when the weather was mid 80's to high 90's. Yesterday it just so happens that a cold front blew into Houston and the temp. dropped somewhere between 20 and 30 degrees. I started the car up last night and went for a ride and it is pinging even under mild acceleration.

I know that my compression is probably too high, but as I mentioned above it never pinged in the summer. Could this be a sign that I need to jet up for the winter? My thought is this: Cold, dense, air has leaned the air/fuel mixture out enough that it is detonating/pinging.

Does this idea sound plausible? Anyone else notice drastic changes in engine performance due to temp. changes?

And one last question: What would cause my oil dip stick to blow out and spray oil all over my header and firewall? I got out and checked it and it was very clearly pushed out of the block. This happened last night as well! Not a good night for the Camaro..
 

·
Retired
Joined
·
26,951 Posts
All my personal experiences with detonation have occured when the engine temps as well as air temps are higher. As you raise compression/increase HP you go to a colder plug to wick more heat from the cyl to aid in fighting detonation... Could this just be bad gas? Did you do anything to prep the engine for running in such cold weather? Could the cold weather have caused your breather/pcv system to be plugged and firing the engine built up pressure in the crank case causing the dip stick to be pushed out?

How warm did you let it get before going for a drive?
 

·
Registered
Joined
·
797 Posts
Discussion Starter · #3 ·
Dennis,
I drove the car for at least 30 minutes last night. It seemed to detonate worse as it got warmer. I am running a 160 deg. thermostat and the car was at temp. when it was doing this.

After driving it around and listening to it ping, I noticed that if I really stepped into it, it would not ping, maybe the secondaries opening stopped it? Regardless, as I pulled up my street, I stepped into it pretty hard and the car was running strong. As I neared the house, I pushed the clutch in and the car stalled immediately. I then noticed that there was smoke pouring out from under the hood! I jumped out, popped the hood, and there was oil all over the passenger side header and on the firewall. It was dark but I poked around until I figured out that the oil dipstick was sitting up and out of it's normal place. I pushed it back in, and fired it up again but it won't idle.. It keeps stalling. I am thinking that maybe one or more of the plug wires came loose from all of the oil.. I will check into it when I get home, and after I fix the 'Vette (see other post today about steaming battery!). It seems that all of my car troubles are happening at once! Great timing!

I just hope that I did not do any serious damage to the engine last night.. I will find out today
 

·
Registered
Joined
·
5,277 Posts
The cold charge is denser and allows more fuel and air into the engine. Combine that with higher compression (and a hot motor which expands the charge) and cylinder pressures will be higher. This could also be a factor of lower humidity. Moisture in the air helps slow combustion and lower combustion temperatures. Of course I can't prove any of this, but it seems reasonable.


-dnult
 

·
Registered
Joined
·
2,372 Posts
The air is colder and denser but the carb does not know anything about that so it is running a bit lean.

Gasoline is reformulated for colder months and switched back when the warmer season occurs.

Because of one or both of these issues, your A/F mixture could probably use a little tweak is my guess.

-Mark.
 

·
Registered
Joined
·
40 Posts
Hey, I took my car out yesterday and noticed the same thing, more like a popping sound when I accelerated. The temp outside was @ 55 degrees and my car temp was running @ 150 - 160 (I have a 160 thermostat in it and was thinking of putting a 180 or 195 in it for the winter but I do not drive it in the winter that much so I left the 160 in it.)

I replaced the distributor a month ago when the weather was nice (upper 60s). I set the time and it was good to go, I had no problems. I will double check to see if anything changed with the timing. The comment about bad gas has me wondering, it has been raining a lot around here, I wonder if some water got in the gas station tanks. :confused:
 

·
Registered
Joined
·
40 Posts
Update: I tried taking my car out today and it sounded like it was running on half of the cylinders when I accelerated. I didn't want to put my foot into it until I figured out what the problem was. I got it home and checked all of the wires. Nothing there so I pulled some sparkplugs and they were covered thick with carbon (They were brand new plugs too, about 300 miles old). I think I am going to have to find a shop that can lean out the carb a little, its an Edlebrock 600CFM. That was probably the cause of the popping too.
 

·
Retired
Joined
·
26,951 Posts
Ken your problem sounds as expected when an engine isn't up to operating temps... If you had a manual choke you could pull it on a bit and the problem would go away... A good start would be at least a 180 stat. If you are in extreme cold weather try a 195...
 

·
Registered
Joined
·
920 Posts
DJD has it right. There are NO advantages to running 160 degree thermostats! YOu will wear the engine out faster, reduce the ability of the mixture to completely homogenize, and the oil temperature will not be sufficient to adequately protect your surfaces.....and with no appreciable power gains at all if that is what your thinking.

Check this chart out on wear vs temperature.



My guess on the pinging is somethings up with the gas if everything was okay before. While sometimes my carbs need idle circuit tweaking in the winter, I have never had to rejet one. Also, I have seen a spring in the distributor come off or break and cause lots of timing to come in early with the combo of the vacuum advance making for light and medium load situtions sound like someones under the hood with a ball-peen hammer! I would completely recheck the timing curves for the distributor and keep your foot out of it until you find this out. Detonation is very destructive as well all know.
 

·
Registered
Joined
·
40 Posts
Thanks for the help! I replaced the 160 with a 180 degree thermostat, cleaned the plugs and checked my wires. It started up fine but when I took it up the street, it started chugging again so I pulled it back in the garage to check the wires. It felt like it was not firing on all cylinders. I looked in the carburetor and it was covered with carbon too. After blowing it out with carb cleaner I took it back out. It started popping a little so I made it to the gas station and put a half tank of premium in it in case I had some bad gas. The temp was up to a solid 180 now and it felt a lot better. I took it out on the highway to blow more of the carbon out of it. It seems to be running strong now, no popping or chugging. I don't know what fixed it, thermostat, cleaning the carbon out or filling the gas tank up or maybe a combination of all. Next time there is a clear day and it is around 50 degrees out, I will take the car out for another ride to make sure it is still running strong. Thanks again for all of the help
.
 

·
Registered
Joined
·
797 Posts
Discussion Starter · #13 ·
UPDATE! I just got through doing a compression test on my car.. The news is not so good.. Here are my results:
#1. 240 PSI
#3. 235 PSI
#5. 240PSi
#7. 230 PSi

Now the bad part..
#2. 75 PSI
#4. 58 (or so, needle only has increments of 5)
#6. 70 PSI
#8. 60 PSI

This all started after the most recent incident where the car was pinging and I stupidly put my foot into it. The car did stop pinging once the secondaries opened, but obviously it was only the roar of the engine drowning out the bad sounds.

Now my questions. What would cause every cylinder on one bank to read so low, while the other bank of cylinders is right where they are supposed to be?

Not that this is relative, but when I pulled the header on the passenger side, the #2 exhaust port is COVERED in oil.. It was literally running out of the port when I pulled the header. The inside of the pipe was also covered with oil, and showing signs that this had been occuring for a while. So, either rings, valve seals, or intake gasket leaking on that port??????

Also, there are little puddles of oil on TOP of the intake manifold on the bank with the low readings. Every intake manifold retainer bolt on the even cylinder side is buried in a little pool of oil.. This is all very strange..

Tomorrow I will pull the head on that side, and see if I can figure out what the heck happened. I find it hard to believe that a head gasket would go bad between all four cylinders at once.

I am open to suggestions as to what I should be looking for. Thank you!
 

·
Retired
Joined
·
26,951 Posts
Originally posted by Kens68:
Thanks for the help! I replaced the 160 with a 180 degree thermostat, cleaned the plugs and checked my wires. It started up fine but when I took it up the street, it started chugging again so I pulled it back in the garage to check the wires. It felt like it was not firing on all cylinders. I looked in the carburetor and it was covered with carbon too. After blowing it out with carb cleaner I took it back out. It started popping a little so I made it to the gas station and put a half tank of premium in it in case I had some bad gas. The temp was up to a solid 180 now and it felt a lot better. I took it out on the highway to blow more of the carbon out of it. It seems to be running strong now, no popping or chugging. I don't know what fixed it, thermostat, cleaning the carbon out or filling the gas tank up or maybe a combination of all. Next time there is a clear day and it is around 50 degrees out, I will take the car out for another ride to make sure it is still running strong. Thanks again for all of the help
.
I think getting to 180 before putting your foot to it is what solved your problem... Plug wires and cleaning things up didn't hurt though...
 
1 - 14 of 14 Posts
Top