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Hybrid = colder plug?

C

CSVT1214

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Nov 1, 2003
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Plainville, CT
I just installed new plugs and plug wires due to carbon tracking found on Cylinders 2 + 3. I'm running Autolite APP104 plugs at .054 gap.

Over the years, I haven't really been able to get decent life out of my spark plugs. I was running Denso Iridiums a few years ago until I got a little bit of a misfire. I pulled all the plugs and found they were perfect except for # 6 which had an electrode wore down while the others like new. Each time I have slight misfire, I find a slightly different issue.

I stumbled onto a thread on the old forums and now I'm wondering if I'm running the correct plugs and gap for my hybrid setup.

Should I be running a colder plug and decrease the gap? Could this be the cause of my so-so gas mileage? I never seem to pull more than 20 MPG trying different driving habits.

http://www.contour.org/ubbthreads/s...&page=7&view=collapsed&sb=6&o=&fpart=all&vc=1
 
I've been doing a little reading about when to use colder plugs too, so I guess here's what I've found. The way I understand this is that whenever you are incresing the combustion chamber temps a colder plug should/could be used. If your hybrid setup is running higher compression than a stock SVT engine then it seems the combustion chamber temps would be higher. I don't know if a hybrid setup runs higher compression than stock, but the the hybrid listed in the thread you posted says it's 11.2:1 and the stock SVT 2.5L is 10:1 right? Another thing that can slightly raise the combustion chamber temp is a deleted EGR, but if you still have yours obviously this isn't a contributing factor.

As far as plug life and gas mileage that seems kind of strange to me. From what I've read about other cars running colder plugs the colder plugs can actually foul more often because the colder plug doesn't burn off carbon that collects on the plug like a hotter plug does. The plugs not wearing the same also seems a little out of the ordinary. Could this be some kind of a symptom of having the 2.5L heads on a 3.0? I haven't read nearly as much about the hyrbrids as I have the full 3L so I hope I'm not way of base here.

I guess I had been reading about colder plugs because I deleted the EGR on my car, so this kind of reflects what I've found while checking into that. Maybe someone with a hybrid can add to this and correct me if I'm not making sense.
 
That seems to be the general consensus of what I've found on other websites as well. Yes, my 3L hybrid setup has 11.2:1 compression. I'm still running my EGR along with a stock tune as well. I did also read what you said about a colder plug running the risk of being fouled. I believe this would only be an issue for someone who ran colder plugs when your setup doesn't actually call for it.

The 3L hybrid setup is not very common here on the forums anymore due to the parts availability and ease of the installation for a full or ported 3L. At the time when I did my swap in 2005, it was still very common. I just don't remember seeing posts/threads about running different plugs and now I'm wondering if there was a better option than an OEM replacement.
 
So a stock tune on a hybrid 3L should not run rich compared to the stock 2.5L right? I can't think of any reason it would because you have the stock fuel delivery system in place. Stock injectors and stock tune should not make the car run rich, but the gas mileage and plug issues seem to point to something being a little off.

I guess I dont' think running a cooler plug would hurt at all, it could be worth a shot with your higher compression. From what I've read about EGR, cooling the combustion chamber can help efficiency because knock/ping is basically bad for efficiency. However if you had knock/ping issues you would know it, especially if it was happening consistently.
 
RFcsvt said:
So a stock tune on a hybrid 3L should not run rich compared to the stock 2.5L right? I can't think of any reason it would because you have the stock fuel delivery system in place. Stock injectors and stock tune should not make the car run rich, but the gas mileage and plug issues seem to point to something being a little off.
Click to expand...

I wold say that it would. The stock tune is going to be looking for certain values, and with the 3L displacing more air its going to think that its lean, more air in, more out and would have to adjust to make sure it was fueling correctly.
 
BrApple said:
I wold say that it would. The stock tune is going to be looking for certain values, and with the 3L displacing more air its going to think that its lean, more air in, more out and would have to adjust to make sure it was fueling correctly.
Click to expand...

Good point. That would make sense then for the poor gas mileage and the short plug life. Maybe time for a tune.
 
Well I plan on finally getting it tuned this summer now that I've cleared on my long running IMRC CEL. If it's running rich as a result of the stock tune, that's fine by me because that will be resolved. Now, if the plugs are not in the correct heat range or gap, that is something I'd like to address first.

According to this condition chart, my plugs would fall under the "too hot" condition. They never appear as bad as the picture shows, but they are always more white than the brown to gray in normal condition. I replaced my plugs in the fall but but due to carbon tracking, I just did them again with the plug wires. When I pulled them, they all had a little white residue forming.

reading_spark_plugs.jpg
 
now i have been running a hybrid with the motorcraft plugs and have not had any issues. but i do see why it might be a good idea to run colder plugs. good info guys thanks a lof
 
yes sir still running the stock tune. I have had no issues with the motorcraft plugs. but she will be getting tuned here soon.
 
Well I made the switch to a colder plug. Switched from APP104 with .054" gap to APP103 with .050" gap. So far it's running great. Gas mileage has improved but still working on it and testing. I need to adjust tire pressure but right now with new plugs, wires, and cleaned air filter, it's much better.

I'll report back after some more driving with this setup.
 
Happy to say my gas mileage has increased from 18-19 MPG to 21-22 MPG with the new plugs, wires, cleaned air filter, and tire pressure increased to 38 front - 36 rear. The power is smooth all the way through, and I'm not getting a rich smell from the exhaust at idle anymore. My guess is the remaining MPG increase will come from a tune for the 3L swap.

With my driving habits, I should be getting around 24-26 MPG right now.
 
That is a good increase. 24-26 is about where I was at with a baseline tune on a full 3L with 24# injectors, I ran two tanks of gas through it and got that both times. I haven't even burned a half tank since my tune was finished, but I bet it will be very similar based on what it's done so far.
 
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