If I recall that tune up was more targeted for the 5 liter engines. You'll benefit from new plugs, wires, cap and rotor, but the 351 does just fine with the factory gap on the plugs and running the timing at 10 btdc.
6 Liter Tune Up Loss of MPG
Howdy y’all,
I just did the 6 liter tune up on my 96 351. I did not do the timing advance yet however. I gapped the new plugs to .54 and I am noticing a loss of about 2mpg from what I was getting before and not much of a noticeable increase in performance. Idle is fine, engine is running fine, just worse fuel eco. Any thoughts?
I just did the 6 liter tune up on my 96 351. I did not do the timing advance yet however. I gapped the new plugs to .54 and I am noticing a loss of about 2mpg from what I was getting before and not much of a noticeable increase in performance. Idle is fine, engine is running fine, just worse fuel eco. Any thoughts?
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Gotcha, i've heard so many mixed thoughts on whether it works for the 5.8. So many people swear by it but I think it might just be a placebo effect for the increase in power. I'll bring the gap back down to .044 and hopefully its back to normal. New wires, coil, cap, and plugs were worth it atleast 👌If I recall that tune up was more targeted for the 5 liter engines. You'll benefit from new plugs, wires, cap and rotor, but the 351 does just fine with the factory gap on the plugs and running the timing at 10 btdc.
What plugs did you use? These pushrod fords seem to like the cooper core ones for what ever reason.
I would also double check that all the plug wires are seated good, and double check the connection at the coil. I have seen these have corrosion built up and not make a good connection once removed, its almost as if they where sealed by corrosion until you un-hooked it. As a final check I would verify I did not disturb and crack any vacuum lines while doing the pass. side especially. Be easy to make a small crack in one of these and change things in engine (tho yours being a '96 should be able to compensate much easier). Id also consider doing a memory clear on the ECU as well and let it re-learn everything.
Personally I think its based in good sense and likely does work great if your replacing worn stuff, the better condition your stuff is in originally the less I see the 6litre tuneup helping (rather being noticable). On my own trucks I have never done this, and this alone. Always has been exhaust and other parts at the same time.
I would also double check that all the plug wires are seated good, and double check the connection at the coil. I have seen these have corrosion built up and not make a good connection once removed, its almost as if they where sealed by corrosion until you un-hooked it. As a final check I would verify I did not disturb and crack any vacuum lines while doing the pass. side especially. Be easy to make a small crack in one of these and change things in engine (tho yours being a '96 should be able to compensate much easier). Id also consider doing a memory clear on the ECU as well and let it re-learn everything.
Personally I think its based in good sense and likely does work great if your replacing worn stuff, the better condition your stuff is in originally the less I see the 6litre tuneup helping (rather being noticable). On my own trucks I have never done this, and this alone. Always has been exhaust and other parts at the same time.
I used the Autolite copper core plugs. Ill double check the connections tomorrow. I have done a whole lot of exhaust work to get some good airflow and that has been a significant increase. I definitely manhandled my way through the passenger side of the engine when installing the plugs because the accessibility is so bad. Ill check vacuum as well.What plugs did you use? These pushrod fords seem to like the cooper core ones for what ever reason.
I would also double check that all the plug wires are seated good, and double check the connection at the coil. I have seen these have corrosion built up and not make a good connection once removed, its almost as if they where sealed by corrosion until you un-hooked it. As a final check I would verify I did not disturb and crack any vacuum lines while doing the pass. side especially. Be easy to make a small crack in one of these and change things in engine (tho yours being a '96 should be able to compensate much easier). Id also consider doing a memory clear on the ECU as well and let it re-learn everything.
Personally I think its based in good sense and likely does work great if your replacing worn stuff, the better condition your stuff is in originally the less I see the 6litre tuneup helping (rather being noticable). On my own trucks I have never done this, and this alone. Always has been exhaust and other parts at the same time.
Agree on the copper plugs.
Doing a 6L tuneup without the timing advance is missing out on the single most important part to it. I don't think the gap and wires do much of anything, but it does increase the risk of skipping because of the big gap.
Doing a 6L tuneup without the timing advance is missing out on the single most important part to it. I don't think the gap and wires do much of anything, but it does increase the risk of skipping because of the big gap.
This ^.Agree on the copper plugs.
Doing a 6L tuneup without the timing advance is missing out on the single most important part to it. I don't think the gap and wires do much of anything, but it does increase the risk of skipping because of the big gap.
Sorry for a potential dumb question, but why wouldnt Ford just produce the Bronco with the timing set to 12-13 btdc rather than 10? Is it just a safety buffer?Agree on the copper plugs.
Doing a 6L tuneup without the timing advance is missing out on the single most important part to it. I don't think the gap and wires do much of anything, but it does increase the risk of skipping because of the big gap.
Also would skipping be the reason for my MPG dropping? I feel like I would notice it in how the engine runs, but it seems like it runs fine. Should I just go back to stock gap or maybe just decrease it to .05-.052?Agree on the copper plugs.
Doing a 6L tuneup without the timing advance is missing out on the single most important part to it. I don't think the gap and wires do much of anything, but it does increase the risk of skipping because of the big gap.
If you're not going to bump the timing, return the gap to the factory spec. By running a larger gap, and not increasing anything else, all you're doing is mimic-ing a motor with worn out spark plugs.Also would skipping be the reason for my MPG dropping? I feel like I would notice it in how the engine runs, but it seems like it runs fine. Should I just go back to stock gap or maybe just decrease it to .05-.052?
Important to keep in mind that Ford released this thing to a million different locations. Think things like climate- the temps, humidity, elevation, etc. How about the gas quality, or the terrain customers might see with hills vs flats, how about customers trying to hold a gear with A/C running running while pulling a trailer with oversized tires on top of it, and more. Basically, they design it with a margin of error in a time with primitive computer systems with limited ability to counter things like spark knock (note: these things don't have knock sensors). It is easier for them to set the timing a little bit lazy and not have a wave of potential service issues with customers up in arms and service techs being frustrated at the suggested timing not working for their area.Sorry for a potential dumb question, but why wouldnt Ford just produce the Bronco with the timing set to 12-13 btdc rather than 10? Is it just a safety buffer?
They left a lot on table, potentially, depending on how and where you use your truck.
Well saidIf you're not going to bump the timing, return the gap to the factory spec. By running a larger gap, and not increasing anything else, all you're doing is mimic-ing a motor with worn out spark plugs.
Rotors, caps, and plug wires are no all created equally. For rotors and caps, you want ones with brass terminals. They will be gold vs the silver of the pot metal terminals.
Plug wires should be spiral core, not solid. And the less ohm resistance the better. IMHO, Taylor Thundervolt 8.2 wires are the best. They have only 50 ohms of resistance per foot, whereas parts store special wires will have upwards of 1500 ohms of resistance per foot. That means a lot of spark loss.
Plug wires should be spiral core, not solid. And the less ohm resistance the better. IMHO, Taylor Thundervolt 8.2 wires are the best. They have only 50 ohms of resistance per foot, whereas parts store special wires will have upwards of 1500 ohms of resistance per foot. That means a lot of spark loss.
I got MSD for rotor and cap and coil, Ford performance wires. Are those beneficial at all? Went with the most recommended on the 6 liter write-up.Rotors, caps, and plug wires are no all created equally. For rotors and caps, you want ones with brass terminals. They will be gold vs the silver of the pot metal terminals. Plug wires should be spiral core, not solid. And the less ohm resistance the better. IMHO, Taylor Thundervolt 8.2 wires are the best. They have only 50 ohms of resistance per foot, whereas parts store special wires will have upwards of 1500 ohms of resistance per foot. That means a lot of spark loss.
If you're not going to bump the timing, return the gap to the factory spec. By running a larger gap, and not increasing anything else, all you're doing is mimic-ing a motor with worn out spark plugs.
Like user Jermil said, the 6 liter may have only been designed for the 302. Is there any benefit for doing it in a 351?If you're not going to bump the timing, return the gap to the factory spec. By running a larger gap, and not increasing anything else, all you're doing is mimic-ing a motor with worn out spark plugs.
Re-read the first few comments. The 6 liter tune-up was designed by users with the 5.0 in mind, not the 5.8. Replacing parts and generally showing the engine some love will almost always increase performance after time but if you're running a 5.8 with new cap, rotor, plugs and wires... that's likely about as good as it's going to get (other issues, not withstanding). As mentioned... many variables can make a difference (temps, elevation, etc., etc.) and these older rigs don't have the modern computer systems that can adjust mechanical settings on the fly (or any of the potential problems that may come with them), so tuning to your location, conditions and general use are the best things to be aiming for, rather than a procedure not designed with your engine or specific needs in mind.
In my reading here over the years, MSD isn't what they used to be. Still not terrible but not the "great" benefits they used to be. I've been very happy with my Ford racing wires and I love the numbered system. I'm sure they're better than generic parts store, off the shelf plug wires but for top performance, I'd listen to more knowledgeable members input given prior.
Good luck and Bronc-On!
In my reading here over the years, MSD isn't what they used to be. Still not terrible but not the "great" benefits they used to be. I've been very happy with my Ford racing wires and I love the numbered system. I'm sure they're better than generic parts store, off the shelf plug wires but for top performance, I'd listen to more knowledgeable members input given prior.
Good luck and Bronc-On!
Right, the Quality of parts can make a huge difference in Performance.
On our newer rigs the timing bump only effects the engine at start up,
after the engine is actually running the PCM (computer) takes over
and regulates the ignition timing advance.
I still did the 6L timing bump cause' i like the 1 second hit the key & it fires right up.
(while standing outside like some kinda show off.)
On our newer rigs the timing bump only effects the engine at start up,
after the engine is actually running the PCM (computer) takes over
and regulates the ignition timing advance.
I still did the 6L timing bump cause' i like the 1 second hit the key & it fires right up.
(while standing outside like some kinda show off.)
How many tanks have you ran through it to confirm there is indeed a 2 MPG drop ?
because 2MPG in our rigs is a significant percentage drop..... maybe just the first tank was crappy garbage gas?
Its just hard to imagine a tune up slaughtering your mileage like that
because 2MPG in our rigs is a significant percentage drop..... maybe just the first tank was crappy garbage gas?
Its just hard to imagine a tune up slaughtering your mileage like that
Is that right? I thought the timing bump is for mechanical advance, and the PCM still adds a set amount per its tables...On our newer rigs the timing bump only effects the engine at start up,
after the engine is actually running the PCM (computer) takes over
and regulates the ignition timing advance.
I still did the 6L timing bump cause' i like the 1 second hit the key & it fires right up.
(while standing outside like some kinda show off.)
If it only affects initial start-up, then no one would be seeing any performance changes, for better or worse. Then the 6L tune-up would only be about coil/cap/wire/plug, which means it's purely about the quality of the replacement parts.
I’ve only run through one tank. Judging off the rest of the comments, gapping the plugs really has no benefit if any for the 5.8. I’m sure some spark is skipping and causing the loss of mpg. However it could also be a crappy tank of gas like you said. I’m gonna run one more tank, and if it’s still bad, i’m gonna go back to stock gap. Thanks everyone for the input, I learned a lot!How many tanks have you ran through it to confirm there is indeed a 2 MPG drop ? because 2MPG in our rigs is a significant percentage drop..... maybe just the first tank was crappy garbage gas? Its just hard to imagine a tune up slaughtering your mileage like that
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