How to fix weird Knock Retard

[ShoBoat]

Interesting Z. Never thought of that, I will look into it though.


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[Larrylu]

Thanks for sharing the theory and results. I've had that same problem for a long time but recently ( this spring) it went into an unexplained total remission. I chalked it up to the return of summer gas.  Not complaining about the mystery cure, but I think I'll do your fix anyway cause it just makes such good sense.

[ZSHO]

I have to say quite honestly what troubles me is for us guys and gals of course,swapping the stat for a colder one,depending how much coolant we loose or how hot it may be,the knock sensor wires are so close to the stat assembly making it more vulnerable to coolant loss.  Z

[14 TUX BL]

I recently had a few incidents of noticeable hesitation/bogging. No codes, checked the knock sensor wire and all looked good. I always use Sunoco 93, tried filling up on Mobil 93 just in case. Problem has dissipated for now, moved the knock sensor behind the adjacent loom to be safe.

[SHOdded]

Sunoco is not a Top Tier gasoline, but I assume your regular station was a high-volume one at least?  I know a couple of people who had KR with Sunoco gas resolve it by moving on to Exxon or Shell etc.

[ShoBoat]

Sunoco is not a Top Tier gasoline, but I assume your regular station was a high-volume one at least?  I know a couple of people who had KR with Sunoco gas resolve it by moving on to Exxon or Shell etc.

Agreed, I have personally noticed when filling up at a really busy station vs a dead one. KR was noticeably more with the dead one. Corn is always best when fresh


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[14 TUX BL]

Sunoco is not a Top Tier gasoline, but I assume your regular station was a high-volume one at least?  I know a couple of people who had KR with Sunoco gas resolve it by moving on to Exxon or Shell etc.

Agreed, I have personally noticed when filling up at a really busy station vs a dead one. KR was noticeably more with the dead one. Corn is always best when fresh

The Sunoco station is indeed a high volume station, one that I've been going to for a long time (it's close too). I read where Mobil was Top Tier gas and Sunoco was not, but for some reason we have very few Mobil stations where I live. But I think it is definitely a better choice and will be using it just to see if the problem returns.

Quick aside:
A couple of years ago I had a new Coyote Stang that intermittently lost power. I thought maybe it could be the gas so I went elsewhere for fuel, but the problem continued and it eventually threw a code. Turned out it was a loose OHC sensor plug.

[ZSHO]

I tend to stay away from gas stations that have a 5-10 cents off a gallon especially that particular day. Z

[ZSHO]

If your issues continue personaly would pay a visit to your local dealer and possibly a re-flash is in order. Z

[wasinger3000]

So what's the consensus on knock in relation to fuel economy. Is it more economical to run a higher octane to prevent knock which will reduce the amount of fuel sprayed in compensation of the knock. Or is it not worth the price increase over 87? I'm taking the f150 on a trip over 4k miles and it's not tuned so no need for 91.

[ShoBoat]

So what's the consensus on knock in relation to fuel economy. Is it more economical to run a higher octane to prevent knock which will reduce the amount of fuel sprayed in compensation of the knock. Or is it not worth the price increase over 87? I'm taking the f150 on a trip over 4k miles and it's not tuned so no need for 91.

We run 91 in our 11 Explorer Limited. I noticed a jump in economy since the change from 87. From 17L/100km down to 14.5 ish. (Sorry about the metric) Mixed driving. It's also better for the car/truck. Keep in mind that around these parts 91 has no corn so that might also be a factor.


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[ShoBoat]

Forgot to mention that ours has the factory tune.


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[SHOnUup]

So what's the consensus on knock in relation to fuel economy. Is it more economical to run a higher octane to prevent knock which will reduce the amount of fuel sprayed in compensation of the knock. Or is it not worth the price increase over 87? I'm taking the f150 on a trip over 4k miles and it's not tuned so no need for 91.

I've read that using 93 gets better mileage and ends up being same money spent as using 87...but your vehicle would appreciate the higher octane, and is better for it.

Rich

[wasinger3000]

So what's the consensus on knock in relation to fuel economy. Is it more economical to run a higher octane to prevent knock which will reduce the amount of fuel sprayed in compensation of the knock. Or is it not worth the price increase over 87? I'm taking the f150 on a trip over 4k miles and it's not tuned so no need for 91.

I've read that using 93 gets better mileage and ends up being same money spent as using 87...but your vehicle would appreciate the higher octane, and is better for it.

Rich

Yeah I don't really ever want to use 87 just not sure if it is worth using in a truck that gets terrible milage as it is. I'll be using archoil in the fuel so I'm not worried about deposits.

[14 TUX BL]

Yeah, if the issue presents itself again I'll take a trip to the dealer.

Went for a ride tonight, and in the hot/humid air it performed really well. Will keep an eye on it ...