Put 87 Octane in. Poor performance since. P0456 to top it off

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txhookem

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I had been driving my wife's Jeep for about a month which takes 87 octane. When I went back to the Lincoln (2002 3.9L), I brain farted and put 87 in there. Since then it has been jumping and just acting crazy as in a misfire or knock sensor issue maybe.?.?

So far this is where I stand:

I changed the plugs (bosch platinum) but didn't check gap :( (I need to get back in there anyway to change my coils since I've already purchased them)
engine generates a emissions code: P0456 - Evaporative Emissions System - Small leak detected
I changed my water pump and serp belt as well

So what is the consensus?
-knock sensor issue?
-bad plug gaps?
-coils?
-emissions code related
 
It won't run off of 87. That's outside the range it can compensate for. Get the 87 out and put 91+ in.
Fords don't like Bosch plugs at all. Put some NGK or Motorcraft in. Set the gaps.
It may be time for new coils.
The evap leak is an unrelated problem.
 
Thanks joegr for the quick reply. I only put that 87 in once. I put octane booster in that tank after I realized what I had done like 2 days later, and its been 91+ ever since, been a few months now. I'll kill the Bosch then.

Is there a common place to look to address that evap code on the LS?

Also, Should I get iridium plugs or stick to platinum?
 
Okay, I didn't realize that you had been through a few tanks since then. I would stay with the platinum. They will last as long as you need before it's time to change the coils anyway. If the plugs don't clear it up, immediately change the coils too (all of them, and use Motorcraft).
No common issue on evap leaks that I know of, but I would start with the seal on the gas cap.
 
Shoot. Forgot to mention I got a locking gas cap to address that issue, but it didn't help. Thanks for the plug info.
 
Some years ago Dave Vizard did an experiment in which he loaded instrumentation into a car and then drove it on a test loop that was 10 miles or more. The purpose was to analyze octane requirements necessary for the variety of driving conditions in the test loop.

Over most of the loop he found that the necessary octane stood in the mid-sixties. The test engine was a carbureted SBC of the performance persuasion.

The conclusion he arrived at was that for most city/highway driving high octane is unnecessary. It's only under demand circumstances that what's required by manufacturers is, in fact, necessary.

When I'm racing I start with a mostly empty gas tank with a bit of 93-94 remaining. I add five gallons of C116. And I have the 'fuel' part of my spray system filled with methanol which is usually considered to have a rating of about 110-115. So I do have a working knowledge of 'octane'---actually going back more than 50 years. When I was in high-school I worked 'crew' on an Offy-powered Midget roadster that used methanol as fuel.

It's unlikely that you hurt your car by using a tank full of 87---even without the booster.

KS
 
cammerfe said:
Some years ago Dave Vizard did an experiment in which he loaded instrumentation into a car and then drove it on a test loop that was 10 miles or more. The purpose was to analyze octane requirements necessary for the variety of driving conditions in the test loop.

Over most of the loop he found that the necessary octane stood in the mid-sixties. The test engine was a carbureted SBC of the performance persuasion.

The conclusion he arrived at was that for most city/highway driving high octane is unnecessary. It's only under demand circumstances that what's required by manufacturers is, in fact, necessary.

When I'm racing I start with a mostly empty gas tank with a bit of 93-94 remaining. I add five gallons of C116. And I have the 'fuel' part of my spray system filled with methanol which is usually considered to have a rating of about 110-115. So I do have a working knowledge of 'octane'---actually going back more than 50 years. When I was in high-school I worked 'crew' on an Offy-powered Midget roadster that used methanol as fuel.

It's unlikely that you hurt your car by using a tank full of 87---even without the booster.

KS
Click to expand...

Mr Howie (IIRC) did a similar study in his LS and found similar results.... to the point he runs a 89-91 blend for best results.
 
Been running regular 87 for at least 100,000 miles. Not sure when I started, first couple of years was premium only then gasoline prices spiked and the cost difference between regular and premium reached 40 cents per gallon. Fuel economy is the same and so far no issues. Currently at 189K, plugs were done at 77K and plugs and coils at 120K.

2000 LS V6 Manual Tranmission
 
Thanks for the info guys. After hearing your stories, reading a few articles, and referencing the user manual, I actually think I'm going to make the switch to 87 for a while and see how that goes. As long as an agressive knock doesn't start I won't worry about it. I got some NGK GP (7090) plugs to replace those problematic Bosch plugs. Hopefully that will alleviate my woes.
 
txhookem said:
As long as an agressive knock doesn't start I won't worry about it.
Click to expand...

youre ok with a little knock just as long as its not aggressive?




as long as the cars knock sensor is working fine that shouldn't happen, the PCM will just pull timing out and make less power to protect itself.

however if that knock sensor ever fails....
 
1LoudLS said:
youre ok with a little knock just as long as its not aggressive?




as long as the cars knock sensor is working fine that shouldn't happen, the PCM will just pull timing out and make less power to protect itself.

however if that knock sensor ever fails....
Click to expand...

who doesn't like detonation in the morning
 
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