Cactushead

Under low load (accelerating moderately without kicking down a gear)I have been noticing some pinging. 2001, 6 cyl, AT with 123K. In the last year all new..
Plugs, air filter, gas cap
Fuel filter
Cleaned throttle body (this was causing another issue I started a thread on) which raised and cleaned up the idle.

Always use 87 Kirkland gas and Techron FI cleaner about 2x year. Just tried 89 octane and it seemed to clear up the problem. Any thoughts?

millball

Well, I guess you confirmed that the 'pinging' was indeed spark knock when the higher octane fuel cleared up the knock.

Seems to me that the spark knock must be relatively minor, otherwise the engines' knock sensor would tell the PCM to retard the timing, so that the engine would not sustain any damage from the continued pinging.

You might be able to improve the situation with a moderate "Italian tuneup". Blow a little of the carbon out of her.

Just out of curiosity, What is your fuel mileage??

Cactushead

I haven't checked my mileage in a long time so I will see what my next tanks gets me. The carbon should not be an issue as I regularly clear it out on the highway....plus the Techron.

millball

I don't think that Techron removes combustion chamber carbon.

They may claim that it can, but I don't buy it.

Gasoline detergents, if they work at all, mostly remove and prevent deposits that restrict the breathing of the engine on the intake valve stem and disc outside of the combustion space.

Such intake valve deposits can contribute to engine power loss if they are severe, as they sometimes are.

I once had a VW with such severe intake valve deposits that it would barely run.

Cactushead

I have been using Costco gas for years and it is top tier. If I don't use that it is Shell which is also top tier.

Cactushead

278 miles from full till the light came on. Filled up with 93 octane today and no ping at all.

ThorInc

You might want to get your timing belt done and everything that goes with it...or just keep running 89+.

Cactushead

Had all of that done a year ago but how would that have anything to do with my issue?

Malcolm99

He is suggesting the T-belt is stretched throwing your timing off. I would suggest a voltage problem like weak Alt, bad connection, and or Battery. Could also be related to Coolant temp as it contributes to timing advance, what is the position of the T-stat 6-O'clock?. Also an intake leak will lean you out by drawing in unmetered air, how did the double electrode plugs look white, brown or black. Your milage seems spot on for a daily DD.

MudHippy

Timing belts don't stretch.

Malcolm99

Very true, but they can have cord failure (similar to stretch) changing the spec due to foreign material entering cover, installed to tight, poor quality belt, worn or warped cam sprockets, misaligned pulleys or tensioner, antifreeze or excessive moisture on belt, extremely high or low temps, tensioner failure, oil contamination. And actually since he had work done "recently" in T-belt years, it would be wise to inspect it. Also if the head was machined and not decked that would throw timing off.

Cactushead

None of this would surprise me since about 85% of service i get done is flawed.

ThorInc

Now that's just scary!

Cactushead

Just under 30K on these.

Malcolm99

Looks like you are slightly lean on 3 plugs, one might suggest this is due to the fact that they are on the end of the fuel rail(s) and you are maxing out the duty cycle on the injectors but that would mean you have a modified intake or an intake leak, or your MAF isn't metering properly, faulty iAC, Vac leak in the Fuel pressure regulator, incorrect thermostat position, faulty A/F sensor, ect,.

Cactushead

Recently had it in for a low idle issue that turned out to be a dirty throttle body. They also ran a diagnostic so should any of these issues you mentioned be picked up?

vital22re

iTrader: (2)

i'm curious if your ECT matches actual coolant temp of it it reads warmer than the actual coolant temp.

Cactushead

Latest tank with 93 octane = 293 miles and still probably had another 10-15 miles before the light would have come on. Refilled with 93 again.

ThorInc

I'll throw this in as many will disagree and ask for copious proof; I always get better performance and gas mileage with 93 octane; I first discovered this with my 2 stroke v6 carburetor outboard.......on one specific lake the 93 always left me enough fuel to make me not worry about making it back with gas to spare, full out of course.

MudHippy

The bigger myth is higher octane doesn't improve performance. When in almost all cases it actually does.