So I got a question for you Yoda peeps

So I normally 87 octane in my 1990 22re 2wd daily driver pickup runs perfect smooth idols smooth . But In the past I have sometimes put 91 octane in my pickup now here’s the weird part when I put 91 octane in it idles rough driving down the road it drives fine but after when the trucks been sitting for an hour or two after driving it it has a hard time starting sometimes cranks and cranks but eventually starts question is has anyone else had this problem ?

 

Just for the sake of argument, what brand of gas do you tend to patronize?(Chevron, Shell, Mobil, World, etc)

 

Shell or Chevron

 

My truck pinged a lot on 87. On 89 octane it wouldn’t audibly ping but would noticeably pull timing under WOT and get worse gas mileage. 93 would mostly cure it. I advanced the timing to gain a little low end power. Fuel brands make a difference in my case. It runs worse on local grocery store gas but runs good on Shell and Chevron.

 

Odd. Shell, Chevron, Mobil, Union 76, etc are usually considered Top Tier gas. Especially Chevron. Have you checked timing recently?
Again, for the sake of argument, is the truck running ND or NGK plugs?(kinda reaching on this one)
My only other thought is the particular service station may have had issues.

 

Try advancing your timing when you run higher octane and see if you notice a difference. I can advance my timing as far as the distributor turns and still not ping using 92 octane.

 

Running the higher grade fuel allows the ECU to advance the timing farther before it starts to get a knock signal. This advanced timing keeps more heat in the engine and engine bay that would otherwise go out the exhaust. This extra heat in the engine bay effects the ignitor and high-tension cords. This is why you might find issues doing warm starts and have to crank a bit more than otherwise.

 

To a certain degree you could advance timing right up till the engine spits out parts or melts! This because there is a feed back system between the knock sensor and the spark advance.

​​​​​​this system and sensor arrangement is much faster than your foot and ear.. If you can detect the knock you've got bad bearings ;-)

 

I’m using the Oem NGK plugs

 

Just a note: For the last 20 years or so, IIRC, I've had the Bosch Platinum +4 plugs in both mine. Plenty of power, no fouling, as long as I give them a good freeway run once in a while. No knocking or pinging regardless of the fuel's name or octane rating. No noticable improvement with the highest, or lowest octanes. By the same token, I've never put it on a treadmill, either, so I may well be missing something.
I've gotten 100K miles on every set I've used. I replaced them at that point just to be safe, but not out of necessity. All 4 leads, and the center conductor, still in good shape, although the ground leads were a tad shorter

Maybe I'm just an advertizing sucker, though...

This year I put in those E3 plugs for the 4Runner, and they seem quite good for it, although the mileage seems to be down some on it.
I strongly suspect the O2 sensor, on that, though. We'll find out this summer. No CEL lite, yet, but it's got 70K miles on it, and I think it time to replace it. Probably clogged up, at least partly.

Anywho, just my experience to date.
Pat☺

 

I would never run any other plug but NGK

 

I would only run the factory specified spark plugs, which are either NGK BPR5EY or the Denso W16EXRU plugs that Toyota sells at the dealer. The Toyota Denso plugs don't have the screw-on base that the aftermarket versions have.

 

Yep that’s what I roll👍

 

Ok, I'm having a blonde moment, as the saying goes. May I ask what you mean by "the screw-on base"? I mean, they're threaded, like most spark plugs are, where it goes into the engine, so I don't understand the phrase you used. What am I missing here?

Thanks for any help in advance!
Pat☺

 

I think he’s talking about the other side of the spark plug where the boot goes in Sometimes you could take off that tip but I could be wrong

 

Ok, my last guess and I'll leave you alone. EGR clogged/stuck?
Seems if this was the case than octane wouldn't matter, it'd run weird on either.

 

Yes, this is what I meant. I didn't word it very well.

 

Ohhhh!
Thanks
I confuse easy. Don't mind me. Like I've always said, as a mechanic, I make a great radar technician

A question for all you pro's out there, if I may: Could my switch to the E3 plugs in the Runner be causing my loss of mileage? This winter, and yes, I strongly suspect the addition of ethanol to the local fuel for the winter may be part of the trouble, but my mileage has dropped from 19-20 MPG to 17. I was just wondering if non-OEM plugs could be contributing, though.

Thanks for any advice

Have fun, all!
Pat☺

 

The old grey bearded engineers who spec's all these parts, yeah we're not gonna talk about that cost cutting engineer, knew what they were doing.

little things like changing your spark gap have significant effect on the system. There are plenty of accounts of "I used this or that sparkplug and now...", this is a big portion of why lots of us swear by only using the OEM spec sparkplugs. A few key points are load and wear on the other ignition components (ignitor/coil) and the 80's era tech (remember back in the 80' " noone would ever need more than 256kb of RAM ")

 

the oem ignition components are really good. when i bought ‘87 #1 in 2013, it still had the original yakazi wires and denso plugs w/97k miles.