What's the diagnosis?

[Duckbill]

For a while now my truck's been running poor. It's pinging real bad during accellaration or under a load(pulling trailer). Also, while accellarating, when I get into the higher RPM's the engine seems to kinda "retard" itself. A few weeks ago, my engine light came on while pulling my trailer on the highway (70mph). It stayed on for a couple of days and then went off by itself. I finally aquired a code reader today. I thought the code would still be in the memory, but apparently not. It is reading nothing. My gas mileage is fine, but I'm definitely short of a little horsepower.
My truck is a '99 Tacoma 4 X 4 3.4 V6 with 110K miles on it. I have a K & N filter and induction kit. Throttle body and MAF are clean. No engine light, no codes. What could it be?

[onemeantaco]

what octane are you using if you use lower octane gas you could have spark knock the fuel may not be combusting properly

[Duckbill]

For the last year and a half I've been running 87 due to gas prices. Before that I always ran premium, just because my truck ran so much better with it. I may have to switch back, but OUCH. These gas prices are ridiculous.

[superjoe83]

i would put a new knock sensor in it, thats the only thing that limits timing advance, if it is not working properly, the ECU sees no knocks or pings and advances the timing, which is giving you the pinging

[Duckbill]

I get what your saying, but wouldn't I be getting a code if the knock sensor was bad?

[CR50HC]

Is your timing off? Are you using the correct heat range spark plug?

[Duckbill]

Just changed the plugs and wires a month ago. I put in the recommended NGK's and the high dollar Belden wires.
I might need to have my timing checked.

[superjoe83]

Originally Posted by Duckbill

I get what your saying, but wouldn't I be getting a code if the knock sensor was bad?

Not necessarily, The knock sensor is a pezio crystal which produces voltage when vibrated, the sensor may sill put enough voltage out to keep the ECU from setting a code but not enough to detect knocks

[Duckbill]

Thanks Superjoe, I'll consider it. I just hate the fact that they get $180 a piece for them . That's just robbery for no more than those things are.

[Duckbill]

UPDATE! Switched to 93 Octane. Pinging is gone, but engine still retards at higher RPM's when accellerating. It's not constant, but is worse when A/C is on. Still no engine light. I'm afraid I'm going to have to take it in soon

[dwposnut]

My 98 2.7L 4x4 just started doing the same thing. I replaced both oxygen sensors last week @ 138,000 miles and 3 days later the performance dropped significantly. All fluids are fresh and levels have been checked. It even seems like the the disk brakes are hanging up just a little bit, but I know that's not the problem. Let me know if you find anything out.

[skegg]

Originally Posted by dwposnut

My 98 2.7L 4x4 just started doing the same thing. I replaced both oxygen sensors last week @ 138,000 miles and 3 days later the performance dropped significantly. All fluids are fresh and levels have been checked. It even seems like the the disk brakes are hanging up just a little bit, but I know that's not the problem. Let me know if you find anything out.

I foung these forums when searching to check out the same problem: 98 Taco, 2.7 pings under any kind of load including a slight up hill climb. Runs alittle better on super UL gas but still pings. It's starting to drive me nuts, any suggestions?