'99 SR5: CEL(P0325) & sluggish performance after accelerating to highway speeds

[lycaon_guy]

I've been a long time lurker here and bought a 99 4Runner in February 2014. Sometime after having the timin belt replaced (I wasn't sure when it was last replaced & the rig has about 225k) the check engine light would come on after accelerating to ~ 55 mph or driving "aggressively." After driving around town for a while (maybe 30-50 miles?) the CEL self clears. While the CEL is on the preformance seems more sluggish.

I ran the code at autozone tonight and got a knock sensor 1 circuit (bank 1) - P0325. I've been searching this problem but haven't found any solutions. Any ideas?

I replaced the O2 sensor and am swapping the spark plugs & wires tomorrow.

Cheers!

 

[TheDurk]

Have you followed the protocol in the FSM?

The ECM will set timing to maximum retard as fail-safe when P0325 is set, so there goes your acceleration. I don't understand why you aren't focusing on the knock sensor and it's wiring--why mess with the plugs and O2 sensor?

 

[lycaon_guy]

Have you followed the protocol in the FSM?

The ECM will set timing to maximum retard as fail-safe when P0325 is set, so there goes your acceleration. I don't understand why you aren't focusing on the knock sensor and it's wiring--why mess with the plugs and O2 sensor?

Durk,

Thanks for the link to the FSM. I'm new to all of this and I didn't realize how the ECM would limited the timing (if I'm understanding you correctly) and acceleration that way. I'll look around for a scanner and see what waveforms pop up. If I can't borrow one, would you recommend buying one or finding a shop to read the waveform for me?

I read somewhere of a couple of guys with a similar problem swapping the plugs as an initial first step. I also didn't know when they were last done, so I figured replacing them would be a good idea. I replaced the O2 sensor when I first got the truck because I was getting horrible gas milage.

Thanks!

 

[TheDurk]

Durk,

Thanks for the link to the FSM. I'm new to all of this and I didn't realize how the ECM would limited the timing (if I'm understanding you correctly) and acceleration that way. I'll look around for a scanner and see what waveforms pop up. If I can't borrow one, would you recommend buying one or finding a shop to read the waveform for me?

I read somewhere of a couple of guys with a similar problem swapping the plugs as an initial first step. I also didn't know when they were last done, so I figured replacing them would be a good idea. I replaced the O2 sensor when I first got the truck because I was getting horrible gas milage.

Thanks!

You don't need an O-scope or to worry about waveforms. Just an OBDII scanner to pull and reset codes and a DVM or test light to check circuits is all you need. Swapping the plugs side-to-side and seeing if the code changes from P0325 to P0330 should tell you if a sensor is shot. The other checks will chase down wiring problems. Try the swap first. These wires may well be brittle and that is often the source of the problem, if it's not the sensors. You may have to replace the harnesses just because you troubleshot them. It's worth doing, then they won't bother you for ten years.

 

[lycaon_guy]

You don't need an O-scope or to worry about waveforms. Just an OBDII scanner to pull and reset codes and a DVM or test light to check circuits is all you need. Swapping the plugs side-to-side and seeing if the code changes from P0325 to P0330 should tell you if a sensor is shot. The other checks will chase down wiring problems. Try the swap first. These wires may well be brittle and that is often the source of the problem, if it's not the sensors. You may have to replace the harnesses just because you troubleshot them. It's worth doing, then they won't bother you for ten years.

Okay, where exactly are the plugs? In the document you linked to, it references IN-28. Do you have that section too?

edit: I can get a OBDII scanner tomorrow night! Nevermind, I found the full service pdf... I think I can find the plug

 

[lycaon_guy]

You don't need an O-scope or to worry about waveforms. Just an OBDII scanner to pull and reset codes and a DVM or test light to check circuits is all you need. Swapping the plugs side-to-side and seeing if the code changes from P0325 to P0330 should tell you if a sensor is shot. The other checks will chase down wiring problems. Try the swap first. These wires may well be brittle and that is often the source of the problem, if it's not the sensors. You may have to replace the harnesses just because you troubleshot them. It's worth doing, then they won't bother you for ten years.

School finally let up so I got a chance to loosen the timing belt cover and find the 3 prong connector and test it. It looks like my sensors are okay . Just ordered a wire harness, finger's crossed.

Thanks!

 

[Koch13351]

Or try running premium gas and see if does it still