buck bridges

Hey All,

1995 3.0 ATM 151k miles

Picked up this truck a couple of months ago, replaced the thermostat as a hopeful fix for my lack of O/D function and to my surprise, there was no thermostat in my truck. Installed an OE thermostat and filled the coolant back up.

I got about 20 yards from my house and the CEL flashes on. Check the codes and I get 5-2 (Knock Sensor Fault) and I have no idea how that happens. Take it to a shop to diagnose and the report says, "Knock Sensor found along with excessive resistance in knock sensor sub harness" Quoted $450 for labor, plus parts.

When its started and runs the first few miles, it runs like a CHAMP. Then the moment the CEL comes on, it turns into a different truck. Sluggish and no power. Turn it off and let it cool down, drive it again and the same thing, a few miles of running strong then CEL crashes the party, truck goes south.

Here is a listen to the engine.


I've always had POOR MPG which might have been attributed to an EGR problem, (replaced faulty EGR temp sensor) but this is the worst.

A couple of possible mistakes on my part?

1) Added a bottle of Seafoam in the same tank that I'm currently using. Tank was full but at time of CEL, it was 1/4 full. Could Seafoam have caused a carbon breakup that caused the problem?

2) While replacing thermostat/housing, I took off the nuts directly above and below thermostat on the water pump. Tried to take that part off along with the housing to clean off corrosion but it wouldn't budge. I later thought the timing alignment might have been messed up, causing the knock sensor CEL?

I'm using 87 octane fuel from the same place as my other vehicles so I don't think it was bad gas. Any ideas or suggestions?

scope103

In "Yotatech-speak," the pigtail.

Code 52 has nothing to do with carbon breakup or timing or Octane. Nothing. To be clear, it has nothing to do with knocking! Code 52 says "Hey, I haven't heard from the knock sensor in a while. I better tell that driver to do something!" And, to save the engine in case it IS knocking but the ECU can't tell, it dramatically retards the timing. (Meaning: sluggish, no power, bad mileage)

So you need to replace the pigtail. (The knock sensor itself is quite rugged, and probably okay.) To do that, you need remove the upper (plenum) and lower intake manifold. $450 is about right, and the parts won't add up to much.

Good luck!

buck bridges

Thank you scope. I just needed a break down and you broke it down! The bummer is, I just had the valve cover gaskets replaced. Grrrrr. Would have been a good time to get this fix done too.

I'd like to save a few bucks and just replace the pigtail but you know Murphy's law will kick in if I do and the sensor will go out in a few months. I'll update the progress soon.

Thanks again for taking the time to explain the error code.

buck bridges

Spoke to a couple of toyota mechanics that said the knock sensor should be replaced as well, just as a precaution. It would be a bummer to have the sensor go bad in a couple of months. On the other hand, the truck is 19 years old and who knows how long until the HG blow. Currently at 151k miles. Trying to justify the cost. Also, OE parts all the way or can I slide with an aftermarket?

scope103

OEM $160: http://www.toyotapartsoverstock.com/...archTerm=knock
Aftermarket $110-$140: http://www.rockauto.com/
It's always "best" to just replace everything. Or is it? As you point out, no matter how many brand-new parts you put in, the rest of the truck is 19 years old. You just have to be smart about it.

buck bridges

I appreciate your wisdom scope103... Guess I'll go with the OEM sensor just to be safe and plan for the long haul, unless of course the truck has plans for an early retirement. I will post an update when the work is done. Thanks again man

buck bridges

Found a reasonable price, (cough) to get the sensor and pigtail replaced. Found a few threads on how to do the job yourself but it might just be a bit too much for me.

Quick question, since we will have the plenum opened up, is there any other part that should be replaced for good measure?

okamikai

Hi there, take the opportunity to change all the gaskets related to the intake, I was told to do this, but not sure how will this be any improvement/demeanor, I was told to use shelac adhesive on the gaskets, I have used the product before, bur never for this, anyway looking forward to see how this job goes.