Here's the deal. I just installed a new longblock on my 1988 3.0L. Set the ign timing and drove it for a week. Rechecked the timing and noted that it kinda varies at idle. I adj the TPS (thanks to some helpful advice from this board!) and that really helped - much steadier idle and timing stays dead on at 10* BTDC. But the check engine light came on while I was test driving it just before the TPS adj. now there's a code 52 that wont go away. I searched this board and saw many people needed new knock sensors and/or wires. But my code came up as soon as I messed with the timing, and I could see bad timing causing a knock. I don't want to tear into my new motor and spend the time/effort/money to replace that sensor if thats not the problem. :pat: Or am I just in denial? Does anybody have any other ideas before I waste a weekend?

 

Greetings,
Ah yes, the old knock sensor! Before you go tearing into the engine as a last resort try this: Make sure that when you adjusted your timing that you had the jumper wire in place("te & E1") and re-check your timing, make sure your TPS is adjusted properly,also a lower grade fuel will cause this code i.e. 87 octane. Try all this and clear the code if it comes back as a 52, start wrenching!! They're a PITA to replace no kidding, but there are your options in case you are in denial and want to try them before you start wrenching!

Good Luck!

 

thanks for the input. I guess i just had to hear it. I know the jumper wire was in place - I made sure the light was flashing. I feel that I got the TPS right (it seems to have really helped the idle and corrected the wandering ign timing issue I had before) although I struggled a bit adj. it - the directions I got had varying specs and kinda conflicted with other directions I saw online, but I took my time and marked the TPS before I moved it and it ended up being real close.
Also, I never ran anything other than 87 octane in the 100,000 miles I put on this thing, but that was the original 3.0L. I can't imagine this rebuilt one (by a reputable source from what I understand) is that much different. Unless they shaved down the heads a bunch and I have higher compression! I also drove it almost a week before the light came on, so the fuel octane seems less likely to be the issue. Thanks, though, I hadn't thought of that and I did ask for other ideas!
Anyway, next week I'll dig into it and hope for the best!!

 

It could just be the knock sensor wire. It costs a whopping $11, and gets frayed after time. If the rebuild company didn't replace it, that could be your only problem. The real biatch is, it will cost you $100 in intake plenum / manifold gaskets to replace the $11 wire.

 

HIJACK ON> Have any of you braved just changing the wire and not the sensor. I've heard that the actuall sensor rarely ever go's bad, but I hate to change my buddys, and spend his money and my time, and not change the sensor to. HIJACK OFF>

 

That was my fear, too, but when I got down to the sensor & wire, it was quite obvious that it was only the wire. It was really chewed up. The outer insulation was completely gone in a few places. The most frustrating part of the whole ordeal is that you're going to pay $100+/- just for the gaskets for the parts you have to remove to get to the $11 wire (as previously bitched about)!

 

When I got my Runner I drove it down 400 miles with a bad sensor...oh yes it was alot of fun...After I found out what code 52 was I called around looking for one...dealer told me you have to buy both the pigtail and the sensor as they were one package...Short version is if you haven't had the head gasket recall done I'd suggest doing it...the knock sensor has to be replaced everytime you go past the plenum according to the manual but it usually is the wire that's gone bad...My new sensor was free.