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Bought a 93 hardbody, engine knock.


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Bought a 93 Hardbody 4x4 with KA24E TBI motor.


It has 139k miles. PO had for a week and head gasket blew. Had shop XYZ replace head gasket, rebuild head, and timing chain. Said it ran fine for a day, then the rattling noise happened, which he thought was timing chain, but it's most certainly detonation.


This morning, probed the computer, found Air Intake Temperature Sensor code. Went to find it, it was missing! So got new one, replaced, and the ECU now says 55 which means everything is normal.


Did this solve the problem? Of course not. Checked timing. 30 degrees static. Yeah, not good. Ran it down to 10 degrees per spec. Changed F***ing autolite plugs someone put in to NGKs.


Still detonation. Ran it to 0 degrees, ran slow, ALMOST got rid of detonation.


HERE'S THE WAY IT HAPPENS: It starts up, and knocks like an SOB on cold startup, clearing off in about 3-5 seconds. Then idles normally. It will free-rev normally if you push the throttle slow, up until about 2500 rpm. If you give it a hard whack of throttle, there's detonation. After putting in a full tank of 92 octane, driving to the gas station carefully at 0 degrees timing, knock is still there, though it doesn't happen accelerating slowly, but right at where you even out (like 1/8 throttle, just maintaining speed) it knocks, but straight decel or accel it does not unless romped on. It also begins to detonate if you get to high up in the revs. Haven't had it past 3500 yet.


So that's it, any ideas? I'm leaning towards fuel or something at this point being the ECU's happy, though of course we know that doesn't mean anything. Plugs looked normal even being shitty autolites when I took them out.

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question. where did you check the comp at? i need to cehck the one in my pathfinder but i cant find a diag port.



as for your problem, might be that the cam timing is off. i know its already been done but it may be off enough that it is acting weird. hows the fuel filter? could be clogged enough that its not getting enough fuel at more than 12 throttle.

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You know, I'll check the fuel filter. Still don't think it's that, but couldn't hurt. The ECU is under the passenger's seat. Remove the seat, unbolt it so you can see the LEDs, and follow the Haynes manual instructions for figuring out which mode it's in.


Easy way is turn ign to on, turn dial fully clockwise, wait for lights to blink 3 times, then turn back full counter clockwise, wait for red and green leds to blink, count the blinks, then match with the code in the Haynes manual.

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The ECU uses crank angle sensor, RPMs, knock sensor and throttle position sensor input to calculate the ignition advance. Something is telling it to advance too much. Throttle position sensor adjusted incorrectly? maybe?

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Does the KA single cam truck motor use a crank sensor? I didn't think it did, have to check. I am wondering about the TPS. Timing light is dead on, no erraticness.


Bought a boroscope from work today. 36" long 4mm wide with light. FREAKIN' AWESOME. They're on sale at NAPA right now, hint hint! :D (The 18" ones are cheaper.) Figured that will get me down the timing case without removal, which will make verification of correct number of links possible without a mess and lots of work. Plus it's just cool, and what if your buddy needs a colonoscopy?


Anyone know the values of the TPS on a 93 tbi KA? I'm going to see if it's in my Haynes manual, think it might be, can't remember.

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Does the KA single cam truck motor use a crank sensor? I didn't think it did, have to check. I am wondering about the TPS. Timing light is dead on, no erraticness.


Anyone know the values of the TPS on a 93 tbi KA? I'm going to see if it's in my Haynes manual, think it might be, can't remember.



You should be able to verify the timing marks without counting the links.


When the crank pulley is set to zero on the timing mark, check the position of the cam marks, and is the distributor drive spindle in the right position?

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You know, I know the position of the drive spindle in the L, but I have no idea on the KA. I'd guess it's similar. And really, I just needed an excuse to buy a new tool. :D


It does have a crank angle sensor it seems, it's just in the distributor, not at the crank like on the Miata I had.


Changed the wires, cap, and rotor this morning, no change. Beginning to think about CAS and TPS, though TPS does have a white mark from previous reinstall, and it is lined up.


I'd think if the crank angle sensor was going out, that would register on the computer, but maybe not?

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The CAS is similar to the L and Z dizzy drive spindles and is also splined to make it even more accurate.


Drive spindle:




CAS bottom:



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The splined end at the distributor will make it more accurate, but I was wondering if the spindle was installed correctly into the oil pump? One tooth off at the pump and you have greatly affected your ignition timing and the CAS readings to the computer. A bad reading to the CAS will cause the computer to then try to compensate for the timing issue.


This a freebie to be able to verify the timing/dizzy alignment before you spend money on parts.

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Thanks guys for all the good suggestions, been working too much to work on the truck, but may do an hour tonight. I pulled some pictures off the Mitchell's application at NAPA, it looks EXACTLY like the L as far as position and everything, minus the splined portion of the dist. so that's good. I'll line it up tonight if I have a chance and see if that is the problem.


Seems to me the CAS being off a tooth would certainly cause the problem, and it's easy to do, but still not sure why it would have run correctly for a day then gone shitty, but maybe the guy I bought it from just thought it ran correctly, or maybe the shop did something to the ECU? I dunno. Anyway, making sure everything is in order is what I should have done in the first place, but I've only spent a day on it and did everything else it was going to need anyway. I'll keep you all posted.

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So I'm looking at it last night, the drive spindle does appear to be correct. It doesn't look quite as cockeyed as the L, but maybe it's because my motor sits back a little in the D21 bay, vs. straight in the 510. Either way, a tooth to either side moves it quite a bit. The oil pump says hecho en mexico, so that's going to be replaced with a Japanese unit. It's also rather hard to push into the timing cover. Not too bad, but not as free as I'd like it.


Also, the distributor needs a bit of force to seat all the way, but now as I'm typing, maybe that's the o-ring seal...hmm.


Anyway, chain and everything looks okay. I'll check it out more tonight and in a day when I'm off. Assuming all mechanical timing components are okay, any other ideas? I'm thinking TPS, and O2 sensor is just a 1 wire, it should just run pig rich if anything were to fail in it.

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Denial is a powerful thing. Leaning towards a rod knock. Not a bad one, but quite possibly a spun bearing that just didn't sound that loud. I've spun them before but they made lots more noise. :( Guess it gives me an excuse to rebuild the bottom end. At least the top end has been done already.

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So here's something interesting: ARP doesn't seem to have head stud kits or rod bolts for KA series motors. So not having built one yet, are the stock fasteners plenty strong? I know the L series rod bolts suck, which is why I used ARP to begin with. Considering the relative newness of the KA vs L series, one would think they engineered better head bolts/rod bolts than what was stock on L series long ago?


Anyone have any problem with stock Nissan head/rod bolts on the KA single cams? My next thought is to go order some from Jaremko Nissan. I figure the head bolts should be okay, but the rod bolts I'd like to replace unless you guys have other info that they're fine to reuse?

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Brought my Datsun guru/fabricator over tonight to listen to the truck. Yup, rod knock. So now to figure out if I want to rebuild bottom end and transmission or just yank motor....leaning towards doing both seeing as it's 139k. My luck the motor will be all fresh and I'll toast a trans bearing. Gotta see how much Chuck wants to refresh a unit tranny/tcase. Probably more than I want to spend right now, we'll see.


The 720 4x4 is up on craigslist now, in case anyone's interested.


At least Gracie 2 looks beastly huh? ;) A pretty yard ornament, soon to be a pretty garage ornament.





Edited by HRH
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Yes indeedy, and rest assured, even though I am selling the 720 and probably will be selling the 620 also, I will still have the 510. What's more, I will have the only Datsun hardbody I know of! I saved a few parts off the 720 I cut up. :D










Going to graft the tailgate no problem, haven't figured out badging for the hood. And need to change the steering wheel cover too, think a 720 Datsun steering wheel cover might fit over, not sure. Either way it's loosing the Nissan badging, exterior-wise. Though if I rebuild the motor, I could have Joe weld in Datsun on the valve cover from that spare 69 valve cover I have. Hmmmm.


Now I am going to go drown my rod-knock sorrows in some doggie loving, on the couch, watching Mad Max to regain focus.

Edited by HRH
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