tbenson11

okay im new to this i try my best to do my homework and figure thing out on my own but this truck has me mind blown..okay so its a 91 cabn chassis i bought a 92 motor ecu and harness and put in it. fired it up and had a knock. motor had high miles and it sounded like a rod so i pulled it back out and rebuilt it from top to nottom with all Lc parts >plastigauged all bearings checked out perfect so i put it back in fired it up and it still knocks not at an idle and u can rev past it also but around 2500 to 3 grand it has a constant knock does it going up and down in rpms...iv tried plugs wires distibutor had the head ckecked and also tried a complete different valve terain took the valve cover off and started it noothing has worked ..a couple things im in sure about is it seems to have more then one knock sensor and the knovk sensor wire has been cut to bypass the short harness for it only one is plugged in but no 52 code untill u un plug the one ..the egr has been takin off the engine and from what iv read it been done correctly...im just out of ideas and tired of throwing parts at it , one of u smart toyota guys please tell me what im doing wrong...i can get a video and post it if needed

Co_94_PU

iTrader: (-1)

Just how thorough was the rebuild.. What parts were replaced, which were reused, which were resurfaced, were the galleyways cleaned in depth..

Plastiguage doesn't ensure roundness. Ect ad nauseum blah blah..

You need to be clear about it. Is it knocking(bad clearance, lack of oil, ect), or pre-ignition

wyoming9

iTrader: (1)

First thing I will ask is what kind of oil pressure do you have ??

You did go with a new oil pump with a high mileage engine??

What work was done to the block ??New Pistons ? If not what did the bores measure ??

Sometimes piston slap sounds just like a Rod knock

When you pulled the main and Rod bearings did you find one or more that were worn hard enough to cause your knocking ??

any scoring to any of the cam journals they too can knock

blocked oil passage already caused damage

tbenson11

tbenson11

well iv spent all day looking for the problem and once again came up with a noise..i tried driving it today and having a couple other 22re vehicles I can tell its low on power
I did find a couple other things that may or may not be related
the truck runs a good bit better with the tps unplugged and doesn't seem to be pulling any vacuum to the throttle body at all
I checked the internal timing and it looks spot on but the ignition timing I cant get where I believe it should be, on one tooth I can get about 10 or 12 degrees and the next tooth nowhere close I can barely catch it with the timing light it goes at least 20 degrees retarded
with the jumper in it should cancel any sensor that would change the timing right? the tensioner chain and guides are all new could the combination of timing and bad throttle body and or tps cause a knock of some sort?
im really at a lose here iv never had so much trouble with such a simple engine in my life...anyone have any ideas at all?

Co_94_PU

iTrader: (-1)

If you do not get a vacuum reading(on the gas filter , that's the multi port thing at the rear of the intake) at idle you have a significant leak you need to find. It's causing you to run lean, a contributed factor for pre-ignition.

You need to get that distributor put in correctly, and the timing set. Yes the timing jumper should put it in base timing mode, but only if it is received the idle (idl contact closed from tps). You should double check that tps position, and its signal levels.

tbenson11

thanks for the reply I will check vacuum and I have a new throttle body and tps on the way so fingers crossed it will finally run like it should

skypilot

iTrader: (1)

To set timing on the distributor you MUST put the jumper in the right place so the ECU doesn't mess with you by adjusting the timing while you are trying to adjust it. You will not win, put the jumper in. Did you run valve lash? I use Delta re-grinds with good results.

Now fuel pressure, there is a filter on the side on the engine, how new is that? How good is the pressure regulator? Is the return port line plugged? How good is the pump?
I like AN plumbing, so much better than stock and you can get rid of that useless pulse modulator, M12x1 banjo fitting Iffin I remember.
Also please stop throwing parts at it, this is simple engine, I feel you are making it hard.

You can drop me a line too and we can talk.

tbenson11

iv finally got it timed correctly the obd port was packed with crap no letting it jump so It is now dead on 5 degrees..i have another complete engine that ran but smoked that iv been swapping parts trying to find the issue.. iv tried another tps and throttle body with no success. that valve that runs coolant through on bottom of the throttle body is new it still runs way better with the tps unplugged it barely stays running with it plugged in... I changed fuel filter on the side on the engine and 4 new injectors when I put the engine in..tested fuel pressure and it reads good .. iv ran and checked valves several time and tried a complete other valve terrain...im leaning more towards vacuum now it doesn't have many vacuum lines left but I changed them all anyway...I noticed the brakes being spongy can the brake booster be bad and cause a vacuum leak? what should the vacuum gauge read at an idle?

tbenson11

so there is no vacuum leaks it pulls 18 19 pounds at an idle... im completely out of ideas ...im my hours on hours of reading forums iv heard where having the egr gone it can cause a ping with out a resister of some sort? and both of the vacuum switches that belong on the valve cover r gone im not sure what they did but is this correct?

Co_94_PU

iTrader: (-1)

The egr temp has no effect on mixture, the fake signal (resister) just prevents the engine fault code.

It had "new" rod bearings and knocked, it has newer rod bearings and knocks. I'll ask again about the bottom end parts "kit", what was done down there? New crank shaft or was the old one micrometers for roundness? New wrist pins, connecting rods, or piston?

Exactly how are these two knock sensors mounted, and where? Is it pulling out timing when this knock occurs? Have you localized the noise with a stethoscope yet?

tbenson11

My bad I thought I already said everything I did but it was a complete rotating assembly crank rods bearing pins and pistons from LC which I heard was good stuff from this sight. I plastigauged it all trying to prevent this exact thing .. iv put all new valves in and have a valve job done same time they bored the block..there is a knock sensor 10 a lock to the oil filter and one on the same side down between the motor mount...I think It has to be a ping of some sort cuz it changes with timing change but never goes away...what I don’t enderstand is how it runs so much better with out tps plugged in.. it was a chore keeping it running long enough plugged in to get the timing set..there is nothing more frustrating then putting all the best parts and tons of money in something and it make noise and run like total ˟˟˟˟

Co_94_PU

iTrader: (-1)

Much better, more in depth.

As mentioned the platigauge doesn't ensure things are round. It is possible one of the rod landings aren't round due to stretch and or wear. It's also possible the new LCE parts have a slightly different size on a particular surface. This is the sort of thing "blue printing" shows. Bearing caps need to be torqued in place and bore gauged in several orientations, typically your machine shop will do this and tell you the measurements for each one. Similar the crank needs to be measured with a caliper..

Ok so theory out of the way. You might have one bearing that is a little looser than the others, so it's going to be a little louder than the others during "ping" (pre ignition), or they are all doing it at different times.

It sounds to me like you have maybe confused the oil pressure switch (located either below the oil filter, or behind the engine mount) with the knock sensor. The knock sensor needs to be in the central location, between the oil and fuel filters.

You might need a new sensor, they are susceptible to damage from shock like dropping off the bench. You might need to clean up wire connector.

My suggestion is to visually verify the sensors are in the correct location (pressure switch will have a hole, knock sensor will be solid). If it doesn't start acting correctly after that put a higher octane fuel in it and see if there is any change.

If that fuel change has a positive effect its a timing and fuel mixture issue and not so much leaning towards something mechanical out of spec (bearing clearances). You will need to preform a careful inspection of the tps, vafm, thier wires and connectors. Both should have clean smooth resistance curves with no flat spots or dropouts when you move them from closed to open.

There is also the inate issue with a vane air flow meter, spring fatigue, over time the spring will lose some tension. This results in it moving more (opening easily) for a given air flow. There are no published specs that I am aware of for this. If there was a published spec we could hang a weight from it and get a "calibrated" reading and not have to "throw parts at it'..

Iirc, you are mix-matching years have you cross referenced the part numbers. Does the vafm match your engine computer?

Your butt dyno is telling you there is more power with the tps unplugged because the ecu is running in "open loop", a fail safe rich condition with fixed/different timing.

Co_94_PU

iTrader: (-1)

Does it hold idle now on its own?

If you need to hold the revs it is a sign of a vacuum leak, the vafm contains the fuel pump switch and it needs a certain amount of flow or it shuts off the fuel.
Typical issues are,
cracks in the accordion pipe, which show up when the engine started to fire off and shake.
Loose clamps.
Badly seated hoses (like the idle valve under the throttle body, its a common one due to its location being harder to get to with Bear paws)

YotaRick27

Compression test?

tbenson11

parts finally came I wanted to rule out mass air meter so put a new one on and also a new knock sensor in..so its official I have changed or replaced every sensor or parts u possibly can.. internal external timing is dead on I even swapped a harness just because I was out of ideas...I put 100 octane in it the noise gets much quitter but still runs like total ass.. you pull out on the road you're lucky to see 35..it idles much better now but it u lay ur foot on the pedal it wont stay constant it surges from 1500 to 3000 just like you're turning the key on and off..sitting at an idle if u shove it straight to the floor I falls flat on its face doesn't take fuel what so ever just pops bangs backfires out the intake...had a couple shops look at it I tell them what all iv done they don't even want to mess with it.. im at the extent of my knowledge I have no clue what is wrong with this truck..ecm?? where do I begin now