1986 Toyota Pickup 22RE engine with only 60K original miles. Had all the signs including the error code that the throttle position sensor had an issue. Took the throttle body off and inspected. Lots of carbon build up so cleaned it up with carb and air intake cleaner. TPS spring was mechanically sticking and not snapping back as it should. Cleaned it and it started to snap back just fine. Tested the TPS and set it up by the book. Installed it back with a new gasket. Cleaned the cold start injector that's toward the back of the intake manifold on the same side as the TPS, the one with a fuel line and the electronic connector.

Put it all back together and tried starting. It was very hard to start but fired up eventually. Engine is shaking and knocking pretty bad. It was hesitating to start just a little bit before all this work, but nothing like this. It was not shaking or knocking before the work.

Pulled the following codes:
5 Open or shorted O2 circuit
7 Open or shorted Throttle Position Sensor circuit

Took the wire off TPS while running - idle speed changed but knocking and shaking still there. Tired starting with the TPS wire off - doesn't start.

Here is a video of the problem: https://photos.app.goo.gl/kB3gr6uVfwo1mxdF9

Please help figuring out the next steps on troubleshooting as I'm lost at this point.

 

Sounds like the timing chain may be hitting the timing cover... which means the tensioner is shot, or the plastic guides broke. Which would make it run out of time. Low miles some times isn't a good thing, unless they've been started occasionally and maintenence still kept up.

 

You can take a cut broom handle and use it to find exactly where your knock is coming from.

 

It was running great, except for a slight hesitation at startup, before I took off the throttle body, the cold start injector and the TPS to clean them. Can a bad TPS or any of my cleaning cause the engine to shake and knock like that? I ordered a new TPS since engine trouble codes point to it still.

 

Valvetrain. Pull the valvecover and check timing chain as suggested. Next compression check, possibly bent valve which would cause the poor running and the noise.

 

OK, I will pull the cover... Meanwhile, I pulled the spark plug wires one by one with the engine running. Cylinder 1, 3, 4 - RPMs dropped when pulled. Cylinder 2 - no change in RPMs. Replaced the plug on cylinder 2 - no change. Nice strong spark on cyl 2 when connected to the wire and laying on the valve cover.

 

Pulled the valve cover. Plastic guides appear to be fine on the timing chain.
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How do the lobes and rockers look?
i once had aftermarket adjusters that wore quickly, leading to excessive lash.
Another test you could try is, with both valves closed, put compressed air in the cylinder and see if it escapes into the intake or out the exhaust, in which case would indicate a bent/burnt valve.

 

Everything looks really good under the valve cover. I didn't see anything suspicious. I went ahead and adjusted the valves - a couple were too tight on the exhaust side (including cylinder 2) and one was loose on the intake. Put it all back together and it seems it's knocking less, though might just be a placebo effect. Engine still shakes and idles rough.

Since I have spark on cylinder 2 but RPMs don't change when I remove the spark wire does it mean I definitely have a dead cylinder that's not firing? If so, could I have done something while cleaning the throttle body and the TPS to cause this? Again, it ran fine before I did the cleaning so I don't know how it could have a bent valve or other major engine damage without driving or running the engine. I was thinking maybe I moved some wires around and it could have messed up the injector on cylinder 2 or something along those lines?

Also, with engine running and removing spark plug wires: Cylinder 1 and 4 - RPMs drop. Cylinder 3 - RPMs go up. Cylinder 2 - no change.

 

Well, I have ZERO compression on Cylinder 2. Other 3 are at 190 each.

All new exhaust from the manifold back was installed last week. Drove fine after that. And then I did the throttle body cleaning and now somehow I've got zero compression... How effed am I?

 

Pretty F’d. No compression means it’s going somewhere, either into the intake or out the exhaust. Do the compressed air test and see.
Either way, probably going to need a valve job.

 

do the tests for compression before pulling things apart. head gasket failure is another possibility.

 

Words to live by.

 

Did a leak down test with a compressor and the air was rushing out of the intake. I figured I'd do one more valve adjustment before tearing things apart and found that the intake valve on cylinder 2 was way out of spec. Adjusted all valves again after the engine was warm and got compression back on cylinder 2. So happy I didn't rush into tearing the engine apart! All cylinders now show this:



It starts right up, sounds great and the 2 codes have cleared.

 

Good work! That’s real healthy cylinder pressure.

 

Just wondering what would have caused the intake valve get that far out of spec?

 

No idea. This all happened after I replaced the whole exhaust system because it had holes and rusted beyond repair per muffler shop. Not sure if these two are connected though.