This problem is slowing me down. My rig won't go above 35 mph!

It's got a rebuilt 22re with 6k miles. It drove fine for a year, but now it shakes on idle, and backfires through the intake on throttle blips as well as being absolutely gutless. I've done a fair amount of troubleshooting already, but I'm at a dead end.

Here's what I've tried:

all new vacuum lines
new spark plugs and wires
new cap and rotor
new injectors

checked throttle position sensor
checked O2 sensor
checked air flow meter
checked coolant temp sensor

adjusted timing
adjusted valve lash
Fuel pressure test: good
compression test: 150, 150, 150, 135


Oh man, if anyone has any ideas, you're wiser than I.

 

Check that the timing chain has not jumped a tooth or loosened up for another reason. Who rebuilt the engine? Do you know if quality parts were used?
Check the hose between the AFM and throttle body for cracks that could be letting in unmetered air, along with anywhere else that could be causing a large vacuum leak such as the intake gaskets.

The compression numbers seem low for a rebuilt engine. Put a few drops of oil in the cylinders and check it again and see if it raises significantly. If it does, the rings are having problems, or maybe they are not seating all the way for some reason. Another test to run is pump compressed air into the cylinders, mainly #4, and see if the air comes out the intake or exhaust to make sure the valves are seating properly.

 

Hey, thanks for replying.

I did check the timing chain, and it seemed a little behind, but I don't know if it was a whole tooth behind. Engine Monster in Colorado Springs rebuilt it. I lost the damn parts sheet, so I actually don't know.

I checked all around for any leaks, and have only found little cracks in the vacuum lines, which are all replaced.

Thanks for the tips on the compression and leak down test. I was wondering why the compression was low too. I used a cheap gauge which already broke, so maybe that's why.

 

One quick way to check the timing chain is to turn the crank to TDC, then take the cap off the distributor and rotate the crankshaft backwards until the rotor in the distributor moves. Seeing how many degrees that takes will give you an idea of how loose the chain is. I have never heard of that particular engine rebuilder, but maybe someone else here will have some input. Their engines are very cheap compared to Yota1, LC Engineering, or 22RE Raceworks, which makes me suspicious that lower quality parts were used. Hopefully the compression problem was just the gauge and not your engine. Autozone or Oreilly's might loan compression testers if you want to test again. If they stand behind their work then they should take care of the engine if that is actually the problem. Let us know what you find, good luck!