(Also posted on another forum--I'm too lazy to retype!)
Hi guys,
I recently went through a timing belt/water pump change and valve adjustment on my '94 4Runner with the 3vze. The truck had been dripping coolant after shutoff, about a cup or so each time. Sadly, it's still dripping coolant...but that's not the reason for my post.
I CAN'T GET THE DARN THING TIMED. My idle is WAY off--250-500 RPM, and it'll stall if you leave it alone. At cold startup it idles at around 1200 RPM, which I'm happy with. Also, give it some gas and it revs right up--in fact, it's driveable as long as you pop it into neutral at red lights and give it just a touch of throttle. Having said that, it's idling incredibly rich, almost to the point that the fumes burn my eyes.
Here's what I'm seeing:
- Unstable idle, will stall
- Jumping TE1 and E1 (or whichever the diagnostic ports are, I can't remember right now) has no effect on idle speed
- No codes
- Timing light jumps between 10 and 20 (? About 2 inches "up" from the 10 degree mark on the crank pulley.
- Persistent miss at idle and part throttle
Here's what I've done over the past month-plus:
- Water pump and thermostat.
- New timing belt--assembled everything, rotated assembly with breaker bar on crank bolt through two complete turns and all marks matched up
- Valve adjustment. I couldn't get the SST to work, so I wound up pulling the cams. That made a tough job MUCH easier. With the cams out, I cleaned everything I could see to clean. New valve shims adjusted to be on the loose end of spec (.013) for the exhaust, and right in the middle of spec (.009, IIRC) for intake. Unfortunately, this step required that I remove the distributor.
- All manifold vacuum lines replaced with new tubing
- Throttle body and intake plenum cleaned. I did not remove/clean the IAC.
- VAFM replaced with a junkyard unit--original failed FSM DVM tests (never threw a code)
- Replacement TPS switch--original failed FSM DVM tests (but never threw a code)
- Checked intake air tube for cracks/leaks, none found
- Plugs cleaned and re-gapped. Plug wires look to be fine.
- Verified spark to all cylinders by pulling plug wire at distributor cap just enough to create a gap for a spark to jump across (only got shocked once!). The idle dropped a little bit each time I pulled a plug wire.
- Verified proper EGR function by pulling vacuum on EGR at idle--idle sagged and the engine nearly stalled
- Ohm'd fuel injectors, all of which were replaced about four years ago. They all checked out, right in the middle of spec (can't recall the reading, sorry)
- Ohm'd ECT sensor without engine running. Reading was right in between the 68 degree and 100-whatever degree spec, so I called it good.
I've given this thing my weekends for the past two months, and since it was due for a safety inspection I dropped it off at my mechanic's and asked him to check my work at the same time. He couldn't find anything wrong, but also couldn't track down the cause of the miss. He said he verified that the TPS was adjusted properly, but from what I've read a faulty or improperly adjusted TPS will show up as no change in RPM when test ports are jumped (if that makes sense). If I unplug the TPS, the idle RPM goes up.
Just as an aside, the engine has 183,xxx miles on it, and the HG recall was performed around 110k (previous owner). I have no evidence of HG leaks--no bubbles in coolant, not using coolant (besides what winds up on the ground after I shut off), the oil isn't milky. I did the "dollar bill" test at the tailpipe for a burnt valve, and it passed. I'm still going to perform a compression test, and I guess I need to re-check the TPS sensor. Any other suggestions?
Linear Mode
