Casey Peterson

Hoping to get some suggestions on my 4Runner I just got it back from the shop for a pretty serious valve cover leak and crank seal leak and when I drove it out of there it was running like garbage. Would really struggle to run smoothly under 2500 rpm and wouldn't climb hills hardly at all even in first gear.

So at the shop they said they set it back to factory ignition timing, I guess since they had it all apart. To eliminate variables I had them do cap/rotor plugs. The shop then advanced the timing 4 degrees, which I would say helped wake the engine up quite a bit, it does decently well in town, but driving out in the freeway I can't climb even the slightest inclines without dropping into 3rd gear and really screaming the engine, this was not how my truck ran prior. I have driven it to work and back for years and have a good idea of what it can do on certain hills etc and it is seriously lacking torque between 2000 and 3000 rpm.

Is this a consequence of timing adjustment? Why does it run so ˟˟˟˟ty at the factory setting? I am kind if stumped and my shop tech is as well. Any advice is appreciated.

thook

but, it ran fine before taking it to the shop? how does it idle?

Casey Peterson

It idles rough at like 500rpm, seems like it is always about to die, shakes the truck. It has done this for a long time though, the power loss is a brand new problem.

It is strange though because it seems to rev in neutral pretty smoothly. I was convinced it was misfiring but now I don't know what to think.

scope103

It sures sounds like ignition timing.

I don't want to get you chasing wild geese, but some have found that the annular rubber ring in the harmonic balancer has failed, and the first sign is the outer ring (with the timing mark) shifts on the inner ring (attached to the crank). If yours shifted only, say, 10°, then if you carefully set the timing, it will be OFF by 10°.

I've advised using a soda straw or chopstick in the #1 spark plug hole to feel when the piston is at TDC. If your timing mark doesn't line up with zero, you've got a problem. You COULD just try playing with the timing ("by ear") until you find the sweet spot, but if you have a failing harmonic balancer you probably want to replace it. It's only going to get worse.

thook

does engine temperature seem to have any effect on how it runs? eg...better cold, worse when hot, etc

might also test the distributor at the pick up coil connectiong

Casey Peterson

I haven't experienced any difference in performance whether it's hot or cold.

Casey Peterson

Is it possible to screw up the timing when you install a new timing belt? They had to put a new belt on there when the seal failed because everything got covered in oil. I am sort of guessing they are having to screw with the ignition timing now to try and compensate because the valve/cylinder timing is now out of harmony, but I am not an expert on how exactly that is supposed to work. Thoughts?

thook

uh...yeah. the "timing" belt has every thing to do with mechanical and, consequently, ignition timing. if the mechanics pooched the installation, you'll never get the ignition timing set correctly.

how mechanically inclined are you? perhaps take it back even and request they double check the work? if they're obstinate about it, go somewhere else or have look yourself. pretty sure you can pull the front timing cover back without having to remove a lot of stuff just to see if both cams are lined up on the rear timing cover marks while the crankshaft is at 0 degrees. that'll be verifying mechanical or cam/crank timing. and, make sure the rotor arm is pointing at 11 o'clock, as well.

it's a common mistake to get one or both cams off a tooth and then be unable to get the ignition timing to set correctly. more so with novices, though. but, whatever's going on, it certainly sounds like it's their error since it didn't run that way before going in. of course the idle issue would be caused by something else since it was running that way beforehand. however, whatever's creating the idle issue could be exacerbating the power loss.

anyhow, if you've got a hunch of a mechanical timing error, then check it out. sounds plausible to me

Casey Peterson

Great advice, seems like the most plausible explanation, especially since once I suggested they start doing fuel pressure/vacuum/compression tests they were pretty reluctant.

thook

well, running those tests are likely unnecessary since, again, the problem only started after they fiddle with the timing assembly.

scope103

Actually, it's easy to set the ignition timing even if the valve timing is messed up. Your timing light will correctly show that the #1 plug is firing at 10° BTDC (which is determined by the crank position), even if the cam isn't in the right place. But you're on the right track; if the belt was put on with the left cam in the wrong place, then the distributor (which is geared to the left cam) will follow. You can reset to 10° BTDC, and the ignition timing will be correct, but the valve timing won't be.

But I don't think you can take your truck back and say "I don't like the way it runs. Some guy on the internet says you messed up the cam. I want you to do it over." I don't see a lot of evidence in support of this theory, but it isn't TOO hard to check yourself. I'm pretty sure you need to remove the upper water outlet fitting to partially remove the upper timing cover, but after that it's a piece of cake. You don't need to pull the cover clear; just enough to see the tops of the cam sprockets. Don't forget that the cam sprockets turn 1/2 as fast as the crank. If you don't see any marks at TDC, give the crank another full turn to rotate the cam sprockets 180°.

Another possibility occurs to me; the shop may have forgotten to put in the jumper (TE1 to E1) when setting the timing. Depending on temperature and other factors, that could easily lead them to setting it 4 or more degrees off. It's unlikely a real shop made a mistake like that, but that's very easy to check. You just need a $30 timing light (which you should have anyway).

thook

aw now...don't go misrepresenting was i said. i said plausible. plenty of threads discussing cams being off and unable to get the motor running right. and, okay...you can technically set the IG timing. still..is it running right?

and, hell...i'd take it back. if it's running worse than before, it's not a matter of liking. not like it's a paint job or something