'91 SR5 V-6 running poorly

[dhjenkins]

A friend of mine bought this truck from 3 states away sight unseen, and it ran like crap, so he brought it to me with a knock-sensor fault code. I replaced that, and while I was in there, re-shimmed the lifters back to specs, replaced the timing belt, then did a tune-up, vacuum leak check, and even cussed at it for a few minutes. It runs better, but the milage is still at about 10-12 mpg.

According to the guy that he bought it from, it has a reman'ed block & heads. The heads I'll buy, but the block looks original, so I have 2 questions.

1, Is the engine code stamped on the side of the block specific to HIS vehicle?

2, Is there something else that could be causing this besides poor compression? I'm set to test that next weekend when he brings it back (he needs it for work), but in the mean time I wanted to get a little more info; I don't usually work on Toyotas.

TIA

[alltrac165]

1) No
2) Looks like you got most the bases covered. How's the power? Are you sure the valve timing is correct? How about ignition timing? If everything you did is good, and it's not compression, then try the O2 sensor and wiring, or check the cat, or check for vacuum leaks. Nothing really unusual about this particular engine other than it had some problems with head gaskets for a few years.

[dhjenkins]

The power isn't very good at all - and it doesn't sound good very good either, like the timing is way off; but it's set at 10 deg. BTDC which is supposed to be dead on. Now that I think about it, is it possible the camshafts were switched when they were rebuilding the motor? or are the L & R cams the same grind or impossible to switch? I really have no faith in whoever rebuilt this motor.

I'll go ahead and test the 02 - I figured it would trigger an error code if it were bad, but looking over the code list, I guess it only considers it a fault when it's an open or short...

Thanks, I'll post back with any results...

[dhjenkins]

PS - what's the diameter of the exhaust pipes (stock) supposed to be? I figured what he has is OEM, because they look older than dirt, but they're only about 1-1/2", which seems tiny compared to my '93 V-6 (non-toy) SUV, which has stock 2-1/4" pipe.

Thanks again...

[Smoke]

Did you have the box terminals jumped , TE1 and E1, when timing was checked?? Not sure on the exact size of pipe, 1 1/2 0r 1 3/4 but they are small!!

[dhjenkins]

Yup, got 'em jumpered. I went ahead and set it to 5 deg, and it actually runs a bit better, after I replaced the "already replaced" cap & rotor - I should have known it hadn't been done. Checked the cat flow, not too bad, muffler has several leaks, so he exhaust leak I thought was in the engine compartment could just be from harmonics. Gonna put a 'summit special' on it & new pipes from the cat rearward.

The engine sounds alot better, but still doesn't have much power (I don't know how strong one is running right, though) and alot of injector noise. Seems like it's working harder than it needs to, so maybe the tranny is slipping...That'll have to be someone else's problem - I don't do automatics.

[Smoke]

The 3.0 is no power house but it is a reliable engine for DD. It lacks the ability to breathe freely due to the faulty exhaust cross over design air the air intake system!! Headers and the intake mod is a must on these engines to made any kind of decent horse power.

[dhjenkins]

I was starting to think that might be the case, because it's got a glass-smooth idle and besides the exhaust leak, sounds fine - no pops, misses, stuttering or anything to indicate that it isn't running well - just the lack of performance...

Thanks for the help...