The xB started hesitating, badly. Yet in neutral it revs/idles with no issue. Where do I start?

I was heading to the Humane Society this morning to photograph new dogs/cats, and it started hesitating under load.  Not badly but very noticeable.  It's only 3-4 miles so I didn't think too much of it, since I was almost there.

Coming home, I barely made it in the right lane with the hazards on.  It started hesitating BAD, barely moving the car.  But if it's in neutral or clutch in, it revs all the way to redline with no weirdness, no noises, no problems.  Sitting at a light, it idles beautifully.  But start driving and I had to keep slipping the clutch and shifting up/down to try to get some 30ish mph to make it home.

I would think plugs, clogged injectors, etc.  But wouldn't that be ALL the time?

EGR? 

I would first suspect bad gas.  If that is ruled out I would look at the output of the TPS and MAF.

Could be lots of things.

Do you have a way to monitor fuel pressure? Low pressure will bog it under load but allow idle and free rev.

Check the intake tract.  For all you know a mouse decided to move into the air filter last night and is restricting flow.

How is the exhaust?  Any recent damage?  I recently fixed a low power complaint caused by a tail pipe pinched half closed.  Damaged cats can cause similar problems.  

Was this a sudden problem or has it been developing over a couple days?

In reply to logdog :

Dammit, I didn't mention the exhaust pipe did break after the cat over the winter and I hose clamped it in place to a chassis brace so it didn't bang around. Had planned to repair this spring.

Guess I'm looking underneath when it finally stops raining.

Jerry said:

In reply to logdog :

Guess I'm looking underneath when it finally stops raining.

All you need is a scuba mask!

I had a problem like this that was fuel (pressure) related — dying fuel pump in my e30 made it feel like I would run up against a lowered rev limit, but would rev freely without load.

In reply to DocV :

Pretty much what happened.  So I'll check the (broken) exhaust tomorrow and if that's not it I'm guessing fuel pump.  (I'll look at obvious stuff like air filter, air box, ... as well)  The sun is supposed to come out finally, I think it's rained two weeks straight.  I don't miss living near the OH river.

Does it have spark plug wires?  Misfiring under load, especially when it's wet out, sounds like a classic case of bad plug wires. When the throttle opens, the density in the cylinders goes up, and the resistance across the plug gap goes up *a lot*. If the wires are old, the insulation can't hold in the current, so it cross fires, or the current just grounds through the engine. 

My first guess is catalytic converter.

Toyota ignitions and fuel systems are pretty bulletproof.  Not to say they can't fail, but it wouldn't be the first thing I look for.

The catalyst can break and the honeycomb goes sideways.  In neutral it revs easily because there is enough airflow to support it, but under load the volume of gasses you're trying to move through make a mess of things.

One way to test it is to remove the upstream O2 and see if it works a little better.  That is best done cold so you are in open loop operation.

My wife's xB acted up a couple of years ago. It was hesitating  and the solution was a new CAS (I think). I'll see if she kept the bill to see for sure.  

Edit: It was the VVT gear actuator.

Codes?

When I've had that problem it was air metering related.  MAP or MAF sensors being bad or air getting around them.

Hehe so my internet car problem diagnosis went as well as expected...  And no CEL's.

xB1 or xB2?

Sounds like a clogged CAT.

In reply to malibuguy :

Jerry said:

Hehe so my internet car problem diagnosis went as well as expected...  And no CEL's.

No CEL doesn't necessarily mean no fault codes. Have you had it scanned? It would be unusual for something this severe to not trigger any kind of fault.

logdog said:

Could be lots of things.

Do you have a way to monitor fuel pressure? Low pressure will bog it under load but allow idle and free rev.

Check the intake tract.  For all you know a mouse decided to move into the air filter last night and is restricting flow.

How is the exhaust?  Any recent damage?  I recently fixed a low power complaint caused by a tail pipe pinched half closed.  Damaged cats can cause similar problems.  

Was this a sudden problem or has it been developing over a couple days?

i was going to suggest most of these things. I've experience similar problems in 2 different vehicles. Both happened suddenly one day with lead up. One car had a clogged fuel filter, the other had a bad cat. Neither gave a CEL (although the one with the bad fuel filter was OBD1 so it was a little dumber).

Dont leave us hanging.  What did you find?

logdog said:

Dont leave us hanging.  What did you find?

Hehehe well...  Took it to my local place, SCCA guy.  He drove it home and back two nights/morning, no issues.  highway, local, nothing.  Finally at lunch the 3rd day when we were ready to call it, it happened to him.  Same thing, thought a Camaro behind him was going to run him over.

Without a real history we went with plugs, dirty air filter replaced, I said wires if they look even possibly suspect but he didn't so they must have looked ok.  No CEL's but he cleared the computer then ran a tool after it happened and got two errors both related to the front O2 sensor, one basically said it was dead.  So we replaced that as well.

I have only driven it a little since, some local, to work on the highway and back once last week.  It got nice early in the week so I drove the Abarth while I could.  Then the WRX later in crap weather.  And Tuesday I went to drive it but I had a flat and couldn't get the stupid metal valve stem cap off.  Wednesday SCCA meeting and busy last night, today I borrowed a Dremel tool to cut the damn thing off hopefully in the next hour.

'03-04?

I found, though painful experience, that '03-04 Toyotas with the 1ZZ engine have very problematic PCMs.

The first thing you learn working on cars is that it is never the computer.  So having a computer problem is kind of a mind breaker.

I fought a certain Matrix that ate a PCM.  We had to get FIVE different PCMs from the only rebuilder who would touch them before we got one that actually worked.  The fact that our normal suppliers wouldn't touch them should have been a hit upside the head with a clue-by-four, but we don't get to choose what comes in the door....

In reply to Knurled. :

What makes me sad is my first xB had zero issues.  Sold it at about 175k miles and replaced an alternator that warned me for a week with increasing noise that "hey dummy, you need to do something about this".  I don't have a history on this one before Oct 16 when I bought it but it must not have been a good one (it's an '04).

My ex wife's 05 xB just yesterday had its first problem at 189k.  The dash went wonky and all the gauges read full for about 15 minutes.

Both my first gen xB and my Dad's each had a coil fail and give very similar indications to the OP. In my case there was nothing for codes but in my Dad's it popped a fault code.