99 Avensis 1.8 funnies?

Hi All,

A mate is trying to sort an Avensis, if you slowly take the revs up to about 3k it starts dropping and rasing it's revs, like a boy racer would, revving it at the lights? ;-(

He's scoped the injectors and they are definatly cutting in and out (with the drop / raise in revs).

The camshaft sensor checks out ok, as did the map and throttle position sensors.

The lamba sensor is running flat out all the time (above .9V) and he has swapped out a coil with no change in symptoms.

Anyone know where he can get access to the crankshaft sensor and/or has anyone seen this particular fault before please?

All the best ..

T i m

Reply to
T i m
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Update, he's found and scoped that now ... fine.

Reply to
T i m

If the lambda is showing a constant 0.9v, then either it's broken (unlikely as they're far more likely to fail to 0v), or the ECU isn't entering into closed loop control.

I'd start by checking the coolant temp sensor, and for any obvious leaks around the inlet manifold.

Reply to
moray

Check the intake trunking after the MAF for a split that is opening, and allowing un-metered air in...

tim..

Reply to
Tim..

Ok thanks. An update on that is that he took the lambda sensor out, cleaned it, gave it a tap and it seems to be behaving itself now. However is has made no difference to the main fault.

That was his next thought and was considering sending it away for testing.

He says he will check that (so thanks) but feels it may be ok as he thinks it also runs the in car temp gauge (and that's ok)?

He's checked that but even with one of the big inlet pipes off it does the same thing (suggesting it would have to be a pretty big leak)?

He will do some more checks and report back (thanks).

All the best ..

T i m

Reply to
T i m

Thanks for that Tim but he suggests this model is pre the MAF system?

All the best ..

T i m

Reply to
T i m

I may be wrong, but I am pretty sure Toyota never used a MAP system, so therefore you will find a hot wire or hot film mass air flow sensor on the airbox.

Tim..

Reply to
Tim..

Hmmm, well, my mate seems pretty convinced it isn't a MAF system and if it helps, I watched him use a hand vacuum pump to progressively put a vacuum on a doodad up on the bulkhead and watch it's output go from

1 to 4 volts or so ... ?

There are some wires going into the airbox but we believe that is the inlet air temperature sensor?

I've just looked with him and there are no other wies between there and the throttle position sensor / idle control valve?

All the best ..

T i m

p.s. He has just shown me a loose MAF sensor and I can't see anything like that in there either. :-(

Reply to
T i m

In which case, I stand corrected and it must be a MAP system, given your mate was miti-vacc-ing the map sensor!

You would be best to post *all* info over at

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where the expert guys will be able to shed some of their knowledge. Tim.

Reply to
Tim..

Using the IR thermometer the temp of the engine was 40 deg C and at that temp the temp sensor was ~2K ohms (within spec I believe).

All the best ..

T i m

Reply to
T i m

;-)

Oh, ok Tim, who are these folk please (I have looked at the link and got through to a Forum etc).

All the best ..

T i m

Reply to
T i m

T i m gurgled happily, sounding much like they were saying:

What do you mean by "the temp of the engine"? What were you measuring? The coolant temp sensor is dipped into the water jacket of the head and is measuring the temperature of the water as it passes around the head. It's very likely different elsewhere in the engine, and sure as hell different to the outside of the head.

Reply to
Adrian

Fair enough, my point was with a warm engine [1], the resistance of the temp sensor was within max / min range and looked 'good' on the internal gauge (so wasn't actually faulty).

So, any idea what the actual fault is please Adrian?

All the best ..

T i m

[1] The general mass of the block rather than engine mount or some other irrelevant place. ;-)
Reply to
T i m

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