Exhaust Emmissions And Fumes 1998 Avensis Lean Burn

[bluetoy]

HI Guys,

Need your help badly.

2 probs might be related.

1998 Avensis1.8 fe7 eng: Went for mot failed badly on the 3 emmissions test. carrird out the usual (fuel cleaner, oil additive and oil change with filter, redex etc) replaced coolant temp sensor and cleaned all breather hoses. Just scraped through mot. Now 3000mls later getting slight hesitaion on acceleration and what appears to be a rich mixture/ exh fumes entering car when cruising and opening drivers or passengers window although there is no smell when heater set to incoming circulation of air from outside. Appears exhaust sealed correctly. Cat has been replaced twice in last 5 years although lean burn sensor hasnt. oil consumption normal for a 207k engine and not excessive. fuel consumption hasnt changed still good at 43+mpg. Tail pipe slightly dirty/black. Staring 1st time, even when cold revs 1500rpm drops to 750 rpm as normal.

poss cat blockage or sensors??? How do I determine? Has anyone had this prob b4? Read somewhere plugs or leads may be failing although there is no misfire

Assistance and advice most welcome

[Konrad C]

I would make sure the HT leads are properly connected to the plugs and see how the car runs. The leads tend to breakdown when hot. If that trick does not work, then it is all change with the leads and plugs.

The HT leads work twice as hard in the Avensis compared to most other cars, because they fire twice as much. They fire a second wasted spark during the exhaust cycle.

When changing the plugs try and get the Denso versions. I went to EuroCarparts as they were cheaper than Toyota. You have to order as they may not stock, but the saving is worth it. Get the leads anywhere but the quality counts. I bought my leads from the same source as the plugs.

The misfire is a kind of hiccup when trying to accelerate on a warmed up engine. Otherwise the car runs smoothly.

Any codes from the EML? Try to jumper the Diagnostic socket pins 4 and 13 to see if anything is stored. two flashes then one will be the sensor.

See how it goes.

[bluetoy]

there appears to be no management light on car. Garage that did mot put diag equipment on car but no faults stored on ecu. There is no misfire as such... more a flat spot .on acceleeration but does not appear all the time. the most worrying thing is I cant explain the fumes in car. Garage says reading mostly due to unburnt fuel. So as you suggest it may be down to plugs / leads failing

[Konrad C]

I am suggesting the HT leads first - check that they have a decent connection with the spark plugs first by pulling the leads off, then pushing the centre cable about a eight of an inch, then reconnecing the leads to the spark plug by pushing outer cable home with a firm click. Keep pushing the outer part of the lead until it is flush with the cover.

Now if the car still misbehaves, then you will have to change the leads.

Think about changing the spark plugs too if they have been in the engine more than 5 years or you don't know the service history. I use Denso Iridium plugs.

I changed my plugs and still had misfiring or hiccup under load with a warmed up engine. When I changed the leads, the problem was cured.

Another oddity is that when the HT leads were breaking down, my car was sensitive to the quality of the petrol - Shell petrol was fine, but supermarket petrol made the car hiccup more! It took a while to find the real cause but it was the HT leads.

Once it is all fixed, you will notice how sharp the throttle is at light loads and no more hiccups, which actually is a misfire.

This is my experience which sounds like you have a similar problem.