1999 Avensis Underpowered / Shaking Under Pressure

[damien1234]

Hi there,

I have a 1999 Avensis 1.6 with 60000 miles. Over the last few months I have noticed the following.

1. The car is very underpowered.

2. When I am travelling up a hill at say 2500 revs in 4th gear ( with the econo light still on) the car starts to misfire and shudder slightly.

If I have a number of people in the car the same happens.

It is very frustrating to drive.

I have replaced the spark plugs with original denso plugs.

I have replaced plug lead number 3 as I was told that this one can cause issues.

No improvement was found.

I removed the leads 3 and 4 from the coil and a white powder was evident.

I have disconnected each of the injector leads in turn but no issue was found.

I have had the car connected to a computer twice but nothing showed up.

I have been told now that it may be a blocked fuel filter. I was going to order one from a main dealer but he said that the pore size is large and is unlikely to have blocked.

Can anyone put me in the right direction

Thanks

Damien

[Avensis luna 03]

Check the plugs again for a thin black line down the side of the porcelain, a sign of a faulty plug lead. I know you changed the number 3 lead but I'd be inclined to suspect one of the others. Can you borrow a working set from a mates car to test.

I had a similar problem on a 99 1.6 and a full new set of leads transformed the car, from driving like a wreck, it now drives like the day it first came out of the garage.

[damien1234]

Hi there,

Thanks a million for your help. I will take a look at the plugs as you say. Did you change the coil as well? I replaced the rear coil with a 2nd hand one as well.

When I removed the plug leads from the rear coil last week, there was a white powder evident and the connections looked blackened (even though lead 3 is only about 4 months old)

When I removed the plug leads from the front coil they were spotless.

As leads 3 and 4 go to the rear coil, do you think this could be the problem?

damien

[Thomas Jorgensen]

2. When I am travelling up a hill at say 2500 revs in 4th gear ( with the econo light still on) the car starts to misfire and shudder slightly.

Does the engine shutter regardsless of load? Eg, if you the car is static, and you rev the engine up to 2500RPM or so, does the engine shudder? What if you floor the pedal? Is the engine able to go over 4000RPM, or does it shudder badly and staying between 3-4k?

If the above is the case, I'd bet it's the Crankshaft sensor. My brother just replaced it on a 1998 Avensis 1.8l. No ECU code for this fault. Idle perfect, but very strange engine shake over 3500RPM (The threshold for strange behavior started at eg. 4000RPM, lowering to 3500RPM after engine (sensor) was heated. Btw, it's not that easy to replace, as it is positioned below water pump, firewall side near the crankshaft pulley.

-Thomas

[Avensis luna 03]

Hi there,

Thanks a million for your help. I will take a look at the plugs as you say. Did you change the coil as well? I replaced the rear coil with a 2nd hand one as well.

When I removed the plug leads from the rear coil last week, there was a white powder evident and the connections looked blackened (even though lead 3 is only about 4 months old)

When I removed the plug leads from the front coil they were spotless.

As leads 3 and 4 go to the rear coil, do you think this could be the problem?

damien

Hi Damien,

I hear what you say about the white powder. It is clearly some kind of corossion and should not be there. But this is the coil pack you have changed, is it not? And you still have the problem?

I didn't have to change the coil pack. Just the leads.

I changed the full set of leads, not cheap, about €100 from the toyota garage if I recall correctly. Is there anyone near you with the same car that you could swop those couple of components and see what's wrong.

It does sound to me that its a problem with the spark being impaired. That could be the coilpack, leads, plugs. Process of elimination.

No sign of any black marks on the sides of the plug porcelain?

Hope this helps.

Joe

[damien1234]

Hi Joe,

I took your advice and removed the plugs. The plugs are only about 9 months old (denso plugs). no sign of any black mark or line on the porcelain was evident.

Strangely all of a sudden over the past few days the car has gone back to normal ( i.e. more power and not misfiring). This has happened before I removed the plugs.

The only thing I noticed was when I was going up a steep hill yesterday at 60mph in 4th gear at 3500rpm, the slight juddering started again, but not half as bad as before.

Do you still think it may be the plug leads?

Thanks,

Damien.

[Avensis luna 03]

Hi Joe,

I took your advice and removed the plugs. The plugs are only about 9 months old (denso plugs). no sign of any black mark or line on the porcelain was evident.

Strangely all of a sudden over the past few days the car has gone back to normal ( i.e. more power and not misfiring). This has happened before I removed the plugs.

The only thing I noticed was when I was going up a steep hill yesterday at 60mph in 4th gear at 3500rpm, the slight juddering started again, but not half as bad as before.

Do you still think it may be the plug leads?

Thanks,

Damien.

Hi again Damien,

Not sure to be honest. I know I spent ages tinkering with my 99 trying to find the cause and occasionally you would have a period when it would be better than before. Also, it always seemed to run ok when cold.

It's a bit funny that reading from your original post, it seems to be when going up a hill or under load with passengers. Almost like as though it was flooding?

The only way to be certain is to swop for a set of leads that you know are working. My money would still be on the leads or that coilpack.

Keep us posted.

Joe

[damien1234]

Hi Joe,

I think i have the problem solved. I bought a set of plug leads (not genuine toyota ones) and fitted them. There was an immediate improvement in power. The only problem was that after time the car would again start misfiring. I found that the leads were coming loose from the plugs. I have slightly squeezed the metal piece of the lead that covers the plug. This seems to have corrected the problem.

Hopefully this is the issue solved.

Thanks to everyone for the help.

Damien :D