2001 1.0l 16v vvti running rough

[Pauloyaris]

New to the forum & joined as both me & my mrs have mk1 1.0 vvti Yaris. mine is a 1999 which runs great & totally reliable. the mrs has a 2001 excellent condition gls but it has a problem when she first starts it. sometimes it will run great but most times it will show signs of firing on 3 cylinders & jerky performance. i,v cleaned the air flow sensor with no effect & taken it to a garage & they checked everything but couldn't find anything wrong even after connecting it to a computer & checking for faults. Any help on this would be most appreciated as it's a fantastic car let down by poor running.

[Madasafish]

Checked plugs? Remove and check gaps.Fouling?

Coil packs  - unlikely.

Check al HT  mountings - when cold for corrosion. Fully remove from engine and check for cracks/damp/signs of tracking.

Check air filter clean and no leaves in housing.

[Gerg]

2 hours ago, Madasafish said:

Coil packs  - unlikely.

In the event that you did need a coil pack, then it is worth shopping around.  I have just bought one for our 2001 1.4 Corolla vvti (I think it is the exact same part as a Yaris, as it happens), I got an NGK branded one (made in China) for well under £40.  It's a perfect fit and has cured the bad misfire (which, helpfully, did throw an ECU code up).

I checked the Toyota dealer price, it is £168.

This is the second (different!) coil I have had to change on this car in the last 2 years, the car's done 130,000 miles, for what it's worth.  The previous coil I bought was an Intermotor branded one - there are plenty of choices, many I'd not heard of.  Intermotor was a make of electrical parts I'd known about for decades.  It was at the cheaper end of the price spread, it is still working fine.  Off the internet, the Intermotor is available for under £29, if you don't mind the wait, and are happy that the coil is at fault.

The price from a breaker is around £18, with a 30 day warranty.  Not exactly a bargain.....