MK3 1MZ with Rough Idle / Running

[tomos]

Symptoms;

- Idle hunting between 600-800rpm resulting in a very lumpy tick over
- Stinks of fuel (my eyes are burning)
- When warm and driving up to a junction for example as soon as I stop off throttle the revs will drop so low that the car cuts out.
- Ticking noise which sounds like an exhaust blow

Following on from getting the OBD II up and running on the MK3 the fault codes read are below;

- P0135 O2 Sensor heater circuit Bank 1 Sensor 1
- P0141 O2 Sensor heater circuit Bank 1 Sensor 2
- P0155 O2 Sensor heater circuit Bank 2 Sensor 1
- P0758 Shift solenoid B Electrical
- P1410 EGR Valve position sensor circuit malfunction
- P1765 Linear Shift Solenoid Circuit Fault

I'm thinking there's air getting in somewhere around the manifolds causing the O2 sensor faults, also noticed the Throttle Position Sensor sat at 14.5% without any application to the throttle pedal when looking at the data stream. O2 Sensors all reading 0volts on maxidiag with engine running.

With the ignition ON I cleared the codes and ran a fault code check, immediately threw up the EGR fault. The others all re-appear once the engine has been run.

Where on earth do I start?

[cdwood2010]

First question, does it run the same on both ECU's?

Actually i don't have a second question. I do have a cool link that might prove useful as a research tool......

http://www.datsc.com/tabid/122/OBD-E...a/Default.aspx

Actually i do have a second question; can you list what you've tried / ruled out so far?

c.

[cdwood2010]

Oh and i think we have 2 banks of O2 sensors, one of which aint there any more (bank 1 probably, hence zero volts) , but that bank-2/1 should be working.

c.

[Paul Woods]

Those O2 heater circuit codes are probably because there is no power being fed to the sensors, probably a lot of other faults too if someones hacked about with the wiring.

[thomp1983]

The being rich enough to sting your eyes is a very clear sign your o2's aren't working.

With the ignition on check your getting 12v at the engine of the o2 connectors?

[tomos]

First question, does it run the same on both ECU's?

Actually i don't have a second question. I do have a cool link that might prove useful as a research tool......

http://www.datsc.com/tabid/122/OBD-E...a/Default.aspx

Actually i do have a second question; can you list what you've tried / ruled out so far?

c.

They do run differently.

OLDER ECU - Pulls from low revs but not as cleanly as you'd expect. Hunts at tick over when warm sometimes cuts out when the revs drop too low.

NEWER ECU - The Avalon ECU pulls but almost feels like an electronic limiter/coil pack power supply issue, at lower revs with full throttle it can make the car act like its on kangaroo juice. Not noticed it at higher revs. Hunts at Idle moving between 600-800rpm at a quicker rate very lumpy, engine rocking, similar to the tick over of a WRC car but just dropping too low but hasn't cut out on me yet.

Tonight I had a spare 30mins so set about improving the wiring to the ECU using one of the connectors Chris kindly donated, I'm much happier with it now. Pics below show the older ECU with crap wiring black and white loose wire was the data line, and the Avalon ECU with new plug fitted, bloody fiddly things to get the old pins out of but done!

1.jpg

2.jpg

3.jpg

I've not tested anything yet but it looks like I should start at testing the power to the Lambdas at both ends.

[tomos]

I've had to revert to the older ECU for now due to the limiter type behaviour with the Avalon ECU when cold (very dodgy pulling out of junctions with crap visibility). The Lambda's are getting 12v or at least at the plug before the sensor itself.

The exhaust has a bit of a blow, when finished testing the voltage to the lambdas I decided to run the engine and look for where the blow was coming from, it appears to be the flexi's on the Y-Branch, no massively visible holes but definitely losing exhaust gas when you hold your hand near them. Are these bespoke? i.e. should I remove it and get another produced or are there suppliers out there?

Need to get my head around the wiring now :icon_mad:

Thanks,
Tom

[Jiff Lemon]

Probably no suppliers out there, so its a DIY job. You may be able to chop out the flexi's and get someone to weld new ones in?

[cdwood2010]

If you drop the flexi section off the car it might drop to bits. If the flexi joints are blowing then they tend to com apart so expect to repair them if you start looking.

As Jeff says, you can buy new joints and just get them welded in, but it might be worth finding someone who can just build a new section on the car.

When you start on the wiring, just post up on here and we can all jump in.

C.