1UZ-FE AFR varying between banks - A problem?

[DaveEFI]

Is the injector dead time correct in the software?

[stevieturbo]

Is the injector dead time correct in the software?

Wouldn't make a difference bank to bank.

[DaveEFI]

Is the injector dead time correct in the software?

Wouldn't make a difference bank to bank.

Dunno the Link, but on some you can set the dead time for each injector.

[stevieturbo]

Is the injector dead time correct in the software?

Wouldn't make a difference bank to bank.

Dunno the Link, but on some you can set the dead time for each injector.

Never heard or seen of that.....nor do I know anyone who has ever done a comprehensive test on every single injector, at every voltage and pressure level....to even consider such a pointless action.

[DaveEFI]

You could say that allowing setting the pulse width to each injector separately could be pointless too. But I'd say it worth looking in the software for any obvious funny as regards that. Before tearing the engine apart.

[Ian C]

Dave,

There are tables in the Link software to adjust the injector pulse width, one is to compensate for changes in battery voltage and the other to add time to short pulse width according to the injector manufacturer's table.

These adjustments are however applied to all injectors, there is no (or at least if there is I have not found it) adjustment for individual injectors.


Dave & Stevie,

I have received a suggestion, from Lextreme forum, to check that the injectors are seated properly as an air leak between an injector seal and intake manifold could cause the symptoms I am seeing. Given that I struggled to swap the injectors, without fully stripping the top end, with limited access and visibility the chances of a badly seated injector are a real possibility. So I am planning to take thin gs apart yet again for a better inspection.

Thanks again for your help and suggestions to date.

Take care,
Ian

[stevieturbo]

An air leak is possible...but presumably you'd have other symptoms too, and would have noticed damaging an o-ring or similar when fitting ?

Simple test is either some easy start around each injector and listen for an engine speed change ( or an afr change for that bank ), or a drop of thick oil around the base of the injector that might seal any leaks up momentarily.

[SimpleSimon]

Have you considered cam timing difference from one bank to the next ? a failing water pump bearing could create this error or damaged cam pulley key-ways etc

[Ian C]

Update

The problem was eventually traced to defective / incorrect / substandard injector seals.

Following the last post (on the 16th August) I decided to try and check for a leak by squirting differential oil around the seals between the injectors & intake manifold (as suggested by Stevieturbo). Started an engine run but stopped it quickly when I had a strong smell of petrol to find fuel mixing with the diff oil round the nearside injector seals. Deciding enough was enough I removed both fuel rails and stripped them for inspection.

The rubber seals, fitted new when the engine was checked over before fitting, looked decidedly secondhand. Some of the O-rings were deformed and were not resilient - they stayed deformed when squeezed out of shape and just felt and looked wrong. I ordered new seals from the company I had bought the Link ECU and other upgrades from (Brands Hatch Performance) and when they arrived I was surprised to discover that the bottom seal (called the insulator in the Toyota 1UZ manual) was very different to the seals I had fitted. The new seals were like a flattened donut whereas the original seals were more like a cup. The O-rings were not noticeably different but felt more resilient. However the proof is in the pudding and with the new seals fitted I had no leaks and the difference in the lambda reading side to side is under 3% (previously 15%). Whilst not prefect I have decided that it is something I can live with and it is time to move on.

So a very big thank you to all those who have responded to my plea for help and for all the suggestions & tips.

Best regards,
Ian

[stevieturbo]

Good find...and why I usually always say #historymatters when it comes tom diagnosing anything.

And equally why I would always say to log both banks where possible, we should not assume both banks run the same and widebands are so cheap these days...it's better to know, and not assume.