Running Lean - stumped as to why

[CrUZida]

When you don't know whats wrong, start again.




Will put it all back together with

• Cleaned injectors and all new seals
• New manifold gaskets (upper and lower)
• Different (spare) lower manifold
• Different (spare) fuel rails
• A lot of care

I'll probably take the drivers cam cover off while its apart this much too, see if anything is astray in there.

[Hibba]

From person experience, its very hard to tell when a std 1uz is missing. Because they are so smooth. We had one where i used to work that was only running on 4cy's because 1 coil was dead, But yet it still idled smooth. It just had shit all power.

Can't remember reading it, but i assume you've checked both caps/buttons and coil's? like it may be dropping one coil under low load.

[CrUZida]

Coils do 2 cyls on either side, which is one reason why its so smooth on 4 cyls, its still 'balanced'

[CrUZida]

Ok, another major update.

Installed my Microtech/loom, spare lower manifold, 440cc injectors (Microtech is tuned for these), on to the motor.

Finally got it running (spaghetti junction eat your heart out), and she sat happily at 12:1 on the driver side.

So I KNOW its not the cams/valves/pistons/fuel pump/etc.

Things that were different to before

• ECU
• Loom
• Fuel Rails
• Fuel Injectors
• Lower Manifold
• Lower Manifold Gaskets
• Ignitors

Everything else was the same.


So hopefully about midweek I'll pick up my cleaned injectors and my new manifold gaskets. Put it all back together and see how it goes.

[oldcorollas]

good stuff! it is good to narrow things down!

[thechuckster]

stu: is your post missing some italics?... he's 'narrowed it down' to about 25% of the entire motor

[oldcorollas]

no.. better than the cams being out hh heh
is a relatively small list above from which to narrow it down further...

[CrUZida]

Ok, got the injectors cleaned, put it all back together with the same manifold, rail, gaskets as when it was successfully done with the Microtech.

No difference.

Replaced all the capacitors in the ECU.

No difference

So from the list above, here is what is left.

• Loom
• Ignitors

Chances of being ignitors, slim.

Chances of being loom, slim, but plausible (to an extent).



The symptons are now like this.
Start the car from stone cold, runs at about 14.5:1
When the temp gauge moves 1 bar (5 bars is normal temp), she's around 16:1
Slowly get leaner as gauge moves up, peaking around 18.5:1
When gauge gets to normal temp, she drops to about 600rpm, and sounds like she's struggling.

I pulled off all the leads one at a time, and all made a *slight* difference to engine note, and all had massive sparks.


I plan to move the o2 sensor to the passengers side bank on the weekend, to make sure its still doing the 1 lean bank thingo.

Then if that checks out I plan to make sure I've hooked the loom up correctly as per factory, although with the amount of people who do it dodgy, I doubt this is a problem.

I've measured the injector resistance at the ecu end, all 4 drivers are the same.
I've measured the injector current at the ecu end again, all 4 drivers are the same.


If I get no further this weekend, its going to an EFI specialist.

[oldcorollas]

air/water temp sensor incorrect for ECU?

[CrUZida]

AFAIK pretty much all Toyota coolant temp sensors are the same, and it checked out at 30degC and 80degC compared to the 7MGTE TSRM, so I'm going to assume its correct and working.

Air temp sensor is in the AFM so I'd hope thats correct !

[JustCallMeOrlando]

Put the Microtech on and sell it. It's not worth spending any more time and/or money on.

[CrUZida]

Where's the smiley face

[JustCallMeOrlando]

No smiley dead serious for once ( )

[Jaemus]

the loom seems more likely to my (admittedly inexperienced) way of thinking. I had a mate chasing a similar problem with an SR20 for almost a year, and it turned out to be a short in the loom. And, hehe, with dishwashers, (the ones i work on, they have an equally complex electronics and wiring harness compared to a modern EFI system) after you've spent hours chaging every component, its always the damn loom!

[CrUZida]

I've measured the current through all 4 injector drivers and its the same, and the resistance of all 4 batches is the same, so the voltage must be the same, and therefore it can't be the loom...

But, that said, I'm also leaning towards the loom...