Running Lean - stumped as to why

[rms]

What is wrong with 16 /19 to 1 AFR on cruise ????
Pretty normal for current production vehicles.

If it does not miss you can run as lean as possible, there is no load on the engine.
Can also run up to 50 deg ignition on light load.

[CrUZida]

I wouldn't be seeing 60psi in the rail if there was any form of blockage.
Car runs smooth as, no misses.

If it was tuned for 16:1 at cruise then I'd be happy. But being a) a Toyota ecu from the early 90 (ie, notorious for running rich) and b) running 50% more fuel pressure than stock is should be running rich as.

Once its running where it should I plan to remove the pump and put in something that will run the pressure as per stock.

[whatthe?]

Tried another AFM?

[Duk]

I wouldn't be seeing 60psi in the rail if there was any form of blockage.

You could pressurise the fuel rail to 60psi (or any pressure) thru a hole the size of a pin prick so long as the fuel doesn't drain away faster than the fuel can be pumped back in thru the pin prick sized hole.
Fuel use at idle is going to be less than that at highway speed so my point was, at idle you may have 60psi but at cruise what is the fuel pressure?
What are idle and 60km/hr AFRs like?

[ViPeR_NiPPleX]

So a tuned delco was on previously and suffered the same condition? Couldn't be tuned out?? Stock induction setup/exhaust?

[CrUZida]

Tuned Delco was on previously, and had the same issues. Which basically rules out any sensors/etc.

You could pressurise the fuel rail to 60psi (or any pressure) thru a hole the size of a pin prick so long as the fuel doesn't drain away faster than the fuel can be pumped back in thru the pin prick sized hole.

Granted, but you wouldn't get a flow rate of 300L/hr at 60psi a hole the size of a pin prick.


I'm about to reinstall the gauge in the rail and see what the pressure are under different conditions.

[whatthe?]

Did you fix the pump voltage issues before you changed the ECUs over?

[ViPeR_NiPPleX]

under full load the motor is running a respectable AFR? Does the motor run smoothly when cruising? Does the stock setup run a fuel ECU? I can understand why you'd be head scratching when after swapping over the whole efi system as to why the condition still exists. Could it be a cylinder dropping out when under cruise? Ignition related?? Guessing this is a 1uz.

[thechuckster]

that fuel pressure is quite high ... in fact 60psi is crazy high for idling - are you sure there's not a restriction somewhere before it gets to the rail?

i think putting a gauge on the rail and doing a static test would be a good start.

[fixeruperer]

Tuned Delco was on previously, and had the same issues. Which basically rules out any sensors/etc.

How does this rule out sensors as the problem was still there ? it rules out ecu tho.

[CrUZida]

Just put a gauge on the rail. 52psi at idle. Bit lower than previous 60psi. Checked voltage at the pump, only 12.6v now, hence the lower pressure, but still more than it should be.

Went for a drive, pressure ranges between 48psi and 52psi, depending on conditions.
Cruise control set at 70kph and the AFR's settled around 15.5-15.7:1
Giving it full throttle sees it eventually dip around 12:1
Using moderate throttle accelerating up a hill sees 15-16:1
Warm idle sees 16.1-16.4:1

Voltage at injectors was checked. 13.7V at idle.

How does this rule out sensors as the problem was still there ? it rules out ecu tho.

Because they use different sensors.
MAP vs AFM
GM air temp vs Toyota air temp
GM coolant temp vs Toyota coolant temp
GM knock sensor vs Toyota knock sensors
GM o2 sensor vs Toyota o2 sensors.

The only sensors the same are the cam/crank angle sensors.

Does the motor run smoothly when cruising? Does the stock setup run a fuel ECU? Could it be a cylinder dropping out when under cruise?

No fuel ecu, just the old style fuel resistor (which is not installed, ie bypassed).

There is a chance that is not properly running on 8cyls (as the power feels down), but the 1UZ is smooth enough to barely notice it.
However both the passenger and drivers side of the firewall are almost too hot to put your feet there, which indicates both banks are running at similar temps.
I've put the low power down to the fact that its running lean.

[ed]

Everything is spot on

well, the title of the thread suggests something's not

all im saying is go somewhere that in 30mins they can confirm your rich/lean cruise condition. you say the car is 100% but the afrs are wrong. im saying go somewhere to confirm the afrs ARE actually wrong... 'my floor is hot' isnt really a calibration device.

you may be chasing a ghost, thats all. in my books, if a number doesnt make sense, recheck the number another way

[amichie]

Assuming the ECU is pre OBDII (if not just get it checked) it should have the long term fuel trim available at the vf terminal of the diagnostic connector. Check that and see if the ECU is trying to lean it out or richen it up.

[CrUZida]

... 'my floor is hot' isnt really a calibration device.

Granted its akin to the butt dyno, but I've been around this motor long enough to know when somethings wrong. And since the exhaust is almost identical to what was in my Cressida I know the floor shouldn't be THAT hot (I expect some warmth due to the exhaust being close).

Amichie, what voltage should the Vf be?
From memory 0.5V is unchanged, but which way is rich, which is lean ? 0.75 and 1V lean, 0.25 and 0V rich?
Does the car need to be running, or just ON ?

[thechuckster]

is the ECU mapped for those injectors or something bigger?