So in the second video, I only spotted the MAF getting to 0.2 g/s one time, and the rpm was over 2000.

in the first video, that MAF reading moves much more. I see it at 0.5 g/s at 1800rpm!

 

Possibly a software flaw where you have to multiply by a factor of 10 or 100

At wide open throttle of highest RPM ( normal 4000 or sport 5000 mode ? ) the normally aspirated should be around 175 grams / second , idle 4 grams / second which is a wide variance I couldn't explain

With a meter on the MAF center wire ( green / Yellow ? ) should read 1.2 volts DC on the middle wire of the MAF connector

as you open the throttle it should climb to but not on 5 volts DC to see it function but not a calibration

 

I’m not worried about the actual number, I’m used to seeing that, it’s the lack of movement in the video where the car is driving poorly.

Theres a big difference in the MAF between those two videos. That MAF might be the culprit.

 

Not sure what the MAF should read.
not sure if it is reading accurate or not.
when not having a reading on a known working part its hard to say.


i can swap the maf with the other one i have here and see if the reading is any different or not.

question tho.
if the maf is reading low would the ecu not attempt to lean out the mixture to resolve this?

i am just trying to get my head around these readings and what they mean and how to understand them

is there a known working part number substitute for the MAF?
i mean whenever buying anything second hand you never know what you are going to get

 

Look, the car is operating off of a preprogrammed fueling map from the factory….until the engine warms up. Until then, there is a chart that tells the ECU how to fuel the car. What happens when the RPMs are at 2,000 and the MAF is barely reacting…. I don’t know. You’re showing two videos. One where the car is running well, and the MAF is moving along with rhe RPMs. Then you show a video where the car is running well and now the MAF barely moves?

yeah. Let’s see the other MAF. Could be that the MAF is fine, but there’s a wire that’s wonky. Could explain why hot restart responds differently than a cold restart. Swapping out the MAF would not change that. To cross bad wiring off the list, you’d have to run an ohm check when it’s running well, then again when it’s running poorly?

Even if the wires ohm out there, it could be happening in your ECU. Could be a failing circuit, or connection in the ECU case,

 

When the car is warming up, it is running on lookup tables in the ECU, with no feedback from the O2 sensors. So the ECU is simply taking the inputs from the various sensors and fuelling to match those inputs. It has no way of knowing if that fuelling is correct or not.

Once the O2 sensors come into play, then the ECU can correct to obtain the correct exhaust emissions. Before that happens, it's running like an engine with a carburettor, there is no reference to what the actual air-fuel ratio is.

I've not heard much good about the aftermarket parts, all I can suggest is getting a known good used part. MAF's do fail, I had one go bad on an XJR and it was the reverse. Occasionally it gave a full load air signal, the ECU injected fuel accordingly and the car would flood and stall.

 

This is same yeah? Lucas 20am?

looks decent price.

 

Looks the same , minus Lucas placard , legal line in sand

Chinese copy ?

There is a E mail link to seller and the origin is on the description part on the E - bay page

You can take apart and see if one of your originals has silicone migrating into the circuit board , now how do you remove the silicone ?

 

One of mine does not have the placard either.
one of mine has rivets and the other has crews. Maybe one was repaired?

Potential cheapo new or 30yo second hand?
what has better life expectancy?
how long is a piece of string is same question imo

 

so.
little update on the MAF.
so the app was only showing a reading change when the car was moving.
when the car is stationary there is nor reading changing on the app.
no idea why this is at all.

now i have not had a chance yet to swap the mafs,
however i did just do a voltage check on the MAF when i got home.
at idle it is reading 1.2v and i started to open the throttle body and saw the voltage climb as high as 2.8v.
no ide what revs this was at as i was doing it myself from under the bonnet so could not see the cluster.
this indicates the MAF is working in a seemingly normal function.

now i know everyone says the car should rest with throttle at around 12%.
right now mine is showing 11% and at WOT it is showing 98%.so i believe this to be OK.

 

**extra post not needed*

 

Ok so.
for those playing along at home,
i put the orginal ecu (GF) back in. (The one that is currently in my parts car)
and it runs bad. Slower to start, idles high, idle drops slowly, little flutter in idle on occassion, i restarted the car about 6 times with it in.
fuel trims through the roof. Running even richer.

afterwards i out the other ecu (WB) back in and all went back to how it has been

what is interesting tho is that when (WB) was in the parts car originally the parts car ran ok.
when (GF) was in my car i was getting stalling, struggling to hold idle,
now with (GF) in parts car it is idling very low. Just holding on.

really doesn’t help me get any closer at all. Either ECU might actually be better.
and who knows what is wrong around it.

 

just a thought.
could the secondary air pump have anything to do with this?
i have absolutely no idea what it does or how it works...

also out of curiosity what are these two lines and what do they do?

 

EGR or smog pump

I wouldn't take the line in the red circle off

More later when I took mine off

 

Those lines go back to the EGR.

Regarding the secondary air pump, "Air injection is used to promote reaction in the exhaust down pipe catalyst, reducing the time required for the catalyst to reach working temperature. The air pumped into the exhaust manifolds mixes with exhaust gas and oxidation takes place. The heat generated in this process reduces the time required for the catalyst to reach operating temperature. Air injection is enabled by the ECM following each cold start and remains on until the engine coolant temperature reaches 95°F (34°C). At 95°F the air injection circuit is switched off and closed loop air / fuel ratio control is enabled. If the engine speed exceeds 2500 rpm while air injection is enabled, the ECM will switch off the circuit.

On 1993 – 94 MY vehicles, air injection is also enabled for approximately 30 seconds after each hot start.

The ECM switches the air injection relay, which in turn switches both the air pump clutch and the air injection solenoid vacuum valve. The solenoid vacuum valve controls the vacuum signal to the air switching valve. The air switching valve performs two functions. It backs-up the air injection check valve and it prevents air from being sucked through the pump and check valve into the exhaust. Such leakage would cause an air / fuel ratio error at the oxygen sensor. The vacuum supply to the air switching valve is sourced from the intake manifold through a delay valve. The delay valve is used to ensure that the air switching valve is held open during short periods of high engine load.

The ECM monitors its output to the air injection relay for on-board diagnostics."

Can you verify that the air pump comes on?

Do you know where the Air Pump Relay is located for your model year?

Your model year happens to have an Air Switching Valve located behind the air pump. It works via vacuum. Perhaps the vacuum tubing has ruptured? Can you locate that valve and check the vacuum tube?

 

They must be the lines for the secondary air pump.
we don’t have egr like the US market does
Unless i have been given fake info all this time

no idea how to check anything on the air pump.
will do some looking around and see

 

Not sure if the regular XJ6 uses the same secondary air pump as an XJR..... on my XJR, both the mechanical valve that attaches to the pipe in between the exhaust manifolds and the pump was not functioning.... along with the air pump motor itself being seized, AND the internal electronic solenoid valve being stuck open as well. I'm fairly convinced that part of my particular running issues were either leading to poor O2 sensor readings from false air readings from this.... or perhaps exhaust bypassing through the stuck-open components and being sucked into the MAF and causing bad readings, since the feed hose for the pump connects to the bottom of the airbox across the engine bay.

The good news is that if you do have the same style pump as an XJR.... it's a Chevy part.... 90's Corvettes/Camaros basically used the same pump and mechanical valve. So if you want to do further testing, I'm sure you can find some Chevy-related information that might help. I fixed mine with a used unit from a Camaro... and stuck a small crank breather filter on the inlet port. Since the thing isn't running all the time, the long hose that goes all the way across the engine bay is rather pointless. But once it's functioning properly you should hear it on start up..... sort of like a Kazoo/humming sound for about a minute or so when cold-starting.

Down the line if I feel feisty about it I may just send my ECU across the pond to Andy and have him remove the SAP programming all together to get rid of all the hardware since I have no emissions requirements to adhere to where I live.

 

Can’t say i have ever heard anything like that.
but if i am not listening for it maybe just never noticed.

i think the pump is the same but there is jo hose across the engine bay as on the N/A it is mounted above the alternator.

 

Since you do not have EGR valve ( located top of intake manifold between cylinder 3 and 4 you could have the exhaust manifolds for being EGR installed and they capped the lines , mixed manifolds not in stock as they manufactured the whole engine / car ) , there is a EGR temp sensor with 2 wires nearby located on top nearer to the engine block

The secondary air line is the very back of the back manifold pointing aft as a flexible aluminum 1 inch line that is not rated for EGR gas heat drawing off the exhaust , you can check the exhaust manifold clamp is tight and the flexible thin aluminum skin tube is not compromised as posable

If you pull off the lines in your red circle it has fine threads and the lines are not a perfect shape / off angle to reengage the threads

Odd that the relay is on the right as the supercharged pump location

 

When i get a chance i will do some looking and follow those lines.
i know they run around the back of the block and then dunno after.

and also look at the plumbing regarding the secondary air pump