If the solenoids had failed you would notice pretty immediate driveability issues. The intake valves they control keep the engine responsive in the low-mid. Did you use the entire rev range? As I said earlier one out of the way place for a vacuum leak is the plastic vacuum plenum before those solenoids.

For avoidance of doubt the VFAD nipple you talked about earlier is the one under the throttle body, correct?

 

Sorry - did I use the entire rev range for what?

Ill check the plenum right before the solenoids but i dont recall noticing a plenum...maybe I was working too quickly. The upper intake manifold is two pieces. is that plenum a part of the manifold? if that plenum is damaged what options does that leave me with?

and yeah, the vfad nipple is blocked when i had the aftermarket intake on. the one directly behind the tb facing downward. when i put the stock intake back on, i put the vfad system back on as well

 

Stock intake threw a P0171 code. Lol

So ill take apart the upper intake manifold this week.

 

Try wiggling the maf plug while you watch g/s . If that hightlights an issue ...I have a cure.

 

I meant if you used the entire rev range while driving. The intake valves activate at different rpm ranges, the last one over 7500 or so, so thereight be clues there. The vacuum "box" is that which the intake solenoids attach to, and where their vacuum line from the intake goes in. That box is plastic and can crack. Th

 

MAF flow stays pegged at 4.4g/s after a long drive when i go and try to wiggle the MAF.

I am confused by something now though.

@ciprianrx8 posted a helpful chart showing the MAFs stock voltage and its respective flow rate. I checked that table and my voltage is 1.12 - 1.13 so the g/s the MAF is seeing is correct.

But how can it be correct AND have a vacuum leak behind it causing the LTFT to spike? Or ... can it be correct at the MAF and incorrect past it thus causing the ECU to correct it with higher fuel trims? Bear with me

 

That test Ciprian mention just tells you if the maf has been rescaled by a past tune...... IE maf g/s lines up with voltage on the stock scale.
If you had a leak g/s is lower than if you didn't because the air that bypasses the maf isn't being measured.

 

Not sure I follow. Your intake voltage and g/sec are both too low for 800rpm idle. So the sensor is correct, and you have unmetered air getting in somewhere.
4.4grams comes through the MAF,, another gram or so comes in somewhere else.

 

Right. Thats how I understood it. I measured the voltage at the MAF and the g/s reading....and I measured 1.13 volts which then corresponds to the 4.4 g/s I also measured. And all of this is accurate to the table that Ciprian posted so then can I deduce that there isn't an issue at .... the MAF ? But the LTFT suggests otherwise....

I know Im probably missing a key bit of information here or I'm misunderstanding but would love to be cleared up.

Sorry, maybe I misunderstood Ciprians table I thought I was supposed to use that as a reference table to measure the voltage at the MAF and then see the corresponding g/s so I measured 1.12 volts at the MAF which corresponds to 4.4g/s?

 

Yes you have it right. If the car was only getting 4.4g/sec it would not be able to hold a steady 800 rpm idle. It's not enough air. So there's air getting in somewhere else, and it's having to add fuel trim above the fuel required for 4.4g/s to compensate. You MAF voltage correctly corresponds to the airflow it interprets with a stock intake.

Are your air straightener screens before the MAF in good shape? Both are present?

 

Air straighteners are straight and present. Both of them.

Im going to double check my work under the UIM later this week. I replaced all the orings on it, the solenoids behind it, i replaced the SSV....basically a lot was touched under there and I dont know, maybe on reinstallation something got pinched?

Though in my experience, im overthinking it and its probably a defective sensor / solenoid or something because....a smoke machine is not showing any kind of leakage....

 

Is the MAF clean? Was it cleaned with anything other than MAF cleaner? As poitned out earlier can you try a different MAF?

 

I don't know if the previous owner did anything but i doubt it considering its been 4 years and the car has been fine. I cleaned it with MAF cleaner only.

Ill try a different MAF and report back.

 

Replace all of your vacuum hoses while you have it apart. Inspect the oil metering injector nozzles respective vacuum hoses and vacuum distribution block. Make sure the rubber gaskets for each of your vacuum chamber solenoids as well as the rubber gaskets for the purge solenoid are good. If you have the new/revised oil fill neck, make sure that those hoses also routed correctly from down by the flange where it mounts at the middle iron. Ensure your lower intake manifold service ports have vacuum caps that are intact, replace them as a precaution if anything.

You should just go ahead and replace any soft rubber seals everywhere in the system. Additionally, ensure that the rubber seals at each of your injector seats for the secondary rail look good and aren't cracked/split/missing/damaged.

 

Interesting, would the vacuum lines at the OMP injectors cause a lean condition if it were bad?

Also - whats the "rubber gasket at vacuum chamber solenoid" The solenoids clip onto the UIM, i dont recall a gasket being involved on the solenoids..

 

Yes, more notable at idle. The engine operates at a vacuum at idle and will pull some air through the injector nozzles that counts as metered air since it pulls as one of the three lines just before the throttle body. A leak there could be noticeable at idle but less apparent when the throttle opens and nearly all the air is coming through the throttle body.

Another place to check is your full "jet" air line that had the small hard pipe section behind the alternator and is a piece of hose again behind the thermostat housing into the fitting at the very bottom of the lower intake manifold.

If you take a good look at the solenoids where they click into place in the vacuum chamber, there is a little donut kinda looking seal to create a airtight seal between the two components.

 

Edit. Nvm. Still chasing. The lines leading to the solenoids vent to atmosphere so the smoke is expected to come out from the back caps of the soolenoid.

After sitting with it yesterday and reading everyones input I decided to go and smoke test the car again. This time I wanted to test the solenoids (per @Ricky SE3P ) by plugging my smoke machine into one of the lines that lead to the solenoids.

In this case, I used the line for the SSV that leads back into the solenoid and lo and behold - smoke is just pouring out of the backside of the manifold. I recorded a short video below. Ill take apart the upper intake manifold and look at the donut seals Ricky was referring to. Now the question is: are those seals sold seperately? Is it the same donut seal as the purge valve solenoid seal?

Edit: What is still unclear is whether the solenoid itself is defective and leaking, if its the gasket where the solenoid meets the upper intake manifold plenum, or hell maybe its even the vacuum chamber before the solenoid but ill take a closer look.

 

Good news ! Looks like the vacuum tank might be ruptured. Take some pics and post when you find the source!

 

If thats ruptured, I'm in need of a new upper intake manifold?


Rip....

Ill keep you guys posted when i get everything apart.

 

I believe one of the seals between the solenoid and the vacuum tank might have gone missing during replacement. Just seems too coincidental for it to have all of a sudden started at the same time you did the replacement for the solenoids. Either that, or the line is connected in the wrong spot.

If you haven't already started to take it completely apart I want you to try something. The small vacuum line that has the green and white check valve in it, disconnect it from the upper manifold and plug/cap that port on the upper manifold and start the car. If something with that vacuum chamber or solenoids is the problem, your idle should be much more stable and your g/s reading for your MAF should be back up to where it is expected to be.

I'm going to make a short little video clip here in a little while to give you a visual as well. That will be incoming in a second post.

 

 

I believe I have gotten the correct part number.

N3F1204B5

https://www.jimellismazdaparts.com/p...N3F1204B5.html


23-612A In the diagram above.

 

Thanks @Ricky SE3P I appreciate you taking the time to film a short response video. This is feeling like early 2000's era of forum problem solving lmao.

But anyway - i think my previous video might have been a red herring and not actually be accurate in diagnosing a leak despite the crazy amount of smoke coming out.

I have my upper intake manifold apart and I can confirm the three seals at the solenoids are there. But i noticed that the back caps of the solenoid was wet with oil so i think im pressurizing the solenoid and pushing those caps loose which probably doesn't indicate something wrong.

I recorded two videos demonstrating what im talking about.



and watch this one second.

 

So yeah .... just watched your first video again .... the ssv line is not where you plug your smoke tester in. Try the vfad nipple.

The lines to the actuators are open to atmosphere when valve is off so makes sense they leak out those caps.

 

But if they're open to atmosphere, then my first video proves nothing right?

It would leak if pressurized but thats expected.

So back to square one?