Caps Maf Riser Mod

[Petrus]

Does it rain in Malaga?

Not much - but he might wash the car quite frequently 'cos of the dust?

Not arguing the point as it simply is valid, however, not much of an effort to temporarily chuck the cover on the head when rinsing the car ;-)

[Petrus]

Couldn´t wait any longer so have started taking things apart.

1. Taking thecam cover off is définitely the better procedure.

2. The manifold mounting holes are crud collecting corners so take care and prepare.

My TwinAir filter element is way affective appearently: Very dirty at one side, clean at the other.
Need to wash & coat.

Still on the fence about the splash/vanity plastic. Think I will refit. Not worth any potential problem is it?! 

[househead]

Still on the fence about the splash/vanity plastic. Think I will refit. Not worth any potential problem is it?! 

Not really imo!

Some people have painted theirs. Looks pretty good, but obvs you have to use a paint which can handle high temps.

[Petrus]

So scrubbed the cam cover, cleaned the plastic and put it back on.

Car started after just a few seconds of cranking.
No petrol smell.
Runs slightly high but not oddly so. Have not driven it, so it will learn yet I suppose, hope 

I was a bit surprised about how much of a restriction the insert with the ´grid´ is.  Taking it out wíll flow better.  I can imagine that  the OEM set up will get confused if you just take it out.
Anyway; dunnit:
The eagle eyed will spot the alu spacer 

[jvanzyl]

Prolonged cranking is due to o2 sensors beginning to age.
As they get older they don't adjust as fast. Don't forget to give the maf sensor a clean.

[Carolyn]

Prolonged cranking is due to o2 sensors beginning to age.
As they get older they don't adjust as fast. Don't forget to give the maf sensor a clean.

Probably just clearing fuel rail and injectors that are full of air....

[Petrus]

Prolonged cranking is due to o2 sensors beginning to age.
As they get older they don't adjust as fast. Don't forget to give the maf sensor a clean.

Yes, cleaned it.

The cranking I attributed to priming as the whole fuel system had gurgled empty on the rags.

Will find out tomorrow.

[Petrus]

Probably just clearing fuel rail and injectors that are full of air....

What I figured.
If anything it started quickly considering.

Have a nice road trip planned for tomorrow direction Lake Iznajar. It does not get more interior Andalu´  than between there and Córdoba.
My date is planning the restaurant stop sómewhere thataway.
Perfect learning opportunity for the ECU and experiencing any difference for me.

Thanks for the feedback on the vanity plastic Carolyn. Not worth the hassle.

[Petrus]

Found some extra illustrations of the vane holder that is removed; it is quite a restriction.
Sadly, because the intake is precisely calibrated it cannot simply be removed without recalibrating the whole panorama.

[jvanzyl]

You taken it out for a spin yet?
Interested to see if your cranking was prolonged or not this morning and your thoughts on the extra torque?

[Petrus]

No, not yet.
Will go for a coffee in a moment but that is not going to be informative.
The trip is planned for the afternoon. Hope to have no time for feedback till tomorrow but hey, nothing as fickle as ... béééép.... (politically correct censored)

[Petrus]

What the h... a quick coffee and a longer ride 

Started brisquely, ran a bit whoolly, rich.
5 kms to the restaurant, not even getting up to temp. Stopped, still ran on the heavy side, lowish idle.
Coffee down, out on the highway. Then a bit of B-road, provincial road, highway and provincial road back home.
The exhaust note quicky changed back to the original crisper running.
At home it idled as usual, a tád low if anything.

Not a long drive so no in depth opinion.
First impression is that from 2k to 4,5k revs it responds and pulls like in a lower gear. Impressive.

Makes sense as the vane thing ís quite a restriction, the injectors are bigger squirts and the advanced ignition is more efficient.
Still quite a ´boost´ from such an appearantly innocuous modification. Seriously, had not expected it to be so noticeable.
Perhaps it is my car being >100 kilos lighter. As I write,  it responds and pulls like in a lower gear yet without running out of steam as in a lower gear so it móves.
Overtaking on the two lane roads is notably easier; it immediately pulls and goes on the rev band.
Ergo; sofar sogood.

[jvanzyl]

Glad you're noticing the difference! I'll get round to fitting mine at some point.. can't remember if it's mot friendly or not..

[Wilky1974]

Glad you're noticing the difference! I'll get round to fitting mine at some point.. can't remember if it's mot friendly or not..

Yep! It's MOT friendly. Have run this on my 2002 PFL without an issue .

[Petrus]

Ok, back at my laptop.

The ecu is still learning some details appearantly; starting is inconsistent. Cold is ok if lumpy, hot os spot on, in between it seems to be looking for sómething; taking some time.
Because of the latter was rather relieved it started brisquely this morning; on the parking lot of a small rural hotel out in the white on the map. A wonderful place to stay but not to get stranded 
Anyway, it started.

Changing up goes without the pick up hesitation now.

For the rest the extra response/torque is as I wrote unexpected.

Refitting the vanity plastic was a good suggestion. It rained last night when it was parked outside 

[shnazzle]

It's never going to get cold starts right consistently. Without o2 feedback and with non-calibrated setup all it has to go off is long term fuel trims. So unless every cold start is under the exact same environmental conditions, it's going to fumble a bit.
Take the bad with the good.
Good news is there are a number of other compensation tables that will smooth it out on the fly (IACV and timing control to reach a target rpm). Bad news is it doesn't remember those settings. So it has to go through the PID loop every time you start the car

[jvanzyl]

And if all else fails and you get fed up with extended cranking, have a look at the age of your 02 sensors... just saying.. I've been there before.

[shnazzle]

And if all else fails and you get fed up with extended cranking, have a look at the age of your 02 sensors... just saying.. I've been there before.

O2 sensors don't do a thing during start up. 
That's fuel status 1.0. Which is cold startup. 

O2 sensor heaters are still heating the elements and the ecu ignores the input.

[Petrus]

It's never going to get cold starts right consistently. Without o2 feedback and with non-calibrated setup all it has to go off is long term fuel trims. So unless every cold start is under the exact same environmental conditions, it's going to fumble a bit.
Take the bad with the good.
Good news is there are a number of other compensation tables that will smooth it out on the fly (IACV and timing control to reach a target rpm). Bad news is it doesn't remember those settings. So it has to go through the PID loop every time you start the car

Thanks for sharing the insight.

The driving has réally improved.
As I wrote the difference is beyong expectation. It stands to reason and no doubt more pronounced because of my lighter car but it still is awesome for such an appearantly innocuous mod. I mean it is not in the same league of change as different cams or forced induction yet it is like driving in a lower gear.

[Beachbum957]

First impression is that from 2k to 4,5k revs it responds and pulls like in a lower gear. Impressive.
it responds and pulls like in a lower gear yet without running out of steam as in a lower gear so it móves.
Overtaking on the two lane roads is notably easier; it immediately pulls and goes on the rev band. .

That is exactly what others have seen with the mod. While a dyno test confirmed there was more torque and HP at full throttle, the most noticeable changes are at part throttle, with better throttle response, and needing less throttle to get the same acceleration.  For us, the result was also better MPG on winding roads where you are accelerating and braking often, staying in the range of 3,000 RPM to 4,500 RPM, but rarely using full throttle.

Incidentally, a friend went from the MAF mod to stage 1 cams and a head that was ported and cleaned up. The cam and head work didn't play well with the MAF mod, but the dyno chart with the cams and no MAF mod was almost exactly the same as stock cams with the MAF mod.  Having driven their car, I think the throttle response with the MAF mod was actually slightly better.

[Petrus]

That is exactly what others have seen with the mod. While a dyno test confirmed there was more torque and HP at full throttle, the most noticeable changes are at part throttle, with better throttle response, and needing less throttle to get the same acceleration.  For us, the result was also better MPG on winding roads where you are accelerating and braking often, staying in the range of 3,000 RPM to 4,500 RPM, but rarely using full throttle.

In other words; easier driving! The mpg is ofcourse a nice bonus but not on any list of mine ;-)

Incidentally, a friend went from the MAF mod to stage 1 cams and a head that was ported and cleaned up. The cam and head work didn't play well with the MAF mod, but the dyno chart with the cams and no MAF mod was almost exactly the same as stock cams with the MAF mod.  Having driven their car, I think the throttle response with the MAF mod was actually slightly better.

I had read that earlier and though I am aware that the head desígn and the long stroke make a cam set less effective as an improvement it is still rather a lot of effect from such a relatively simple mod. for little money.
If anything it is a surprise that it was not taken up by more users.

[Petrus]

Still have a question about this mod.

I understand the ´trick´; to get more ignition advance at more load than the ECU measures.
To compensate for less fuel added by the ECU, larger injectors are fitted.

At high to max load, the ignition advance is on the OEM curve anyway, but what about the fuel/air ratio with the now potentially too large injectors?

The O2 sensors tell the ECU to keep the injectors in check and so restore order to OEM parameters: Ergo the ECU turns dówn the fuel whick because the Yellow injectors have a larger increase in capacity than needed to compensate for the load trick.

From several sides I have been told that, with an exhaust permitting this, the MAF mod adds about 5 hp  because the gate is removed.
So obviously the flow measued by the ECP at full throttle flow gets the fuel corresponding to that load: Remember the ECU turning dówn the fueling whick.

We knów that opening up the exhaust allows the engine to pump more air, that the OEM tables of the ECU can allow for 10% more flow, more fuel. The ceiling of max flow signal, the max values in the tables, allow for 10% more power.

Now the question.
Does the trick of fooling the ECU that less air flows through, raise the ceiling?
I mean, the logic would be that if the signal from the MAF mod is 10% down, then flowing 10% more equals the 100% signal in the OEM setup?!
So what if still more air passes through the MAF; with the larger injectors, thát is no longer a mechanical limit; there is more than enough fuel squirt availeble for the 10% of the exhaust and recuperation of the ´lost 10%´.
The crux of the question is how much room is there in the OEM tables and does the MAF indeed move the whole table, thus defacto that room?

[shnazzle]

The OEM tables are static. But, the long + short term trims can adjust up to a whopping 30% each way (or was it 35?) before an error is thrown.

BUT.. you'll notice the MAF mod doesn't use fuel trims to do its "magic". I think on Cap's thread he was trying to keep it under 10% or even less. He used the MAF position, veins and injectors to tweak it.
Remember the idea of the MAF mod wasn't to increase airflow or fueling.
The idea was to advance timing.
Cap found on a flow bench that to his surprise that one of the best cone filters (PPE) actually provided less MAF signal than the stock box at the same CFM. Even more interestingly, stock box without veins even less MAF signal. I reported the same on my Hurricane intake.
That means 2 key things that are often twisted around about the MAF mod;
1) speed of air does NOT increase MAF voltage
2) CFM is (in this setup) unrelated to the speed of the air
This is key... The MAF mod does not pretend there is more air. It pretends there is less LOAD. The pipe still flows X air, but it pretends X-n is being flowed.
E.G. 200CFM in,170CFM reported. Whereas the stock box it's 200CFM in, 200CFM reported.

OK so now we have a voltage from the MAF.
The ecu uses a MAF-based fueling strategy.
Sees low load.
Looks low on the fueling table for the given RPM.
Looks low on the ignition table for given RPM.

Fuel is low and timing is advanced for the supposed lean condition.

O2 sensors pick up lean condition and increase fuel and timing. Car runs shit for a bit and within seconds/minutes we're back at square as the car trims out the issues.

Cap saw this on his wideband. So, how do you prevent the o2 sensors from seeing lean?
Make it so that there is more fuel, without the ecu knowing about it. Increase the injector size.

Going back you now have
- Low load = advanced timing from ignition table
- low fuel = lean
- "normal" CFM = lean (for this load)
Then...
- more about 20% more fuel (I think) from the 2zz injectors. Compensates for the lean condition, O2 sensors read stoich or near. Car thinks all is good.
You've shifted down on the ignition table.

Compared to stock 1zz you have more advance, which (compared to an oem ecu) can unleash more power as you're reducing the safety margin built in for knock (hence the 98 fuel).

So, if The OEM tables are static. But, the long + short term trims can adjust up to a whopping 30% each way (or was it 35?) before an error is thrown.

BUT.. you'll notice the MAF mod doesn't use fuel trims to do its "magic". I think on Cap's thread he was trying to keep it under 10% or even less. He used the MAF position, veins and injectors to tweak it.
Remember the idea of the MAF mod wasn't to increase airflow or fueling.
The idea was to advance timing.
Cap found on a flow bench that to his surprise that one of the best cone filters (PPE) actually provided less MAF signal than the stock box at the same CFM. Even more interestingly, stock box without veins even less MAF signal. I reported the same on my Hurricane intake.
That means 2 key things that are often twisted around about the MAF mod;
1) speed of air does NOT increase MAF voltage
2) CFM is (in this setup) unrelated to the speed of the air
This is key... The MAF mod does not pretend there is more air. It pretends there is less LOAD. The pipe still flows X air, but it pretends X-n is being flowed.
E.G. 200CFM in,170CFM reported. Whereas the stock box it's 200CFM in, 200CFM reported.

OK so now we have a voltage from the MAF.
The ecu uses a MAF-based fueling strategy.
Sees low load.
Looks low on the fueling table for the given RPM.
Looks low on the ignition table for given RPM.

Fuel is low and timing is advanced for the supposed lean condition.

O2 sensors pick up lean condition and increase fuel and timing. Car runs shit for a bit and within seconds/minutes we're back at square as the car trims out the issues.

Cap saw this on his wideband. So, how do you prevent the o2 sensors from seeing lean?
Make it so that there is more fuel, without the ecu knowing about it. Increase the injector size.

Going back you now have
- Low load = advanced timing from ignition table
- low fuel = lean
- "normal" CFM = lean (for this load)
Then...
- more about 20% more fuel (I think) from the 2zz injectors. Compensates for the lean condition, O2 sensors read stoich or near. Car thinks all is good.
You've shifted down on the ignition table.

Compared to stock 1zz you have more advance, which (compared to an oem ecu) can unleash more power as you're reducing the safety margin built in for knock (hence the 98 fuel).

So, if you increase the airflow of the car via exhaust or pre-MAF intake, nothing changes. As long as the fine-tuned calibration of the flow around the MAF remains the same. You're just shifted on the ecu load maps. Regardless of where on that map you are.

[Ardent]

Great read.
Which reminds me. When back on the road. Must recheck my trims now I've changed zorsts.

[Petrus]

Thanks Patrick.

The crux I was looking for being that the tables are 30-35% ´wide´ anyway.
So one cán flow 30-35% more air, the ECU will not throuw an error, the Yellow injectors squirt too much and the O2 signal makes the ECU turn down the whick in effect matching the air flow.