Tricking a 4age 20v silvertop ECU

[Flannelman]

OK, I posted a video of my car with an open plenum with a stock ECU.

To do this I opened the top half of the plenum and held open the AFM with a hand brush. This is needed as the AFM controls the fuel pump and must be open for it to operate

Result was an idle @ 500rpm, occasional backfire out the intake and loss of throttle surge under 4000rpm. The EGT never exceeded 1300F (cruise is 1400F)

Ive had a skim over the basics of how the Toyota ECU operates and from my understanding the ECU gets it information from not only the AFM but, TPS, and MAP as well. As this has (and will be) used in racing situations, the TPS is mostly either at 100% or 0%. As the brush holds the AFM fully open, this is informing the ECU that there is a large volume of air entering the engine so fuel volume will be high. Ultimately, the overall air/fuel ratio will subsequently be rich.

Speaking to my tuner about this operation I was informed that this idea is bad and will result in a melted piston as the computer no longer knows the correct injection pulse width.

I have used this on the street, however fuel consumption is large so isn't an option for day to day running. The main reason for this is a test to see just how much a restriction everything before the intake ram tubes are. As my tuner wont let me run the car up on the dyno in this state of tune, the only other way is to drag race with a before and after runs. Calculations can be made to see if a power increase or decrease has happened.

Before I do this, can someone correct my neanderthal understanding (if this is a bad idea) and expand further on what my tuner is saying?

[Lloyd]

Silvertop uses the AFM rather than a MAP sensor. The AFM is the main source of information for the ECU as to how much fuel to use, the TPS accounts for some of that information but you wouldn't want to rely on it completely. Slight variations in fueling will have a big influence on power/driveability/reliability/fuel use. If you're just holding it wide open then you may as well not even use it.

A lot of ECUs will pick that the rpm/AFM/TPS don't all quite add up to what the computer would expect and then it starts running in limp mode anyway, though I don't think the Silvertop is quite that clever. Overfueling is going to cause some issues, though not as much of a concern as underfueling. Borewash, fouled plugs, dead oxygen sensors, excessive fuel consumption, lower power outputs etc. Better than melting it though.

The AFM isn't really a restriction anyway so there isn't much point running the plenum open.

[Grrrrrrr!]

Google simple manometer, make one (Plastic tube, water, food colouring(makes it easier to read), Piece of wood to hold it), plumb one end into intake tract just before plenum, leave other end open to atmosphere and use it to measure how much pressure drop (restriction) the inlet tract is causing next time you are on the dyno.

[Lith]

OK only have few moments but first things that come to mind based on the assumptions you have provided, I could be wrong but from my gut feel:

- YUCK. I hate this idea. Ok, got that off my chest.

- Why is he proposing it is going to "melt pistons"?!?! Did he provide reasoning? More on why I ask that in my next points

- With increased load, ignition advance requirement goes down and fuel requirements go up... there will be points that (at a guess) you could be running 10+degrees retarded timing at cruise and EXCESSIVELY rich mixtures.... the side effects I assume will be....

- How rich I suspect it could run could be enough for it to run pretty crap, potentially foul plugs, bore wash, and oh yeah use a lot of fuel - obviously when at cruise

- Soaring cylinder/EGT temperatures. Be interesting to see what you can do to your exhaust valves/manifold and I suppose this is where you might start melting pistons if things get hot enough to start dieselling

I don't know how bad it will all get, but I see the potential for some nightmarish tune stuff happening... especially at light loads.

Good luck

[Flannelman]

Grrrr!
That's a clever idea. I know of this trick and overlooked it completely. How foolish of me!

Lith, I've got an EGT and it didn't signal "thermal meltdown imminent". The main reason I wanted the dyno so I could see the air/fuel ratio under load plus see what the torque curve is doing. It would have confirmed good idea/bad idea very quickly.

[thegreatestben]

I just sold a link and complete loom for $250 that did away with the AFM.

Why would you bother with this sort of thing?

[Flannelman]

Because all I have is time and very little money. This results in me wanting what I can't afford. So until I can I will try and get the most out of what I have.

It's also learning new things as by the sound of it this is something new to the toyspeed community. Whether it works or not is irrelivant, toyspeed will benifit from whatever information I find out.

[sergei]

Because all I have is time and very little money. This results in me wanting what I can't afford. So until I can I will try and get the most out of what I have.

It's also learning new things as by the sound of it this is something new to the toyspeed community. Whether it works or not is irrelivant, toyspeed will benifit from whatever information I find out.

If you have very little money perhaps the best thing you can do is not to screw around with cars.
Besides this is not "new" to toyspeed.

The AFM offers very little to none in air restriction. AFM is the MAIN sensor for the ECU.
Opening plenum is a good way to lose power band. The factory intake is NOT restrictive.
If you don't want AFM for whatever silly reasons, you should get blacktop loom+ECU+map sensor and adapt it to your car. This is pointless.
Although by getting complete blacktop might be of the benefit (if you retain factory inlet).
If the only goal is to make the thing louder, then by all means....

The benefit for toyspeed will only be of entertainment value. Since the silvertops where around a lot of owners where pondering how to "unrestrict" them, including me. All your toothbrush mod does is create flat spots and reduces midrange at best, at worst you will kill your bores by always over-fuelling.

[Flannelman]

Sergei, I found your first sentence of that post vexing. From then on your condisending word structure just added to it.

If what I'm doing is a well beaten path, direct me to the search function and who/what to search for so I can see what they did and learn from there experience.

[Bling]

I don't get it either TBH, why not just get the blacktop bits as suggested?

Why not bang a carb on it? Even that would surely be a step up from running a configuration that is stopping the ECU from being able to do it's job properly.

Not having a dig, just none of it makes sense to me if you're trying to improve the engines power.

[Lloyd]

YUCK. I hate this idea.

If you have very little money perhaps the best thing you can do is not to screw around with cars.

Why would you bother with this sort of thing?

It's not just Sergei saying that, he is just being a bit more blunt about it

The Silvertop is fairly well tuned to get the most out of it standard while maintaining some sort of reliability and driveability. If you don't want to spend money then it isn't really worth touching it.

Is your goal just to run with with an open plenum? If so, google it. Basically the Silvertop runs an AFM and the blacktop runs a MAP sensor. You can't just swap them. If you've ported the head then the bigger throttle bodies on the blacktop may be of some benefit, but it'll be fairly minimal. The small amount of money you have to spend on it would be better spent on brakes/tyres etc rather than engine modification. The intake systems aren't particularly restrictive.

[Flannelman]

Alright, I get it. It's a stupid idea and I will forever treat it as such.

Still doesn't explain why I managed to go 1.5sec faster on Taupo track 3 using this technice.

[Lith]

As I stated above, the biggest issues I see are at light load - and that all depends on what the factory map is like etc, I have no idea how they are tuned so I wouldn't say for sure how it's running as that'd be silly. For the same reason, I am also not going to say "Yeah mate, she'll be right".

From your posts, and having met you... I figure you as reasonably smart - so I am assuming you have figured that a light breathing mod on a car running a 1.6litre engine, and no tuning to suit isn't going to give you the power increase required to knock off 1.5 seconds a lap all by itself?

If you really want to make it interesting, try keeping it partly opening - so instead of maxed out, try 75% or something like that.

<disclaimer: I didn't force you to do this, nor did I promise it was safe or going to give good results >

[Flannelman]

Ok, so each port has a flow potential of 200cfm (~200hp potential) the AFM was flowed to only support 160hp (not much more than standard)

By opening the top of the plenum, it begs to ask where is the restriction? Is it the AFM or the shape and size of the plenum?
As what info has been given today, the AFM isn't as serious as first thought but the plenum shape/size hasn't. I have found info on other sites that after market plenums are bigger with shorter runners, aiding top and loosing everywhere else.

Since noted, if the ecu (overfueling and less advance) + loss of plenum for hemlotz tuning should = LOSS OF HP, but this example hasn't.

I can't quantify the results other than the 1.5sec track time gain (10km/h quicker down the straights too)
So im a bit lost on this situatoon

[jondee86]

Can't really see what all the fuss is about

With the AFM and the throttles wide open the ECU is going to command
maximum fuel. Open the top of the box and you will get a bit more air
into the engine. As a result the engine does not run as rich as usual at
WOT and you get a bit more power. Your results on the track clearly
prove that.

Not surprisingly, fuel consumption and driveability at less than WOT will
be sub-optimal, but I don't think you made this experiment with driving
to the mall for a loaf of bread in mind

Cheers... jondee86

[Flannelman]

Thanks jondee86.

No, it was never my intention of having this as a permanent alteration. Only a rude, crude "race tune".

[Lith]

I would take it to a dyno operator who will just take your money and find out whether it's worth it, at this stage it's all fairly circumstantial evidence and if it turns out to be basically no gain then I'd call it not worth it - in my opinion. You could even do some kind of ultra rough testing, get a passenger who is reliable with a stop watch and do a 3rd gear pull from say 2500rpm - find out how long it takes to get to peak power, once with the "normal" setup and once with your new setup.

There is software out there (I've written some of my own) which uses datalogs using speed Δ versus time to calculate power throughout a pull and plot against rpm or speed - you can definitely get useful data using this kind of method, even if its not going to show where exactly in the rpm the gains are. Given how casually a 20v tends to accelerate in 3rd gear, the time scale of the entire pull (and as such, any changes) should be enough for a human to be able to measure if they are worthwhile - so if you can't get a measurable difference in a FULL 3rd gear pull, I would call it a waste of time.

[Bazda]

1.5s faster and 10kph faster down the straight on the same day?
Different days produce different results, tail wind, air temp etc. Maybe your driving is better etc.

You need to do a straight line test from point A to point B and measure the time.
Or take it to the Dyno which will give you accurate results.

[mr30%jr]

/

on a stock engine, why would you not use the AFM its going to give you optimal AFR for a production motor have you even looked at the AFR over a run and datalogged it a wideband?

[Flannelman]

Car is off the road for warrant repairs. Engine too smokey and leaks too much oil.

Replacement engine is similar to mine (its one I built for a friend, same head work)

When its all in and working again then I will post some data (and a video for the non-believers) of the results.