Tricking a 4age 20v silvertop ECU

[85AW20v]

So at wide open throttle when on the track, is the oxygen sensor doing anything as in optimising fuel or does the ECU run a predetermined map? Just wondering if I need to reconnect my sensor on the racecar. I'm not worried about economy - just power....

[Flannelman]

It is my understanding that the O2 sensor is used under closed loop operation. Which is light load. Under acceleration the O2 sensor is ignored, going into open loop operation. This falls on base fuel maps installed onto the ECU.

At which point closed/open loop occurs in regurd to MAP/throttle input is an unknown, but under full throttle it is 100% open loop.

Because of this understanding, I think that what I'm experimenting with is a viable option.
I also understand that if anything melts from my actions, I have no one to blame but myself so don't recommend this to anyone.

In further interest, I have an app for 1/4 mile timing. In stock trim it measured 15.07@154km/h. Rather quick for a ST 20V with mear bolt on gear, and basic blueprinted engine.

[sergei]

It is my understanding that the O2 sensor is used under closed loop operation. Which is light load. Under acceleration the O2 sensor is ignored, going into open loop operation. This falls on base fuel maps installed onto the ECU.

At which point closed/open loop occurs in regurd to MAP/throttle input is an unknown, but under full throttle it is 100% open loop.

Because of this understanding, I think that what I'm experimenting with is a viable option.
I also understand that if anything melts from my actions, I have no one to blame but myself so don't recommend this to anyone.

In further interest, I have an app for 1/4 mile timing. In stock trim it measured 15.07@154km/h. Rather quick for a ST 20V with mear bolt on gear, and basic blueprinted engine.

I have seen a stock 20V Marino (ST) with 2 12" subs in the back and exhaust do 15.1s on meremere many years ago (while my stock Trueno did flat 16).

[Flannelman]

Same here. The previous engine was a consistent 16.2 sec at meremere, dropping to 15.8sec with a header change. It's time began to slip due to damage of the snout of the crank from a loose harmonic balancer.

A month before the engine was swapped, the same app came up with 15.96@143km/h

The replacement short block has only minor changes. ARP rod bolts on shot peened stock rods. Stock ST Pistons, rods balanced independently, crank lightened by "flappy" sanding disc, journals polished to 2000grt wet/dry sand paper and polished with 3M cutting compound and finally balanced with the harmonic balancer. Block was sanded internally, with all casting flash removed, ARP main cap bolts. The new rings/bearings/oil pump I class as mandatory on any rebuild.

The head received the same treatment as my own, with the addition of the valves being lapped in manually with valve grinding paste. Both the head and block got a skim more for a true flat surface than compression increase.

The difference that is the reason behind the hp increase is the full exhaust. It was the same that got the last motor to 15.8sec.

Just looking now at putting a conclusion to this thread. So i ask, ignoring all other situations found under normal driving conditions, what is a target time difference on the drag strip that most/all toyspeeders would deem that what I am proposing (opening the plenum to atmosphere increases Hp) is plausible. The above data is so an educated guess can be given.

[Lith]

The first drag meet at Masterton in a couple of weeks, support the local venue, have some fun and get an actual official time whI checked can be considered valid data. Those apps can do OK as a thumb suck but comparing it with official times is potato.

[Flannelman]

Definitely be doing this on a strip. Time cards are hard evidence!
That, and the thought of trying to explaine 150+km/h on an open road to a police man is not the kind of meeting I want!

[Bling]

http://toyspeed.blakjak.net/profiles/quartermile.php

Aim for Loudtoy.

[Lith]

Definitely be doing this on a strip. Time cards are hard evidence!
That, and the thought of trying to explaine 150+km/h on an open road to a police man is not the kind of meeting I want!

Definitely, it'll be interesting to see how it goes. I'll be impressed if it goes 150+kph!

[RomanV]

It is my understanding that the O2 sensor is used under closed loop operation. Which is light load. Under acceleration the O2 sensor is ignored, going into open loop operation. This falls on base fuel maps installed onto the ECU.

At which point closed/open loop occurs in regurd to MAP/throttle input is an unknown, but under full throttle it is 100% open loop.

I just did some datalogging tonight.

One of the variables I can datalog is the long term fuel trim.

It doesnt 'stop' at *any* load or rpm combination.

It shows that above 3500rpm onwards, full throttle, it's all still yanking out 5.47% on every data point.

I dont think this means it runs closed loop while at full throttle though - just that it comes up with a 'constant' which it can apply across most of the map based on what it sees while operating under low load closed loop conditions. A fudge factor to account for slight variances in injector sizes, fuel pressure, signal from the airflow meter, etc.

I didnt think to datalog the oxy sensor readings, but I wouldnt be surprised to find that it still does monitor the oxy sensor for lean spots while at WOT.

But again, this is a slighly later motor so I cant comment on how the logic of your one works.

Just looking now at putting a conclusion to this thread. So i ask, ignoring all other situations found under normal driving conditions, what is a target time difference on the drag strip that most/all toyspeeders would deem that what I am proposing (opening the plenum to atmosphere increases Hp) is plausible. The above data is so an educated guess can be given.

That's not how it works, because it could be anything! For better or worse.

How it works is that you do 5 runs with the airbox on.
5 runs with the airbox off.

Then you come back and tell us if there was a repeatable difference. It's the only way, anything else is about as worthwhile as reading taro cards.

FYI though I was just doing some other datalogging on my car where I've had the filter element exposed in the engine bay.

Intake temps were between 30-40 degrees, maximum MAF reading was 151.9 grams / second.

I rejigged my intake so it was scooping air from the front, where it's not susceptible to engine heat etc.

Now has intake temps of 20-24 degrees in similar conditions.
Maximum MAF reading has increased to 159 grams per second.
Makes sense to me that these both point to more power being made by avoiding the heat.

Is there an air intake temp sensor seperate to the airflow meter on silvertops?
Would be interesting to see how hot it gets between airbox off or on.

[Flannelman]

I wish I could post up the 23 page file I have on toyota ECUs. It has great information on how the ECU calculates information from its sensors.

The air mass sensor (air flow meter) measures both flow and temperature. This is important to the ECU as it determines correct fuel requirement by amount of air and its density. As stated, low intake air requires more fuel than high. Low airflow requires more ignition timing that high.

As some variables to consider with opening the plenum, ignition timing is reduced as the ECU believes maximum air is entering the engine. Also the injector timing will be reduced as the air mass sensor will hold 30+intake air when with the plenum open and with a GZE bonnet allowing more cooler outside air into the engine.

I now fully understand why my dyno operator didnt want to do this on his dyno. Retarding an engine + Fuel lean out = Scorched engine components.

Some saving points is that fuel enrichment comes from the TPS. The moment the TPS is moved, fuel enrichment is activated. Also, the O2 sensor has a range of +/-20% in fuel input. (That's under closed loop operation tho). In general, the MAP is used to determine load which is a requires more fuel and as RPM increases fuel volume increases.

So, for a "fair" test, not only will I have to do a minimum of 3 runs, but with when the plenum opens ignition timing will have to be advanced. It may sacrifice some power being over advanced in the top of the rev range, but should improved everywhere else.

I will add this to the 3 runs "stock", 3 runs "open", 3 runs "open/advanced". I hope I can squeeze in 9 runs on a Friday Night Wars...

[RomanV]

Remember that your car doenst have a MAP sensor though... It's generally airflow meter or MAP, not both.

Either way, I look forward to results, best of luck.

Remember though, if in a worst case scenario and it doesnt go how you were expecting. Bad results do not mean you've failed.

Failure is making a change without quantifying the results, and being happy with something that's worse. This is how many people fail at car mods!

If you make something worse, quantify the change. Find out it's poor then try something else again, that's how you make steps in the right direction

Pretty much all of the clever people I look up to in terms of car mods etc go through this process.

[Lith]

Failure is making a change without quantifying the results, and being happy with something that's worse. This is how many people fail at car mods!

[Flannelman]

RESULTS

CLOSED PLENUM TIMESLIP

60'............2.429
330'...........6.668
1/8...........10.137@70.70MPH
1000'.........13.117
1/4...........15.630@89.25MPH

OPEN PLENUM TIMESLIP

60'............2.328
330'...........6.440
1/8...........9.846@71.96MPH
1000'.........12.783
1/4...........15.276@90.15MPH

CONCLUSIONS
Due the the final mph has minimal increase, peak hp (6500+) is no change.
However, mid range (3500-6500) there IS an increase. This is seen in the time decrease and speed increase up to the 1/8 mile.

ANYTHING ELSE?
Ran with full interior, plus spare, minor tools and 1/2 a tank of Gull E10 98
The runs where with wing mirrors tucked in
I ran 10W-30 oil instead of the usual 20W-50
STILL USING STOCK ECU, BLACKTOP INTAKE AND SILVERTOP EXHAUST CAMS

Course of action...
At present, I am constructing a new larger plenum. With this I can alter the ram tube shape and length.
Ultimately, these bolt on mods are only going to get so far. If I want to go faster both the core engine and ecu are going to need to be change.

Until then, I'm happy with 15.2 And a new personal best by 0.4sec!

[Flannelman]

In a rush!

this was done by 13 passes, 6 close plenum, 7 open.

fastest closed plenum was 15.59sec but I didnt get the timeslip for it

[Lith]

Cheers for sharing, did you get an average time for open and closed? The difference in those times is so close it could almost be attributed to the cleaner launch you got on the 15.2 - 2.3x is getting into realms of a decent launch, 2.4+ is pretty bad... as you get closer to the 2.1-2.2 range you find that FWD drag times can drop quite quickly without changing too much. 15.2 @ 90mph isn't too shabby for a basic silvertop

[Lith]

On the topic of open versus closed plenum, in the interests of the science of speed me and a couple of mates got together with the intention of trying a few different things out some things on one of their cars - a mildly tinkered with black top 20v 4AGE. The intent was to try a couple of different length trumpets, but it turned out to be difficult/impossible to fit the 130mm length ones we had available so the test became much more basic but still has things relevant to this discussion I believe.

Behold, a dyno comparison!

Key-
Light green: Open trumpets, bonnet closed
Red dashes: Factory plenum fit using TRD intake with factory airbox (bonnet closed or open resulted in exact same power curve)
Light blue: Factory plenum using TRD intake using a short ram pipe with pod filter attached - bonnet open
Red: Open trumpets, bonnet open



nb: AFR and timing was adjusted, and suitable pauses were done to ensure ECT and relative state of tune were comparable between all runs etc - because science.

[Flannelman]

Lith

Looking at the 60' times are rather shocking. My lowest on the day was a 2.278 but overall managed to get 15.297@89.78mph. Close, but not the quickest or fastest.

60' times are close overall. However, one of the best comparisons is this one

CLOSED PLENUM

60'........2.429
330'.......6.668
1/8........10.137@70.70mph
1000'......13.117
1/4........15.630@89.25mph

OPEN PLENUM

60'.........2.408.....................(0.021 stupidly close)
330'........6.546.....................(0.122sec gain)
1/8.........9.956@71.98mph.......(0.181sec gain @ 1.28mph faster)
1000'.......12.893...................(0.224sec gain)
1/4.........15.388@89.73..........(0.242sec gain @ 0.48mph faster)

better yet, on another open plenum run

60'..........2.666....................(wheel spin!! 0.237sec slower)
330'........6.827.....................(0.159sec slower
1/8.........10.214@72.62...........(0.77sec slower @ 1.92mph faster)
1000'.......13.129....................(0.012sec slower)
1/4.........15.619@90.10mph......(0.011sec gain @ 0.85mph faster.

The real gain is absolutely clear. In the mid range. BUT still hits the wall in the top end. If anything, it hits the wall earlier with the plenum off than with the plenum on.

WHY THE GAIN
Looking at the dyno from lith and these times, the gain is more from the difference in that the ECU is being told 40+C intake temp when the engine is getting low 20C.
The timing and fuel trim is more suited to what the engine wants.

In summarry, the removal of the plenum top may have helped increase airflow to the engine, but is more likely a colder air can enter the engine.
Colder air is the #1 reason for the power increase.

[RomanV]

Interesting results.

I decided I CBF with factory ECU anymore so bought a Link.

Which has been an interesting experience so far.

My car runs a MAP sensor now but I can keep the MAF there for datalogging, or if I want I can ditch everything right up to the TB.

So I've tried open throttle, 90 degree turn with a bellmouth, 90 degree turn with a bellmouth and pod filter, and the airbox setup I started with, that scoops air from front of the car.

Nothing has beaten the airbox so far, everything else I had to pull fuel out across the entire range to get the AFRs right again at WOT.

Something interesting though, with the standard airbox there's a 2KPA pressure drop from 6000rpm onwards, which is why I'd try a short ram type setup with a nice bellmouth.

When I had just the bellmouth attached to the TB, the pressure drop reduced to 1KPA until redline BUT I still had to yank out heaps of fuel to get the AFRs right. Indicating that it was sucking in less air in total than with the airbox/pressure drop.

Next on the menu is to try pipes 1/4" bigger diameter, and from a bigger airbox with a bellmouth in it.

ALL OF THE THINGS

[Lith]

On the topic of open versus closed plenum, in the interests of the science of speed me and a couple of mates got together with the intention of trying a few different things out some things on one of their cars - a mildly tinkered with black top 20v 4AGE. The intent was to try a couple of different length trumpets, but it turned out to be difficult/impossible to fit the 130mm length ones we had available so the test became much more basic but still has things relevant to this discussion I believe.

Behold, a dyno comparison!

Key-
Light green: Open trumpets, bonnet closed
Red dashes: Factory plenum fit using TRD intake with factory airbox (bonnet closed or open resulted in exact same power curve)
Light blue: Factory plenum using TRD intake using a short ram pipe with pod filter attached - bonnet open
Red: Open trumpets, bonnet open



nb: AFR and timing was adjusted, and suitable pauses were done to ensure ECT and relative state of tune were comparable between all runs etc - because science.

To follow up this post for those who are interested, one of the useful things gleaned from this test is that the short ram intake/pod filter setup almost matched the open ITB power curve - especially up high, and definitely matches or pulls away from the stock airbox configuration. There was some discussion on this, and while it's obvious that with the bonnet down (green curve) the hot air intake phenomenon kicks in on the dyno my experience and argument is that a basic shrouded short ram setup more than recovers from this once the car is moving and the only time you see the negative effects is at very low speed or idle.

After all this, Mark decided to build a short ram intake setup for his car and we did some road testing to ensure the tune was on point and also to see if it worked out as we hoped - this is one of those cases where road tuning/logging is in my opinion more useful than on a dyno as really, honestly you CAN'T perfectly recreate driving on the road with a dyno... especially with an intake setup like this.

To determine the effect on engine performance I compared the volume of fuel required to achieve equivalent air fuel ratios, and as a happy coincidence the car needed in the range of 2.5-3% more fuel through most of the rev range at full throttle at road speeds when compared to the stock airbox setup - that's even more than the extra 1.5% required on the dyno with the open trumpets!

I've seen this plenty of times before, but I hope this is something of a myth busted when it comes to hate on short ram intakes - dyno tests for these things do NOT prove anything unless you are doing all your racing at <50kph.

[Flannelman]

That's interesting lith.

Just to add my two cents, I built my new plenum and runs ran 15.37 at meremere V 15.31 with the same plenum, just open.

As traction was an issue when I raced (1500rpm launch, any more and wheelspin) and top end @ 92mph. I'm happy with the result.