20v bt 7age A/F ratios

v33sonata
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20v bt 7age A/F ratios

Postby v33sonata » Mon Jul 04, 2016 7:16 pm

So during WOT im running 15-16:1 A/R until I hit 5500rpms where I am at 14.7-14.3

How can I correct the low RPM A/R?

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Mon Jul 04, 2016 8:09 pm

- What size injectors are you running ?
- What ECU are you using ?
- Are you driving the car to check AFR's or revving it in the garage ?

Those numbers are low for AFR at WOT under load. You should be at least one and
a half full numbers lower at both high and low rpm. If you have the 7AFE ECU and
injectors (is that possible with a 4AGE head ?) you should be close on AFR. If you
have 4AGE injectors and ECU you will be well short on fuel.

You could try cranking the fuel pressure higher and see what happens. It should
improve AFR's across the board if your fuel pump is up for it :)

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby v33sonata » Mon Jul 04, 2016 9:16 pm

its all 20v bt stock stuff. Its while I am driving looking at my wide band. I cranked the pressure up to 40 psi and at one point 44 and its brought the afr more normal but I seem it be having other issues as well viewtopic.php?f=13&t=19166

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Mon Jul 04, 2016 11:26 pm

OK... I did some digging and it seems the 1800cc 7AFE injectors are rated @ 192cc/min
and the 1600 4AGE 20V injectors are rated @ 295cc/min :shock: So contrary to what I wrote
above, you should be pretty close on the AFR with the BT injectors, but you would be way
off (lean) with the 7AFE injectors. Kind of interesting, as the BT injectors would be big
enough for a lot of 2 litre engines.

Now, assuming that the 7AGE breathes about as efficiently as the 4AGE, the extra 200cc
would call for an extra 12.5% of fuel. You should be able to deliver this by upping the fuel
pressure 10% or so over the stock 36psi... 44psi should do it OK. If you have a fuel pressure
gauge installed, check to see if the fuel pressure drops when you crack the throttle wide open.

Do you know what compression ratio the engine is running ? If it is dropping power for no
obvious reason, it could be that the knock sensor is pulling timing.

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby v33sonata » Tue Jul 05, 2016 8:26 am

I took off the Adjustable FPR and am running the stock one again. and its running fine revs to 8k no issues. However at low rmps its missing and hesitating. at thoses low rpms the AFR is between 16-17.7 so she is lean down low. Running more pressure with the adjustable FPR fixed that but caused issues with the ECU. My guess is running the stock and adjustable together isnt working for some reason or...... my FPR is bad.

I'm running 11.5:1 CR

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Tue Jul 05, 2016 2:57 pm

I'm not sure that there is any easy answer. Basically you have a stroked 4AGE
with 12.5% more capacity that will take in 12.5% more air at idle. And that means
the engine will require 12.5% more fuel at idle. I would have thought that the
ECU might have been able to compensate by adding more fuel, but it seems not
to be happening.

If you ignition timing is running at around 15deg at idle, and your engine vacuum
is near enough on spec, then the ECU is doing its best. Note that the BT ECU has
some learning capability, so it will compensate for out of spec sensor readings
if you give it a bit of time to learn. However, learned behaviour is lost when the
ECU gets reset, and the process must start all over again.

If the idle does not improve after a week of normal round town driving, then you
will have to do a bit of juggling with your adjustable FPR. Up the pressure one
or two psi at a time, and give the ECU a bit of time to compensate. It should be
able to find a happy position between too lean and too rich.

Of course, the ultimate solution is an aftermarket ECU :)

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby v33sonata » Wed Jul 06, 2016 10:43 am

using the stock FPR I was messing around and she seems to run when at 16-17 AFR. So today I unplugged the Air intake temp sensor and the AFR leveled out 14.7-14.9 Car got super slow and stopped reving past 6k again. Then went into "limp mode". Reset the computer and reinstalled air sensor. back to 16-17. It seems anytime I add fuel the car goes into limp move and starts acting up until I reset the ECU but when running lean the car runs decent but low end its studdering ????

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Wed Jul 06, 2016 3:15 pm

I believe that the ECU monitors the AFR via the O2 sensor, and will try adjusting
the mixture to keep the AFR within its factory programmed limits. So it is possible
that when it has adjusted the mixture as far as it can, it will then throw a code
and go into limp mode.... but I don't know this for sure.

There is a code for "over lean", and a code for short or break on the sensor wire.

Have you tried retarding the timing a couple of degrees ?

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby v33sonata » Wed Jul 06, 2016 5:30 pm

well after aruging with my buddy who insists its the 02 sensor I finally pulled it off and sure enough its rattling.I'm pretty sure they are not suposed to do that. I was also pretty sure I had replaced it already but I guess not ;/ ill get a new one and try again tomorrow

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Re: 20v bt 7age A/F ratios

Postby yoshimitsuspeed » Fri Jul 08, 2016 5:42 pm

You said the FPR messed with the ECU. Can you give more information? As said, you should be able to increase the fuel pressure or injector size by roughly the increase in displacement to get you into the right pallpark. There is no reason changing the fuel pressure should mess with anything else.
If your O2 sensor is messed up this could be causing problems. You know there are tests for it and all other electronics in the FSM so you don't have to just throw parts at the car right?

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Tue Jul 12, 2016 9:46 am

Hey guys.
I got some things dialed in this weekend. She needed a new O2 sensor. I also got the adapter in to run my single FPR. So here is whats going on now. I'm running about 44psi with 10 degrees of timing. My afr are about 13-14.7 from 0 to 3000 rpms then she leans out to about 16-15.5 until I fit 5500 rpms where it drops to mid 14's again. But now I can only rev to 6800 rpms before it seems like it missfires like crazy. i'm hoping this is due to not having a VSS as my speedocable just broke. (new one already on the way) When I disconnect the battery I can get 2 or 3 pulls out of it past 8k rpms before the computer cuts me out early. It also seems at that point she isnt reving as smoothly and power dies down a bit :/

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Tue Jul 12, 2016 9:50 am

also to add. when I use the stock FPR she runs pretty lean and power down low is all messed up but she ECU doesnt cut my revs down to the 6800 she revs free.

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Re: 20v bt 7age A/F ratios

Postby yoshimitsuspeed » Fri Jul 15, 2016 5:18 pm

It's important to note your throttle position. Under light load it should stay at stoich. With the GZE ECU and my limited experience with the NA and other Toyota ECUs that cutoff will change with RPM. So for example I might be able to give it 80% throttle at 3000 RPM before it switches to open loop but at 6000 RPM it might switch to open loop around 50% throttle. By redline it takes very little throttle input to go open loop.

It will also help to reset the ECU after any big change you make. If it has a bunch of miles on it learning the old setup when you make a big correct change it may not look correct because the ECU is trying to compensate for the old setup. On a fresh reset it should run just a little rich across the board and will start to lean out over time. Idle and cruise will stabilize pretty quick because you spend more time there. On the other hand I have noticed WOT and high RPM bins take a lot longer and you can see AFRs still changing a little after a couple hundred miles.
With the MAP setup the motor only has one way to adapt to VE changes and that is closed loop learning through the O2 sensor. If your O2 sensor was bad it could have really messed up your maps so you would definitely be best off resetting the ECU. It is not likely it will want to adapt a whole lot to big VE changes so if you still find your AFRs going lean in areas and rich in others and if it is actually related to VE changes you might be best off trying to do something like tweak cam timing to try to bring the VE curves closer to stock. Or just go aftermarket engine management hehe but I have always believed the BT ECU should be able to run a 7A reasonably well with a little work.

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Fri Jul 15, 2016 7:43 pm

v33sonata wrote:I'm running about 44psi with 10 degrees of timing.

Just checking, but this is 10 deg of base timing (read in diagnostic mode) not
10 deg when the engine is in normal running mode ? Normal running should show
15-17 deg with the light at idle.

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sat Jul 16, 2016 5:34 pm

jondee86 wrote:
v33sonata wrote:I'm running about 44psi with 10 degrees of timing.

Just checking, but this is 10 deg of base timing (read in diagnostic mode) not
10 deg when the engine is in normal running mode ? Normal running should show
15-17 deg with the light at idle.

Cheers... jondee86


correct.

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sat Jul 16, 2016 5:36 pm

yoshimitsuspeed wrote:It's important to note your throttle position. Under light load it should stay at stoich. With the GZE ECU and my limited experience with the NA and other Toyota ECUs that cutoff will change with RPM. So for example I might be able to give it 80% throttle at 3000 RPM before it switches to open loop but at 6000 RPM it might switch to open loop around 50% throttle. By redline it takes very little throttle input to go open loop.

It will also help to reset the ECU after any big change you make. If it has a bunch of miles on it learning the old setup when you make a big correct change it may not look correct because the ECU is trying to compensate for the old setup. On a fresh reset it should run just a little rich across the board and will start to lean out over time. Idle and cruise will stabilize pretty quick because you spend more time there. On the other hand I have noticed WOT and high RPM bins take a lot longer and you can see AFRs still changing a little after a couple hundred miles.
With the MAP setup the motor only has one way to adapt to VE changes and that is closed loop learning through the O2 sensor. If your O2 sensor was bad it could have really messed up your maps so you would definitely be best off resetting the ECU. It is not likely it will want to adapt a whole lot to big VE changes so if you still find your AFRs going lean in areas and rich in others and if it is actually related to VE changes you might be best off trying to do something like tweak cam timing to try to bring the VE curves closer to stock. Or just go aftermarket engine management hehe but I have always believed the BT ECU should be able to run a 7A reasonably well with a little work.


Yes I have reset the ecu after any changes I do. I'm not sure what you are getting at with throttle position?? I agree the stock BT ecu should be able to run a 7age relatively well. I will do a stand alone once I feel I have the BT ecu dialed in as much as I can and their are not other issues.

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sun Jul 17, 2016 8:30 am

I changed out the speedo cable and reset the ecu and no changes. I started to mess with fuel pressure again this morning. When I run 40psi the afr are almost spot on but she cuts me out at 6800 rpms. I have her at about 39 psi and I can rev fully to 8200 rpms with a slight miss at 7k but my afr are about 15-16.8......... Ahhhhhh what is going on here?

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sun Jul 17, 2016 11:55 am

ive also lowered the timing down to 5 degrees it doesnt seem to effect anything

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Re: 20v bt 7age A/F ratios

Postby jondee86 » Sun Jul 17, 2016 8:54 pm

The only significant thing I can think of about 6800 rpm, is that the BT ECU is said
to switch VVT off at 6800 rpm. So it might be that the ECU also makes changes to
the fuel and ignition timing at 6800 rpm... and (pure conjecture) these changes
might induce knock.. and the ECU then cuts timing ?

There are so many variables that can affect the way the engine runs, that without
a full engine diagnostic it is impossible to guess what might be happening. One test
might be to unplug the VVT solenoid and see what difference it makes at 40 psi and
6800 rpm.

Cheers... jondee86
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Re: 20v bt 7age A/F ratios

Postby yoshimitsuspeed » Mon Jul 18, 2016 4:28 pm

v33sonata wrote:
Yes I have reset the ecu after any changes I do. I'm not sure what you are getting at with throttle position??


I mean is this happening at WOT? Or at partial throttle? If at partial throttle then approx how much throttle?

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Mon Jul 18, 2016 5:16 pm

yoshimitsuspeed wrote:
v33sonata wrote:
Yes I have reset the ecu after any changes I do. I'm not sure what you are getting at with throttle position??


I mean is this happening at WOT? Or at partial throttle? If at partial throttle then approx how much throttle?

at WOT I have not tried at partial throttle.

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Mon Jul 18, 2016 5:16 pm

jondee86 wrote:The only significant thing I can think of about 6800 rpm, is that the BT ECU is said
to switch VVT off at 6800 rpm. So it might be that the ECU also makes changes to
the fuel and ignition timing at 6800 rpm... and (pure conjecture) these changes
might induce knock.. and the ECU then cuts timing ?

There are so many variables that can affect the way the engine runs, that without
a full engine diagnostic it is impossible to guess what might be happening. One test
might be to unplug the VVT solenoid and see what difference it makes at 40 psi and
6800 rpm.

Cheers... jondee86

ill give it a shot

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sat Jul 23, 2016 4:00 pm

I gave up. I ordered MS2pnp and getting a tune next week. Thank you all your help.

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Re: 20v bt 7age A/F ratios

Postby Ratranger » Sat Jul 23, 2016 5:19 pm

Have fun. The MSPNP is going to need mods if you want to keep the vvt, and will not be just plug and play for a 20v.
4age bigport in a 73 spitfire

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sat Jul 23, 2016 6:32 pm

incorrect sir

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Sat Jul 23, 2016 6:34 pm

incorrect sir, the 20v VVT is an on off system which megasquirts system supports. Plus its being Dyno tuned by a local tuner so I am not to too worried

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Re: 20v bt 7age A/F ratios

Postby Ratranger » Sun Jul 24, 2016 10:41 am

I know ms can support vvt, i have my car running ms2 v3 that i built myself. But the pnp for a 4ag is for usdm 16v engines. The 93-95 mr2 pnp may work with the 20v, but there is very little about anyone using pnp for that. Check out the msextra forums, a majority use ms2/ms3 because it is simpler to mod and adapt to all the different set ups.
4age bigport in a 73 spitfire

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Re: 20v bt 7age A/F ratios

Postby jdm86gtz » Sun Jul 24, 2016 2:25 pm

Ratranger wrote:I know ms can support vvt, i have my car running ms2 v3 that i built myself. But the pnp for a 4ag is for usdm 16v engines. The 93-95 mr2 pnp may work with the 20v, but there is very little about anyone using pnp for that. Check out the msextra forums, a majority use ms2/ms3 because it is simpler to mod and adapt to all the different set ups.


I used the MR2 pnp on a blacktop 20V.

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Tue Jul 26, 2016 7:33 pm

After dasy back and forth with DIY and my tuner we went with
https://www.diyautotune.com/product/meg ... ica-3sgte/

as both say it should work. I wont be able to schedule a tune for another 1.5 weeks. As soon as its done i'll up date you guys.

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Re: 20v bt 7age A/F ratios

Postby v33sonata » Thu Aug 04, 2016 7:07 am

So it works. I am not sure if I would recommend it to anyone which I will post in a different area. later today..........

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