EA81 supercharger revamp by Tweety
- steptoe
- Master Member
- Posts: 11582
- Joined: Thu Oct 06, 2005 10:00 am
- Location: 14 miles outside Gotham City
idle adjust screw on the EA82T TB's, not to be confused with the fast idle circuit next to it with the big bolt on hex bodied solenoid - for AC on sort of thing.
The idle adjust is tapered at the end, air enters above butterfly, exits not below butterfly in venturi but straight out below. air adjust, no bloody fuel goes through it ! According to the manual, more than half the air for idle goes through this screws air bleed, the other less than half must be via the butterfly inside
The idle adjust is tapered at the end, air enters above butterfly, exits not below butterfly in venturi but straight out below. air adjust, no bloody fuel goes through it ! According to the manual, more than half the air for idle goes through this screws air bleed, the other less than half must be via the butterfly inside
- Gannon
- Senior Member
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- Joined: Sat Nov 05, 2005 10:00 am
- Location: Bowraville, Mid Nth Coast, NSW
Yeah the screw is just a bypass for the butterfly. Wind it out and it lets more air through making the engine idle faster. Mixtures are set by the ECU and there is no adjustment.
Just make sure your oxygen sensor is less than 80,000kms old and your mixtures should be sweet at idle and cruise.
Just make sure your oxygen sensor is less than 80,000kms old and your mixtures should be sweet at idle and cruise.
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
Ongoing Project/Toy: 1987 RX Turbo EA82T, Speeduino ECU, Coil-pack ignition, 440cc Injectors, KONI adjustale front struts, Hybrid L Series/ Liberty AWD 5sp
Past rides: 92 L series turbo converted wagon, 83 Leone GL Sedan, 2004 Liberty GT Sedan & 2001 Outback
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Ongoing Project/Toy: 1987 RX Turbo EA82T, Speeduino ECU, Coil-pack ignition, 440cc Injectors, KONI adjustale front struts, Hybrid L Series/ Liberty AWD 5sp
Past rides: 92 L series turbo converted wagon, 83 Leone GL Sedan, 2004 Liberty GT Sedan & 2001 Outback
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Tweety, just some suggestions.
I would get some new plugs and start from scratch. Then you can read the plugs and they will tell you how the engine is running. What you'd want to do is put in the new plug, start it up, pull away without letting it idle for too long do a WOT pull up the road (if it can) then pull up and shut the motor off straight away, pull the plug and see what it looks like. Aim of the game is coffee brown, but really you will only want to make sure its not ash white. Black means rich.
You can do the same thing with idle and mid throttle too if you wanted to.
Another thing you can do is If you have a multimeter, you can wire in another point off the o2 sensor and measure the voltage coming out. If you wire it up with some long leads you should be able to put it somewhere where you can see it while you ride. I think from memory that if its above half a volt (0.5v) its lean and below half a volt is rich(I think, someone who's good with there narrow band sensors may need to correct that).
Or failing both of those just take it to a dyno. Most likely they will have the gear to retune it (via fuel pressure and maybe a few other tricks) if necessary. They will definitely be able to help you out with mixture readings though.
Regards
Doug
I would get some new plugs and start from scratch. Then you can read the plugs and they will tell you how the engine is running. What you'd want to do is put in the new plug, start it up, pull away without letting it idle for too long do a WOT pull up the road (if it can) then pull up and shut the motor off straight away, pull the plug and see what it looks like. Aim of the game is coffee brown, but really you will only want to make sure its not ash white. Black means rich.
You can do the same thing with idle and mid throttle too if you wanted to.
Another thing you can do is If you have a multimeter, you can wire in another point off the o2 sensor and measure the voltage coming out. If you wire it up with some long leads you should be able to put it somewhere where you can see it while you ride. I think from memory that if its above half a volt (0.5v) its lean and below half a volt is rich(I think, someone who's good with there narrow band sensors may need to correct that).
Or failing both of those just take it to a dyno. Most likely they will have the gear to retune it (via fuel pressure and maybe a few other tricks) if necessary. They will definitely be able to help you out with mixture readings though.
Regards
Doug
- Tweety
- General Member
- Posts: 1253
- Joined: Mon Jul 04, 2011 9:45 am
- Location: ea81 powered trike Victoria
Thanks guys. I think it is the idle screw like Gannon said. A picture of it is in the manual. I'll put the throttle stop screw back to where it was and screw out the big screw till i get the idle I desire.
[SIGPIC][/SIGPIC]Tweety trike- EA81 (full reco 2014) 32/36 weber, SPFI manifold, 9.5:1 CR, VW auto.
- Tweety
- General Member
- Posts: 1253
- Joined: Mon Jul 04, 2011 9:45 am
- Location: ea81 powered trike Victoria
Here it is from the conversion instructions. yes, IAS idle adjusting screw.

well isnt it great that the mixture is set by the ECU. and no points, I have iridium plugs, very little maintenance. Some injector cleaner would be a good investment.
ps Thanks also Doug for your suggestions. looks like I've saved myself from most of those actions.

well isnt it great that the mixture is set by the ECU. and no points, I have iridium plugs, very little maintenance. Some injector cleaner would be a good investment.
ps Thanks also Doug for your suggestions. looks like I've saved myself from most of those actions.
[SIGPIC][/SIGPIC]Tweety trike- EA81 (full reco 2014) 32/36 weber, SPFI manifold, 9.5:1 CR, VW auto.
If you look up the throttle body setup details, it should tell you to set the butterfly to be open by a certain amount. Then use the IAS to adjust your idle speed.
As the computer has no adjusments, that initial butterfly setting will be what the ECU software works from.
That can change the mixtures as well, depends how far out of "set" it is, how much effect it has.
The TPS also has to be referenced to the butterfly opening, even if it is only a switch type TPS.
As the computer has no adjusments, that initial butterfly setting will be what the ECU software works from.
That can change the mixtures as well, depends how far out of "set" it is, how much effect it has.
The TPS also has to be referenced to the butterfly opening, even if it is only a switch type TPS.
L serious, still.
- littlewhiteute
- Junior Member
- Posts: 623
- Joined: Sat Sep 30, 2006 7:22 am
- Location: Brisbane
Coffee brown is old school leaded fuel.Subydoug wrote:Tweety, just some suggestions.
I would get some new plugs and start from scratch. Then you can read the plugs and they will tell you how the engine is running. What you'd want to do is put in the new plug, start it up, pull away without letting it idle for too long do a WOT pull up the road (if it can) then pull up and shut the motor off straight away, pull the plug and see what it looks like. Aim of the game is coffee brown, but really you will only want to make sure its not ash white. Black means rich.
You can do the same thing with idle and mid throttle too if you wanted to.
Another thing you can do is If you have a multimeter, you can wire in another point off the o2 sensor and measure the voltage coming out. If you wire it up with some long leads you should be able to put it somewhere where you can see it while you ride. I think from memory that if its above half a volt (0.5v) its lean and below half a volt is rich(I think, someone who's good with there narrow band sensors may need to correct that).
Or failing both of those just take it to a dyno. Most likely they will have the gear to retune it (via fuel pressure and maybe a few other tricks) if necessary. They will definitely be able to help you out with mixture readings though.
Regards
Doug
Colour of the metal shell should be dark grey, insulator off-white.
Low volts - (0-.4) - lean; high volts - (.7 - 1.0) - rich.
Regards
Gary
Gary

- Tweety
- General Member
- Posts: 1253
- Joined: Mon Jul 04, 2011 9:45 am
- Location: ea81 powered trike Victoria
Ok, no problems now. havent been out there to return the throttle stop back to its position and adjust idle with the bleed screw. But seems simple enough.
I havent got full power yet. Will swap the iridiums for standard plugs and see how it goes then, and reckon a new injector might be the go but at $600 landed here its a bit rich. might see if an injector place will spruce it up a bit.
This really draws to a close this thread. I'd like to thank you all for participating through the install/ordeal/delight/ordeal....lol. thanks to Dean for selling me the SPFI system to.
Seriously- I'd be a fair bit lost without you all.
I havent got full power yet. Will swap the iridiums for standard plugs and see how it goes then, and reckon a new injector might be the go but at $600 landed here its a bit rich. might see if an injector place will spruce it up a bit.
This really draws to a close this thread. I'd like to thank you all for participating through the install/ordeal/delight/ordeal....lol. thanks to Dean for selling me the SPFI system to.
Seriously- I'd be a fair bit lost without you all.

[SIGPIC][/SIGPIC]Tweety trike- EA81 (full reco 2014) 32/36 weber, SPFI manifold, 9.5:1 CR, VW auto.
- Tweety
- General Member
- Posts: 1253
- Joined: Mon Jul 04, 2011 9:45 am
- Location: ea81 powered trike Victoria
At this stage Steptoe I'd say no. A few observations.
Short test ride revealed much less low down power and acceleration than the
SC. Mid range a little less than the SC but impressive enough. Top end power was way down. In fact Tweety had difficulty getting beyond 100kph.
This SPFI unit apparently was from Alaska. Who knows how long since fuel graced its injector. So me thinks injector cleaner for a couple of thousand kms would be in order.
As for comparison to weber the sPFI in my view is smoother and much smoother than SC. But I'd say this unit isnt running to its full potential. I'd say an injector service form a reputable injector expert would do some good. A new injector is available from the states for around $600 landed here- gulp!
Tomorrow weather permitting a long ride to clean out some cobwebs and get that cleaner in the fuel tank.
Any other suggestions welcome
Short test ride revealed much less low down power and acceleration than the
SC. Mid range a little less than the SC but impressive enough. Top end power was way down. In fact Tweety had difficulty getting beyond 100kph.
This SPFI unit apparently was from Alaska. Who knows how long since fuel graced its injector. So me thinks injector cleaner for a couple of thousand kms would be in order.
As for comparison to weber the sPFI in my view is smoother and much smoother than SC. But I'd say this unit isnt running to its full potential. I'd say an injector service form a reputable injector expert would do some good. A new injector is available from the states for around $600 landed here- gulp!
Tomorrow weather permitting a long ride to clean out some cobwebs and get that cleaner in the fuel tank.
Any other suggestions welcome
[SIGPIC][/SIGPIC]Tweety trike- EA81 (full reco 2014) 32/36 weber, SPFI manifold, 9.5:1 CR, VW auto.