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Offline rarch

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Re: Vacuum value at idle (rough idle problem).
« Reply #10 on: 03 May, 2016, 08:12:11 PM »
Are you aiming for a too low idle speed, I believe it should be around 1200 +/- 100 rpm.  My bike idles at 1300 rpm.

Offline Robo

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Re: Vacuum value at idle (rough idle problem).
« Reply #11 on: 03 May, 2016, 09:14:49 PM »
*Originally Posted by J-man [+]
The Choke function keeps ON ?
A wild guess though.

= IACV Motor
If theres a gap i can get through it !!!

Some people pay for an IAM... I am mad.....

Offline Marudny

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Re: Vacuum value at idle (rough idle problem).
« Reply #12 on: 03 May, 2016, 09:41:09 PM »
*Originally Posted by rarch [+]
Are you aiming for a too low idle speed, I believe it should be around 1200 +/- 100 rpm.  My bike idles at 1300 rpm.

I don't know a position of iacv valve. Maybe I should aim 1200 rpm with map unplugged. But 1200 rpm is almost at the end of vacuum regulation range. I believe that iacv should raise rpm to optimal speed.

Offline Marudny

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Re: Vacuum value at idle (rough idle problem).
« Reply #13 on: 03 May, 2016, 09:53:30 PM »
*Originally Posted by Robo [+]
= IACV Motor

Iacv looks good. Increases idle at cold and decreases with raising coolant temperature.

I bought used throttle body with air box, fuel rail and injectors and all sensors.

But nothing explains higher fuel consumption. I'm sure that vacuum subsystem is sealed. Idling is rough without iacv correction. Tps is correct. Mixture is richer than expected. Everything goes to fuel pressure regulator. Typical fuel pump gives 5 bars. Fuel pressure regulator set it to 3,5 at idle and 4 - 4,5 when needed.

It explains everything - higher consumption (pressure is higher than needed), rough idle (too much fuel at idle). Richer mixture and dark spark plugs

Injectors has minimal open time. Below that they can't operate properly. Even if injectors have minimal open time calculated for 50 psi fuel pressure (as service manual says) which gives 3.5 bars, at 5 bars they gives much more fuel which is uncorrectable. In cars engine management injectors are chosen in that way. Minimal open time at idle.

I'll check fuel pressure at the weekend.

Regards Marudny.

Offline Marudny

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Re: Vacuum value at idle (rough idle problem) [SOLVED]
« Reply #14 on: 05 May, 2016, 11:20:52 AM »
Guys, case solved!

I measured fuel pressure at idle. Service manual says 50psi at idle (3.5 bar). I've got ~70 psi (4.8 bar). After reducing to 50 psi engine started to run smoothly. Additionally measured AFR at idle should be near to 14.7. Got 12 ;-)

New fuel pump is comming, i'll change her and set vacuum again to minimal values (screw regulators to max and set to highest vacuum).

Thnx for every answer and help!


Offline J-man

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Re: Vacuum value at idle (rough idle problem).
« Reply #15 on: 05 May, 2016, 12:14:57 PM »
Congratulations  :152:
and thank you for sharing your hunt.  :028:

Offline FireBladerDk

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Re: Vacuum value at idle (rough idle problem) [SOLVED]
« Reply #16 on: 05 May, 2016, 06:47:42 PM »
*Originally Posted by Marudny [+]
...  After reducing to 50 psi engine started to run smoothly. ...

How did you reduce the fuel pressure during that test?


Offline Marudny

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Re: Vacuum value at idle (rough idle problem).
« Reply #17 on: 05 May, 2016, 07:22:25 PM »
*Originally Posted by FireBladerDk [+]
How did you reduce the fuel pressure during that test?

I have got adjustable fuel pressure regulator with pressure meter and baypass.

Something like this:
http://m.ebay.com/itm/231824730304

Regards, M.

Offline Bifferman

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Re: Vacuum value at idle (rough idle problem).
« Reply #18 on: 05 May, 2016, 08:14:03 PM »
*Originally Posted by Marudny [+]
I have got adjustable fuel pressure regulator with pressure meter and baypass.

Something like this:
http://m.ebay.com/itm/231824730304

Regards, M.

As I said you are way out of my league (higher than).  I can see some of us coming to you for some diagnostic advice as and when we need it :028:

Andy
 :149:

Offline Marudny

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Re: Vacuum value at idle (rough idle problem).
« Reply #19 on: 05 May, 2016, 09:07:58 PM »
I have some general knowledge about electronic fuel injection and don't have typical motorcycle knowledge... but if I could help, I'll be glad.

Again, thnx for suggestions!

Regards, M.


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