Help with high idle

For discussing B&G MS-I/MS-II set-up and tuning of fuel parameters (including idle valves, etc.).
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br1070
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Help with high idle

Post by br1070 »

Hello,

I am running the latest B&G code on a MS2 and I was just able t get the 306 Windsor started for the first time. I am controlling the coil with the squirt and am using a 2 wire distributor with a VR sensor. The fuel system is a FAST 4 85lb\hr injector TBI. I have played with the ve table and spark advance table slightly, but I have an extremely high idle 3500+. I have been able to get the fueling to respond by fuel additions or reductions so I think I am heading on the right path. Any input or suggestions that could help me decrease the idle RPM would be welcomed.

Thank you,
Brad
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kjones6039
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Re: Help with high idle

Post by kjones6039 »

According to your MSQ, you are not using MS to control your idle. Try reducing the idle with the idle stop if so equipped.

Ken
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/ms2extra 3.4.0 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
br1070
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Re: Help with high idle

Post by br1070 »

Thanks for the reply Ken. I have the throttle blade stop screw adjusted so the blades are full closed, but I think I may have an issue with the gasket between the intake and tbi. I'll check it out and see if that helps.

Thank you,
Brad
kjones6039
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Re: Help with high idle

Post by kjones6039 »

Yep.......... Sounds like a vacuum leak then!

Ken
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/ms2extra 3.4.0 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
br1070
MegaSquirt Newbie
Posts: 19
Joined: Wed Jan 21, 2015 7:12 am

Re: Help with high idle

Post by br1070 »

Ken,

I see you are using a similar TBI setup to mine, any tips or tricks to setting fueling? Did you find simultaneous squirts or alternating squirts to work better for you etc..

Thanks,
Brad
kjones6039
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Re: Help with high idle

Post by kjones6039 »

Hi Brad,

The big difference between our setups is the firmware! I am running Extra code, so some of my setup won't be applicable to your MS.

I am running 2 squirts simultaneous, mostly because I run staged injectors and simultaneous is required.

I will attach my current msq, but REMEMBER it is using Extra code!

Ken
You do not have the required permissions to view the files attached to this post.
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/ms2extra 3.4.0 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
br1070
MegaSquirt Newbie
Posts: 19
Joined: Wed Jan 21, 2015 7:12 am

Re: Help with high idle

Post by br1070 »

Hi Ken I uploaded your MSQ and I have to say MS Extra looks like the real deal. I kind of like the simplicity of the B&G firmware, but I like the control and the diagnostic tools that the extra code offers.

By the way I had multiple vacuum leaks lol.

Thanks again,
Brad
kjones6039
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Re: Help with high idle

Post by kjones6039 »

br1070 wrote:Hi Ken I uploaded your MSQ and I have to say MS Extra looks like the real deal. I kind of like the simplicity of the B&G firmware, but I like the control and the diagnostic tools that the extra code offers.
Early on I ran B&G code on a TPI setup on my grandsons Chev 350 truck. When I started the current Corvette project I switched to Extra and have never regretted it.
br1070 wrote:By the way I had multiple vacuum leaks lol.
Had a hunch you were going to find the high idle issue there.

Ken

EDIT: Just curious...... Does the FAST TB use a 4 wire IAC like the Holley Pro-Jection?
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/ms2extra 3.4.0 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
br1070
MegaSquirt Newbie
Posts: 19
Joined: Wed Jan 21, 2015 7:12 am

Re: Help with high idle

Post by br1070 »

If your IAC is this one i found online then i dont think so. The IAC for the fast is from a LS era IAC valve which is still 4 wire, but slightly different i believe.

https://www.holley.com/products/fuel_sy ... arts/543-2

Brad
kjones6039
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Re: Help with high idle

Post by kjones6039 »

Actually, this is the one my Holley Commander uses........

https://www.holley.com/products/fuel_sy ... ts/543-105

Ken
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/ms2extra 3.4.0 Release
36-1, Delphi LS2/7 coils in wasted spark, driven by v2.0 logic board from JBPerformance
Spartan Lambda Sensor from 14point7
br1070
MegaSquirt Newbie
Posts: 19
Joined: Wed Jan 21, 2015 7:12 am

Re: Help with high idle

Post by br1070 »

That's probably the same iac the fast unit uses.....I'm having to research which iac it is because I bought my tbi second hand without sensors.

Brad
br1070
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Re: Help with high idle

Post by br1070 »

Well.....since I attempted to plug the vacuum leaks things have gone a little crazy.....

The idle RPM,AFR, MAP, EVERYTHING except throttle position look like they are riding a roller coaster lol. I have attached a log and MSQ used for the log......not sure where to go from here.

Thanks
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