Guys, this is interesting...
This is on a chevy V8 350 with HEI distributor, MS controlling fuel only.
I was setting a MS-I v2.2 on this engine and I got it idling a couple times. Cranking RPM was something above 300 RPM (but I'm not 100% confident on my memory). Then suddenly it started showing something around 130 RPMs and won't start. I thought it could be MS, then got a MS-II V3 and the same thing happens. It shows ~130 RPMs, it seems that all spark plugs are firing as long as it's cranking, but won't start...
Then I thought it could be the ignition module (4 pin HEI) that went crazy, so I got a 7-pin but nothing changed.
So, here are my 2 questions:
1) As I'm not pretty sure about the cranking RPM when I got it idling, can I be making some confusion? Is ~300 RPM the normal cranking RPM for this engine? Is ~130 too low?
2) Could it be VR sensor misreading?
Low RPM at cranking on 2 different MS
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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Matt Cramer
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Re: Low RPM at cranking on 2 different MS
The Cranking RPM setting simply means "Use the cranking pulse width if RPM is less than this." 130 RPM isn't all that odd a real cranking RPM. Check if the plugs are wet with fuel or dry.
Re: Low RPM at cranking on 2 different MS
Hi Matt, thanks for replying!Sorry, I may have confused you, When I say "cranking RPM" I actually mean the RPM that is being read from tach input. In the "Realtime Display" it is showing ~ 130 RPM...and I recall seeing more than this on the first couple times I started the engine... but maybe I'm wrong...Matt Cramer wrote:The Cranking RPM setting simply means "Use the cranking pulse width if RPM is less than this." 130 RPM isn't all that odd a real cranking RPM. Check if the plugs are wet with fuel or dry.
After some time the spark plugs get wet and then I just got some random sparks...
So, as you are saying, around 130 RPM is OK when cranking? What RPM you usually see in a SBC 350?
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Matt Cramer
- Super Squirter
- Posts: 2951
- Joined: Sat Jul 03, 2004 11:35 am
Re: Low RPM at cranking on 2 different MS
That's a normal RPM to see if it's not lighting off the fuel. It sounds like you're using too much cranking pulse width and flooding the engine.