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 Post subject: Re: Cam sensor success
PostPosted: Wed Sep 16, 2020 10:33 am 
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Supercharged
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Joined: Sat Nov 27, 2004 8:03 pm
Posts: 7209
Location: IRWIN PA
Car Model:
I have Idle Issues as well.

But I think I will have t upgrade Past MSII to go sequential.

I also have a mess with the emissions stuff so It's worth a try.



Greg

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 Post subject: Re: Cam sensor success
PostPosted: Wed Sep 16, 2020 10:46 am 
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Supercharged
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Joined: Sun Nov 03, 2002 9:20 pm
Posts: 12952
Location: Fircrest, WA
Car Model: 76 D100
This is really great info. Very good find on the cam position sensor.


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 Post subject: Re: Cam sensor success
PostPosted: Wed Sep 16, 2020 6:11 pm 
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Supercharged

Joined: Wed Sep 17, 2008 6:48 pm
Posts: 3383
Location: Indianapolis
Car Model:
The cam sensor info is very useful, improved fuel delivery should improve engine performance.

I found on my MS3 that I was able to fix a hunting idle and AFR issue and stabilize pulse width with adjustments to ignition timing and the VE table.

Basically in the 'hunting idle zone' take ignition timing out in the zone where the idle is increasing and add ignition timing where the idle is decreasing.
While smoothing out the VE percentages in the idle zone to achieve the target AFR.

the 10 minute linked video goes through the details

https://www.youtube.com/watch?v=eF_uAxpbzCw

This worked for my new motor.

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 Post subject: Re: Cam sensor success
PostPosted: Wed Sep 16, 2020 7:35 pm 
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Board Sponsor & Contributor

Joined: Thu Oct 31, 2002 5:39 pm
Posts: 23636
Location: North America
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Sacred poo (i.e., holy crap) that is rilly, rilly cool!

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 Post subject: Re: Cam sensor success
PostPosted: Thu Sep 17, 2020 7:53 am 
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TBI Slant 6

Joined: Thu Apr 18, 2019 7:57 am
Posts: 203
Location: Lawrenceville, GA
Car Model: 1966 Dodge Dart
Nice work! I wouldn't worry too much about gear wear, as the gear on a cam position sensor doens't carry as much load as it would in a points distributor application, and it's nowhere in the same ballpark as what the same types of gear are asked to do in an oil pump drive.

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1966 Dodge Dart turbo / EFI project


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 Post subject: Re: Cam sensor success
PostPosted: Thu Sep 17, 2020 12:52 pm 
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4 BBL ''Hyper-Pak''

Joined: Fri Apr 30, 2010 8:17 am
Posts: 41
Car Model:
I'm probably overthinking the wear issue. To me it's less about the load than it is the tooth engagement. Like a differential ring and pinion - which obviously is very different thing.

The tuning video is very much the process I've gone through to tune idle on both of my cars. It's good guide. I use some of those tricks on both cars - especially to tame the RPM drop from park to drive. However, in my case the real issue seems to have been the small pulse widths I was seeing in semi-sequential. If I tuned the car warm, it would go rich at hot. If I tuned it hot, it would be lean from after warm-up enrichment to "hot." After a long freeway drive - forget it. It was choking at 10:1 when I got off the freeway. I tried messing with air density tables, MAT/CLT blend, timing... I was considering trying MAF but read about difficulties with that. This solution cost less than $80 and seems to have worked.

Ultimately, I decided the pulse width was at fault because - and I know this doesn't make sense - the injector seemed to have a minimum pulse width that varied with temperature. When the car was hot, I could turn my VE all the way down to ~15% and get a constant (rich) AFR. Turn it down one more tick, and fuel would cease altogether. I don't believe this is how injectors are supposed to work, but I would liken it to a one-shot circuit in electronics. If you ask them to turn on, they were going to turn on for some minimum amount of time even if you don't ask for that much. This could be common or it might be due to cheap-o injectors. I already had one fail outright, so it's possible.


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 Post subject: Re: Cam sensor success
PostPosted: Thu Sep 17, 2020 6:20 pm 
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Supercharged

Joined: Wed Sep 17, 2008 6:48 pm
Posts: 3383
Location: Indianapolis
Car Model:
Quote:
If you ask them to turn on, they were going to turn on for some minimum amount of time


I think that what you are describing is Injector Dead Time,, Injector Dead Time is amount of time that it takes an injector to open and begin full flow once it is commanded to open and to close and stop flow once the current that caused the injector to open is interrupted.

Usually it is voltage at the injector and/or fuel pressure at the injector that causes Dead Time to vary. Perhaps there is some condition with the wiring or the fuel delivery that is triggered by engine temperature changes, but you came up with a really nice fix that caused the injector Dead Time to be a smaller percentage of the injector open time so the effect of the variation was reduced.

At least that is my take on it,, and again nice work.

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 Post subject: Re: Cam sensor success
PostPosted: Sun Aug 29, 2021 10:02 pm 
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TBI Slant 6

Joined: Sun Jul 16, 2006 9:17 pm
Posts: 221
Location: NW New Jersey
Car Model:
I know this topic is almost a year old, but would like to chime in.

Fuel injectors operate under the electrical principles of "inductance". They are a slave to what is called the LR Time Constant; which means that Inductance in Henries times Resistance in Ohms times 1.1 will give you the amount of time in seconds for the inductor to charge to 63% of max for a given supply voltage. Wow! In short: T = 1.1 X LR. OK, there was mention of "dead time"; how does this play in? The injector will open when a given "magnetic field strength" is reached. The fuel injector's inductor functions as an electro-magnet. The pintle has a ferrite element that the magnet pulls against, thus pulling the pintle from the seat. This is why higher battery voltage yields shorter dead times, because the inductive electro-magnet is able to charge to the minimum magnetic field strength faster.

Getting back to the OP's issue, some vehicles battery charge system will put out a higher voltage while warming up, but then drop after everything settles in. It's possible the fuel cut (exceeding minimum Injector Pulse-Width, or IPW) is caused by lower battery voltage combined with a Battery Voltage Comp Table that isn't tuned properly. More likely, the hot engine requires very little fuel to idle, and the injectors cannot deliver that small amount and still open.

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