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-   -   M103 idle surge ... STILL (http://www.peachparts.com/shopforum/tech-help/373175-m103-idle-surge-still.html)

TnBob 11-10-2015 03:55 PM

Well well...
New fuel pump relay made a great difference ! Not perfect but much better.
Alternator regulator working great. 600 to 3000rpm = 13.88vdc +- ,01vdc

At cold start, no surge but by about 45/50c surge returned but not as radical.
Ranged from ~550 to ~900. popped the IAC connector and rpm instantly went to ~1000 and STABLE. Im guessing that even though very throughly cleaned both the original and the used replacement are failing. Both read correctly for ohm reading too.

At operating temp, 80C, idle surge remained ~550 to ~900 with the IAC connected and went to a STABLE 1000rpm with the IAC disconnected.

TnBob 11-10-2015 06:08 PM

Once again out of daylight.
$4.71 later I have a gate valve with 2 barbs

optimusprime 11-11-2015 11:02 AM

You will get there .

Stretch 11-11-2015 02:54 PM

Quote:

Originally Posted by TnBob (Post 3539041)
Well well...
New fuel pump relay made a great difference ! Not perfect but much better.
Alternator regulator working great. 600 to 3000rpm = 13.88vdc +- ,01vdc

At cold start, no surge but by about 45/50c surge returned but not as radical.
Ranged from ~550 to ~900. popped the IAC connector and rpm instantly went to ~1000 and STABLE. Im guessing that even though very throughly cleaned both the original and the used replacement are failing. Both read correctly for ohm reading too.

At operating temp, 80C, idle surge remained ~550 to ~900 with the IAC connected and went to a STABLE 1000rpm with the IAC disconnected.

It should idling a bit higher than that (from what I've read) when the air idle control valve is unplugged. I wonder if that's due to your resistor fix.

TnBob 11-11-2015 07:31 PM

Dont know ... wish now Id put a pot on that sensor rather than a fixed resistor.

Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site: http://www.ebay.com/itm/1R-9999999R-Seven-Decade-Programmable-Resistor-Board-Step-1R-1-4W-F-/131647177301?

it was soooo nice to have a stable idle even if it was high

Stretch 11-12-2015 12:12 PM

Quote:

Originally Posted by TnBob (Post 3539510)
Dont know ... wish now Id put a pot on that sensor rather than a fixed resistor.

Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site: http://rover.ebay.com/ar/1/711-53200...31647177301%3Fhttp://www.ebay.com/itm/1R-9999999R-Seven-Decade-Programmable-Resistor-Board-Step-1R-1-4W-F-/131647177301?

it was soooo nice to have a stable idle even if it was high

Well is seems from what you're saying the unstable idle can be fixed by disconnecting the air idle control valve and fit in that bit of plumbing. You could then tune the air flow potentiometer to get a lower idle and call it good.

BUT

I have a feeling that the O2 sensor and emissions might not be working as well as they could. You might also get other trouble such as poor fuel consumption / over heating.

##########

That's a bloody good price for a decade box.

optimusprime 11-12-2015 12:52 PM

1 Attachment(s)
No good hiding a problem to make another elseware.This chart might help you .

TnBob 11-12-2015 02:17 PM

The last one is sure the key.

The decade box is repeatable. Seller seems to always have them up.
The 5W Watt 0.1 Ohm 5% cost $0.18 by buying 10 so if you need/want one
pm me your addy. Gonna break the ground plane and install mine there.

Stretch 11-13-2015 07:22 AM

Very kind but I have a source where I can borrow one - thanks anyway

pmckechnie 11-13-2015 08:46 AM

Bob, could you explain this.
"Got some 0.1 ohm 5 watt coming in to get my resistor substitution box wattage upgraded. Will allow me 1 ohm steps from 1 ohm to 10 meg ohm with a 5 watt. $10 from our fav auction site:"
Where are going to put a 0.1 ohm resistor in the ground plain, and why.
I just don't understand.

PaulM

TnBob 11-13-2015 02:18 PM

The resistor sub board came with 1/4w resistors understandably.
Adding the 5w 0.1 ohm brings up my wattage level as watts in series
are additive. Technically my board will become a 5 1/4w sub board

pmckechnie 11-13-2015 03:30 PM

Bob, I don't think it works like that.

Power is calculated from the voltage drop across the resistor times the amps in the circuit.

The amps is calculated from the voltage in the circuit divided by the total ohms of all the resistors.

The voltage drop across your .1 ohm resistor will be very small compared to the lowest ohm you can get from the box.

We need an EE to jump in here.

PaulM

TnBob 11-14-2015 10:57 PM

"Wattage in a Series Circuit is Additive"
Wattage Series

Very good basic answer

optimusprime 11-16-2015 10:05 AM

I will let you carry on ,the way your going you will have more problems in the end .

Stretch 11-16-2015 11:03 AM

Quote:

Originally Posted by optimusprime (Post 3541343)
I will let you carry on ,the way your going you will have more problems in the end .

Bob's free to do what he wants. It is his car!

Don't take an apparent "refusal" to heed your advice personally.

Sit back an watch what happens.

I also think he shouldn't have rigged the temperature sender but I have learnt something => it looks like you can control the idle by changing the thermostat output. This is quite a nice experiment for the future when I borrow a decade box (perhaps next week); so I can try this myself and in some way or other and perhaps get a better understanding of what this crazy CIS system is doing...

...it is a big learning curve for us folks who are used to mechanical diesel systems - cut us some slack.


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