Engine seeking idle...strange dwell reading

[jonas21]

Hello,

i am trying to find the cause of my engine seeking idle. When started cold it seeks idle between approx. 750 and 1250 rpm.
I've connected a dwell reader and checked the reading..it always stays at 14° (reading 7, doubled for 4cyclinders = 14°) which seems odd to me. I didnt disconnect the o2 sensor btw.
Even if i give it gas and run 2k or 3k rpm the dwell reading stays the same. The frequency valve is buzzing continously.
I tried adjusting the air/fuel ratio and got it both to die from lean and rich but dwell always stays the same. (btw doesnt that knob inside the mixture unit have a stop end at lean/rich? i was able to
turn it full clockwise a couple of times)
Only very few times it showed a different reading but then only for some seconds (various around 60-80).

I've attached a picture of the dwell meter i use. Any ideas to what could cause this situation?

19332

-Jonas

[jawn101]

(btw doesnt that knob inside the mixture unit have a stop end at lean/rich? i was able to
turn it full clockwise a couple of times)


Uh oh.....

Normal adjustment is maybe 1/16th of a turn. You will have massively fouled the setting at this point. You probably have a bad meter/bad connections causing the strange reading, but you have a long road ahead of you to dial this back in....

[Bitsyncmaster]

Uh oh.....

Normal adjustment is maybe 1/16th of a turn. You will have massively fouled the setting at this point. You probably have a bad meter/bad connections causing the strange reading, but you have a long road ahead of you to dial this back in....

+1

When your engine is correctly adjusted, a 1/4 or less of the mixture will run the Dwell from maximum to minimum.

Your dwell should read a constant 45 degrees on a cold engine no matter what the mixture is set too.

[jonas21]

Alright thanks! I am quite sure i have the same setting on the mixture unit as before.
Atleast the car runs like before. I have a gas meter to check CO levels but first i'd like to get this idle hunt stopped.

Is there any other point i can tap into to get the dwell reading besides the diagnostic port? The manual of the dwell meter says
it should be possible to tap on the ignition coil.

[jawn101]

Alright thanks! I am quite sure i have the same setting on the mixture unit as before.
Atleast the car runs like before. I have a gas meter to check CO levels but first i'd like to get this idle hunt stopped.

Is there any other point i can tap into to get the dwell reading besides the diagnostic port? The manual of the dwell meter says
it should be possible to tap on the ignition coil.

It is generally accepted that you should not change the mixture to deal with idle hunting. You want to dial in the mixture as specified for the K-Jet specifications, and then idle hunt is usually down to other factors.

You can connect to the wires feeding the FV from the bulkhead (2 wire white connector) or to the orange wire leading to the diagnostic port directly.

[DMCMW Dave]

You have also probably fouled the o2 sensor

[jonas21]

You have also probably fouled the o2 sensor

I replaced that some days ago...i'll do some more testing tomorrow...

[Ron]

Alright thanks! I am quite sure i have the same setting on the mixture unit as before.
Atleast the car runs like before. I have a gas meter to check CO levels but first i'd like to get this idle hunt stopped.

Is there any other point i can tap into to get the dwell reading besides the diagnostic port? The manual of the dwell meter says
it should be possible to tap on the ignition coil.You have to set the CO with a dwell meter for the system to take over and control the idle (IE you do not need the analizer...that's the lambda systems job).

Connecting the dwell meter to the ignition coil gives you ignition dwell.
The diagnostic plug, the Orange wire in the two wire plug usually disconnected and laying between the engine and firewall, or the Orange wire in the Blue Bulkhead connector are places you can pick up the CO Dwell.

Make sure the engine is warm and all other setting are correct first. Plug the adjustment hole with your finger (or something) and wait a few seconds before taking a reading.

======

We need a CO dwell video BIG TIME ( and one for pressures while the WUR/CPR wams up ). Any takers?

[rdarlington]

We need a CO dwell video BIG TIME ( and one for pressures while the WUR/CPR wams up ). Any takers?

I made a video this past weekend of my dwell reading and engine RPM using an Actron 7605 meter. These are about $30 delivered from Amazon.com.

Because the numbers looked good, I felt no reason to make any adjustments. That said, the video shows where to make the connections with the meter.

https://www.youtube.com/watch?v=cpNB1eRktzM

-Bob '82 model with 3500 miles on it as of today, VIN 10904