DRACO A5OG

Gentlemen,

Sorry to bring this up again, but for those who had rich idle issues when warm. Did you find the fix?

I have checked everything twice, CHTS, ICV, Vacumm Leaks, DME, Relay, AFM, Fuel Pressure, New Refurbed Injectors, Plugs and still can't get her to lean out no matter what I do:

AFM adjustment screw has been turned out 9-10 counter clockwise and still reads top fluctuation of 0.81 volts on the O2 Sensor.

I've even taken the screw completely out and plug the hole with my finger and finally got a 0.63 top fluctuation.

I re-installed the Stock Chip and no change on volts.

Soon as I connect the O2 Sensor she would start to lean her out at idle lowering the RPMs 40+/-.

She has perfect runs in all gears with proper Mixture, Strong and Steady. She only acts up on occassional stops or stop and go traffic.

TIA

theiceman

Draco I don't know if this helps but good AFR is good AFR regardless of the engine type. Here are the final results of my trimming out with my LM-1 .Mine is a 78 sc ( CIS car ) and it runs flawlesly.
For me 13.6 was about the optimal setting . That is about a CO for 2.4%

Peter Zimmermann

DRACO: Greetings! The overwhelming number of 3.2 cars that Red Line has found where the problem was rich running at idle have been the Air Flow Meter. So much so that Marc has a very tall stack of ones that he's replaced! Find a known good one and plug it in, I'd almost bet that it'll be the cure. (I'm assuming that you already have the newer-style two-wire head temp sensor.)

Hope all else is well!

DRACO A5OG

Iceman, Thank you so much. i have no complaints about runs juts at idle, She just goes too rich at sometimes. It is really annoying.

Hey Pete, I did swap out the AFM with a known good one but still no change to the readings but will check again because that was before I changed the Injectors and Plugs.

I am going to bench test the AFM tonight.

BTW, does anyone know where the "VFM" is? Need to check out put at idle.

Thanks Fellas!

theiceman

PS Draco that graph is at idle . I bliped the throttle a couple of times to make sure it came back to baseleine.

DRACO A5OG

Wow, that is awsome! So the reading of 0.74 volts, is that from the O2 Sensor?

theiceman

hmm good question. I don't think so though . My 78 has no O2 sensor , well except for the one you put in the tail pipe to do the measurement. That MAy represent that value. I will drag my cursor and see if it changes. If it does when i bliped the throtle it will tell me. The cursor you can drag down the timeline and get all the values for that time.

rusnak

that graph is pretty sweet. I need to buy a serial to usb adapter and rpm sensor. Check that....want to, not need to.

theiceman

you can do all kinds of stuff with it, but since I was just borrowing this one I only hooked up the O2 sensorI used the standard serial to usb connector and it worked fine.

Droops83

Hi Draco,

First off, I would listen to Pete, he knows his stuff, However, I would like to add a couple things . . . I see that you keep mentioning O2 sensor voltage. You should check the CO/AFR at idle with the sensor disconnected, since this will tell you how the engine is actually running; after all, it could be the O2 sensor itself causing the problem, when they get lazy they usually go rich. Also, another thing to check before you condemn the airflow meter is to check the idle bypass passage that the mixture screw controls the opening size of. I often see these clogged with carbon, which will also cause the idle mixture to be richer than it otherwise would be. Try cleaning it out w/ throttle body/carb cleaner if it is clogged (AFM needs to be removed for this, however).

DRACO A5OG

Hey Chris,

Thank you and all you fine Gentlemen in helping me, I really appreciate it.

I agree, Pete is amazing as all of you are.

Yes, I mention the O2 Sensor only because the LM1 I use is at a different site but for a rough measurement, I use the disconnected O2 Sensor and DVM to see if there is any change at all. I used Both the LM1 and DVM/O2 Sesnor to verify CO readings.

So I actually had the O2 Disconnect at Idle. This is how I know she's running rich. In fact, the O2S is doing it's job of trying in vain to lean her out causing the lowering of the RPM's. (right?)

I have actually checked the idle bypass and cleaned it thoroughly.

I will bench test the AFM and Clean it again. I will also check the connectors are not fowled or damamged.

BTW, Do you happend to know where the "VFM" is located. I was told to check for voltage output there after removing some insulation.

So Humbled,

Jim

J. Brinkley

iceman, that .74 v thing is just one of the empty inputs on the lm1. they don't do or mean anything unless you have another input you are monitoring, like boost, egt, fuel pressure, iat.

jim, have you opened up the afm and looked at the copper... substrate I think it's called? where the wiper arms travel?

how linear is the reading while you manually swing the afm door? It's easily possible that 2 out of 3 afms are in the same condition as far as mileage and wear on the inside.

I would not trust any DVM for an accurate 1 volt swing measuring lambda.
The steps are just too small, you'll just frustrate yourself.

You saying that changing the chip and nothing changed is odd, I think it's the most odd thing about what you have going on. After what you've done, there should be big changes swapping chips out.

have you measured vacuum? Are you sure there isn't a cracked boot somewhere?
I would go through a lot of things before I sent my afm out to someone.


I've never heard of VFM

DRACO A5OG

J.,

Yes, the membrane is fine. She was worn and readjusted to follow a new path on the membrane. Readings were linear per LM1 on the road/fwy at full throttle.

I hear you about the DVM, but I know if I can't get below 0.80 volts on the O2S. The LM1 will read her as being rich on idle as well.

Stock chip lowered the RPM's to Stock 780-800 RPMs but it was still rich at idle when I come to stops and the O2S trys in vain to lean her out resulting in the RPM's dropping to 740 RPMs. Performance wise, she had allot of lag in 1st, almost like no throttle response.

I was reffering to the rich idle that did not change when swapped chip to OEM.

I have checked every where for vacumm leaks with Carb Cleaner, Ether & Propane (that was scary) absolute no increase in RPM's. The Butterfly hose from the AFM appears to be cracked around the ICV. but I sprayed a ton of ether there and no response so it may be cracked on the outside but sealed in the inside.

I am going to throroughly go thru the AFM.

Thanks again J.

Peter Zimmermann

Chris: Thank you...and, wow. I completely ignored that Jim might have been setting/checking mixture with the 02 sensor connected. Also, when I sold my shop to Marc I had not seen, up until that time, a plugged idle bypass passage. That is good to know, thanks for the tech tip, and keeping me honest!

DRACO A5OG

I swear guys, I have disonnected the O2S and put a DVM on it to read the voltage.

Going to remove AFM now