idle smells very rich(FIXED), can't go below 1000rpms(FIXED)

[65looter]

guys,

need a bit of help there.
1. idling at 1000 rpms, it's rich. So rich that your eyes are burning!!!!
What am I doing wrong there?
2. I can't get the idle to stay around 850 rpms, as soon as you hit the throttle a tiny bit it jumps to 1000 rpms and stays there.

Find attached my latest msq and a log file.


engine spec:
342 V8
autonomics throttle body
4 injectors 42lbs
4 squirts/alt

[Bruce Bowling]

Looked at the data log, the sensors, tach look good. Have you adjusted the VE table entries at idle?

- Bruce

[65looter]

Looked at the data log, the sensors, tach look good. Have you adjusted the VE table entries at idle?

- Bruce

I have been using the MegalogViewer to tune my VE tables, done it a few times.
I'm sure I'm doing something wrong somewhere, the AFR is showing lean according to Megatune but the smell is bad.
It's so bad that you can't stand 5 min in the garage, you got to go out and get some fresh air

My idle should be 850.
I got the RPM bins set as 680 | 800 | 950 | 1000
Is this correct?

[Mad Professor]

Looking at your two logs you are running at 14:1 or leaner.

You might have high HC that will give you a headake and your eyes water very quickly.

I used a 5-Gas Analyzer to help aim with fine tuning of the slow idle and fast idle, so to pass the emissions tests.
Hydrocarbons (HC), Carbon Monoxide (CO), Carbon Dioxide (CO2), Nitric Oxide (NOx).

As your car was running carb and is using MSD and dizzy for the ign, and you are running fuel only.

I would advice you to connect your laptop directy to your LC-1 WB02 Controler and make sure that LogWorks 3 shows the same AFR as megatune, so at least you know that megatune is getting the true AFR, as if this is being read worng you are going to be in no end of problems.

As I have only worked on small engines upto 2.5l and not big 5l v8's like yours I can only guess.
But I have been able to lean the fuel out to around151 @ slow idle and around 15-15.5: @ fast idle on small engines I have worked on in the past.

Did you have your LC-1 connected and running at all when you was running on carb, as if you had any kind of datalog from then that would give you a good idea of the AFR to start with for your idle and basic AFR target table.

I have just run the MegaLogViewer using your MSQ and your lastest log, and setup a flat 15:1 AFR table and the program shows a drop in the VE table by anything upto 4 points in places.

Also I noted is your two logs that you never get out of warm-up mode.

I would advice to get your engine upto it's normal running temp before trying to adjust the VE table.

I hope this is of some help to you.

Good Luck.

[65looter]

I think I'm trying to tune like when I had my carb.
At idle with the carb, the engine was happy with AFR around 15 - 16....

Now I've just found this:

* Lean mixtures improve fuel economy, but also cause an increase in nitrogen oxide (NOx) emissions. If the mixture is too lean, it may not ignite at all: this causes 'lean misfire,' which can cause rough idle, hard starting, stalling, extremely high hydrocarbon (HC) emissions, and even damage to the catalytic converter. Lean mixtures also increase the risk of spark knock (detonation).
* Rich mixtures are necessary when starting a cold engine, and additional fuel is also needed under heavy engine load. But a rich mixture causes high carbon monoxide (CO) emissions.

I did have a bad smell with the carb....
I'm going to try run a little bit more rich today and see how it goes.


Stay tuned, update later on today.

[65looter]

ok, I now understand more about that VE table than yesterday...
With the help of the MegaLogViewer software I was able to smooth my idle. I have also managed to remove most of the stink.
It's now just below 1000 rpms, I will be able to lower it even further once the engine is fully warmed up.

My battery has gone flat, so I can't do much more today

[65looter]

ok,

here's the latest:
the smell is gone, running too lean wasn't a good idea
the idle is running better



I have notice that the idle screw on the throttle body is VERY sensitive. It doesn't take much to kill the engine or idle at 1200 rpms...
find attached my new log and msq

Can I use the Req_Fuel to lower the idle?

[65looter]

With a careful adjustment of the idle screw and the VE table, I was able to lower the idle below 900 RPMs.