I still feel the car is rich when idling. Very strong gas smell with the car just standing and Idling. Yet BLM's are right on 128.

I had a look at some tables and wanted to ask would lowering the numbers in the Enrich Startup vs Temp table take out fuel at idle?

Between 20 and 40 deg C the number is 25%
56 Deg C is at 19%
68-80 Deg C is at 15%

So would I be correct in lowering the percentage to get less fuel?

 

Startup enrichment is only in action for about the first 30 seconds the car is running. If it's rich at idle when warmed up, look elsewhere.


Lowering the percentage WILL get you less fuel after startup, though.

 

I might try and lower those values a bit and see how it runs. Would you know any tables to look at off the top of your head for fueling idle when warmed up except BLMs as they are dead on 128?

 

What are the cam specs?
If cam has a decent amount of overlap there will be alot of unburned o2 in the exhaust stream.. Therefor when you tune for 128 the car will usually be pretty rich, as the unburned o2 forces sensor to read lean making you add fuel to reach 128.

One way to help this is lower the o2 swing voltage at idle, theer for you actually skew what the o2 thinks is 128.

 

Would a wideband O2 see the same effect?

Teeleton

 

Yes, as it functions basically the same as a narrow band O2 in that it measures O2 content but the output is much more linear over an obviously wider range. HTH

 

Cam is stock as a rock. I will have to get a wideband to fix this problem I think.

 

A wideband will do nothing for your situation, Do you have an exhaust leak maybe? That will do same as above by reading fresh air.
If cam is stock and I assume mostly rest of engine is as well, go to a stock bin and lock blm to 128 and see how it smells then.

If still rich, its probably mechanical.

 

I think this is happening with my 74129 cam. BLMs look good but stinks like raw fuel and idles choppy. I should receive my Ostrich in the mail next week which will make playing with idle so much easier.

 

My cam has enough overlap to need this modification, however, what do I change to accomplish this. I am using current version of Tunercat on a $6E bin.

Thanks

 

Not Sure what its called on the $6E, but will be something like
rich/lean upper and lower threshold at idle.
Or rich/lean toggle voltage threshold.

 

Wouldn't taking timing out at idle RPM's help with overlap?

 

Found this on $6E: Closed Loop Rich/Lean Threshhold vs. Airflow.

What do you think?

 

I had a similiar problem with rich idle. After many frustrating nights, finally replaced the O2 sensor and problem solved. The sensor seemed to be working fine but in reality, it was producing too low of a voltage, especially at idle. After more reading in this board, I feel it may have suffered silicon poisoning.

 

Thanks for info. I did replace my O2 sensor a couple yrs ago but since have had the motor out twice. I wonder if it could be a little messed up from that alone(my buddys helped). What kind of voltage should I see?

 

** ANY ** silicone contaimination will slow them down. You really need a scope to see how fast the transistions are, meters have a very slow sampling rate. Looking at the cross counts would be a better indicator.

 

Considering the low end aromatics have a temp of about 130dF, I don't see how much unburnt fuel could exist after spending time in a column of gases that are at ~800-1,200dF.

I'd love to hear an explaination of how that happends.

 

Grumpy,

What causes silicone contaimination? I can watch my cross counts with TunerProRT, what kind of counts should I look for?