Why can I smell gasoline when I start up my car?

[desertg8]

When I start my car cold in the morning I have a horrible rich gasoline condition coming from the tail pipes. It affixiates my family and myself.

Is there anything I can do to the hp tuner's tune to alleviate this?

[Patrick G]

Lean out the start up (cranking) tables plus the open loop fueling tables at the temps at which this is occurring.

[desertg8]

I did some research on the hp tuners forum and came up with an answer. There is a table which is called closed loop enable coolant temp. vs. startup coolant temp. i.e. If you start the car with a ect of 68 the enable which is right below it is set to 102 degrees. So for a good few minutes with no cats or inefficient high flow cats such as mine you will smell the fuel. Set these values to zero and you will enter closed loop immidiately. Theoretically you need the extra fuel when it is cooler as the fuel does not condense as much when colder. But I should be ok. I love it and my family appreciates it! It was good to do some research to find out the root cause. (Mainly high flow cats are not that efficient coupled with the stock settings which I have just talked about caused this) This might be worth a sticky for those having rich idle conditions when cold.

[Patrick G]

That is actually a bandaid for the problem. The problem is that a modified engine with a cam that has lots more overlap than stock has different fueling requirements at low rpm and start up. You need to adjust those fueling tables to make them appropriate for your mods. Activating your closed loop earlier sounds like a good idea until you realize that cold O2 sensors are not as accurate as hot O2 sensors and they will often give you a false fuel correction at startup. Also, narrow band O2 sensors at the end of long tube headers take longer to get up to operating temps than those surrounded by factory exhaust manifolds and cats. Going into CL early to fight off a cold start rich condition is like taking aspirin to cure a hangover. While aspirin will give a delayed response to the curing hangover, it's the excessive alcohol that causes the hangover. By curbing the alcohol consumption (ie leaning out the open loop & start up fueling tables), the hangover (excessive rich, stinky smell) is avoided.

[JJhummus]

Love the analogy!

[desertg8]

I spoke with my tuner yesterday and I am getting a different answer. Basically he tells me the cranking air will do absolutely nothing for me. Also the computer demands a 14.7 afr right from the get go. The problem with running high efficiency cats is they take a while to warm up and due to the inefficiency of internal combustion engines the first couple of minutes I will smell the fuel no matter what changes I make. The stock cats heat up much faster and do a much better job of filtering the raw fuel. I told him what I did and he told me that would not help much either.

[Patrick G]

I spoke with my tuner yesterday and I am getting a different answer. Basically he tells me the cranking air will do absolutely nothing for me..

Not cranking air, cranking fuel air ratio. It's under the general tab in the fuel section. Also you need to adjust open loop fueling tables. Those are critical tables to adjust during cold start.

Also the computer demands a 14.7 afr right from the get go..

That's not true. Log commanded air fuel and you will see that the ECM starts in a rich condition to allow the engine to start and not die. It does not get to 14.7 sometimes until several minutes after startup.

The problem with running high efficiency cats is they take a while to warm up and due to the inefficiency of internal combustion engines the first couple of minutes I will smell the fuel no matter what changes I make..

The second part is not true. When you have the start up tables adjusted for the changes in airflow and cam profile, you will have much less fuel smell at start up.

The stock cats heat up much faster and do a much better job of filtering the raw fuel..

Agreed

I told him what I did and he told me that would not help much either.

I'm sure it helps some, but it's not the ultimate solution to the problem.

[desertg8]

thanks for the input. he did not like me forcing closed loop as the 02 sensors are not warmed up at that time. so i am not attempting a fix that way. i will look at those tables you pointed me to. he said the ivt will get to over 140 within 30 seconds and go to the closed loop of 14.7.

[G8-4-Speed]

Lean out the start up (cranking) tables plus the open loop fueling tables at the temps at which this is occurring.

Like Pat said

The startup and open loop fueling sounds like where the problem is at. Just reduce the open loop fueling enrichment for the all the lower temps for either ECT or IVT and/or startup fuel.

Another problem is you may be forcing too much idle air at cold startup which will cause the computer to pull all the timing trying to keep the idle at the target rpm. Low timing is just as stinky as too rich.

Hacking the tune for closed loop trying to get the computer to adjust for a problem isn't the fix. It just creates other problems such as misfires and acceleration stumbles when cold.

no sticky.....There are far too many messed up tunes that run rich at idle. With every messed up tune, they all have there magical way of making them crappy. None of which are the same. Making one answer means someone will screw up another part of there tune trying to fix it for another problem. Just like all the engines with cams that idle like garbage. More than one way to fix it and way more ways to screw it up.

[G8-4-Speed]

You are looking for a fix with theories on why it is rich. What does a cold start scan look like. Where is the timing during cold idle? What is the commanded AFR? Where is the TPS and what is the injector pulse at idle?