Rich in open loop when cold

[CJK440]

I'm struggling with a really rich cold start condition on my 04 GT. It has a tork tech blower on a stock long block.

Here is what happens. The car fires, flares to 1500 and stalls unless I pedal it a little to keep it running. I see some black smoke initially but a wicked rich exhaust smell. After a few seconds it will idle by itself and when my LC2 wideband heats up and reads, it shows a 10.5 AFR.

Once the fuel source flag goes from 4 (cold start base fuel) to 0 (closed loop) the AF leans out to a nice 14.7 idle and all is well.

-Once warmed up the car behaves fine
-The MAF xfer is correct at hot idle
-The cold base fuel table is calling for if anything a hair off lambda at the rprm/temp it sees in cold start
-The "base fuel table enleanment table" is all 0's

I was told it may be something like a program glitch and it was suggested to me to scale the cold base fuel table leaner in 10% increments until it reads right. I'm going to try this but I only get one or maybe two shots per day to verify so I figured I'd post and see if anybody has seen this before. If so what was the fix??

 

[01yellercobra]

What injectors are you running? I had to lean out my cold start table when I ran 80lb injectors. I don't remember how much I took out, but I didn't spend a lot of time dialing it in. The car wasn't a daily and it ran well enough for me.

 

[CJK440]

Deka 60's. I did load the SCT injector values for them.

When you leaned your cold start table did you just make a blanket change to the entire table or did you do it another way?

 

[01yellercobra]

Deka 60's. I did load the SCT injector values for them.

When you leaned your cold start table did you just make a blanket change to the entire table or did you do it another way?

I made a blanket change. IIRC I figured out the difference between the stock injector size and the 80's and took away that much percentage. I had to do that for all of the start up tables. I remember having hot start issues too. Once I made that change things got better.

 

[CJK440]

With the cold enleanment table staring me in the face it just seemed like the right tool to do the job. Allowable cell ranges were 0-1.990 so I figured filling the entire table with .2 would add .2 to the commanded fueling off the cold base fuel table.

It didn't make a bit of difference. Either I am misunderstanding how this table modifies the base value or it is a table not referenced by my strategy.

Now I have to wait to try again. This time I guess I'll just add .2 directly to the cold base fuel table.

Does anybody know what trips the computer to switch from fuel source 4 to 0??? Is it ECT related? I'm wonder if there is a way to force it to stay on the cold base table so I can just get it done in one sitting instead of a half day in between tests.

 

[decipha]

it switches when it goes into closed loop

increasing either the base fuel table cold or the startup enrichment table will ADD FUEL, you need to reduce it to lean it out not add fuel

NEVER make a blanket adjustment to a full table, dial in the cells that require adjustment

go to the ECT and time since start that the engine is rich and reduce that cell in the startup enrichment table

everything you will ever need to know is described in the fuel write up

http://www.efidynotuning.com/fuel.htm

 

[CJK440]

increasing either the base fuel table cold or the startup enrichment table will ADD FUEL, you need to reduce it to lean it out not add fuel

I don't understand, by adding I am trying to command a higher lambda. My "base fuel table cold" shows close to 1.00 in the load/temp cell area, last night I added .2 to the table and tested. I didn't have to pedal it after first fire and it ran leaner, close to 12.5 until it went to closed loop. I was going to add more.

NEVER make a blanket adjustment to a full table, dial in the cells that require adjustment

I don't even want to make adjustment to the fuel table at all but for some reason even though MAF is dialed in hot, the AF cold is not matching what should be commanded in the cold base fuel table.

go to the ECT and time since start that the engine is rich and reduce that cell in the startup enrichment table

I don't have a startup enrichment table. I have a "base fuel table enleanment when cold" table which has a min value of 0 and max of 1.990 and that is all 0. I tried populating that all with .2 and noticed nothing.

 

[decipha]

adding to the table will reduce the lamsbe enriching fuel not leaning it out

if you increase the base fuel table then yes it will be leaner since you are commanding a leaner mix

thats odd that its that rich when cold, usually its lean, that would point to something being off perhaps the ACT or VE compensation being out of wack

the enleanment table is the enrichment table SCT with their crap, increasing that table will provide enrichment at startup

 

[CJK440]

adding to the table will reduce the lamsbe enriching fuel not leaning it out

if you increase the base fuel table then yes it will be leaner since you are commanding a leaner mix

thats odd that its that rich when cold, usually its lean, that would point to something being off perhaps the ACT or VE compensation being out of wack

the enleanment table is the enrichment table SCT with their crap, increasing that table will provide enrichment at startup

Well the enleanment table is all 0's now. With .3 added to the base in cells that are affected it will run at around 14.0 until it goes into closed loop. It still flares on cold startup and sometimes drops to a stall but nowhere near as temperamental as before.

VE compensation, volumetric efficiency??

Could manifold volume be affecting this? I have a 03/04 Eaton with OE inlet on top of a manifold which is probably not much different in size to a stock 03/04 cobra manifold. I suppose I could just load the 03/04 cobra manifold volume..

 

[ViperRed91GT]

Not in-depth related, but surprisingly overlooked.. Did you properly set the minimum idle air and TPS?

 

[CJK440]

Not in-depth related, but surprisingly overlooked.. Did you properly set the minimum idle air and TPS?

TB screw adjusted with IAC uplugged. Duty cycle is around .32, integrator adjusted to log ~0. I assume that is what you mean by min idle air.

TPS is set correctly after the above procedure.

 

[ViperRed91GT]

TB screw adjusted with IAC uplugged. Duty cycle is around .32, integrator adjusted to log ~0. I assume that is what you mean by min idle air.

TPS is set correctly after the above procedure.

Yep. Just making sure, as I've seen that play hell on people during startup but it idled "ok" afterwards, similar to yours. Hope you get it figured out.