Problem with running really lean and engine stumbling when starting car?

[linksys42]

Having an issue with a staring lean condition accompanied with rough idle. Weird thing is that sometimes if I let the car sit for a little bit when I go to start the car it stumbles to start then once it does, it runs really lean(off the chart) for a bit then after a bit it goes to 14.7 on my wideband? It doesn’t do it if I let the car sit overnight or if I turn it off and then turn it back on? Only when I let it cool down for lets say 10 to 20 min? Has anyone ever ran into this? Any ideas on what this could be? Started happening when I installed my 650’s (brand new from FIC) and adjusted my trims to compensate on the safc. When it happens the fuel pressure is fine/normal. Thanks

 

[silvreclips]

Maybe a bad front o2 sensor? Or one of the injectors may not have a good connections

 

[GVR4592]

What is the fuel pressure set at?

 

[linksys42]

Maybe a bad front o2 sensor? Or one of the injectors may not have a good connections

O2 is new and it cycles good.

What is the fuel pressure set at?

43.5 psi

 

[GVR4592]

Are you letting the fuel pump prime for a few seconds before you start cranking it over? Are the fuel trims way off or are they pretty close? Can you post up your safc corrections?

 

[linksys42]

Are you letting the fuel pump prime for a few seconds before you start cranking it over? Are the fuel trims way off or are they pretty close? Can you post up your safc corrections?

On a 99 2g the pump doesn’t prime till the ignition is switched to turn the engine over. LTFT are all at 0 or –1 dead on. SAFC settings are –18 all the way across on the lo throttle settings with the 650’s. When the condition happens the stock narrow band front o2 also pegs lean. And the STFT stays at 0 till the engine richens up and then it starts to oscillate back and forth same way with the o2 signal.

 

[turboglenn]

Sounds like vapour lock to me *shrugs*, but it could be a lot of things. BAd temp sensor being one of them. Post start enrichment tables being adversly effected by the signal modifying of the airflow by the AFC??

 

[linksys42]

Sounds like vapour lock to me *shrugs*, but it could be a lot of things. BAd temp sensor being one of them. Post start enrichment tables being adversly effected by the signal modifying of the airflow by the AFC??

I do not have the start enrichment tables for the stock ecu. They are what ever the ecu was pre programmed to use from the factory. The airflow in hz is 44.03 after the correction from the safc at a setting of –18% being pulled out. I have attached a screen shot from evoscan you can see the values while the lean condition is happening. Towards the end you can see that it snaps out of it and goes back to the correct A/F ratio then everything is normal.

 

[linksys42]

Forgot to say the second rear 02 sensor is actually my 0-5v signal off my uego in the graph. I use the conversion table from aem to convert the value. And that value is really lean!