Sudden cold start lean condition
Sudden cold start lean condition My car has been tuned OLSD for a few years now (by me so its not perfect) and has ran just fine, warm or cold but here lately I have noticed a gradual creep to being kind of lean after a cold start (doesn't matter outside temp). The car will start and idle at the desired 14.7ish afr but within 30 seconds to a minute it will start to lean out to around 16.5 or so. At idle it won't stumble or miss but if I drive off it will hit closer to 17.0 afr and if the car bogs just a little slipping the clutch it will stumble and hesitate until the rpms come up above probably 1500 or so and then it moves back to around 14.7 or so. Within a block or so of driving it will be back normal air fuel ratio and it drives just fine after that. At WOT it runs fine as well and at any other rpm or load condition after it runs for a few moments there's no difference compared to before. Nothing on the car has been changed lately to cause this. I know the fuel pump is kind of weak because I have to do the key cycle when its warm to get it to start but its been like that for years and its not any leaner at any other point. Any suggestions on what to look for?
Yeah 100% positive since the MAF is unplugged and there aren't any o2 sensors installed. I can go back through the file itself but since this has only started happening recently I think the tune should be fine as well.
Scan it from a cold start and see if you have any weird temp readings or IAC counts. This sounds like it could be an intermittent sensor problem, but cold start issues can be difficult to diagnose because of the lack of accurate readings and the sheer number of modifier tables involved.
Scan it from a cold start and see if you have any weird temp readings or IAC counts. This sounds like it could be an intermittent sensor problem, but cold start issues can be difficult to diagnose because of the lack of accurate readings and the sheer number of modifier tables involved.
