cole328

Has anyone else experienced this issue? Yesterday, the temperature outside was ~ 90, and car had been in the un all day long. When I got in to start it, the engine fired up (i.e., strong battery), but the RPM's barely registered and the "check engine" light came on Car ran in whisper mode for probaly 8 seconds, and then all of a sudden, the RPM's gained momentum, the car idled normal and the check engine light went away. This is now the second time this has happened. Other than this issue, the car runs very very strong and "as normal." 6,000 miles on it, and always only use Chevron 93 blend gas.

Any insight / comments would be appreciated, as I'd rather not have to take it to the dealership and explain this one off issue just yet. Plus, you guys know more than the dealers anyway.

Cole

Macster

or a coolant sensor the reports either too cold or too high a coolant temperature.

In the case of low fuel pressure, the ECU expects a certain pressure. The only control over the amount of fuel injected is the width of the injection pulse. A low fuel pressure condition would see insufficient fuel injected.

This would cause engine to run lean. Lean engines generally spit and backfire though, although with modern intake and exhaust systems one might not hear these as well as one would have in the past.

In the case of the coolant temperature being too low, the ECU would attempt an enrichening that woudl result in teh engine running too rich.

If the coolant temperated was too high, the ECU would lean the mixture out and you're looking at a similar condition, end result, as if the fuel pressure was down.

You might if you have some device that allows you to monitor/check the intake and coolant temperatures at start up and while engine running -- an OBD2 code reader/data viewer/logger -- you might be able to monitor the readings these sensors supply and look for a disagreement between what the sensor supplies vs. what you suspect the actual temperature is.

For instance, if car sits overnight in 60 degs F temp. and yet upon startup the coolant temperature is above that, significantly... Or if car sits all day in 80 degs. F. temperature and you get in and coolant temperature is 40 degs. F....

Fuel pressure is probably not an OBD2 parameter an off the shelf OBD2 code reader/data viewer is going to be able to pull from the engine controller.

Oh, one other possibility is the gas is old, that is blended for much colder temperature and sitting in sun in 90 deg. F. temperature heated this gas to where it might have turned to vapor and only when fuel pressure climbed engine to cause it to revert to a liguid did engine begin to run right.

You might drive car and run quite a bit of gas out and fill up at station that does a lot of business. You want gas blended for the current season... not the last season...

Which reminds me, Chevron stations -- based on what I observe where I live -- are pretty pricey. Enough so that these stations may not sell much gas and the gas they do have is stale, or getting that way. Higher octane gasolines tend to go off quicker, go stale quicker.

The general rule of thumb is to buy quality/name brand gas from a busy station that will have the freshest gasoline.

Sincerely,

Macster.

Deanski

Vapor lock. That's what it sounds like and I'll bet it was seeing all these cars use pressurized fuel systems. Once vapor gets in and hangs the delivery of fuel, the ECU gets a bit confused and tries to dump off any vapor to get the fuel in as fast as possible to avoid an overly lean mixture.

Deanski

cole328

thanks gents will try some different gas and see if that ends the issue much appreciated, as always