The purge valve should make a rapid clicking sound when the engine is running. When you say no codes, do you mean no CEL or have you actually scanned for codes and there were none? Sometimes certain codes can be stored without the CEL lighting up.

 

I scan for DTCs...and there are none. however, I don't know why i believed that this valve was causing my problems. if it was this valve then I should have issues with every start, or no start. correct me if I am wrong but I have a true bleed-down issue and I should get a fuel pressure gauge and test both sides of the gauge for leak-down.

 

No start on the first attempt could be caused by several things. Inability to hold fuel pressure is one of them. Taking rail pressure readings would help identify if that is the cause.

The purge valve is how the ECM meters flow from the EVAP system (including charcoal canister) into the engine. If the purge valve is stuck open, there would always be maximum flow from the EVAP into the intake manifold. Flow would be greatest during high vacuum conditions like during idle. During start this could throw off fueling accuracy. After the engine is started and running long enough to go closed loop, the system will automatically correct fueling to where it should be. Flow through the EVAP will deliver fuel vapor laden air into the intake. The amount of fuel vapor present in that flow will depend on several factors and change as conditions change.

 

I don't know if this is the proper way of testing a purge valve but what I did was take the vacuum line off from the purge valve to the engine and plugged it off. That way no gas vapours could get into the engine if the purge valve was sticking open.

 

steve, thanks for the great vid...I will definitely look up more on youtube. could my aft o2 sensor be preventing my evap purge valve from operating? I get a code due to the o2 sensor being removed from the exhaust stream via a bung extender. guess I should not have written that I have no codes.
thanks to all respondents.

 

Could my aft o2 sensor be preventing my evap purge valve from operating?

I don't think so. I think the aft sensor is just there to monitor CAT performance.

What's the exact code number you're getting?

 

Check your MAF sensor. When my car had an off-calibration MAFS it was very difficult to start. Replacing my original reads-too-low MAFS and an aftermarket reads-too-high one with a Goldilocks reads-just-right one solved the problem.

 

steve, the codes were 0133, 0134...not together at the same time. haven't gotten them since I last cleared the codes and it has been several days with multiple drive cycles.

 

I was thinking about clamping off the supply line prior to the rail (after running it naturally) and letting it sit for a while. this could atleast eliminate or point to a faulty fuel pump. this kind of process could help until I can get a pressure guage.

 

Those codes are for the pre-cat sensor :slow response: and :no activity detected: that should not cause start difficulties but point to a faulty sensor or wiring. When do you have trouble starting, while hot, cold or other situations? Have you checked both elements of the CTS?

 

Pauline you are correct! the codes must have been 0153, 0154 but they were definitely post CAT. I have an bung extender for the aft sensor and it is too long. the front sensor was recently replaced with a top of the line bosch.
the common denominator for rough starts is the length of time that the car sits.
CTS was replaced 2 yrs ago with the upgraded part. I have not checked it.

 

I agree with Pauline, and suggest you check or replace the CTS.

 

why would CTS be at fault? would it not make all starts rough and not just the first few cranks?
thanks.