Hello,

I recently got my S4 going again and I am trying to solve a hard start issue.

For the work that I have completed already, go here.

https://www.rx7club.com/2nd-gen-gene...ption-1154012/

Anyways, my question revolves around the AWS system and items related to a cold start. (accelerated warm up system)

Once my car is warm, it will idle just fine @ 750-850 rpm. It will start up reliably even on the first rotation at times when it is warmed up. But if the car sits for a period of 8 hours, or less, depending on the temperature, it will be hard to start in a cold condition.. . .

When starting cold, it requires many rotations. It will do a short run and die, before firing up finally. . . No backfires during this time..

During this start up process, it does not go through the 3,000 rpm start.. . I basically keep feathering the throttle until it is warm enough to hold an idle. That typically happens around 1,500 rpm, and then it becomes more solid.

The Dash pot needs replacing, so once warm, I can blip the throttle at times and it will struggle to find idle. (or at least this what I blame the Dashpot for). But otherwise it runs good once warm..

The reasons I can think of that might cause what I am seeing are the following. . .

I could use some help defining these, removing these, or coming up with others.

Failure or misalignment of the AWS (not really familiar with this operation in detail)
Bad switching solenoid.
Air leak at an injector
Air leak at the EGR
Bad cut and check valve
Bad BACV
Misalignment of the throttle plates
Bad temp sensor on radiator or behind water pump?

Any help would be appreciated.

 

I would suspect the sensor on the back of the water pump first. It's always my go-to for this kind of situation, since it's easy to knock the connector off by accident.

If it isn't plugged in the computer assumes a coolant temp of 176°. This is why it runs okay when warmed up.

 

does the fast idle work? the thermowax? not only is it fully adjustable, but the hoses get clogged with junk too, and it goes bad sometimes on top of it.

 

I would check for vacuum leaks with a boost leak checker before anything.