I have roughly 1200 miles on my rebuilt street port engine. Compression when hot is roughly 90-100 on both rotors on all faces. According to my wideband I am idling at ~11.5:1, and when I try to start the car with the engine fully warm it floods and won't restart. It tries to start briefly, then just cranks and stays full rich. This is with the throttle pedal fully depressed, using Rtek 1.8. I can deflood by pulling the EGI fuse, and it floods again the next time I crank with the throttle pedal on the floor.

I have checked for vacuum leaks by pressurizing the engine before the turbo with a boost leak tester. I replaced the plug wires when the engine was rebuilt, and I threw new plugs in today. Starter is a month old. Starts fine when the engine is cold and will bump start when hot, but will not start with the starter. What should I look at next? Searching led me to tons of threads with people recommending compression tests and people not doing them.

 

Bump. I've seen a few threads that suggested coolant temp sensor. I found them for less than $20 on RockAuto, so I'll try that. Any other suggestions?

 

Stock or aftermarket fpr ? I'm
Having the same problem on hot starts( no start) ,opposite side affects ( wb goes lean) . I think I'm vapor locking though .

 

New OE replacement FPR from Auto Zone.

Mine Starr's fine when I bump start it, which makes me think my new Auto Zone starter might not be spinning the engine fast enough. That wouldn't explain my rich idle, though.

 

I suggest fuel pump switch bypass.. Some say it is a band aid and leaky injectors is the problem. I can start car every time though and cheap fix. Mine will do the same thing your does as well except I have a switch and turn fuel pump off till it starts then flip it back on.

 

My injectors were supposedly cleaned and flow tested before I put them in. If the coolant temp sensor doesn't help, that will probably be what I look at next.

 

I didn't use a switch..per say..when I had a problem on one car I had.
I found a stereo cabinet that had a button for the interior lights of the cabinet.When you open it the lights went on.
So I wired it to the EGI fuse to cut power by Pushing the button,...when you let go it would have power.This way you wouldn't have to worry about smacking a switch.The thing would be ON all the time and only cut power when pressed.
I put it in the driver's side speaker grill under the dash.

It does sound like a water temp sender situation though.
I am wondering of you changed Radiators and have the bottom rad Water sensor on the car still.

 

With the engine hot, just bump the starter with the key and the fuel pump will run for about 3 seconds and cut off. When it cuts off try starting the car.

If it fires right up, the output line of the fuel pump is bleeding fuel pressure back into the tank. It took me forever to figure this out and I only realized what the problem was when my fuel pump sock clogged up and had the assembly out of the tank.

 

Here are some links about this type of issue. If I am wrong I am sure I will get stepped on in here, but just from my experience with my car not wanting to start after hot, but will fire up when cold every time. I did have a lower compression engine. I have since rebuilt the engine but still use the switch. I am sure I could tune it without needing it. My plan is to go adaptronics for an ECU before to long anyways and then get it tuned. I think these old ECU's have some gremlins in them. Ohh 1 other thing I am running RTEK 2.1 and 1.7 before that. I never could get it to start really pushing the pedal to the floor when I tried. However I would just throw the swtich and it would crank right over.

https://www.rx7club.com/2nd-generati...thread-932606/

https://www.rx7club.com/2nd-generati...switch-714741/

 

Like a clutch switch? Could add one down there, or tap into the existing one. Just a thought. So there's NO chance of forgetting lol

 

Stock radiator still. The lower sensor was unplugged when I got the car back from having the engine rebuilt, but I reconnected it. Is it possible to plug it in backwards?

 

I don't think so. Bit that isn't your thermoswitch either, that is located on water neck.

 

A little update, I finally had some time to look at the car. I replaced the temp sensor under the alternator and no change. I also determined that the high/rich idle is due to the thermowax still being present with no coolant running to it.

The only issue now is that the car will not hot start. It tries, then floods. Even with the throttle on the floor the entire time. It will push start no problem, I don't even have to be moving very fast to pop the clutch in second and drive away. I verified compression, it is still near 100psi on all faces.

 

Being a s4 you can't hold the pedal down to deflood it, the computer thinks 100% throttle, so it dumps 100% gas

Only s5s you can hold the pedal down to deflood

 

The reading at the ECU for the water thermosensor should be checked for the plug connector might be the problem as opposed to the sensor itself. Pin 2I (Green/White wire) should read 2 to 3 volts cold and the voltage drops to close to .5 volts warmed. You'll also want to check the pressure regulator control valve as it is used for hot starts. And maybe you should check the air temp sensor of the AFM.

 

Rtek ecu. According to them, every ecu with their chip has the deflood feature, though it's never worked for me.

 

My bad, if you mentioned it in the thread i missed it

 

Where is the pressure regulator control valve? A search didn't turn up anything useful.

 

The FSM refers to it as "PRC". It's one of the vacuum solenoids over by the power steering pump.

 

One of the solenoids on the emission harness/rat's nest? If so, that is no longer on my car. It was removed when I did the emissions delete.

 

Yes, and it's not an emission item.

 

So could my hot start issue be caused by this solenoid not being present?

 

It's used for hot starts.

 

I guess I'll look for a replacement solenoid then. Thank you for the help.

 

All of the solenoids are the same, but plumbed differently, thus if you have one you could use it.