Hi All, new member here hoping you guy's can shed some light on this, I looked through a lot of the stickies but can't seem to find my exact prob...... car is a 94 Civic DX 5sp with a replacement ZC sohc. When we installed this motor we swapped the entire D15B7 intake system over along with the stock D15B7 exhaust too. The car runs very well EXCEPT for starting after it has sat for hours or overnight.
The symptoms are when turning the key to start it will crank a long time before sputtering a bit and trying to run......BUT if you crank it for just a sec THEN stop and try again the engine will start immediately but is very touchy about any throttle (bog and die) until approx 30sec or so then it's fine. Also, if the weather is warm this problem goes away.
One thing I have done is checked full pressure (ok at 40lbs), swapped FPR (no change though it was not known if good) and have pinched off the return line from the FPR which immediately solves the starting issue but is not a forever fix obviously LOL.
What would cause it to run so lean on cold start (but run great any other time)?
Thanks for any help

 

With more and more detective work, I'm now wondering if it's the ECT sensor near the dizzy

 

That is where I was about to steer you... check the TWO WIRE ECT sensor near the distributor. It is a resistant circuit and you can find values for specific temperatures in the FSM (online if you don't have one).

 

Thanks JR..... swapped it with OEM new ECT and first cold start this morning was no different....longgggg crank then start. Runs great the rest of the time, good power and MPG.
Where would I need to be looking next?
Appreciate it,
-- Ray

 

Is the fuel economy "too good" ??? I wonder if your issue is fuel pressure related ? Since you now have a 1.6L engine, and the original engine is a 1.5L engine... and you have an ECU designed to run the 1.5L engine. This should make the car run lean overall... which would increase your fuel mileage.

Also, do you know if your ECU "Back Up" fuse is good ? If not, your ECU will not store your Short and Long Term Fuel Trim values and will "reset" them to zero each time the ignition is turned off. More fuel is required during a "cold start" than once the engine has come up to operating temperature.

 

Mpg is normal (approx 33 overall).... one thing I didn't mention but may be of help is the car acted this way before with it's orig D15b7. We swapped the orig intake, exh and dizzy over to the ZC sohc notec to make it as simple as possible.
i have never given the ecm a thought since it runs well any other time.... where would find that fuse?
thanks!
‐‐ Ray

 

Also...anything in the dizzy that may contribute to this issue? I've been thinking of replacing it (it has approx 270k on it

 

Installed new aftermarket dizzy.... did not change the cold start issue (although it does seem to be running better). I did try the mini Vise Grip on the return hose off of the fpr and it started instantly.... would this point to the fpr being bad? Some months ago I tried another fpr from a junkyard and it made no improvement (who knows if it was any good though). Since the engine runs ok and has good power would the fpr still be suspect?
thanks, Ray

 

Are you hearing the fuel pump run then stop EVERY time you turn the key to the on position, without any delay in the start of the fuel pump running? If not, this points to issues with the ECU capacitors. Regardless of whether you're having this issue or not, I recommend replacing the capacitors if you haven't yet.

You could have a failing fuel pump, or bad wiring to the fuel pump.

It could be dirty injectors, a dirty filter, clogged lines, or a bad regulator.