Hard starting when hot

[cp2295]

Okay I just did that where I held the gas pedal all the way to the floor and cranked the engine and it fired right up. So either my computer is screwed up, I followed the procedure wrong, or this PCM doesn't have the WOT lockout like other EFIs.. Or maybe all my injectors are leaking haha

Just to be sure, I held the gas all the way to the floor and cranked at the same time. I did not unplug any sensors or do anything weird, but it fired right up and revved up of course. This is also about an hour after I have run it so it usually would require me to crank it for awhile, but this time it immediately fired up. So I'm figuring I got the leaky injector, and when I held it wide open I was allowing more oxygen in for the highly saturated gas mixture that was leaking in there.

 

[RonD]

Example of it here on a Mazda, very short video:
https://www.youtube.com/watch?v=iFjRB4oF64M

Tester starts engine to show it runs, then turns off key
Then turns on key presses gas pedal to the floor and cranks engine
He gets a no start and then after cranking for awhile he releases the gas pedal and engine starts normally.

And this thread saying the EEC-IV PCMs have the "clear flood mode":
http://www.explorerforum.com/forums/showthread.php?t=199066

EEC-IV PCM was used from about '83 to '95, OBD 1, then EEC-V which for sure has this mode was '96 and up OBD 2

So maybe you do have a good size leak of fuel into the intake.
You could physically unplug all the injectors, and then crank engine

 

[cp2295]

Okay I think I was missing the part where you go to the on position first then gas it then crank it. I was just putting the pedal down and cranking it. I'll try that out and let you know of my results, thanks for all the help btw! Really appreciate it

 

[cp2295]

Okay I figured out the issue the clutch switch that I've bypassed was screwing me over. Anyways I got it to work but I didn't hear any intermittent firing or anything. This was right after driving it so I'll wait about a half hour and let the injector leak out and see maybe if I can get it to do it then. Maybe I'll have someone listen to the exhaust too, and see if they can hear any explosions

 

[RonD]

You would hear it if an injector was leaking, no need to listen to exhaust.

Yes, wait a few minutes then retry.

 

[cp2295]

Alright so on two occasions I've tried it where I wait about an hour after running the truck and then push the clutch in put the throttle all the way down and it'll turn on, then I'll shut it off right after and put it into clear flooded mode again and it won't turn on. Does this mean that every injector is leaking? Would this point the issue at the fuel damper thing on the rail? That thing doesn't smell gassy ever (the vacuum line). I did clean up all the injectors btw when I had the engine apart and replaced all their seals with Borg Warner seals so they should be sealing just fine, just don't know if the injectors themselves have bad seals inside them.

 

[RonD]

Alright so on two occasions I've tried it where I wait about an hour after running the truck and then push the clutch in put the throttle all the way down and it'll turn on, then I'll shut it off right after and put it into clear flooded mode again and it won't turn on. Does this mean that every injector is leaking?

Not every injector, but yes, it reads like fuel is leaking into the intake, once engine fires the computer sees fast pulses from CKP sensor, "clear flooded mode" ends and injectors start working again, so engine starts.
Second time you use "clear flooded mode" not enough fuel has leaked in to cause firing so engine just cranks.

The injector's lower "O" rings are for vacuum seal, upper are to seal fuel from leaking on to outside of intake.


You might try this:
Wait the hour then disable the coil, unplug connector.
Crank engine using "clear flooded mode"

Then pull out 1 spark plug at a time and see which one, or ones, are wet, those cylinders would have the leaking injectors.
It only takes one.

Pulse damper's vacuum line would smell of fuel if it was leaking.

 

[cp2295]

Okay that's a smart way to go about it, still pretty easy too. I'll give that a try and report back the results!

 

[cp2295]

Well I figured it out. I took the spark plugs out one bank at a time. Then I put it in clear flooded mode and cranked it while I had my friend look at the spark plug holes. Bank 1 had no spraying or anything. Bank 2 however he said on the #4 plug shot fuel out the first crank. Plus that plug has some residue on it, whereas every other plug is very clean. So I think it's #4 injector leaking and then leaving residue on that plug and then it gets baked on there. And the fact that it shot residual fuel out leads me to believe that #4 injector is my culprit. Good thing it is only one!

 

[RonD]

Nice work

 

[cp2295]

Couldn't have done it without ya though, thanks a bunch! I'll let you know when I get the money for the injector and get it replaced, and see if it fixes it. Should though don't see why not!

 

[cp2295]

So I replaced the injector, seemed to help a little but still does it (not as bad). So what im thinking is that none of the other injectors leaked because that one leaked so bad that the others didn't, but now since it's done leaking out the pressure is still high causing others to leak.

 

[hilltopfarm]

Keep us posted, I have the same issue on my 03' 4.0L...exactly the same as you with the hard start only after sitting a while after warm, but not when cold first thing in the morning. Driving me hell o' crazy