99 V8 Starting Questions

[Sonny]

Hello all, New X is great. I am finding a few things I want to resolve.

1- Took to dealer where bought (under warranty) They replaced the DPFE for a CEL (I told them about this after getting info here) They 1st replaced the EGR did not help. DPFE took care of the CEL. They did replace it with a Black plastic one, the original was Cast, I guess this is correct. I did notice a difference in the truck when I got it back, it seemed to shift different.

Would the DPFE have any thing to do with the Tranny?

2- I have searched the board on a starting problem I am having, I found some info but then could not find it again, so many posts and ideas...

When I start the truck it needs to turn over several times. If I turn the key on then back off then to start, it fires right up 1st crank.

Also has a MISS, more like a even vibration feel and only at Idle (600-700 rpm) runs great other than that, no hesitations Etc.

What would cause these problems, FPR? If so where is it located on the V8?

Any help here?

Thanks as always,
Sonny

 

[TPLYNCH]

When I start the truck it needs to turn over several times. If I turn the key on then back off then to start, it fires right up 1st crank.

That sounds like the check valve in the fuel pump is not functioning properly. When you turn to On, then Off, then back to ON/Start you are repriming the fuel line.

As for the idle miss, does this occur when the HVAC is in the Off or Panel position?? If not, may just be from your A/C compressor kicking in (does this in ALL postions except Off/Panel/Floor on '99+ Ex's)

 

[Sonny]

Originally posted by TPLYNCH
That sounds like the check valve in the fuel pump is not functioning properly. When you turn to On, then Off, then back to ON/Start you are repriming the fuel line.

As for the idle miss, does this occur when the HVAC is in the Off or Panel position?? If not, may just be from your A/C compressor kicking in (does this in ALL postions except Off/Panel/Floor on '99+ Ex's)

The check valve? Does this mean dropping the tank to replace?

The Idle Miss is all the time AC off/on, when the Ac kicks in the idle does not go up or down maintains steady 5-600 rpm's.

I did take it out in the dark and checked the plug wires, there is a lot of light pollution but I did see some sparking. I am going to change plugs and wires this weekend. I think I will do the Fuel filter also.

Thanks, if you have any other ideas on what to check let me know.
Sonny

 

[dogfriend]

Idle speed of 500 - 600 rpm sounds too low. My 97 powertrain manual says the idle speed should be 700 - 750 for the 5.0L (V8) engine.

A bad IAC valve may cause idle problems including idling too low. Also, the IAC should kick the idle speed up slightly when the A/C compressor comes on. On my 4.0L OHV engine, it kicks the idle up about 100 rpm or so (from 800 to 900). This may be different for your engine but it should kick the idle up some.

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[Agent_51]

Doesnt sound like your fuel system is holding any residual pressure. I cant remember what holds that but for some reason im thinking its the fuel pressure regulator.

You might want to see if you can run down to autozone and rent a fuel pressure gauge, then check your residual pressure against whatever OEM spec is.

Theres my shot in the dark.

 

[TPLYNCH]

The check valve? Does this mean dropping the tank to replace?

Yes, it is integral to the fuel pump I believe, which means dropping the tank and replacing the entire assembly. Not worth the trouble IMO. Until the FP dies, just keep taking the extra 5 sec's to turn the key twice.