I know the 2v had an issue that Ford released a updated PCM flash for. If your running a tune you may want to talk to your tuner. The original issue was that fuel was vaporizing in the rail after the engine got hot and cause a hard start. I think that the update basically increase fuel pressure to overcome the vaporization, don't quote me though.

 

I was going to bring it up with my tuner for my next revision. I wasn't sure it was fuel pressure since I have a PPRV delete and always prime it a time or two before cranking to make sure there's plenty of fuel.

 

Does it crank slow? My old firebird would crank slow and start like **** when it was hot, never figured it out but I think it was the starter.

 

Cranking speed is normal. Just doesn't pop.

 

My car does the same thing

 

check your fuel pressure

if you have a leaking injector.

check the fuel pressure and turn off the engine and see if the pressure drops to 0

if it dose then it mostlikely a injector leaking down and basicly flooding the engine and also having to wait for the pressure to come back up

 

Not sure that would be indicative of a leaky injector as it will leak, but likely in the opposite direction, back into the tank. I've got a PPRV delete to minimize restriction and hesitation, but that also allows it to drain back into the tank, which would mimic the symptoms.

Not to mention it would be odd for this to only occur on hot shutdown.

 

Have you tried resetting your ECM? unplug your battery and turn light switch on for 30M, maybe your ECM learned something it wasnt supposed to.

Im thinking the Fuel pressure is dropping after the fuel pump warms up, and the pump or Pumps is not operating at full capacity causing a lag or irratic pressure in the system. When you gas it and open up the injectors fuel flows in and starts the vehicle. Does it stumble immediately after starting hot? your pump may be on its way out.

 

I have this problem, actually made a thread about it. My tuner said its a fuel pump problem? It's not holding pressure or something. Also when I actually get it started i smell gas pretty strong

Happens like 1/10 hot/warm starts and is embarrassing

 

Mine does the same thing. Started doing it after the supercharger install 3 years ago. At the same time the PPRV was deleted and svt focus pump installed.

 

Yeah it's sounding like it's an adverse effect of the PPRV delete.

Fuel pump may be going out. My dads truck would do the same and my buddies ranger just recently acted up and replaced the fuel pump and boom started ever time

nick lentini

I don't think it's the pump. Those pumps are pushing enough to keep me as low as ~11.5:1 AFR under boost, so I don't think they're weak.

It sounds like this is the EFI equivalent of vapor lock (oh how I don't miss that on my Cutlass), and is exascerbated by a lack of a PPRV. Not much I can do.

 

My F150 does the exact same thing. Everything checks out on the spark side so it's gotta be the fuel side Id think

 

My vote is the fuel pump because I've changed a lot of fuel things so far to try and get rid of it, except the fuel pump I have changed any sensors though

The car only did it maybe like 6 times in the winter but summer time it usually happens every other day if I say run into a gas station real quick.

Must be a 4.6 issue

 

Miine does the same. Also it tries to stall for the first few minutes after startup. The hot weather seems to make it worse. Mine actually started after the long tubes, cams, 60lb injectors, and tune. I took it back to the tuner and he basically shruged his shoulders and said it's a 2v with cams.

 

Fuel pump may be going out. My dads truck would do the same and my buddies ranger just recently acted up and replaced the fuel pump and boom started ever time

nick lentini

 

It has two new GT supercar pumps and dual FPDM's so probably isn't the pump, but I wonder about the PPRV valve. I know I took it out; could that be it?

 

I still have mine! And it still does it so that can't be it

 

My bronco does this... im afraid its the pump lol. Aint nobody got time for that

 

I've datalogged the O2 sensors and noticed that the sensors are pegged when the car is not idling, as soon as the sensors start reading the idle is fine.

 

mine did it. I just cycle the key till the gauge peaks at 40 and barely push pedal and it starts. Only did it when engine and outdoor temp was high.

 

This is quite common on our cars, it is caused by heat soak and fuel vaporization in the rails. It can be remedied by richening the higher ECT temperature cranking AFR in the tune's Cranking A/F Ratio function.

Here are the settings I most often use (here the mix is increased by 0.8 "AFR" at 200°F ECT, and a bit more at higher coolant temperatures):

(the non-highlighted values are the stock numbers)

This corrects the problem on most GTs. Similar values were used in the last factory calibrations for the 2004 MY...

 

So when getting dyno tuned we basically have to tell them to change this? ....good information right here I figured when I changed pumps it would fix itself.

 

^ I think you told me this on mustangforums back in 2010 :lol

 

This will unlikely be more than many care to know, nonetheless it is part of what needs to be known to properly tunes an engine--so here goes.

Lambda (λ) is a dimensionless (ratio) value like AFR, where λ 1.0 indicates a perfect oxygen to fuel ratio for any fuel. I.e. when the perfect amount of oxygen is being combined with the perfect amount of fuel (whatever those quantifiable amounts might be). This is called the stoichiometric mixture. Measuring lambda works for any fuel, λ 1.0 will always be the perfect mix regardless of the fuel being used.

A lambda value of less than 1 indicates a rich mix, for example λ 0.9 (0.9:1) indicates that only 9/10ths of the perfect amount of air is being mixed with perfect amount of fuel--not enough air = rich.

Lambda 1.1 (1.1:1) on the other hand indicates that 1.1 times the perfect amount of air is being mixed with the perfect amount of fuel--too much air = lean.

O² sensors are often and more correctly called lambda sensors as they do not actually measure oxygen but rather the ratio of the oxygen content of the burned fuel to that in the atmosphere (they are vented to the outside).

So what is what we know and love as AFR? Turns out that he quantifiable stoichiometric (λ = 1.0) mix for gasoline is 14.64 to 14.68:1, with 14.7 the commonly used value as it is close enough. I.e. 14.7 parts of air (not oxygen, air) mixed with 1 part of gasoline. To convert AFR (for gasoline) to lambda just divide the AFR by 14.7:

• If AFR is 13:1 then λ = 13/14.7 = λ 0.88;
• If AFR is 16:1 then λ = 16/14.7 = λ 1.1;

All wideband O² systems I have seen actually measure and report lambda, then multiply the lambda value by 14.7 (many can be programmed for other fuels) so as to display AFR in terms we can relate to.

While on this subject, the stoichiometric mix for E-10 (10% ethanol) gasoline is 14.13:1; but before you run out to reprogram your wideband O² system remember what I said above, "wideband systems...measure and report lambda" and generally convert that to gasoline AFR for display to we humans. Therefore, and withing reason, it doesn't matter what the display says as long as you know that AFR 14.7:1 = λ 1.0. Rich will always be displayed as less than 14.7:1 and leans will always be shown as more than 14.7:1.