nitrous36

Hey I have a procharded mustang v6 and have been fighting with a hard starting issue for a while. Ill give you all the details I can to help.

I have put in new fuel injectors, new fuel pump, new coolant temp sensor and new IAT sensor over time and the car still does it. Usually the car does this after sitting 30 mins to an hour. The car is more likely to do this on hot days. It does occasionally on cold winter days but much less than in the summer.

I even put a fuel pressure guage on the rail to watch bleed down. Im sure fuel pressure leak down is not the problem b/c sometimes the car will hard start even after sitting as short as 5 min - 10 min with pressure still on the guage.

With new injectors and fuel pump in Im sure its not a fuel issue. I could be wrong though. But I did notice the temp guage is always at a certain reading when the car wants to do this. So that lead me to replace the coolant temp sensor and IAT. Car still does it, Im puzzled. The temp guage is usually around the 1st quarter mark when the car doesnt want to start.

Been fighting this a long time. What else could it be? Any help appreciated. lilroush, anybody?

Fink

spark issue?


You mean that it just cranks and cranks and then eventual fires?

nitrous36

Sometimes when its hard starting, you can hear it trying to fire. Sometimes the motor will sputter and die if you let go of the key. I was thinking possible spark issue. Like maybe the spark is getting washed out before it can ignite. The plugs are gapped at .035 as recommended by procharger. So Im not sure or think spark gap is an issue.

It usually will just keep turning over and over without firing at all. Sometimes though it will eventually fire on its own if you hold the key. But thats not good to do. So to get it to fire I usually always have to open the throttle a good bit, sometimes WOT to get it to fire.

The key cycling trick:
If I turn the key back and try again when it doesnt fire the first time, I can sometimes get it to crank on the second or third try.

It could be an air issue. When its hardstarting if I open the throttle(lets more air in) it will crank. And its worse for hard starting on hot days when the air is hotter and thinner. On cold days when the air is colder and denser this happens less. So its possible its an air/fuel issue.

On the tuning side of things we've added air and fuel, and we've taken out air and fuel. No matter what we try nothing works. So I dont know if its a tuning issue or some other underlying issue with the car.

LilRoush

I'm guessing it's a mixture issue at start up.
Is it hard cranking (similar to a dead/dying battery) or is it turning over and not firing?
Timing could be something as well.

nitrous36

Turning over and not firing. But to get an idea of what it does, read through the last post above yours. Because sometimes the car acts like it wants to fire.

nitrous36

Ive thought about it being a mixture issue. But nothing we done to the air/fuel in the crank file seems to help.

Never thought about timing though. How can I be sure its a timing issue? Because sometimes the car will start fine and other times it wont. If it was timing wouldnt it do it everytime?

Is the timing different between warm starts and cold starts? The car only does this on warm starts after sitting a 15 minutes or more.

LilRoush

Hum... how does it run once it does start?
I had a coil pack go out one time. Car was a bugger to start, but once it started it ran fine. Not sure why it did that, you'd think it would fail or work.. not fail part time. But then again I guess not working right means failing. Haha

nitrous36

The car runs fine once started. Its funny you mentioned the coil pack. Because I thougth about that, but like you I figured if it was bad the car wouldnt run right or even run at all. What car were you having this issue with?

But in a last ditch effort to try something I have considered that next. I mean Ive been through the injectors, fuel pump, the expensive stuff. So what do I got to lose in trying the coil pack. lol

LilRoush

It was on a friend's 2001 V6.

mustangman02232

im going to +1 the coil pack,