Frequently get hesitation for half a second
 

ONE OF THESE DAYS this stupid car will be all sorted out... I hope.

Ever since installing the Cobra short block, adding Cobra dual pump tank and getting a new tune, my car has occasionally completely stopped supplying fuel and/or spark for a half second... then it comes right back like normal. This used to just happen while cruising normally. Not getting on the throttle.

Now it's doing it when I get on the throttle half of the time. My tuner is checking it out. Anybody here seen this happen before? It almost feels like it thinks it hitting redline and cutting fuel even though it's nowhere close to redline.

I do have the correct BAP for dual pumps. (40 amp)

Re: Frequently get hesitation for half a second
 

I've had this problem with my car for years, although it happens sporadically. I original though it was the fuel pump, well the original took a dump and I replaced it with a focus SVT unit. Unfortunate, I still get the same thing happening every once in a while.

If I remember correctly someone claimed it could be moisture that found its way to the spark plugs. You could try pulling the ignition covers and giving all the plugs a shot of compressed air. Honestly I've never tried this fix as it happens so rarely that I forget about it until the next time.

Re: Frequently get hesitation for half a second
 

Hmm, wouldn't it only affect certain plugs in that case so it would still fire but not on all cyls? What's happening on mine is it feels like the computer just tells the entire engine to stop firing or it's not activating the injectors.

It's starting to happen really often. Like twice during the same 50 mile drive.

Re: Frequently get hesitation for half a second
 

Did you do the PPRV delete? That can cause hesitation as well.

Re: Frequently get hesitation for half a second
 

moisture in the coil packs can cause a misfire but I think thats pretty consistent when it happens.

if youre logging fuel and spark I would think it would be pretty easy to see in a log

Re: Frequently get hesitation for half a second
 

I actually don't know, isn't that on the fuel tank? I'm not sure if the shop did that when installing it or if maybe it was already done on this used tank. That would make a bit of sense, as the entire issue started when the tank was put in.

Re: Frequently get hesitation for half a second
 

This is more than "hesitation" though, I probably shouldn't have used that word in the thread title. It's more of just a total and instant cut-off of ignition for half a second, then it returns like normal...

Re: Frequently get hesitation for half a second
 

yes the PPRV is in the fuel tank, its part of the pump assembly before it gets to the hat. Theres a hose off of each pump, they Y together and theres a one way check ball, it keeps fuel in the line when you turn the car off for quicker start up. Its a restriction so many people delete it for more headroom but there have been hesitation issues with it in place

There's a spot in the tune where your tuner can put a limit on the fuel pressure the FRPS senses. He also needs to change a couple values.

I really need to write these down so I don't have to look at my tune every time. But a lot of the time the hesitation can be tuned out. Depending on how close to maxed your fuel system is.

Re: Frequently get hesitation for half a second
 

Just mentioned the PPRV delete to my tuner... he texted back saying he already tried it, lol. Crap.

Re: Frequently get hesitation for half a second
 

Yea, I know the feeling, almost like someone tapped the brakes real quick and it jolts the entire car. I only experience it while cruising in 5th never during acceleration runs, which makes me think it is ignition related rather than fuel.

Re: Frequently get hesitation for half a second
 

Yeah it feels exactly like that. My tuner says he'll figure it out, I'll let you know what he comes up with when he does. It's Bob Monks (aka Bobcat), he's a wizard. Very well known around the midwest, one of the best Ford guys around. No doubt he'll find the problem eventually.

I thought it doesn't hurt to see if anybody online already ran into the same issue and found the solution though.

Looking forward to this car finally being at 100% in time for spring. :gears:

Re: Frequently get hesitation for half a second
 

I had the same problem at WOT switching from 3rd year to 4th, and all it was the BPV blowing air to the MAF sensor and throwing the ECU out of wack. Once I rerouted through BPV dump problem solve. I know my car is supercharge but I hope this help you out.

Re: Frequently get hesitation for half a second
 

My car's supercharged too, but the BPV is vented to atmosphere. It also used to happen sometimes even when driving like a sane person and just cruising along maintaining speed though. Something else could be up with the MAF sensor though that confuses the computer! Hmm...

Re: Frequently get hesitation for half a second
 

Hmmm I wonder if it is something as stupid as a dirty MAF sensor, but you'd think that would show up when logging fuel/spark.

Re: Frequently get hesitation for half a second
 

I used to have a similar issue with my turbo Focus when water got into the intake. It would blow onto the MAF and momentarily stall, but that was only in boost. I eventually moved the air filter.
Similar hesitations have been lean spots in part throttle and fixed through tweaks of the MTF table in the tune. Issues with the tune are usually consistently reproduce-able and not random. I've found random issues point to physical faults, meaning not in the tune.

Re: Frequently get hesitation for half a second
 

So apparently it was something about fuel pump voltage in the tune. Got the car back last night and so far no more hesitations.

Re: Frequently get hesitation for half a second
 

nice, at least it wasnt something you had to buy a buncha crap to fix

Re: Frequently get hesitation for half a second
 

Great to hear.

Re: Frequently get hesitation for half a second
 

Good news for you, unfortunately not a answer for me as the car is on the stock tune, only mod being SLP LM1's.

Start with the basics. Clean the MAF, new plugs, fuel filter, etc.