Fuel Delivery

mattmm04

Member
Apr 21, 2019
49
1
8
Virginia
I have a 01 cobra with a vortech charger installed. 255lph Walboro in the tank with 47# ford racing performance injectors. Dynoed and tuned and runs amazing except for one fault that happens time to time. Sometimes after full throttle and off throttle and back on during up shift the engine seems to stall for a second or two and then picks up and goes on. I've mentioned this to the tuner and his thoughts were the fuel rail pressure sensor first and then possibly the fuel pump driver module. He mentioned that a code is usually thrown for either one but there is no code. But I do have codes for the rear o2 sensors but the car has no cats on it so I don't know if that's a related issue or not. I have ordered both a new driver module and fuel rail pressure sensor since they're original and it's almost 20 year old car. Fuel pressure doesn't ever drop below 30 but with just a little bit of time I had this evening without pissing off everyone in the neighborhood worked the throttle while watching the test gauge and seen spikes of almost to 70psi by flicking the throttle back and forth. Research I've currently seen has shown that more pressure usually means lower flow. But that's where a boost a pump comes in to keep up with the fuel demand. I don't have a boost a pump at this time but have been asked why and how it's been running without the boost a pump.

My gut feeling is I'm running out of fuel up top. So my question is should I go ahead and order the boost a pump or am I needing to look at something else?
 
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No more info. How much boost are you running? I had a 310 Aviator pump on a BAP. At the time it was a 2V on 14psi through a D1SC. A BAP is always safe insurance. If you go lean at WOT then your motor is gone
 
So I got a chance to drive it after I went ahead and changed the fuel rail sensor and the fuel pump driver module. Same results. When under hard acceleration and shifting from at top around 6k. Then going off the throttle and back on from the shift there’s a hesitation before it picks up and goes on. Doesn’t matter what gear I’m up shifting to and it only happens when shifting from above the 6k range. Doesn’t matter what the temp is outside as it did it when the winter but seems to be more apparent with warmer temps. Personally feels like I’m running out of fuel at the top and have ordered a kenne bell BAP that will be here next week. Still have the same downstream o2 codes and nothing else
 
.028 is going to be too tight for your application. I know iridiums are a superior core, but they still feature projected tips. Save those iridiums but try some NGK BR7's. They still have copper cores but they are non-projected tips. Try them at .032 but go no lower than .030
 
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Needs the boost to keep up. Should have went with your gut instead of throwing parts at it bro. It happens
When I got the new plugs and pulled the first plug out I was wrong about what I had changed them out for when I bought the car. They were Motorcraft platinum that were gapped way out and replacing 20 year old electronics is just a assurance that they don’t fail as well in the long run.
I have a kenne bell boost a pump coming and I’m certain that it’s just starving for fuel. Main thing I need to do is install a boost gauge and a AFR gauge. I’m hoping today I find today and find out what’s happening. It’s something that been on my list the installation of the charger.
I drove it last night to see how the voltage was at when hitting high rpm and voltage went low as 12.8 but more consistently stayed at 13 and around 13.6 under all other conditions.
Goal today is to find a local store with a quality AFR gauge and install it and see if I’m getting lean at high rpm.
Also wanting to replace the coils on the car as well. Has the original stock Motorcraft coils on it and wanting to upgrade and seen Accel and MSD but haven’t seen any other brands to look so any input on that would be appreciated.
Im not going to close the plugs any further. I feel what I have done has corrected what they needed to be in the first place. The results have improved the symptom I’m having
 
Yep. They are only like $3 a piece or something like that.

Ive got the Autometer wideband Pro A/F gauge and it works like a charm
 
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Ever since AM joined up with BAMA and their complete :poo: tunes, I stay away from AM. Modular Head Shop is where I would have gone to but you should be fine.

If you ordered an AFR gauge, I hope it comes with the 8' harness, O2 bung, and everything else
 
I’ve heard the tunes were a joke but the only tuner near me needed me to have a sct whether I got it from them or someone else. Hardly get much from them, mostly from LMR but time to time AM will have better deal. The AFR has the whole kit but had to go to LMR for gauge pillars
 
After installing the BAP and installing those NGK plugs. Gapped to .032 and results were almost a complete fix. Just the tiniest hesitation left but for the most part a complete turnaround. I did install the boost switch so the BAP is activated when it hits 3.5. I’m still having to wait to install a boost and AFRgauge. The AFR gauge I ordered was u fortunately out of stock so I’m having to go hunt for another one once I cancel the order. But what do you guys think about upgraded coils? Still has original Motorcraft coils in and thinking it may be time to grab some new ones
 
Glad to hear that I was able to help. You can play around with the gap to troubleshoot any other issues. Just dont go below .030. Replacing the coils is a good idea seeing how old our cars are. I replaced mine with OEM Motocrafts. When it comes to coils, there are no "upgrades" for these motors
 
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I had the same problem! Took my car to a tune shop. They tuned it! Ran fine! At a certain rpm it would cut out for a split second like no power for a 10th of a second. I bought tuning software, spent one year learning how to self tune while driving under load. I made my own tune and compared them both. There was a variable of .008 at 4800 rpm wide open throttle that my airflow table wasn't getting enough fuel under a certain load. I added a .05% increase in fuel at the load and rpm in airflow table and boom no more issue! It can sometimes be the tune but sounds like the gap on the plugs were incorrect. Thankfully your motor didn't go boom!