FEOA Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
511 Posts
Discussion Starter · #1 ·
My car started surging (feeling like it was hesitating / cutting out) under boost the otherday. I decided I needed to be able to watch the fuel pressure, I made a high pressure hose to extend my guage on the rail. Bled the system and held it against the window with the windsheild wiper. I also was told that turbo'd cars needed almost half the stock n/a spark plug gap.

I was running .52-.56 (as reccommeded) but was realized that with higher compression (boosted) cars you should run smaller gaps to make sure the spark ignites. I reduced the gap to .32, I am running the MSD coil pack so is .32 where it should be? or should I have left it .52 since the higher spark from the MSD might equate for the spark jumping a stock gap on a turbo'd engine?

Driving the car now its running even worse. Watching the fuel pressure it stays around 20-21 until it gets under load. Then starts bouncing violently between 20-45psi. Then when it hits about 3 or 4psi of boost it rails the pressure guage at 50psi.

The car runs like crap and hesitates even when it's not loaded up or boosted and right before it is boosting up until about 2-3psi the fuel guage is bouncing all over and the car is stuttering. It's got to be one of three things...

-Fuel pump has had it's last day
-A-FMU is broken (not sure what's inside to be broken)
-A-FPR is broken (again not sure what's inside)
-Clogged filter (I did put in a stock replacement about 8K ago, so I'm guessing this isn't it?)

Any ideas, I need some input here as I don't want to just start replacing any one of the above peices without being pretty sure it's bad, they all cost from 60-300 bucks a piece.
Ideas?

Thanks guys, and Congrats to Jeff on that DYNO run, 220+ HP out of an escort!
 

·
Administrator
Joined
·
39,360 Posts
thats prety weird. when i first used the fmu it took a while for it to work good. maybe your fmu needs a new disk? the fuel pump is good for 6psi stock. the hesitation sounds like a super lean... or rich condition. what is your o2 reading when this happens?
 

·
Registered
Joined
·
5,296 Posts
How's the pulsator between the pump and it's mounting bracket? The seals in mine crapped out giving me low pressure. I replaced it with a piece of hose because nobody makes the pulsator anymore :roll:

BTW: this is the same device that causes the "my car dies out while accelerating on the on ramp" issue.

Matt 8)
 

·
Registered
Joined
·
2,709 Posts
I'm curious... are you using adjustable PWM for fuel or a rising rate FPR? Also, are you using the stock ECU for a fuel map?

What are the brands of the products you're using?

What is the plug condition?
What happens at high rpm under partial throttle? WOT?
 

·
Registered
Joined
·
511 Posts
Discussion Starter · #5 ·
Pulsator, that could be it, I've heard that this is suppose to equalize the pressure for fewer oscilations.... These go out?

The A/F guage reads pretty normal. The plugs looked great when I pulled them an regapped them to .032.

The FMU is a procharger unit. The FPR is ACCELL I believe, I pulled the FMU out of hte system and drove it to the store..... I still surged but the fuel pressure wasn't going toggling from 20-45 like it wasy but it instantly threw a CEL. I'm assuming since my FMU wasn't hooked up for this test it sensed the system was going lean.

The ECU is stock just a lower pressure FRP (about 20) 24# injetors and a procharger AFMU. Set to about 9:1

Too late to take it to the shop and check the CEL code. I'm going to put on the stock ford coil tonight maybe somethings going on with the MSD pack. Also I'll pull the Pump and take a look at the pulsator.

Thanks guys. Any more ideas?

Tim
 

·
Registered
Joined
·
511 Posts
Discussion Starter · #6 ·
I found most if not all of the problem

When installing MSD ignition systems even though the instructions state only install spacers on the Focus model vehicle "PUT THEM ON YOUR ESCORT"

I'm out about a hundred bucks :(



It sure idles like crap with that stock coil pack but it seems to run much better through the power/boost conditions

On a side note my idel FP is 19-20psi with 24# injectors. The a/f guage shows it might be slightly rich but it smells very rich. Is there a ways to lean it our a little? Maybe lowering the pressure? The ACELL FPR is as low as it will go though. Any ideas or would raising the FP be better assuming that the ECU will decrease the pulse width of the injectors with feedback from the 02 sensor? I'm assuming 19psi is lower than the 24# injectors were designed to operate under. Raising the pressure might smooth the idle out but will the ECU adjust the pulsewidth.
 

·
Registered
Joined
·
511 Posts
Discussion Starter · #7 ·
Correction, this morning I realized the MSD coilpack wasn't entirely the issue.

It still stutters when I'm running around. Under 3-6psi boost the car is pulling so hard you can't feel the hesitation, but up unitl then it's pretty noticable (almost like you're on a lightly bump road).

The Fuel gauge still shows it jumping around back and forth between 20-40psi before it hits 3psi boost. But when it's hesitating the fuel pressure is pretty stable at 20psi. Step hard on the gas and the metter bounces between 20-40 then once the boost starts pulling the meter stabilizes at 60 or so. Is this normal (pressure) behavior for a A-FMU?

Could something as simple as cheap plug wires cause this hesitation (they're only about 2K old) the connection in the boot around the plug feels very iffy.
 

·
Registered
Joined
·
511 Posts
Discussion Starter · #8 ·
Or
.
.
.
.
.
It could be as complicated as a dropped valve seat :cry:

Another guy had identical issues on a n/a engine:

Well, I finally got an answer to the problem. I took the car to another mechanic. He did a compression test on the cylinders, paying particular attention to the one that kept misfiring. While the problem was occuring there was almost no compression in that cylinder. We've decided that the valve in cylinder 4 was going wonky. We're going to have to remove the head, rework the valves, replace all the gaskets and at 97,000 miles the timing belt is due to be replaced anyway.

Cheers,
Donovan
--------------------------------------------------------------------------------
herefordman

The steel valve seat insert has loosened in the aluminum head, your one of the lucky ones, and appear to have caught it before it cracks, falls out, and smashes the piston top and head all to crap, this is really common with this engine, Ford should be ashamed of themselves to have such a highly repeatable problem.
 
1 - 8 of 8 Posts
Top