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Old 08-10-2004, 04:36 PM   #1
anton
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Surging problem when driving

Hey again people.. stuill trying to correct this on going problem, ive had it at the tunning guys a few times now and I dont think they can fix the problem although there trying hard. Now what happen when driving along sometimes along the highway or going up hills it will surge. Now when I got my turbo done at the beginning with just the turbo nothing else it was fine.. Now the only thing i can think it has to do with is either the Fuel Pump, Injectors ( which I doubt) or The Ecu. They are the only things that were changed after this problem started occuring. Im leaning towards it being a faulty fuel pump which sometimes doesnt feed enough fuel therefore causing the surging.. im not sure..The maps have all been checked and they are all fine.. has anyone ever had this happen to them??

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Old 08-10-2004, 04:50 PM   #2
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is it an in-tank fuel pump

and if so, maybe the pickup is sitting awkwardly/in the wrong place/is fouling on something inside the tank

just a thought
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Old 08-10-2004, 05:28 PM   #3
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Yeh I think it is an intank fuel filter, but im not really sure how to get at it..Its only 2 years old so im thinking it shold be fine... thanks for comments
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Old 08-10-2004, 05:34 PM   #4
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fuel pump sitting in the wrong position, dirty fuel filter/system, dissy/plug leads or plugs.

I had the same problem, the leads had a very, very small hole in them and as they heated up, the spark would jump from the lead straight to the block instead of going thru to the plug, hence is was running on 3 cyliders, not 4 like it shound had been.

To test, while engine is idling, test 1 lead at a time by taking it off the plug, and just passing the lead past the block, if there's a spark leak with the leads, you'll see a small blue spark jump from halfway down the lead. good luck with it.
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Old 09-10-2004, 01:10 PM   #5
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Well lets not go rocket scientist on this one...

ok surging like you describe is almost definitely a fuel delivery issue on extreme load when it needs fuel... i doubt those injectors are faulty (i've only ever recieved one dodgy batch from our suppliers before, so i think the set i sent you should be fine, if in doubt get them tested and we'll take ema back under warranty though =p)

Do you have a fuel pressure regulator? What pump are you running? is it a direct bolt in denso one or what?

We will get to the bottom of this... if it ran fine and all you've done now is injectors a pump and an ECU then i suspect the pump... you get a stuffed injector it will run rich and misfire and blow fuel out the back, or run real lean and ping
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Old 09-10-2004, 05:20 PM   #6
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yeh im not sure what fuel pump they installed so i cant answer your question. As to the fuel pressure regulator I dont have one
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Old 09-10-2004, 05:34 PM   #7
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Quote:
Originally Posted by anton
As to the fuel pressure regulator I dont have one
That's gonna be a big problem, I'm guessing you don't have an aftermarket fuel pressure regulator.
Check your reciept, the fuel pump details should be detailed there.
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Old 09-10-2004, 06:16 PM   #8
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when running an aftermarket fuel system an adjustable fule pressure reg is almost one of the most important parts, simple because if you don't control the pressure the fuel sits at the whole time the pump will be pumping as much as it can on the power its getting the whole time(making the amount of fuel going through the injectors unpredicatable)... you turn your head lights on and drain part of the supply and the fuel pressure will go down because the pump isn't chargin away so hard... If you still have the standard one setup your injectors aren't getting the fule they desire, as stock fuel pressure is around 25-25psi those injectors i gave you would be much happier at around 40-45psi to keep the duty cycle nice and low

I'd definitely invest in an aftermarket reg..

a Malpassi Rising rate fuel presure reg - low end model will set you back $160 - $180 trade $200 retail and will do the job, not the greatest on the market but it should hold pressure for quite a while, and they're rebuildable if they leak

if you want something nice, shiny and more than happy to take what ever you throw at it i'd go for either an SX Racing or Sard rising rate fuel pressure reg will set you back around $250-$280 trade and around $300 retail... by far my first choice, but i hate things failing on me, its always the simply thigns that cause the worst head aches...

Both the above models have the additional option of an on board fuel pressure gauge which should set you back around $6, helps in setup hugely as it saves time on hooking a fuel pressure gauge onto the line

While hooking an aftermarket fuel pressure regulator to the late model astina's becomes abit of a hassel in installation though. Our fuel system uses quick release fuel lines using solid plastic instead of actual hosing... this creates the hassl that the fuel rail and lines from the tank don't have barbs on them, making it impossible for a hose clamp to hold on properly. But with a trip to your local Enzed or Pirtec you can get fitting that are one way non removable items. They have an olive inside the fitting that as you tighten the nut it crimps itself into the metal.. only way of removal = angle grinder..

shopping list for 99- 03 Astina aftermarket fuel pressure reg:
- Fuel reg of choice
- a few metres of fuel hose (depending on mounting position)
- 4 hose clamps
- 2 crimp fittings( one for the line to the tank.. one for the rail itself
- 2 barbed hose fittings(to go on the end of the crimp fittings)

after all this, even if as we prevously discussed you do you a bad ground, or a loose ECU wire at least you know its getting enough fuel... and it will both rule the possibility out (unless you have a dodgy pump) and give you the piece of mind that you have the system setup right

kinda typed it all in one go, so if the spelling is off or you need more help understanding something as always i'm more than happy to help
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Old 09-10-2004, 08:01 PM   #9
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Say what????
The job of any fuel pressure reg is to maintain pre-determined pressure at the injectors. It is designed to alter this pressure depending on the vacuum/boost in accordance with the duty cycle of the injectors. An FPR is a tuning device and needs to be taken in context.
If you install a larger fuel pump then the FPR will return the extra volume and pressure back to the tank (you won't notice any change). If you turn on the headlights and reduce the amount of current to drive the fuel pump then guess what... The FPR compensates and returns less pressure back to the tank.

The only difference between the standard FPR and an after market one is that an after market FPR you get to set the baseline pressure, if you run a little rich then you can iron out some flat spots without actually fixing the real problem.

NB. An FPR is not an electrical device. The headlight thing only refers to the performance of associated electrical components

Anyway I guess I don't agree with Doug but that's OK this is a place for people to express their views. My first action would be to look back to the changes made previously and get them right before forging ahead.
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Old 10-10-2004, 02:53 AM   #10
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i totally agree with cosmo... i was under the impression that the car was running without the stock fpr...

hence the quote "If you still have the standard one setup your injectors aren't getting the fule they desire, as stock fuel pressure is around 25-25psi"

I would only put a RRFPR on and up the pressure heaps if your maxing the injectors on a stock fuel setup and need the try and push the extra fuel through... As cosmo said "if you run a little rich then you can iron out some flat spots without actually fixing the real problem." luckily for anton he has injectors and a pump... so enough fuel shouldn't be the issue...

well put on the whole definition though....

I think both cosmo and i were trying to say the same kinda thing just he described it better and i rushed my addition to the thread while getting into my installation info =)
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Old 10-10-2004, 07:07 AM   #11
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Re: Surging problem when driving

Quote:
Originally Posted by anton
Hey again people.. stuill trying to correct this on going problem, ive had it at the tunning guys a few times now and I dont think they can fix the problem although there trying hard. Now what happen when driving along sometimes along the highway or going up hills it will surge. Now when I got my turbo done at the beginning with just the turbo nothing else it was fine.. Now the only thing i can think it has to do with is either the Fuel Pump, Injectors ( which I doubt) or The Ecu. They are the only things that were changed after this problem started occuring. Im leaning towards it being a faulty fuel pump which sometimes doesnt feed enough fuel therefore causing the surging.. im not sure..The maps have all been checked and they are all fine.. has anyone ever had this happen to them??

Cheers
Anton
What sort of RPM are we talkin here? Your not hitting some sort of rev cut are you.
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Old 10-10-2004, 08:30 AM   #12
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If anyone wants to know a little more about what is being said here then here it is.

Quote:
Originally Posted by Bosch fuel injection & engine management. Charles O. Probst SAE
PULSED INJECTION—THEORY

Pressure Regulator
Relative fuel pressure in the fuel system is held constant by the pressure regulator, usually mounted on the fuel rail. As shown in Fig. 2-13, spring pressure normally keeps the regulator valve closed. When the fuel pump turns on, fuel pressure presses on the diaphragm to compress the spring and open valve, returning excess fuel to the tank. The higher the pressure, the more the diaphragm moves away from the return pipe. increasing the volume of the chamber, maintaining the desired pressure. Most systems operate on 2.5 bar (36psi) gauge pressure, but some higher-powered engines use 3 bar (44psi) for greater fuel delivery per millisecond.

Relative Fuel Pressure and Fuel Delivery
For each millisecond of injector pulse time, the amount of fuel delivered through the injector tip depends on the size of the injector opening; that’s a fixed factor. But fuel delivery also depends on the relative pressure—the difference between fuel pressure pushing the fuel out into the manifold, and manifold absolute pressure pushing back, as shown in Fig. 2-14.
As you know, manifold pressure changes with throttle opening. If the fuel pressure were constant for all manifold pressures, then at low engine loads, with the throttle partly closed, reduced manifold absolute pressure would increase fuel delivery. To keep that relative pressure constant as the throttle is opened and closed, the fuel-pressure regulator is connected to the intake manifold by a vacuum hose. Manifold pressure acts on the diaphragm to hold the relative pressure constant.

For example, with the engine off, manifold pressure is the same as barometric pressure. If you measure fuel pressure with the pump running and the engine off, the regulator controls fuel pressure balancing the forces: fuel pressure on one side of the diaphragm balanced against spring force plus the force of barometric pressure in the manifold. The gauge then reads 2.5 bar, 2.5 bar (36psi) more than atmospheric. At wide-open throttle (WOT), manifold pressure is close to barometric, so again, the fuel-pressure gauge reads about 2.5 bar.

When thinking about fuel pressure, remember that the ordinary fuel-pressure gauge measures relative pressure —the amount that fuel pressure is greater than barometric pressure (14.5psi). But barometric pressure is measured from an absolute zero pressure, so 2.5 bar (36psi) gauge pressure actually means 2.5 bar greater than 1 bar of barometric pres sure, or 3.5 bar (51psi) absolute, measured from an absolute zero. When the gauge is not connected, it reads zero: zero here means the difference between the open connection and barometric pressure.

At idle, absolute pressure in the manifold is about 0.3 bar (0.7 bar less than barometric)—old-timers would say “20 inches vacuum”. Now the manifold absolute-pressure pushing the pressure-regulator diaphragm is only 0.3 bar instead of 1 bar. The reduced manifold pressure on the diaphragm allows it to move away from the opening, returning more fuel to the tank, and dropping the gauge fuel pressure in the distributor pipe to about 1 .8 bar (2.8 absolute). The relative pressure at the injector tip is still 2.5 bar (2.8 minus 0.3 absolute). That’s why fuel delivery per injection is not affected by changes in the manifold absolute pressure. When you understand this principle of fuel delivery, you’ll understand the checking of fuel pressures. You’ll also understand how greater delivery for off- road and performance operation may be increased by increasing fuel pressures.

Fuel Injectors
The port injectors (located at the intake ports next to the intake valve) are solenoid valves. Each injector is opened by an electrical signal from the control unit, and closed by spring force when that signal stops. See Fig. 2-15. When current is sent through the connection to the winding, electromagnetic force lifts the solenoid, and fuel is delivered. The lift is about 0.15 mm (0.006 in), and takes about 1 millisecond. When the needle valve is closed by the spring, no fuel flows. The pintle on the tip of the needle valve helps to atomize and distribute the fuel.

Interestingly, the injectors are electrically-hot all the time the key is ON and the relay combination is closed. For fuel delivery, they are grounded in the final stage of the control unit. In early L-Jetronics (until about 1978) each injector circuit includes a resistor to limit the current flow. In these circuits, the initial current-flow must be great enough to rapidly open the solenoid/needle valve, and then flatten out when only a holding current is needed. Since about 1979, L-Jetronics regulate the current in the control-unit final stage, and so do not need separate series resistors. The resistance is built into the injector itself, using a solenoid winding of brass (higher resistance than the previously-used copper winding). This also requires less power than the series-resistor type.

The injectors are held in intake manifold with O-rings that tend to insulate the injectors from engine heat and vibration. If the 0-rings crack, false air enters, leans the mixture and increases idle rpm. In most engines, the injectors are directly to the fuel rail with safety clips. In other engines, they are connected to the rail with fuel lines.

Fuel Metering and Pulse Time
In pulsed injection, the metering of fuel takes place at the tip of the injector as the fuel flows past the pintle. The lift of needle valve from its seat is always the same d assuming that fuel pressure is regulated as described above, the amount of fuel injected into the engine depends solely on the amount of time the control unit applies voltage injector.
This injector opening time is known as the Pulse time, and it can vary anywhere from 2 milliseconds to as much as 15 milliseconds or more. The injector takes about 1 millisecond to open, which is counted in the injection time. The closing time is not counted, but it averages out; pulse time is the effective injector open/delivery time.

If, when the control unit grounds the circuit, you measured voltage at the injectors on an oscilloscope, it would look something like Fig. 2-16. Remember that the injectors are always hot, and are grounded in the control unit. Note that when reading pulse time on a scope, it can be referred to as pulse width – the actual width of the pulse-time voltage on the screen.

Various operating factors determine pulse time as you’ll see below, but there is one other basic factor — called Pulse period. This is the total time from one opening of an injector to the next opening of the same injector. Normal pulse period for the pulsed systems covered by this book is twice per 4-stroke cycle, or once per crankshaft revolution. Half of the total of amount of fuel needed for one firing of a cylinder is injected in each injection. If the pulse period were once per 4-stroke cycle, then pulse time would increase so that all of the fuel was injected at once.

To see the relationship between pulse period and pulse time, let’s take a typical engine that idles at 600 rpm and has a maximum rpm limit of 6000 rpm. Dividing each of those revs/minute by 60 seconds, we can say the engine idles at 10 revs/second, and runs max at 100 revs/second. Fig. 2-17 shows pulse period and pulse time for this engine. Each circle represents 100 milliseconds (ms) of time.

It’s important to remember the inputs that control the basic injection pulse time: air-flow volume and rpm. Fig. 2-18 shows that full-throttle injection time varies from about 6 milliseconds to 9 milliseconds, and that injection time follows the torque curve.

Control Unit
The control unit is sometimes called the brain” of the control system. It receives input of signals from various sensors, processes those signals, computes the pulse-time for the injectors, and completes the circuits in a series of pulses to deliver the required fuel.

The control unit is a complicated piece of electronic equipment. If you open it—and that is not recommended—you’ll find it full of transistors, integrated circuits, and printed circuit boards, as shown in Fig. 2-19. The heart of the control unit is a microprocessor chip, about the size of a thumbnail as shown in Fig. 2-20.

In most cases, the control unit is sensitive to heat and vibration, so it is usually located in the passenger compartment away from the engine. A common location is the kick panel to the right of the passenger’s feet. You may also find it behind the glove box, under the passenger seat, or in the fresh air compartment under the hood.
Wow that was a mouth full :lol:
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Old 10-10-2004, 01:26 PM   #13
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****... i'm on dialup at the moment dude... that sucked...
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Old 10-10-2004, 04:35 PM   #14
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i bought a malpassi RRFPR a while ago. its the one thats all black sorta. still uninstalled, i bought it thinking it would be ok for my car but now im not sure if its overkill or not.
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Old 10-10-2004, 04:47 PM   #15
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Quote:
Originally Posted by MOOCHER
i bought a malpassi RRFPR a while ago. its the one thats all black sorta. still uninstalled, i bought it thinking it would be ok for my car but now im not sure if its overkill or not.
Wait untill you're doing the cams, It will realy be usefull then.
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Old 10-10-2004, 08:34 PM   #16
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haha u got it all worked out for me eh!
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Old 11-10-2004, 12:05 PM   #17
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Re: Surging problem when driving

Quote:
What sort of RPM are we talkin here? Your not hitting some sort of rev cut are you.
Nah not hitting the rev limiter, just normalish driving
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Old 11-10-2004, 06:14 PM   #18
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haha u got it all worked out for me eh!
As long as it's your money then yeah, I'll helpyou spend it.
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Old 12-10-2004, 09:21 AM   #19
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haha well ive spent $$ on that fuel reg now its just sitting there!
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Old 22-10-2004, 01:50 PM   #20
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