I would start over with a chip that caters to your new intercooler. A would suggest a chip that has some adjustable features.
Fuel Pressure Problems
- Thread starter 1QUIK6
- Start date
I would start over with a chip that caters to your new intercooler. A would suggest a chip that has some adjustable features.
Did notice yesterday in 3rd at WOT, as the FP started to climb my voltage on the Scanmaster started to drop. At WOT in 3rd it settled to around 13.2V & thats about when the WOT FP peaked out at 68#. It should have gone up to 75#- 24#boost - 51#static. Could be that the 108A alt. just isn't going to put out the amps that the FP needs? The voltage not being consistent at idle has me wondering if the alt. is working properly. I checked the grounds on the car & they check good.
I always thought the general consensus was that 70 psi is the ragged edge for electronic injectors. Anything at 70 or higher can possibly cause irratic, unstable fuel delivery, depending on the injector. The injector wigs out. Some fuel pressure regulators are designed to regulate fuel within a certain range. Have you checked to see if your make of regulator is capable of pushing the pressure beyond what you're seeing now? If it were me, I would be switching injectors if you think you're leaning. 13.2V isn't that bad. Ignition requirements cause the drop. Inconsistent voltage at idle would tell me to change out the alternator.
Add up all your amperage draws and make sure the alternator capacity is not at the limit. The only draw that changes with rpm and load is the ignition. If your charging system is already at the edge before high rpm/WOT, I think you get the picture. Add to that a fault with the charging system.the ignition is fused at 10 amps. so this less than 10 amp draw is causing a problem
Paul
OK let's start adding up the current draw during a WOT run....
ignition.....absolute max for a stock ignition is 6.5A...so let's give it a value of 5 A
Injectors...that would be about 1 amp per injector at full boogie...6 amps
Ecm? not sure...but I bet not much....but I'll give it 5A
It's winter...10 A for the blower motor....
maybe it's dark out....15 A for headlights
almost forgot ..fuel pump.....10A
I got 56 A....can anybody add something else?
Paul
ignition.....absolute max for a stock ignition is 6.5A...so let's give it a value of 5 A
Injectors...that would be about 1 amp per injector at full boogie...6 amps
Ecm? not sure...but I bet not much....but I'll give it 5A
It's winter...10 A for the blower motor....
maybe it's dark out....15 A for headlights
almost forgot ..fuel pump.....10A
I got 56 A....can anybody add something else?
Paul
gauges
cluster lights (night time)
radio? Some people like Deep Purple @ WOT.
Scantools?
Alky injection motor? Don't know if he has one in this case.
Laptop running off cigarette lighter?
Bad connections? (bad powers, grounds)
weak battery? Causing charging system to over work.
Radiator fan? I would assume these are shut off at WOT. Confirmed?
Parasitic amperage draws eliminated as a possibility?
All amperage draw values confirmed?
I'm not sure about this, but is it possible for an alternator to lose output as rpm increases? Would that be the design of that particular model or a bad internal component? I understand that different alternators have a max recommended rpm. Could that be playing a part? I know my old stocker alternator always seemed to lose output with rpm, down into the 12V range. Even, sometimes below 12.6V. My new one seems to maintain output better at WOT. In the 13s. Aftermarket.
cluster lights (night time)
radio? Some people like Deep Purple @ WOT.
Scantools?
Alky injection motor? Don't know if he has one in this case.
Laptop running off cigarette lighter?
Bad connections? (bad powers, grounds)
weak battery? Causing charging system to over work.
Radiator fan? I would assume these are shut off at WOT. Confirmed?
Parasitic amperage draws eliminated as a possibility?
All amperage draw values confirmed?
I'm not sure about this, but is it possible for an alternator to lose output as rpm increases? Would that be the design of that particular model or a bad internal component? I understand that different alternators have a max recommended rpm. Could that be playing a part? I know my old stocker alternator always seemed to lose output with rpm, down into the 12V range. Even, sometimes below 12.6V. My new one seems to maintain output better at WOT. In the 13s. Aftermarket.
good list....let's add another 20 A for all that stuff....so we are up to 76 A.
Stil got a ways to go to get to 120 A....
Maybe the thread starter can give us a better indication as to what was actually running at the time so we can get a better idea of the electrical load....
I still don't think that the ignition is gonna put you over the top:biggrin:
Paul
Stil got a ways to go to get to 120 A....
Maybe the thread starter can give us a better indication as to what was actually running at the time so we can get a better idea of the electrical load....
I still don't think that the ignition is gonna put you over the top:biggrin:
Paul
My DFU requires a 20 amp fuse. Fuel pump and injectors, 15 amp fuses each. All aftermarket. I'm not sure what actual draw numbers are. That is what was recommended by the CPU manufacturer.
I recently had to upsize my alternator wire because the terminal end was showing signs of overheating. That was with the stock alternator (1984 GN). It was 10 gauge. It is now a small battery cable size. Can't remember the gauge size, but it is definitely overkill. Overkill is better than under with electrical circuits.
If you have a bad connection, it most definitely would push it over. Bad powers and grounds are the first things that should be checked, but unfortunately are often ignored.
I recently had to upsize my alternator wire because the terminal end was showing signs of overheating. That was with the stock alternator (1984 GN). It was 10 gauge. It is now a small battery cable size. Can't remember the gauge size, but it is definitely overkill. Overkill is better than under with electrical circuits.
If you have a bad connection, it most definitely would push it over. Bad powers and grounds are the first things that should be checked, but unfortunately are often ignored.
fuel pump, injectors, and ecm have been accounted for. Just because a device has a 20 amp fuse doesn't mean that's what it is actually drawing. The ignition is fused at 10A, but can only draw a max of 6.5 and in actual operation is somewhat less. fuses are there to protect the wiring from a short circuit and not an indication of actual operating current.
I see that the original poster was at the track, so we can eliminate the wipers
Any body have anything else that was overlooked in the list and wants to contribute? Or maybe the current ratings are wrong? We are still a long way away from 120A. Just trying to get to the bottom of this myth that WOT takes a lot more current than the alternator can dish out.
Paul
I see that the original poster was at the track, so we can eliminate the wipers
Any body have anything else that was overlooked in the list and wants to contribute? Or maybe the current ratings are wrong? We are still a long way away from 120A. Just trying to get to the bottom of this myth that WOT takes a lot more current than the alternator can dish out.
Paul
In my best Glenn Beck voice.....
Here is what I know.....voltage dropping has been an issue from day one. And everybody is reading it from a scan tool. No one seems to be able to hook up a voltmeter to the battery or alternator to compare the values. I have witnessed this only once on my car and just by coincidence, I had a voltmeter hooked up to the ECM (internally) on the voltage line that is read by the ECM for batt voltage. Diacom was reporting falling voltage (heck, this was at idle ) but the voltmeter was reading 13.5v. It's never happend since.
As far as I know alternators do not "crap out" at higher RPM. I've never heard that in my 45 years of learning automobiles. But I think Altavos may have something to say about that
So, I think the thread starter had better report in and between the two of us maybe we can finally get his issue resolved. Nothing worse than having a poor running TR:biggrin:
Paul
Here is what I know.....voltage dropping has been an issue from day one. And everybody is reading it from a scan tool. No one seems to be able to hook up a voltmeter to the battery or alternator to compare the values. I have witnessed this only once on my car and just by coincidence, I had a voltmeter hooked up to the ECM (internally) on the voltage line that is read by the ECM for batt voltage. Diacom was reporting falling voltage (heck, this was at idle ) but the voltmeter was reading 13.5v. It's never happend since.
As far as I know alternators do not "crap out" at higher RPM. I've never heard that in my 45 years of learning automobiles. But I think Altavos may have something to say about that
So, I think the thread starter had better report in and between the two of us maybe we can finally get his issue resolved. Nothing worse than having a poor running TR:biggrin:
Paul
Just to add to my one time experience....I have a suspicion that it may be a software problem inside the ECM. The real answer here is for the original poster to put a voltmeter on the battery or alternator and see if there is a difference and then go from there...I just don't trust using one tool (scan tool) as the absolute answer. I'm done....it's been nice taking with you...
Paul
Paul
Don, what matters at the injector is the psi across the injector, which in this case will always be the static fuel pressure so long as the regulator and pump are working and the pump is keeping up. I've also read that if this gets up to 70 psi or more then some injectors start to have problems, but he is only at 51-55 psi. I think he is just running out of pump volume. If you look at the flow charts that Lee gave the link to, you can see how fast the pump volume is falling as the output pressure gets near 70 psi, and here (unlike at the injector) it is the output pressure that matters.
Turn the boost down 4-6 psi and set the static fuel pressure to 48 or so, which gives you up to a 21 psi increase to your observed max of 69 psi, and see what the tune looks like. Work the boost up to maybe 20-22 psi which seems to me like will be your limit with your pump, and see how fast the car is. I'm assuming your fuel filter is in good shape, and I think it's time to step up to a bigger pump system.
I've been through this routine on my car, with a bosch 204 pump and 40 lb/hr injectors. Up to a base of 60 psi I could make it richer at wot, but past that it didn't matter. Went to 72 lb/hr injectors and dropped the static pressure to 37 psi and now all is well (and .5 sec faster from other mods) and the inj duty cycle is still only about 70%. Look at those pump curves and see how much more volume the pump can deliver at 60 psi than 80 psi
.Very good point. The pump pressure/volume relationship slipped my mind.
Are the pulleys original size?
The manufacturer of my new alternator warns against overspeeding the alternator. I'll have to look at the paper work to see what the reason is.
Are the pulleys original size?
The manufacturer of my new alternator warns against overspeeding the alternator. I'll have to look at the paper work to see what the reason is.
My car seems to run best at the recommended fuel pressure that the chip is burned for...
For whatever reason, it seems to go lean in high gear if I crank up the pressure. When I lowered the fuel pressure, the O2's balanced-out.
I suspect the problem may be too much baseline fuel pressure won't allow the pump to keep up with the boost curve at higher boost levels.
If your chip is burned for 25psi boost @ 68psi, then you need a 43psi baseline to maintain the fuel curve.
If you start out with 50psi fuel pressure and add 25psi boost to that, then the chip needs to see 75psi at the injectors to maintain the same curve.
If your pump will only give you 68-69psi, then you will be 6-7psi short, and go lean.
At least that's how I try to make sense of it.
If it were me, I'd try lowering the baseline fuel pressure to the chip maker's recommended setting, then try to add fuel in the chip if so equipped.
The added FMIC might have really made a difference in the fuel requirements.
I'd have a new chip burned if I were you... TurboTweak Home
Erics chip put me straight into the tens...right out of the box.
For whatever reason, it seems to go lean in high gear if I crank up the pressure. When I lowered the fuel pressure, the O2's balanced-out.
I suspect the problem may be too much baseline fuel pressure won't allow the pump to keep up with the boost curve at higher boost levels.
If your chip is burned for 25psi boost @ 68psi, then you need a 43psi baseline to maintain the fuel curve.
If you start out with 50psi fuel pressure and add 25psi boost to that, then the chip needs to see 75psi at the injectors to maintain the same curve.
If your pump will only give you 68-69psi, then you will be 6-7psi short, and go lean.
At least that's how I try to make sense of it.
If it were me, I'd try lowering the baseline fuel pressure to the chip maker's recommended setting, then try to add fuel in the chip if so equipped.
The added FMIC might have really made a difference in the fuel requirements.
I'd have a new chip burned if I were you... TurboTweak Home
Erics chip put me straight into the tens...right out of the box.
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