Archangels

so after a long awaited return for my FC due to being store for the winter time, i brought it out last night, drove it around a while not bagging on it since it still had a full tank of gas from the season prior, drove it to work today and what-not then when i got home, i had revved it to redline and it started to run like a bag of ****, i checked it out, took it around the block, still the same thing, now has an odd hessitation and stumped me, i brought it home and checked the fuel pressure and noticed at idle (being lumpy now) it was bouncing between 20psi-28psi and not staying constant, the only way it would stay constant is if i revv the car in neutral, the fuel pressure then jumped to a steady 40psi~ and does go a little beyond depending on how hard i rev. the vehicle....

any idea's why my car would all of the sudden decide to run like a bag of ****?, i swear, 4years of this has taken a toll on me, i'm about ready to part the ****** out and crush the shell.... i need help....

papiogxl

iTrader: (6)

The fuel pressure jumping would more than likely be a symptom of an instable vacuum source. So I would say check vacuum at idle, morethan likely it will jump around, probably between like 15 inHg and about 5 inHg.

My guess would be a vacuum leak causing the problem, but that's just a guess.

Archangels

i couldnt see a vac. leak and checked all of the lines....

Zanity

iTrader: (1)

did you test or just look at them?

i've heard this is one symptom of a dirty or clogged fuel filter.
not sure though.

good luck.

arghx

iTrader: (3)

pressure test for air/vacuum leaks. it is the most accurate way to diagnose and locate them.

Archangels

the fuel filter was changed 500km ago....

i put a jumper onto the green connector and turned the key to the "on" position, the FPR read 38-40psi.... however when it's on part throttle or idling it bounces from 20-30psi.... thus probably causing my hessitation....

the only thing i can think about to fix the situation is to wire the pump to a constant 12v, idea's guys?...

HAILERS

Pull the vacuum line off the FPR and plug the line. The pressure should now read 37-39 constantly. Go for a ride. If the fuel pressure acts as before, then it's not the vaccuum source. Right? But if the pressure stays steady, then it's not the pump?

20psi is an unreal figure for a stock FPR. So it could be pump/fuel filter related.

Archangels

i took off and plugged the vac. source going to the FPR and it does not change, even if i plug it or let it breath freeley, i should also note that i have a new fuel filter and pump with approx 2500km's on them and i am running an aftermarket aeromotive 1:1 rising rate FPR....

when i do a rev through the RPM band the fuel pressure is fine at 40-42psi where it was when the car was tuned, but on part throttle and idle it's low and the same goes for my vac. it reads just under -10 on my boost guage, but the vac. source to the FPR is a direct line off of the front of the intake manifold....

i'm stumped.... it sound like a vac. leak, such a stupid thing to happen when all you're doing is revving the car....

HAILERS

I'll drop out on this. I'm not sure how that aftermarket FPR works.

On the stock FPR the more vacuum you have the lower the fuel pressure is in the rails. Usually something like 28-32 psi at idle and if the car were a non turbo, it would read 37-39 at WOT. IF it were a turbo it would be 37-39 psi plus one more psi for each psi of boost added to that.

At part throttle the pressure is going to be somewhere b/t the 37-39 and the 28psi. Hard to say just where.

Seems when you adjust your aftermarket FPR you'd set it at 28-32psi at idle. Then ????

Archangels

^^ typically yes from what i understand....

but what would cause the pressure guage to bounce so irratically?, the car idle's rough and stumbles, yet when i DO go to WOT or a hard rev. for example, the pressure jumps properly and accordingly....

it goes to 40-43psi on a rev thankfully, and i do notice i make a few psi of boost from a rev....

when the vehicle was tuned it was seeing approx 30psi at idle, it stayed rock steady aswell and jumped when throttle was manipulated....

what are a few things i can check to diagnose the problem?, i have the next three days off and would really like to fix the car, if i jumper the connector by the strut tower will it cause the fuel pump to run at a constant 12v~ or is that only used as a test, where/how do i check resistances at the pump/relay and where are they?, what do they look like?...

hope i'm not asking for too much, this car's been very stressful, i parked it and it was fine, bring it out and not even 24hrs later it's back to it's same-old games....

i can rule out a blown motor couldnt i?...

Archangels

how can i test for air/vac. leaks?, it's definitly something i should try....

arghx

iTrader: (3)

I learned the pressure testing trick from a friend of mine who has a Vr-4. Those things are horrible for boost leaks.

http://www.boostpro.net/prodtester.html

at the bottom here you will see "universal/dsm" pressure tester. I actually bought this from the site, but I think it is a 3" PVC cap tapped 1/4 NPT with a tire valve fitting installed, or a male air compressor fitting. Those are hardware store parts. You would connect this to your turbo using a couple of some kind. It all depends on what kind of turbo you have and whether you have a TID or whatever. I use a 4" --> 3" and connect it directly to the compressor housing on my upgraded turbo. With my motor on the engine stand I hooked it directly to my Greddy TB elbow using 3" coupler. Any old coupler will do really, no need for an expensive silicone one.

They show a gauge in the pic but you don't really need it if you have a boost gauge in the car, although it is more convenient because you don't need someone to look inside the car and check. What I would do is hook my air compressor up (I had a male air compressor fitting) and adjust the regulator slowly to pressurize the system. Then I would feel for air escaping and spray slightly soapy water around the engine bay. I take an empty windex bottle, fill it with some water, and add just a bit of dish soap.

Here is a custom pressure tester for an FD to test each LIM runner:



I've never done this, but if you don't have an air compressor at home you may be able to take the car to a gas station and test using the tire inflator, provided that you use a tire valve on your tester.

Archangels

a friend of mine has a tester for a talon so maybe i can adapt it to work on my FC, hmm....

either way tommorow i will be ripping the upper intake manifold off and checking for leaks and what-not, i've done it a few time's so i've become fluent in doing so....

this is frustrating to say the least, i'm still certain it's a fuel pump relay however, while in the "low" setting it's not getting proper voltage....

RotaryRocket88

iTrader: (7)

Have you tested the idle voltage at the fuel pump with a multimeter? It's supposed to be 9V when the resistor is inline, then back to 12V when any kind of load is on the engine.

arghx

iTrader: (3)

hook the tester up first, so you have an idea where to look before you pull the UIM off. if you have a Greddy TB elbow you can just use a 3" coupler from Pep Boys to make it work, again it doesn't have to be high quality. Pep boys has a decent selection of couplers and reducers actually.

Archangels

i have quite a few spare couplers at my disposal thankfully....

i just dont understand how something this stupid could happen so suddenly, guess my plan of attack tommorow is to read the voltage at the pump on the connector (correct?) and go from there, can anyone explain why it would read proper pressure with load and end up being sparatic without and at idle?...

Archangels

* Update *

So today it's +2 out and i'm barely able to work on the car, however, it's sat since saturday night and today when i opened the hood and turned the car to the "on" position i noticed the fuel pressure sit at 39-40psi with the car off, i turned it on and it stayed around the same, car came to life and purred, after it was warm i revved it a little and the fuel pressure moved slightly to approx 42psi and down as the revv's fell, i took it around the block, came back and it was still idling fine at 1100rpm, the vac. reading on my boost guage was -12 ( i have a large street port ), and the fuel pressure never dipped down any lower....

so i'm confused, the last time i drove the car it idled at around 850rpm, the vac. reading was lower, and it idled lousy.... would it matter that it's a fair bit colder today and that it is lightly raining?... i notice the engine idle's a little rough though, but rev's and drives fine....

ugh.... i need advil....

HAILERS

39-40 with engine off and fuel pump running is normal. The FPR is seeing atmospheric pressure and no vacuum and no boost.

39-40 at idle and the FPR's vacuum line attached to the FPR.........is not normal. It should be closser to 28-30psi. I guess with the boost gauge reading -12 the figure might be closer to 32psi at idle. But it shouldn't be 39-40. Seems there is no vacuum going to the FPR. Where are you getting the vacuum for the FPR from?

The higher than normal idle could very well be the water thermowax's piston not extending enought or lack of engine water to the thermowax or ?? the engine had not gotten up to operating temperature yet.

Archangels

i drove it and it idle'd the same, it's a couple hundred higher but if i remember correctly when i adjusted the TPS i set it that way to have it idle smooth....

i figured 40psi at idle wasnt proper, it wasnt that high prior, it sat at approx. 30psi or so then would move up with a rev. yet today it's not having the symptoms as it did prior, i'm confused....

however with a large street port i have the FPR vac. source coming from the top nipple on the front of the intake manifold nearest the front of the car.... the vehicle was tuned as such yet only showed symptoms of akward fuel pressure and what-not recently....

perhaps the fuel pump relay is the issue?...

HAILERS

Let's see if I remember how the fuel pump relay/resistor work. When starting the car, the assy sends full batt voltage to the pump. Once started the assy sends only approx 9vdc to the pump.

Then while driving with no load on the engine the assy sends approx 9vdc to the pump. Then you stomp the gas pedal and the ECU sees LOAD and the assy now sends full batt power to the pump.

There's a green/red wire at the assy that goes to the ECU. The ECU puts a gnd on that wire if NO load is seen by the engine. That makes the pump see 9vdc. Then if your under load the ECU removes that ground and the assy now supplys full voltage to the pump.

You could remove or depin the green/red wire from the assy or the ECU plug and see what happens. OR backprobe the fuel pumps feed wire and observe the voltage on it at low load conditons and at high load conditions.

When I said *assy* above I meant the fuel pump/resistor assy.

Archangels

ahh, excellent....

i was wondering what would happen if i snip that wire, running a constant 12v does not have many downfalls in my eyes to be honest, it seems to be affected on the "low" 9v setting anyways....

however, if i wanted to run a constant 12v to the pump, how would i do so?...

i'll check and see what i can figure out tommorow....

arghx

iTrader: (3)

before you go cutting anything in experimentation, all you need to do is cut off the resistor relay in the front of the car. I have personally eliminated the resistor relay in the front (as opposed to relocating it). You don't necessarily need to run the relay at the bottom of the diagram.



There are 6 wires going to the relay by the headlight. Cut the relay off. Tape up the middle two wires. The ones on the left (labeled E and F) are a pair (same colors I think) and the ones on the right (A and B) are a pair. Just solder the paired wires together and you're golden. I'm not sure it even matters if you cross the wires (E to B and A to F). You can skip the whole left part of the diagram for now.

original writeup: http://www.1300cc.com/howto/how2/rewire.htm . skip the resistor relay relocation is what I'm saying. I think there isn't much point in keeping the relay, it just creates a wiring clusterfuck in the car and has no performance benefit. You may have a richer idle but you can mitigate that by adjusting your idle mixture with the variable resistor or whatever EMS you have.

EDIT:



verify with a multimeter. it may accomplish the same thing as what Hailers suggested, I just know this way works from experience.

Archangels

when i tape up the middle two wires do i connect them to one another or do i leave them seperate....