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Crazy afr, maf? injector? Fuel pulsations?

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Old Aug 9, 2017, 09:51 AM   #31
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I have a prosport oil pressure gauge laying around. Should i just install it as a fuel pressure gauge until i order one? I believe they're the same. But i could be wrong.
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Old Aug 9, 2017, 10:04 AM   #32
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You are correct. It was jumping at high electrical load.

Now that i have updated and adjusted iscv and biss its acting differently. With whipers, headlights, fans, a/c on it maintians afr and rpm. With just a/c on, it maintians afr and rpm. Just idling with no electrical loads it maintians afr and rpm.

Once fans turn on to bring engine temp down from 206F to 195F, thats when the afr jumps. And rpm drops about 50 and stay at 750rpm. Until cooling fans turn back off and and returns to maintianing afr and goes back to 850rpm.

Issue is varrying a little once another step is completed. So i will try to keep the symptoms as updated as possible.

I am using a stock fpr solenoid. I hear that a lot of guys bypass it and connect the fpr directly to the manifold. Is this common practice?

Im going to pick up a fuel pressure tester a little later today.

Yes, it's common to do since it is only active for startup to keep the FPR from seeing vacuum until the engine is running.

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I have a prosport oil pressure gauge laying around. Should i just install it as a fuel pressure gauge until i order one? I believe they're the same. But i could be wrong.
Yes, that will work fine.
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Old Aug 9, 2017, 12:29 PM   #33
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If his fuel pressure was off a great deal, one would want to correct that before continuing to tune the car. What you say makes no sense sometimes.

Again, you don't know what I do.
Again, you don't tune your own cars enough said.

Sure sounds like a poor connection somewhere, is your logged voltage changing when the fan kicks on?

Is your ground wire connected from the intake to the firewall?
You also have a ground wire that goes to the battery to the frame then to the bell housing is that still connected to the frame?
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Old Aug 9, 2017, 12:57 PM   #34
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If his fuel pressure was off a great deal, one would want to correct that before continuing to tune the car. What you say makes no sense sometimes.

Again, you don't know what I do.
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All that might help. But I've been around a few properly setup stock cam/stock displacement Evo's, and the 2000's just don't idle perfectly, especially on pump gas. The motor just doesn't flow enough air to need that much fuel.
This is what you said when I told a fellow member to drill his siphon. Hummm seems contradictory to me.
I still would have waited until the real electrical issue was found to drill it out.

Glad it helped
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Old Aug 9, 2017, 02:27 PM   #35
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This is what you said when I told a fellow member to drill his siphon. Hummm seems contradictory to me.
I still would have waited until the real electrical issue was found to drill it out.

Glad it helped
Stock cam/head/motor Evo X on 2000cc injectors, vs the OP here having a built 2.0L, 280 cams, and maybe a ported head with ~1100cc injectors. Two completely different things.
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Old Aug 9, 2017, 07:36 PM   #36
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Stock cam/head/motor Evo X on 2000cc injectors, vs the OP here having a built 2.0L, 280 cams, and maybe a ported head with ~1100cc injectors. Two completely different things.
It is even more imperative that you drill the siphon with 2000cc injectors. With smaller injectors you can tune around it, with big ones you can't.

Completely different really? Not really. All FI vehicles should have a linear base fuel pressure with reference to manifold vac/boost, don't you agree?
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Old Aug 9, 2017, 11:16 PM   #37
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Yes, it's common to do since it is only active for startup to keep the FPR from seeing vacuum until the engine is running.
It's there for hot starts to prevent vapour lock
It's not used on cold starts.



Quote:
Originally Posted by 2winscroll View Post
All FI vehicles should have a linear base fuel pressure with reference to manifold vac/boost, don't you agree?
Surely nobody in their right mind would disagree.........except for the sake of disagreeing just because I said so.


The computer doesn't have an input for fuel pressure so it's got to be a fixed number.
The number doesn't really matter so long as it's fixed and never changes.
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Old Aug 10, 2017, 12:43 AM   #38
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Once fans turn on to bring engine temp down from 206F to 195F, thats when the afr jumps. And rpm drops about 50 and stay at 750rpm. Until cooling fans turn back off and and returns to maintianing afr and goes back to 850rpm.
That might be yet another problem.
I've seen that happen with a pod filter sucking on hot air.


Another thing to check with the fuel pressure gauge.
There's actually 4 easy numbers to check.
After idling and reading the pressure (33PSI)
Clamp the vac line before shutting off.
Shut it off (33 PSI)
Start it up again, pull the vac line off (43 PSI)

Shut it down (43 PSI)
It'll hold that pressure for several days if not weeks.
If it leaks down straight away, there's a leak.

If the FPR is being outflowed with a 255 pump, then those numbers 33, 33, 43, 43 will be more like 39, 33, 44 and 43.
With a 455 you'll be looking at about 60, 33, 70, 43 unless you've broken the FPR.

But I could be completely wrong?
I might be making it all up?
But how would you know?

Last edited by RightSaid fred; Aug 10, 2017 at 01:04 AM.
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Old Aug 10, 2017, 04:55 AM   #39
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Yes ground from manifold to firewall is in place with no corrosion. Same with battery-frame-bell housing.


Thank you all for the help so far.


I'm jumping on a plane this morning and heading out of state for a few days, so I wont be able to do all these check until I get back Wednesday.


I just attached my tune, if someone wants to look at it for inconsistencies and errors, please feel free. note that it is a temporary tune, to correct issue before going to Ver7.
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File Type: bin perfect def 1.4.4beta.bin (256.0 KB, 0 views)
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Old Aug 10, 2017, 06:59 AM   #40
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Originally Posted by 2winscroll View Post
It is even more imperative that you drill the siphon with 2000cc injectors. With smaller injectors you can tune around it, with big ones you can't.

Completely different really? Not really. All FI vehicles should have a linear base fuel pressure with reference to manifold vac/boost, don't you agree?

My point was an all stock motor on 2000cc injectors is never going to idle that great if you want it to idle at stoich. So even with doing everything you suggested, the guy with the 2000cc injectors was probably never going to get what he wanted out that setup, he needed to just go with smaller injectors.


I do agree with the latter.
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Old Aug 10, 2017, 10:33 PM   #41
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I do agree with the latter.
That's the most intelligent thing I've seen you post on here.
So you agree with me?
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Old Aug 16, 2017, 12:15 PM   #42
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Quote:
Originally Posted by RightSaid fred View Post

If the FPR is being outflowed with a 255 pump, then those numbers 33, 33, 43, 43 will be more like 39, 33, 44 and 43.
With a 455 you'll be looking at about 60, 33, 70, 43 unless you've broken the FPR.

But I could be completely wrong?
You are not wrong. A 255HP overruns the factory FPR. I learned this last year when my hard line (feed) rotted out and I put in a -6AN supply line.

Car was tuned on increased fuel pressure the whole time. The newer larger lines held more volume and dropped the fuel pressure. Car was instantly a door stop.

Rather than retune the entire car - I bought an AFPR. And the line "on" pressure is about what it should be line "off". As soon as I turned up the pressure the car would hold an idle, and all the trims fell back in line.



He's on a mini-battery? How old is it..? Mine last 2 years and the 3rd winter I get all kinds of electrical issues in the car and then I get furious and replace it.
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Old Aug 17, 2017, 07:10 AM   #43
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Mini battery was in the car when i bought it. Could be 2-3 years old. But i have no clue. Tested it a few times when the alternator went bad. No issues with voltage/resistance, corrosion, or getting continuity on the battery case.

Im back haha.
I will have fuel pressure number up, hopefully by noon.
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Old Aug 18, 2017, 09:53 AM   #44
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Okay, here are the fuel pressure numbers.

Idle 40-43: afr jumping car struggles to idle
Cruise 37-39: afr jumping
Slight accel 40-43: afr consistent
Wot 40-65 (i did hit 70 in second gear)afr is okay. A tad lean

So its only doing the issue at idle and cruise. Im starting to think is either the inj latency or something with the tps. Its consistent now that i rescaled inj. Not electrical load based
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Old Aug 19, 2017, 09:40 AM   #45
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When fpr vac is unplugged fuel pressure climbs to 49 then drops to 46
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