Need help figuring this out; lean spot at ~3k rpm
08-15-2011, 05:03 PM
#77
Nordschleife Master
Thread Starter
Took the FPR apart just now, everything looks fine on it. Still having trouble believing it was the FPR but the problem still has not come back once since i put the stock rail back on. There were a few fine metal shavings on the top side of the diaphragm, my guess whatever was left over from machining. Also the spring looks a bit 'weathered', not sure if they are all like that though. Also found a few scuff marks and a couple of slight nicks in the bore. I dont think these have any effect on how the FPR operates because nothing really moves or touches the bore when the regulator is assembled.
Sent an email to Aeromotive asking what they think. Ordered another regulator which should be here Wednesday..really hoping this lean spot doesn't come back as soon as i swap the other rail / new regulator back on!
Sent an email to Aeromotive asking what they think. Ordered another regulator which should be here Wednesday..really hoping this lean spot doesn't come back as soon as i swap the other rail / new regulator back on!
08-23-2011, 09:24 PM
#79
Nordschleife Master
Thread Starter
Ok so apparently i still have not figured this problem out after all!
Here are the developments over the past week.
The internals of the Aeromotive i posted above are all normal. I bought a Fuel Lab adjustable regulator and tried that, i could swear the problem was not as bad but was still happening. So this made me think something was up with the adjustable regulators and heat. I had read a few other posts from other forums (Evo and Supra) where someone had mentioned they believe the spring on the inside began to react different when exposed to heat. On a side note the internals of the Fuel Lab regulator are far superior to the Aeromotive.. i would recommend the Fuel Lab over the Aeromotive any day of the week!
So after running the stock rail / regulator and not having the issue last week, i decided to run the stock regulator with the CEP fuel rail. I got an adapter to run the stock 3-bar regulator with the CEP rail and hooked everything up this morning and amazingly the problem is now worse?? When i say worse, i mean its happening even on a relatively cool engine and under almost all circumstances when i am accelerating.
Here is the setup as it stands now. I made a bracket and a new line to get this all to work and i am pissed i wasted my time on making everything a clean install.
Anyhow the absolute last thing i can think of is the suction sock inside the tank is clogged up causing the pump to cavitate, allowing air bubbles into the fuel system. I am going to run down the tank tonight and tomorrow will drain and replace that suction sock, aswell as replace the fuel filter again (only 6k miles on it) and a few other rubber lines at the back. After that i am outta ideas! The only common component at this point is the fuel rail and damper, i cant see how either of these would be causing the problem?? I am beginning to think the problem when i had the stock rail on the car, i just didnt notice it or get it hot enough.
Currently i am looking at buying an S2000 to run for a few months.. this will atleast take the edge off trying to fix this damn car and allow me to make a damn track day this year!
Here are the developments over the past week.
The internals of the Aeromotive i posted above are all normal. I bought a Fuel Lab adjustable regulator and tried that, i could swear the problem was not as bad but was still happening. So this made me think something was up with the adjustable regulators and heat. I had read a few other posts from other forums (Evo and Supra) where someone had mentioned they believe the spring on the inside began to react different when exposed to heat. On a side note the internals of the Fuel Lab regulator are far superior to the Aeromotive.. i would recommend the Fuel Lab over the Aeromotive any day of the week!
So after running the stock rail / regulator and not having the issue last week, i decided to run the stock regulator with the CEP fuel rail. I got an adapter to run the stock 3-bar regulator with the CEP rail and hooked everything up this morning and amazingly the problem is now worse?? When i say worse, i mean its happening even on a relatively cool engine and under almost all circumstances when i am accelerating.
Here is the setup as it stands now. I made a bracket and a new line to get this all to work and i am pissed i wasted my time on making everything a clean install.
Anyhow the absolute last thing i can think of is the suction sock inside the tank is clogged up causing the pump to cavitate, allowing air bubbles into the fuel system. I am going to run down the tank tonight and tomorrow will drain and replace that suction sock, aswell as replace the fuel filter again (only 6k miles on it) and a few other rubber lines at the back. After that i am outta ideas! The only common component at this point is the fuel rail and damper, i cant see how either of these would be causing the problem?? I am beginning to think the problem when i had the stock rail on the car, i just didnt notice it or get it hot enough.
Currently i am looking at buying an S2000 to run for a few months.. this will atleast take the edge off trying to fix this damn car and allow me to make a damn track day this year!
08-23-2011, 10:57 PM
#80
Rennlist Member
Why not ruthe stock parts longer to make absolutely sure. Sounds like there is something about the aftermarket rail/fpr/damper causing the problem. Maybe some kind lister will test those parts on his car to see if he gets the same results...
08-23-2011, 11:53 PM
#81
Jon you have horrible luck. Never seen a person work on their car so much and yield so little in return. Maybe see what Dave has to say about the problem since you have narrowed it down to the rail. Maybe you just got a bad one
08-24-2011, 01:55 AM
#82
Nordschleife Master
Thread Starter
I ran the stock rail / damper for almost 100 miles of stop and go, heat soaking..etc and i could swear it never happened, but maybe i just never go the conditions right. There was one particular hot and humid day in that mix also. After i change the suction side tank filter, if i have the same results, the stock rail will be put on yet again for test purposes. Its just such a PITA to swap the rails, takes all of an hour or so to do but it makes a damn mess as its basically unavoidable to pull the injectors out of the rail dumping fuel everywhere.
I have been talking to Dave about this and i am the only one who has this issue.. so the problem must be elsewhere. I honestly do not think the rail itself is the problem considering its literally a block of machined aluminum. The only thing left is the damper, but i cant see how that would cause the problem i am having.
Anyhow i am really considering picking up an S2K. I am going to spend another day or two on this and if i cant figure it out, i am just going to put this car back into storage for a few months while i decide what to do with it. Too frustrating to continue working on it right now.
I have been talking to Dave about this and i am the only one who has this issue.. so the problem must be elsewhere. I honestly do not think the rail itself is the problem considering its literally a block of machined aluminum. The only thing left is the damper, but i cant see how that would cause the problem i am having.
Anyhow i am really considering picking up an S2K. I am going to spend another day or two on this and if i cant figure it out, i am just going to put this car back into storage for a few months while i decide what to do with it. Too frustrating to continue working on it right now.
Last edited by Techno Duck; 08-24-2011 at 02:13 AM.
08-24-2011, 02:12 AM
#83
Rennlist Member
I ran the stock rail / damper for almost 100 miles of stop and go, heat soaking..etc and i could swear it never happened, but maybe i just never go the conditions right. There was one particular hot and humid day in that mix also. Once i change the suction side tank filter and have the same results, the stock rail will be put on yet again for test purposes. Its just such a PITA to swap the rails, takes all of an hour or so to do but it makes a damn mess as its basically unavoidable to pull the injectors out of the rail dumping fuel everywhere.
I have been talking to Dave about this and i am the only one who has this issue.. so the problem must be elsewhere. I honestly do not think the rail itself is the problem considering its literally a block of machined aluminum. The only thing i can think of is the damper, but i cant see how that would cause the problems i am seeing.
Anyhow i am really considering picking up an S2K, i think the am just going to put this car into storage for a few months while i decide what to do with it. Too frustrating to continue working on it right now.
I have been talking to Dave about this and i am the only one who has this issue.. so the problem must be elsewhere. I honestly do not think the rail itself is the problem considering its literally a block of machined aluminum. The only thing i can think of is the damper, but i cant see how that would cause the problems i am seeing.
Anyhow i am really considering picking up an S2K, i think the am just going to put this car into storage for a few months while i decide what to do with it. Too frustrating to continue working on it right now.
08-24-2011, 02:18 AM
#84
Nordschleife Master
Thread Starter
What i am getting at is the parts left are the rail itself and the damper. I dont understand how the rail itself could be causing this as its a block of aluminum. The damper is all that is left and i cannot see how that could be causing such a huge lean spot. Besides the damper seems to be working fine, as the gauge shows no pulsation in the pressure.and all it is is a spring loaded diaphargm. But anything is a possibility at this point.. maybe the damper internal to the rail is defective causing excessive pulsating at that engine load.. seems far fetched but who knows.
This makes me think i may have just not gotten the conditions right when i was running that stock rail, because the only part i could think of that was problematic was the FPR, which has been ruled out by trying 3 separate ones.
Like i said though, i am going to drain the tank and replace the filter and a few other original lines / hoses back there anyhow. If that turns up nothing the stock rail will be put back on yet again.
This makes me think i may have just not gotten the conditions right when i was running that stock rail, because the only part i could think of that was problematic was the FPR, which has been ruled out by trying 3 separate ones.
Like i said though, i am going to drain the tank and replace the filter and a few other original lines / hoses back there anyhow. If that turns up nothing the stock rail will be put back on yet again.
08-24-2011, 09:23 AM
#85
Three Wheelin'
Join Date: Feb 2007
Location: Indianapolis,IN
Posts: 1,408
Likes: 0
Received 0 Likes
on
0 Posts
Jon, I cant imagine how frustrated you are, but the sock/lines performed fine for a week with zero issues. Changing them out would make me feel better as routine maintenance, but they wont care what rail is on the car.
Having said that, I can't imagine the rail being the problem, either, but the gun is smoking.
Having said that, I can't imagine the rail being the problem, either, but the gun is smoking.
08-24-2011, 02:49 PM
#86
Professional Hoon
Rennlist Member
Rennlist Member
Join Date: Jan 2010
Location: Melbourne, Australia
Posts: 7,090
Likes: 0
Received 4 Likes
on
4 Posts
From what i have read in your thread is that its not the FPR. but the fuel rail hasn't been ruled out yet. when you changed it back to stock the problem went away and when you changed it back the problem came back. you tried a few different FPRs and still the same problem.
Would the volume of the fuel rail have an effect on anything?
a good test might be getting a different fuel rail. Borrowing 1 of a lister or see of CEP will lend you one for test purposes.
Or even a different brand fuel rail. someone must have 1 laying around and willing to lend you one.
Goodluck!
Would the volume of the fuel rail have an effect on anything?
a good test might be getting a different fuel rail. Borrowing 1 of a lister or see of CEP will lend you one for test purposes.
Or even a different brand fuel rail. someone must have 1 laying around and willing to lend you one.
Goodluck!
08-24-2011, 04:42 PM
#87
Addict
Rennlist Member
Rennlist Member
Join Date: May 2001
Location: A suburb of Silicon Valley, CA
Posts: 2,099
Likes: 0
Received 7 Likes
on
3 Posts
I feel your pain, as I have this same issue on my car. I have been chasing this for over a year now with no luck.
My issue started when I added a Lindsey afpr. Like u I taped a fuel gauge to my windshield, drove and watched. My fuel pressure was fine and I got a rising rate with boost so I ruled out the afpr.
I sent out my new injectors to RC engineering for clean and flow. No fix but now I rule out the entire fuel system. My thought is something is telling the computer to shut down the injectors at 3k rpm. Replace tps. No. Install known good MAF. No. Known good DME. No. I am now thinking of replacing the 26 yro speed sensor (ref signal dropping out at 3k?). If that does not do it, my last hope is the piggyback controller?
My issue started when I added a Lindsey afpr. Like u I taped a fuel gauge to my windshield, drove and watched. My fuel pressure was fine and I got a rising rate with boost so I ruled out the afpr.
I sent out my new injectors to RC engineering for clean and flow. No fix but now I rule out the entire fuel system. My thought is something is telling the computer to shut down the injectors at 3k rpm. Replace tps. No. Install known good MAF. No. Known good DME. No. I am now thinking of replacing the 26 yro speed sensor (ref signal dropping out at 3k?). If that does not do it, my last hope is the piggyback controller?
08-24-2011, 06:33 PM
#89
Addict
Rennlist Member
Rennlist Member
Join Date: May 2001
Location: A suburb of Silicon Valley, CA
Posts: 2,099
Likes: 0
Received 7 Likes
on
3 Posts
Not to encroach on techno ducks post, but I modified my fuel rail to eliminate the risk of fuel leaks and engine fires that have occurred on other 951's. I cut off the stock fpr, welded on a AN fitting then ran steel braided fuel line on the fire wall instead of directly over the exhaust to my afpr. Also the afpr allows for additional tuning capabilities over a fixed 3 bar regulator.
08-24-2011, 07:06 PM
#90
Burning Brakes
OK, another WAG. Isolate your plug wires from the fuel rail and injectors by an inch or so - thinking the firing pulses are backfeeding through the harness to the DME - some harmonic interference might be sending the wrong signal. Hey, its free and easy.