Back from Tuning and car is acting strange! Help!!
10-11-2008, 01:20 PM
#1
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Location: Bristol, Tn
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Back from Tuning and car is acting strange! Help!!
I finally got my 95 T/A back on the road and she runs great and sounds good at low RPM and no boost, but when I took it to my tuner today to dial her in and see how she runs with boost, we both are scratchig our heads??? Here is a brief summary of my car/engine.
95 T/A A4, Yank 3000 stall, forged 383 with unported Dart 180's, 22X/23X cam, D1SC w/twin intercoolers, Lonnies Dual intank pumps, MSD Digital 6, 58mm throttle body, etc...
Car drives and runs great, but makes no real power.
1. We plugged the scanner in and at idle we see 3-5KR.. Anything above 2KRPM it goes max at 12KR.. There is no signs or sounds of detonation.
2. At Full throttle Fuel Pressure drops to 33psi and hovers around 39-41 at idle... Still using stock Fuel Pressure regulator. Can not determine if 2nd pump is coming on at 5psi of boost, there is no spike in pressure.. At WOT we can not get Air/Fuel any richer than about 11.5, even tried to make it real fat but would not go any richer!!
3. ** This really screws with my head. The D1SC is pulleyed 7.65/3.4 which should make 15+/- psi of boost around 6K. I can only make 5psi at 6.2K!!! I did make 6psi once...
This is really driving me crazy. I guess Murphey has got me again!!
95 T/A A4, Yank 3000 stall, forged 383 with unported Dart 180's, 22X/23X cam, D1SC w/twin intercoolers, Lonnies Dual intank pumps, MSD Digital 6, 58mm throttle body, etc...
Car drives and runs great, but makes no real power.
1. We plugged the scanner in and at idle we see 3-5KR.. Anything above 2KRPM it goes max at 12KR.. There is no signs or sounds of detonation.
2. At Full throttle Fuel Pressure drops to 33psi and hovers around 39-41 at idle... Still using stock Fuel Pressure regulator. Can not determine if 2nd pump is coming on at 5psi of boost, there is no spike in pressure.. At WOT we can not get Air/Fuel any richer than about 11.5, even tried to make it real fat but would not go any richer!!
3. ** This really screws with my head. The D1SC is pulleyed 7.65/3.4 which should make 15+/- psi of boost around 6K. I can only make 5psi at 6.2K!!! I did make 6psi once...
This is really driving me crazy. I guess Murphey has got me again!!
10-11-2008, 02:12 PM
#2
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Join Date: Oct 2004
Location: St. Charles, IL
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More information would be of help here. Stock knock retard module in the pcm? What octane fuel are you putting into the motor? Where is your FPR getting its vacuum/boost signal from? What size injectors are you using and what was the pw when the a/f ratio was at 11.5?
With all the piping that is used for the twin intercooler setup, check all the connections REALLY well to sure sure they are tight and that all the hoses are completely pushed on the tubing. What are you running for a filter and inlet connection to the D1SC? What kind of tuning has been done to the pcm?
Obviously, if the pcm is pulling 12 degrees of timing, the motor is not going to make any real power. You should determine why this is happening - false knock or the real thing.
If you are using a hobbs style switch to activate the 2nd fuel pump, try jumping across the terminals to check the operation of the 2nd pump. If it doesn't come on, there is an issue with the wiring and/or pump. I would definately look at the FPR a little more as well. The fact that the fuel pressure drops to 33lbs at wot is a huge issue. You could try removing the blower belt and connect a f.p. gauge to the system and monitor it when driving to see if the fuel pressure responds correctly without boost.
With all the piping that is used for the twin intercooler setup, check all the connections REALLY well to sure sure they are tight and that all the hoses are completely pushed on the tubing. What are you running for a filter and inlet connection to the D1SC? What kind of tuning has been done to the pcm?
Obviously, if the pcm is pulling 12 degrees of timing, the motor is not going to make any real power. You should determine why this is happening - false knock or the real thing.
If you are using a hobbs style switch to activate the 2nd fuel pump, try jumping across the terminals to check the operation of the 2nd pump. If it doesn't come on, there is an issue with the wiring and/or pump. I would definately look at the FPR a little more as well. The fact that the fuel pressure drops to 33lbs at wot is a huge issue. You could try removing the blower belt and connect a f.p. gauge to the system and monitor it when driving to see if the fuel pressure responds correctly without boost.
10-11-2008, 04:06 PM
#3
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Boosted_Z28>>
I have the LT4 knock module. Using 93 Octane fuel. Mototron 60lb. Running the stock fuel pressure regulator. Double checked all clamps and they are tight. I using the ATI hard molded intake with the big K&N filter. Tuning was done by a local tuner. We scanned it and made adjustments accordingly. Really do not think that it is real knock, especial 3-5* at idle.
Is an aftermarket FPR needed?
I have the LT4 knock module. Using 93 Octane fuel. Mototron 60lb. Running the stock fuel pressure regulator. Double checked all clamps and they are tight. I using the ATI hard molded intake with the big K&N filter. Tuning was done by a local tuner. We scanned it and made adjustments accordingly. Really do not think that it is real knock, especial 3-5* at idle.
Is an aftermarket FPR needed?
10-11-2008, 10:34 PM
#4
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You can try running some higher octane rated fuel just to verify that it is false knock that is causing the timing to be pulled from the motor. If it still pulls timing with the higher octane gas, it would probably be safe to presume it is false knock that the sensor is seeing. I believe you can have the knock sensor turned off, although this is not the most advisable way to eliminate that problem. As I mentioned in the above post, I'm sure this is causing the motor to be way down on power. Be careful though, you definately want to address the low fuel pressure/lean condition BEFORE you go back and do any more dyno tuning. As I mentioned before, make sure the FPR is seeing boost as well as vacuum. Also, you should verify that the 2nd fuel pump is operating properly. Please post again to let us know what you find out. Good luck.
10-12-2008, 12:55 PM
#5
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Location: IN
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You really need an aftermarket adjustable FPR for starters. To me, it seems your fuel pressure is a little low for your setup. Getting an adjustable FPR and getting more fuel may be helpful.
Also, its possible you are getting belt slip. This also could cause the low boost/power levels. SDCE makes a good tensioner (even though I think they are crooks for charging as much as they do).
When you do get more boost (after the bugs are worked out, you will), you are going to need more than those small intercoolers can provide without getting into detonation. I would most of all reccomend meth injection, and also a larger front mounted intercooler over your smaller twins. The twin intercoolers from ATI usually can't keep up past about 8#'s of boost.
The quick fix/more expensive alternatives to meth injection and larger intercooler would be run some race gas. But for how much it costs, you really should look for the FMIC and meth injection for the long term.
Also, its possible you are getting belt slip. This also could cause the low boost/power levels. SDCE makes a good tensioner (even though I think they are crooks for charging as much as they do).
When you do get more boost (after the bugs are worked out, you will), you are going to need more than those small intercoolers can provide without getting into detonation. I would most of all reccomend meth injection, and also a larger front mounted intercooler over your smaller twins. The twin intercoolers from ATI usually can't keep up past about 8#'s of boost.
The quick fix/more expensive alternatives to meth injection and larger intercooler would be run some race gas. But for how much it costs, you really should look for the FMIC and meth injection for the long term.
Last edited by CALL911; 10-12-2008 at 12:57 PM.
10-13-2008, 04:51 PM
#6
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Call,
I want to go with a FMIC, but with the T/A's there are not many options.
I pulled the intake tubing and tightened the belt some more. I have the 12rib setup with the ATI tensioner. The belt felt a little loose, plus there was black dust on the blower that must have came from the belt slipping.
I am ordering a AFPR tonight.
Boosted: I spoke with the tuner and he said that my FPR is seeing both boost and vacuum. I am new to the FI realm and have just a very basic mechanical knowledge of this stuff.. Is my stock FPR faulty? I have read on here that some of the big HP guys are still using the stock FPR. What I dont understand is why is my pressure dropping so much with Dual 255lph pumps?
I want to go with a FMIC, but with the T/A's there are not many options.
I pulled the intake tubing and tightened the belt some more. I have the 12rib setup with the ATI tensioner. The belt felt a little loose, plus there was black dust on the blower that must have came from the belt slipping.
I am ordering a AFPR tonight.
Boosted: I spoke with the tuner and he said that my FPR is seeing both boost and vacuum. I am new to the FI realm and have just a very basic mechanical knowledge of this stuff.. Is my stock FPR faulty? I have read on here that some of the big HP guys are still using the stock FPR. What I dont understand is why is my pressure dropping so much with Dual 255lph pumps?
10-13-2008, 05:29 PM
#7
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Location: Moore OK
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Bet your second pump isn't coming on - Should be seeing 50+psi under boost with your setup, even on the stock regulator.
The 60s saved you from going too lean, but I would not be surprised if your fuel system is part of the problem. In fact at 30psi I wonder if it is lean. How many widebands has it seen? Just the one at the dyno? I would want a second opinion.
Either boost is going somewhere or there is a huge restriction. Exhaust? Clogged cat? Is the throttle blade opening all the way?
The 60s saved you from going too lean, but I would not be surprised if your fuel system is part of the problem. In fact at 30psi I wonder if it is lean. How many widebands has it seen? Just the one at the dyno? I would want a second opinion.
Either boost is going somewhere or there is a huge restriction. Exhaust? Clogged cat? Is the throttle blade opening all the way?
10-13-2008, 05:44 PM
#8
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jsetzer: The tuning was done on the street, not a dyno. I have an AEM wide band in the car. No exhaust restrictions, Longtubes, no cats, 3in flowmaster with cut out open.
I am debating on the AFPR. Some say yes and alot of people say the stocker is fine.
How can I check to see if my stocker is bad??
I am debating on the AFPR. Some say yes and alot of people say the stocker is fine.
How can I check to see if my stocker is bad??
10-13-2008, 07:49 PM
#9
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Location: IN
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A stock FPR will not hold up on your setup. I don't know anyone with a D1SC (or equivilant T-trim or higher) that does not have an aftermarket adjustable FPR. Trust me, you need one. You need to make sure you're 2nd fuel pump is coming on during boost, and you need a tensioner as you said yourself the belt looks loose and there are other signs of slippage.
10-13-2008, 10:58 PM
#10
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Location: Cleveland, WI
Posts: 1,178
jsetzer: The tuning was done on the street, not a dyno. I have an AEM wide band in the car. No exhaust restrictions, Longtubes, no cats, 3in flowmaster with cut out open.
I am debating on the AFPR. Some say yes and alot of people say the stocker is fine.
How can I check to see if my stocker is bad??
I am debating on the AFPR. Some say yes and alot of people say the stocker is fine.
How can I check to see if my stocker is bad??
Bill
10-14-2008, 07:59 PM
#11
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Location: St. Charles, IL
Posts: 690
Not sure that the FPR is your problem here, but it is certainly worth upgrading to something other than your stock unit as others have mentioned. As I and a few others have mentioned, you definately need to check to operation of the dual fuel pump setup.
You will need to have a fuel pressure gauge attached to your fuel system. With the car running, I would simply jump across the hobbs switch with a wire to check the function of the 2nd pump, relay and wiring. If the fuel pump is operating properly, you will see a definate "jump" in the system fuel pressure. As SMOKNZ mentioned, you should also test the operation of the hobbs switch. Remove it from the engine and apply a low amount of air pressure to the switch using an adjustable air regulator. While doing this, have either a self-powered test light or continuity tester connected to the terminals of the switch. When you reach 5 psi on the reglator, the self-powered test light should come on or the continuity tester should show a closed circuit. Verify these first.
You will need to have a fuel pressure gauge attached to your fuel system. With the car running, I would simply jump across the hobbs switch with a wire to check the function of the 2nd pump, relay and wiring. If the fuel pump is operating properly, you will see a definate "jump" in the system fuel pressure. As SMOKNZ mentioned, you should also test the operation of the hobbs switch. Remove it from the engine and apply a low amount of air pressure to the switch using an adjustable air regulator. While doing this, have either a self-powered test light or continuity tester connected to the terminals of the switch. When you reach 5 psi on the reglator, the self-powered test light should come on or the continuity tester should show a closed circuit. Verify these first.
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