6.0 runs rich with 58 psi fuel pressure
09-07-2020, 09:26 AM
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6.0 runs rich with 58 psi fuel pressure I'm new to the LS world and have had quite a few issues with this swap. My truck is a 1999 Chevy K3500 dually, had a 5.7 with a 4L80E. I've been working on swapping a bone stock 2006 6.0 lq9, with another 4L80E fewer miles. I got my fuel psi back down to 58 psi but the truck still runs rich. 2 new upstream O2 sensors, new plugs and wires.
The problem now is with the vacuum hose for the brake booster. The truck has hydroboost brakes. If i plug the vacuum hose, it won't idle. Runs good at higher rpms but no idle. Runs rough with vacuum hose unplugged..
Any ideas??
The problem now is with the vacuum hose for the brake booster. The truck has hydroboost brakes. If i plug the vacuum hose, it won't idle. Runs good at higher rpms but no idle. Runs rough with vacuum hose unplugged..
Any ideas??
09-11-2020, 06:22 AM
#2
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If you just swapped engines, but kept the older PCM, then you need a new tune. The rich condition could be fixed with a tune. The rough idle is probably another tune issue. Do you have HP tuners?
09-11-2020, 03:41 PM
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09-11-2020, 03:43 PM
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09-11-2020, 04:33 PM
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"Back down." Why was it not 58psi before? What points is it running rich (all speed/loads?, idle and low speed?)
You have 58 psi with, or without the vacuum hose connected to your fuel pressure regulator? Does it change when you disconnect the FPR hose (and plug the hose so you don't have a manifold leak)?
You have 58 psi with, or without the vacuum hose connected to your fuel pressure regulator? Does it change when you disconnect the FPR hose (and plug the hose so you don't have a manifold leak)?
09-11-2020, 04:48 PM
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"Back down." Why was it not 58psi before? What points is it running rich (all speed/loads?, idle and low speed?)
You have 58 psi with, or without the vacuum hose connected to your fuel pressure regulator? Does it change when you disconnect the FPR hose (and plug the hose so you don't have a manifold leak)?
You have 58 psi with, or without the vacuum hose connected to your fuel pressure regulator? Does it change when you disconnect the FPR hose (and plug the hose so you don't have a manifold leak)?
I have installed an inline regulator from Jegs, now i have 58-60 psi all the time.
It runs best at higher rpms, but at idle / low rpms it runs rough and blows smoke out the tail pipe.
When the vacuum hose for the brake booster is open, it will idle rough but still runs, when i plug the booster hose it won't idle at all, and dies
09-11-2020, 06:04 PM
#7
I'm not sure but when I hooked up the fuel lines and tried to run it I had 80 psi at the test port on the rail. I don't have a factory regulator, I looked all over the fuel rails.
I have installed an inline regulator from Jegs, now i have 58-60 psi all the time.
It runs best at higher rpms, but at idle / low rpms it runs rough and blows smoke out the tail pipe.
When the vacuum hose for the brake booster is open, it will idle rough but still runs, when i plug the booster hose it won't idle at all, and dies
I have installed an inline regulator from Jegs, now i have 58-60 psi all the time.
It runs best at higher rpms, but at idle / low rpms it runs rough and blows smoke out the tail pipe.
When the vacuum hose for the brake booster is open, it will idle rough but still runs, when i plug the booster hose it won't idle at all, and dies
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09-11-2020, 07:37 PM
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09-11-2020, 10:08 PM
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The truck 06 LQ9 fuel rails does not use a vacuum referenced regulator and is a returnless system, the regulator is in the fuel pump itself. The injector flow rate in the tune is progressive meaning the number in the flow rate table changes. The older trucks with a vacuum referenced regulator have a static (same) number across the flow rate table.
Are you using the vacuum port on the Aeromotive regulator? Have you tried running without the vacuum hose to the regulator with the regulators nipple vented to the atmosphere? Is there a return line to the fuel tank?
Here are the differences in the injector flow rate in the tune, first with a vacuum referenced regulator, the second without a vacuum regulator. You can see the numbers are progressive. (like your stock LQ9 should have but not necessary the same numbers).
Are you using the vacuum port on the Aeromotive regulator? Have you tried running without the vacuum hose to the regulator with the regulators nipple vented to the atmosphere? Is there a return line to the fuel tank?
Here are the differences in the injector flow rate in the tune, first with a vacuum referenced regulator, the second without a vacuum regulator. You can see the numbers are progressive. (like your stock LQ9 should have but not necessary the same numbers).
Last edited by RedXray; 09-11-2020 at 10:19 PM.
09-12-2020, 08:15 AM
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The truck 06 LQ9 fuel rails does not use a vacuum referenced regulator and is a returnless system, the regulator is in the fuel pump itself. The injector flow rate in the tune is progressive meaning the number in the flow rate table changes. The older trucks with a vacuum referenced regulator have a static (same) number across the flow rate table.
Are you using the vacuum port on the Aeromotive regulator? Have you tried running without the vacuum hose to the regulator with the regulators nipple vented to the atmosphere? Is there a return line to the fuel tank?
Here are the differences in the injector flow rate in the tune, first with a vacuum referenced regulator, the second without a vacuum regulator. You can see the numbers are progressive. (like your stock LQ9 should have but not necessary the same numbers).
Are you using the vacuum port on the Aeromotive regulator? Have you tried running without the vacuum hose to the regulator with the regulators nipple vented to the atmosphere? Is there a return line to the fuel tank?
Here are the differences in the injector flow rate in the tune, first with a vacuum referenced regulator, the second without a vacuum regulator. You can see the numbers are progressive. (like your stock LQ9 should have but not necessary the same numbers).