l33 to l59 fuel system conversion

fly_champ · April 30, 2006

I have been looking for several weeks for information dealing with 5.3L fuel injection/ecm systems. I have been completely unsucessful, so I thought to post at a forum where the technical level was high.

The problem: 5.3 L33 does not allow running on alcohol.

The answer: 5.3 L59 allows alcohol running, so convert the l33 to match an l59!!

The reason: Access to CHEAP alcohol, and the numbers on a gas pump.

So far, the only part that I can find that is different between the engines is the ecm tune, and the fuel injectors. I suspect a couple of additional differences like fuel pressure and fuel resistance sensor, but don't know exectly what they are. I can't seem to locate any online resources dealing with engine specifics.

- If I am sucessful with the conversion, I will make a web page about it.

- I have a high level of general engine knowledge, but not in this specific area.

Shocker · April 30, 2006

Start by checking out this thread:

http://www.gm-trucks.com/forums/index.php?showtopic=50928

ChevyTech007 · April 30, 2006

I will check into it. Here is some info.

E85 Flex Fuel Description

E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.

The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.

Air-fuel ratios and the corresponding ethanol percentage are updated following each purge-off sequence. the fuel alcohol content percentage value can be read on a scan tool.

When an E85 compatible vehicle is built, an ECM or PCM replaced, or if the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10% or less ethanol content.

A minimum of 7.5 Liters (2 gallons) must be put in the tank in order for the vehicle to recognize a re-fueling event. It is not necessary to turn the ignition off in order to have the re-fueling event recognized; however local safety regulations should be followed.

After the re-fueling event, the system registers the amount of fuel that was added, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines if the fuel added was either ASTM Gasoline or ASTM E85. Based on that determination, the system adjusts to the expected alcohol mix in the fuel tank, and then the fuel trim and O2 sensor activity fine tunes the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or E85 to gasoline, can result in driveability symptoms due to the inability of the system to adjust for fuel composition by not attaining closed loop operation.

Switching Between Gasoline and E85

No special precautions need to be taken when switching back and forth between gasoline and E85 other than re-fueling events must be 7.5 Liters (2 gallons) or greater, and the vehicle must remain in closed loop long enough, usually by the time the engine has maintained full operating temperature, to calculate the composition of the new blend in the tank.

fly_champ · May 2, 2006

E85 Flex Fuel Description
E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.

The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.

<{POST_SNAPBACK}>

This is very useful info, but it still leaves me with "when a flex fuel vehichle is built"

I was kind of looking for "all you need to do is", or "additional info is here".

If I may, I would like to rephrase my questions to "are there any non-ethanol-compatible parts on the L33", or "is the only difference really the injectors and the ECM tune?"

The other forum links didn't appear to be well informed with what is actually required to do a conversion. Some friends and myself have sucessfully converted a couple of toyotas by changing only the fuel pressure regulator. We didn't have to make any other modifications, besides manually turning the regulator to compensate for different fuels. Another person I know personally has sucessfully converted a TDI jetta to run on alcohol, by changing the fuel pump, and running the glow plugs below 1000RPM. The efficiency of the TDI is outstanding, it consistently gets 60+MPG (no joke).

As I mentioned before, the only part difference a mechanic friend of mine could fine was the fuel injectors themselves, which had four ports as opposed to the stock L33's two ports. I don't know the pound rate of either, but I imagine the ethanol injectors are capable of a lot more pound rate for cold starting with E85. I find it very interesting that there is no fuel sensor required. If the injectors really are the only different part, could I change only the ECM tune and up the alcohol content of the tank until I run out of injector capacity on start up? I was sucessful at finding posts at a ECM reprogrammer's forum with the data from both engines' ECM, but I don't have their software to be able to read it (expensive).

If I become confident that the injectors and the ECM tune are all that is required, I will likely but some new injectors, and the reprogramming software and attempt a conversion. Since all the components are easily reversed to stock, This could be tested over a weekend, and put back to stock if it didn't work.

If I may pry, chevytech, where did you get your information from, as there may be additional resources to draw from there?

Levman74 · May 2, 2006

An E-85 compatible vehicle also has fuel system components that are compatible with the high alcohol content, such as special gaskets and o-rings.

ChevyTech007 · May 2, 2006

It's off the GM Service Information site. You have to work at a dealer to have access. I will try to get some more info. Just have not had time.

fly_champ · May 2, 2006

It's off the GM Service Information site. You have to work at a dealer to have access. I will try to get some more info. Just have not had time.

<{POST_SNAPBACK}>

Thanks chevytech, I look forward to getting more info.