E85 mix?

[w_howey]

I know I run 24lb ford injectors in my 4.6, and I think Tom runs 21lb injectors, corvette maybe??, in his 4.7. But I don't think it is as simple as just adding volume -- mine is OBDII, so from what I understand the computer is fairly adept at making mixture/delivery adjustments based on the sensor inputs -- I think Tom has posted that he has an adjustable MAP sensor to make similar adjustments on his earlier (renix?) system... Someone with more electrical brains than me can add more accurate information!:gag:

An adjustable map for the Renix??? REALLY???? I knew there were ones for the Chryco injections before OBD-II, But have not seen one for the Renix...

 

[xj-grin]

An adjustable map for the Renix??? REALLY???? I knew there were ones for the Chryco injections before OBD-II, But have not seen one for the Renix...

Tom may be OBDI, I don't know for sure, and have no experience with Renix systems... I am pretty sure he is using some sore of adjustable MAP though... Old Man??

 

[JJacobs]

The OBD2 PCM uses fuel trims to compensate for engine wear, fuel quality, minor vacuum leaks and so on. Using the feedback from the o2 sensors it will add or subtract fuel to hit its target. With E85 the long term fuel trims will eventually hit the PCM's limit as it slowly adjusts and then the CEL comes on.

It really is as simple as running a larger injector or upping the fuel pressure and letting the computer figure out the rest. All the converter boxes are doing is intercepting the injector pulsewidth signal and multiplying it by around .3.

This can be viewed on a scan tool as soon as you put E85 in the tank. Short term fuel trims will start to climb as soon as it goes closed loop. After the ST goes high enough it resets to zero and the long term trim bumps up a number. ST continues to climb until LT goes up another tick and so on, it may take a week or two to put out a lean code.

 

[w_howey]

Tom may be OBDI, I don't know for sure, and have no experience with Renix systems... I am pretty sure he is using some sore of adjustable MAP though... Old Man??

Damn.... you almost had me turned on there....:laugh3:

The Renix system is dumb as a post to begin with.. There is no CEL light to turn on.. That foolish maintence light runs off the timer. I was just thinking of getting a better mix rather than just boosting to Ford 24lb. injectors which would be about 21 percent more than the stock 19lbs./hr injectors...

 

[xj-grin]

The OBD2 PCM uses fuel trims to compensate for engine wear, fuel quality, minor vacuum leaks and so on. Using the feedback from the o2 sensors it will add or subtract fuel to hit its target. With E85 the long term fuel trims will eventually hit the PCM's limit as it slowly adjusts and then the CEL comes on.

It really is as simple as running a larger injector or upping the fuel pressure and letting the computer figure out the rest. All the converter boxes are doing is intercepting the injector pulsewidth signal and multiplying it by around .3.

This can be viewed on a scan tool as soon as you put E85 in the tank. Short term fuel trims will start to climb as soon as it goes closed loop. After the ST goes high enough it resets to zero and the long term trim bumps up a number. ST continues to climb until LT goes up another tick and so on, it may take a week or two to put out a lean code.

While I won't pretend my small brain actually gets most of that, it does make sense with my setup, which includes 24lb ford injectors, likely a touch large for my 4.6L's requirements on dino, but grand for corn. 2.5 takes of pure E85 including altitude time (10k) and no ill effects or CEL yet...:clap:

 

[YELLAHEEP]

It really is as simple as running a larger injector or upping the fuel pressure and letting the computer figure out the rest. All the converter boxes are doing is intercepting the injector pulsewidth signal and multiplying it by around .3.

So...... If a guy was to install larger injectors on a stock H.O. engine with the intention of running E85 a majority of the time, is there a problem if he had to fill the tank with the usual 87 octane when E85 isn't available?

I built a '96 for daily driver status so I could stop feeding my Cummins $150 a week. I like the idea of going Flex Fuel in my DD both for fuel savings and emissions benefits........ Is it REALLY as simple as you say?

If so, I'd like the info on the injectors I need to get.

Sure wouldn't mind paying under $3 a gallon instead of the going rate for Diesel......

 

[xj-grin]

So...... If a guy was to install larger injectors on a stock H.O. engine with the intention of running E85 a majority of the time, is there a problem if he had to fill the tank with the usual 87 octane when E85 isn't available?

I built a '96 for daily driver status so I could stop feeding my Cummins $150 a week. I like the idea of going Flex Fuel in my DD both for fuel savings and emissions benefits........ Is it REALLY as simple as you say?

If so, I'd like the info on the injectors I need to get.

Sure wouldn't mind paying under $3 a gallon instead of the going rate for Diesel......

Troy,

I would think, based on my experiences, that your 96, being OBDII, could handle it with just slightly larger injectors. That said, my mortgage broker ("dotcom" over on Colorado4x4.net) has been running E85 in his 03 Rubi 4.0 with no modifications for like 6 months, with one CEL thrown at 10k in altitude, easily reset back in town... As for switching back, I have done that twice now on road trips where no E85 was available, with no issues, other than the slightly better MPG on dino...

chris