Hey guys so I got my wideband installed and put some E85in my car as I plan on running E85 going forward. I fired the car up and once the 91 ran through the system the computer started adding fuel at idle up to 25 on the LTFT so I took those cells in the tune and multiplied by 1.25, reset the fuel trims and started over again. again the fuel trims at idle maxed out at 25 and my wideband is still showing on the lean side. I know E85 requires more fuel, but is a ~56% increase in fuel at idle normal to be still reading lean? or do you guys thing I may have developed a vacuum leak somewhere? Im running the Weiand intake and recently replaced all the gaskets on it.

Also I just ran it up the RPM band driving around the neighborhood holding in each gear and i was seeing some duty cycle hits of over 110% at partial throttle. Previously, with pump gas I was seeing mid 70% at 7500+RPM and WOT. Im running 42# SVO injectors @ stock LS1 pressure, could ths maybe be a bad fuel pressure regulator and not a vacuum leak?

Thanks for suggestions!

 

That's not how you add fuel correctly for E85 as that throws off all your airflow values. You need to change the stoich a/f multiplier table or cut your injector table. Also if you were at mid 70% duty cycle before on gas it will probably be right on the edge with E85 and maybe even not enough. Your pump may be done and dropping fuel pressure though as it shouldn't increase 50% or more unless the tune was way off before.

 

Hey NicD

I am running a Walbro 255 in the car with maybe 60 hours on it, so I dont think its the pump, I already figured I was going to need to step up the injectors to 60's.

By stoich a/f multiplier are you referring to the Stoich AFR field? If so I changed that to 9.8 per what I read over on the HP Tuners board.

Can you please advise on what you mean by cut the injector table? or if I edited the wrong field.

I really appreciate the response

 

A single walbro 255 on E85 is only good to around 450 rwhp N/A I would think.

Yes, the stoich AFR field, if you changed it to 9.8 that should take care of a majority of the fueling corrections required with fine tuning being all that's left. Cutting 35% out of the injector flowrate table is just another way to accomplish adjusting for E85 without affecting airflow values or changing reported a/f ratios vs the stoich field but either works fine and since you already did the stoich field leave it be.

 

Thanks Nic. The car only made 41x on 91 so I would think even given a 5% increase with E85 Id still be under that 450 number. My big concern right now, is with 91 in the car it idled rock solid at about 1350, maybe loping about 50 RPM plus or minus at times, with -1 to -3 on the LTFT (14.5-15 on the wideband) and didnt hunt or surge like a lot of cars with huge cams. Now with E85 ,and no other changes made to any tables in the tune except the AFR, it locks the LTFT at +25 and hunts/ surges about 500 RPM and shows lean on the wideband. I replaced both my narrow band sensors last night as they were under warranty, and reset the fuel trims, however the LTFT soon returned to being maxed out.

To me it seems mechanical or something F'd in the POS 98 PCM as nothing was wrong prior to the E85 running in the car. I'm going to change out the fuel filter and make sure that it isnt plugged as I have read E85 can "loosen up" debris or dirt in the tank that regular pump gas wouldnt.

 

1350 idle speed? Yeah it should be rock solid and not surge at that RPM. I would just check fuel pressure at the rail, make sure that's good. Otherwise put the stoich AFR back to stock and cut the injector flow rate by 35% just to see if there is any difference but I am pretty sure I've done a 98 before on E85 and the stoich table functioned normally as it should.

 

It would load up really bad if I tried to get it to idle any lower than about 1300 on pump gas (eyes watering cant breathe when behind it bad). It seemed to like 1350 really well and would warm up quickly; there is a good amount of overlap in the cam.

 

ended up being the short hose in the tank from the pump to the sending unit had a split in it, car lost all fuel pressure Sunday and discovered the hose split in the tank. Fuel trims are back in line and runs much better

 

hope you replaced it with a hose that won't be destroyed by the e-85

 

I'm pretty sure the hose was leaking for a period prior to the switch over

 

Most fuel line is not ok to put in a tank. The last time I bought submersible fuel line it was about $34 a FOOT......otherwise the regular hp line seems to last maybe a year or so, but watch out for the lean condition when it leaks.

 

My point was more to the fact to make sure you have fuel line and o-rings and what not that is compatible to the e-85. E-85 can wreak havok on regular rubber and steel lines, and anything else that isn't compatible with it.