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P0171 16.4 ltft 20 stft

Slick2500

Slick2500

New member
I swapped in some 42.5# injectors and switched to E85 and immediately the LTFT was pegged at 16.4

When I first start the car the STFT sits between 0-5% then the idle drops down to normal and the STFT slowly creeps up and sits at 20%, the LTFT is constantly at 16.4.

So far I have replaced all the vac lines and Ts with new lines and I replaced the o rings on the injectors. If my car didn't have a full tank of E85 I would just swap back to my old injectors and see if the issue goes away
:th_shakinghead1:
 
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Question: How do I tune for E85?
Answer: There are two main ways that I know of.

1. EASY METHOD: Simply install larger injectors into the car (usually at least 42.5 lb injectors) and then make sure your injector tables are scaled approximately 30% smaller than the injectors you are running. I have seen multiple stories and testimonials lately of using this method successfully. Technically, you can get away with no tuning at all if you are currently on a stock tune set for stock injectors, and then you simply swap to 42.5 lb injectors and E85 at the same time.

http://www.grandprixforums.net/threads/92810-The-E85-Thread-Questions-and-Answers
 
ITHURTZ said:
Question: How do I tune for E85?
Answer: There are two main ways that I know of.

1. EASY METHOD: Simply install larger injectors into the car (usually at least 42.5 lb injectors) and then make sure your injector tables are scaled approximately 30% smaller than the injectors you are running. I have seen multiple stories and testimonials lately of using this method successfully. Technically, you can get away with no tuning at all if you are currently on a stock tune set for stock injectors, and then you simply swap to 42.5 lb injectors and E85 at the same time.

http://www.grandprixforums.net/threads/92810-The-E85-Thread-Questions-and-Answers
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Apparently not............
 
if you wanna switch to the stock injectors I can swap it in the tune so it runs happy on stock injectors, cuz you're only on a 3.8 pulley right?
 
You can run E85 on the stock injectors? And yes I'm still on the 3.8 pulley. Idk if it has anything to do with the injectors and E85 or not, I was gonna grab a can of carb cleaner on my home from work but I forgot and didn't want to have to drive back to town.
 


O-Rly-Owl-British-580x419.jpg
 
really high trims are pretty normal. It shouldnt stay that way the whole time you are running e85 but its not "wrong".
 
If you're gonna gonna go this bootleg swapping injectoRd route and hoping for a somewhat normal trim then darkhorizon would actually be right in this instance

Or you could just get your car tuned change stoich and be done with it.
 


I recently made the 42# no tune swap.

My STFT are mostly +/-1.5, sometimes +/-5
My LFFT is bouncing between +5 and +10

I've only driven a handful of miles, and haven't pushed it yet either...
 
I'm interested to see how this works out for you. I just bought 42# injectors and was going to try the "no tune" e85 swap myself. I've heard it works well but after this thread i may wait till I can tune it or get soemone else to, just to be safe.
 
Car seems to like it so far. FWIW, the car needed all kinds maintenance stuff when I got it. That being said, it has new plugs, wires, 255 fuel pump, fuel filter... Since converting I have done a couple WOT pulls and have had no knock. I would see a couple degrees on 91 with the same mods. The only other change is a drop in ambient temp, but not much.
 
BrandonHall10 said:
Car seems to like it so far. FWIW, the car needed all kinds maintenance stuff when I got it. That being said, it has new plugs, wires, 255 fuel pump, fuel filter... Since converting I have done a couple WOT pulls and have had no knock. I would see a couple degrees on 91 with the same mods. The only other change is a drop in ambient temp, but not much.
Click to expand...

Have you dropped any pulley sizes yet? Or were you still seeing knock with headers on a 3.8?
I have a 3.5 on my mps on a Gen v and I see about 2-3 degrees of knock wot. I was hoping e85 would kill that and allow me to drop a few.

Either way its cool that you don't have any knock with it and your car seems to like the corn. Do you think you gained any hp just from the switch? Besides from the extra timing from killing knock?
 
Still had knock on stock pulley, cai and headers. I wanted zero knock before dropping. Hard to say if I gained anything. I won't pretend I can feel a difference. I can only confirm no ill effects. Will be droping pulley size in the very near future.
 


chrsmi1 said:
Have you dropped any pulley sizes yet? Or were you still seeing knock with headers on a 3.8?
I have a 3.5 on my mps on a Gen v and I see about 2-3 degrees of knock wot. I was hoping e85 would kill that and allow me to drop a few.

Either way its cool that you don't have any knock with it and your car seems to like the corn. Do you think you gained any hp just from the switch? Besides from the extra timing from killing knock?
Click to expand...
Your pistons hate you.
 
Slick2500 said:
Your pistons hate you.
Click to expand...
Yeah they probably do. They'll be alright. Car has less than 100k miles on it and i'll do the e85 switch soon and that should kill my knock. I don't drive it super hard so it's not that bad. I just hope it responds well to the switch.

And i had more knock then that stock, so.....
 
Yes but 6* stock is much better than 3* on a 3.5 pulley. You have to remember when you are making more boost the effects of the kr become compounded.
 
Slick2500 said:
Yes but 6* stock is much better than 3* on a 3.5 pulley. You have to remember when you are making more boost the effects of the kr become compounded.
Click to expand...

I appreciate the info but i was actually being sarcastic with my last comment. I know its bad, thats why I drive it soft and im getting ready to switch to e85. If I wasn't doing the conversion in the next week or two I would pulley up. Its my dd but I only drive it like 20 miles round trip about four days a week. But honestly, thanks, cause if I didn't know that I would have s*** myself just learning that by it blowing up.

Also Brandon, how many times have you changed your fuel filter since the conversion? I've read its best to do it multiple times but I would love first hand info if you have it.
 
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