i have been geting the check engine light with codes 172 and 175, to rich banks one and two, got some dyno time and my AF ratio is 12 in all gears across the board, is this to rich with the mods i have done? see bellow for mods in my sig

 

When you’re just cruising, (closed loop) and the PCM is using the feedback from the oxygen sensors, the air fuel ratio is suppose to be 14.64:1
i think

 

mine is 12, at all rpm in every gear, got the reading from the dyno using a wideband AF sensor in the end of the pipe, so i am geusing i am running pretty rich anyone else got some info?

 

here is my sig with my mods forgot to check the sig box

 

it has been my experience that running a 12.0 fuel ratio is real rich for a truck that is naturally aspirated. if it were a supercharged engine then i could see that. when i have tuned chevy trucks in the past i tried to keep them near the 14 are or a little richer. but not 12. i ran a 12.9 when on a 175 shot of juice but not N/A

 

No, a 12.0:1 A/F is NOT "rich" in these trucks contrary to what ONE04FX4 posted (if we're talking about normal Open Loop operation @ WOT), I don't agree with that and I'll try to explain.............

The ONLY time any car OR truck (EFI) has ANY business running anywhere near 14:1 is in closed loop - lower rpms and light throttle, generally speaking (not at heavy throttle) - where they are supposed to run at "stoich" - now "stoich" A/F for normal gasoline that is no oxygenated is 14.64:1, and if the fuel *is* oxygenated, then stoich is about 14.2:1. Then any time the engine gets a real load out on it, they need to go open loop and get significantly richer A/F's - that is so the engine can tolerate more timing and thus more power can be made - just as they are supposed to work.

Sounds to me like maybe someone was keeping the truck in closed loop, perhaps? If it was being kept in closed loop at WOT, then yes, you can run at close to stoich A/F's, but you don';t make good power - some of the automakers will do that in order to improve fuel economy under heavy load, but they give up significant power in the process.

The actual truth is, absolute peak power is generally made at 13.0:1 in gasoline engines, generally speaking - and you can get away with that in a Honda, or a much lighter Mustang or a Corvette that is N/A, sure.

However, you CANNOT run a heavy truck at those kinds of A/F's in open loop, even for a max performance non-towing type of tune.

Why?

Because you will turn the valves white (but of course you don't see that until you can see the valves with the cylinder heads off), crack the catalytic converters in these Fords & most other vehicles, etc. due to the excessive EGT's (exhaust gas temperatures). That simply CANNOT be done and expect the components to live - not in 2-3 ton trucks or SUV's that are allowed to properly go O/L. Far too many "tuners" never bother to look at EGT's or even have the metallurgy knowledge to understand what the various components can take, etc. But in the final analysis, it really should be the EGT's that determine just where you can go A/F wide - most of us know that "leaner is meaner" - meaning running leaner compared to richer generally yields more power, up to the limit of about 13.0:1 - but you also have to watch the EGT's in the process, and you can just can't run 13.0:1 in a heavy truck @ WOT and have acceptable EGT's.

And by the way - no, a 12:1 A/F will NOT set of a check engine light for a rich condition in these vehicles. Nor did Jesse's truck ever set off a rich code or have anything other than SINGLE DIGIT FUEL TRIMS when his truck was on the dyno! I just finished reviewing all of that this afternoon and talked at length with the dyno facility, and at NO TIME was it setting any rich codes - nor did it EVER show anything other than single-digit fuel trims - and as anyone who actually knows anything about tuning, that is nothing short of excellent.

Now I did go back and take a look and found that Jesse's truck will set lean (or rich) codes LONG before the engine actually goes rich or lean - it's set up in it's stock program to report those codes WAY too soon, if the PCM has to make more than about a 10% correction to hit stoich, while the PCM still has (in his case) 25%+ correction range left - that's just too tight for the code reporting range, and that is why he's getting the occasional rich code when he's up at very high altitudes, but when he was on the dyno at 1500 ft., no codes were being thrown, and the fuel trims are in single digits.

If you are doing an all-out maximum performance drag-race type of tune that will NOT be safe to do a top speed run on for a normally aspirated truck, and NOT running nitrous, then yes, you can run a *little* bit leaner than 12.0:1, but it will still have to be in the 12's in order to keep the EGT's in line and have components live long-term in a 2-3 ton truck or SUV. Now for a towing-compatible tune, then it needs to be at about 12.0:1 in the upper rpm ranges when when the engine is under a heavy load - whether it's a Ford, Chevy, Mopar. In the lower rpms you can get away with a 12.5:1 A/F

And by the way, Jesse - I have looked at your data and talked with the dyno operator and your data looks fine - you are NOT running overly rich, and as you know, you did NOT set any rich codes any time you were there on the dyno - your fuel trims were SINGLE DIGITS.

By the way - thanks for calling today, Jesse - as we discussed, we have scaled the MAF transfer function so that the engine hits the exact A/F we are commanding, which is a little bit leaner than the 12.0:1, and we'll get that email update kit out to you, etc - good talk with you again!

 

man what a jerk.

 

>>>man what a jerk.<<<

I am sorry if my response came off a bit harsh - truly I am. I actually went back and edited that post to explain a bit better, and to tone it down - I really didn't mean for it to come off offensive, I think I was just shocked to see anyone say 14:1 under load - once I re-read it, I can see where it could have been taken that way - my apologies.

HOWEVER..............

I'd like to see your "explanation" as to why you think 14:1 A/F's would *ever* be appropriate under load (WOT, or anywhere other than closed loop) in any gasoline engine, and what the EGT's were as a result.

I just don't think you can justify any 14:1 or close to it under load in a gas motor truck - and I'll bet once you hit any leaner than 13.0:1, the power would have taken a drop and the engine would become more knock constrained - it's basic physics, my friend.

Now if you were talking about tuning a carburetor truck, that would *still* be too lean, though not as bad as they do have a lower BSFC than EFI motors - so you could get away with *maybe* 13.2:1 or so in a truck, and maybe 13.4:1 (on gasoline) in a car, depending of course on the EGT's - say, a max EGT under load of 1420 (F) taken at the hottest cylinder 1" off the exhaust port face.

So if you can accept my apology for the tone of my initial response, I'd really like to hear your justification for why you think that tuning to 14:1 under load would ever be appropriate and on exactly what vehicle - year, make, model, approximate weight, which engine, carbureted or EFI, it's power output, what EGT's you saw as a result, & exactly where you tapped for those EGT's. Oh, and I'd be curious to here at what RPM you peaked the power & torque as well.

I wish you well,

 

Mike I see NO reason for you to appologize to that dic_.
I found out a long time ago that no matter what you say here that there is always some ahole that has to be just that.
Your knowledge of the power trains in these truck is far greater than his ability to sway anyone to even begin to believe what he said..

 

ditto

 

Thanks for the support guys............

I have to say, in all honesty & candor, that my original response could indeed have come off unduly harsh - it doesn't matter that I really didn't mean it that way, or that people who know me as well as Marc & John know me understand my meaning usually - but not all people do, nor should they have to feel insulted, etc., I don't want anyone to feel that way unless they really have it coming - and that's pretty rare.

What matters most, in the final analysis, is the actual impact that it had, and I really do feel that it was appropriate for me to apologize if he felt that way, *and* to go back and edit that post. I'm not the best writer, and from time to time I will say something that comes off as less than polite, or not as professional as it really should be - and I don't want anyone to feel that I treated them poorly.

Thanks again for your posts Marc & John.

 

i was able to talk to Mike in depth on this subject and he taught me alot and it all makes sence now, thanks to everyone who replied, and thanks again mike for increasing my knowledge of todays computer controlled vehicles

 

Dam!!! that guy's good!!!!! (MIke)

 

Hi Jesse, (bigtruck311),

Thanks very much for your time - it's always a pleasure talking with you at length, and I know between you hectic schedule in the military and my schedule it can sometimes be a bit tough for us to "hook up" - I always enjoy our conversations.

Your MAF transfer is now properly scaled, since we got some data on it - wow that was a long time, we originally tuned it back last November, and you got it to the dyno on 6/14/05, and then we just finally got the data in a usable format fro that very nice fellow whose dyno facility you took it to yesterday (or the day before). I think that's a record!

All kidding aside, your truck was one of the more interesting ones, since it had that problem of the code reporting threshold being way too tight - we took care of that, too - as well as some of the other things that you & I discussed, so it should run pretty nice and make more power up top -

Man that thing made GREAT power all the way thru 4500 rpm in that 110 degree heat, that was impressive - Now hopefully we'll gain a few more ponies in the above 4500 rpm range, too!

Have fun!

 

no Mike thank you for your time, every time i talk to you i learn something new and gain a better understanding of whatever we are talking about, thank YOU so much and i cant wiat to get the new tuning in and go romp on my truck some more, you have a great day, tell everyone at your staff that they are the best people i have ever had the opertunity to talk to and they do a great job, thanks again