Re: Only getting Positive fuel trims
 

I haven't dyno'd it yet, but we think it's pushing a around 400hp at the crank. My buddy has a '05 Vette.Those are rated 400hp at the crank if I remember right...it generally runs 8.3@88mph in the 1/8th. I'm right there with him with just a little more MPH on my best runs. He thinks I've got more than 400 at the crank given my Z28 should weigh around 200-300lbs more than his Vette.

My heads have been decked from a overheating issue years ago. After it was fixed, it came back sounding meaner. I'm sure it's picked up some compression points from having them surfaced. I was not told how much they took off, but both were warped about 0.003" each. So I'm sure at least 0.005"came off....possibly 0.010". So, that is certainly helping my numbers.

Re: Only getting Positive fuel trims
 

In case anyone is interested (I was truly hoping more people had this problem) but i've started investigating this issue again. It's very consistent that when I change the values in the "Initial Startup AFR enrichment vs Coolant Temp" or the "Open Loop AFR vs coolant temp vs map" tables to anything other than what is in the stock tune, the negative trims disappear, ALWAYS read 0 and I run rich. The only time a correction is made is if it is adding fuel. If I put these 2 tables back to stock, all of the fuel trims work perfectly fine. It's consistent, happens every single time.

As stated before, this doesn't really make sense, but I'm thinking some other parameter in conjunction with these tables is screwing it up somewhere. Time to start investigating again.

I've already tried changing the "closed loop fuel timer vs coolant temp" to 238 seconds on cold/warm/hot and that didn't fix it. So, I will put that back and start changing things one at a time again.

My next test is to change the "Min Coolant Temp for Closed Loop" value. It was set at 29.75 degrees celcius before, which appears to be stock. I'll set that at 40 degrees and see if it affects it.

Has anyone else in here had their 96 obd2 car tuned by Solomon? It's got to be tune related, and was wondering if anyone else with his tunes had this same issue.

Re: Only getting Positive fuel trims
 

I'm running into a similar issue with only positive LTFC's, tried to track down an actual issue but to no avail yet. No vaccum leaks, no intake leaks, fuel pressure is great, no exhaust leaks etc.. At idle driver side hovers around 7-8% while the passenger side is around 19%. Under any throttle the numbers actually swap sides and my driver side then has 17-19% added fuel. Strange issue you're having for sure. I do not know the previous tune history of my car but our problems are somewhat similar, my car also managed to go into closed loop in under a minute, definitely outside of the default parameters. So I'm leaning towards a tuning issue at this point. Hope you can figure it out.

Thanks, Grant

Re: Only getting Positive fuel trims
 

Do you have any idea if Solomon tuned it? It seems to be consistent with something in his tunes.

Re: Only getting Positive fuel trims
 

Unfortunately I don't know, I've got a hunch that he did tune it however. Due to my location the previous owner would most certainly have either done a mail order tune or datalog/tune from him for certain. There are literally zero dynos or speed shops within about 6-7hrs of where I am. The problems I'm having also appear to be very consistent with yours. I also saw a post on ltxtech.com called "My split BLM problem". The author of that post also had Solomon tune his car and was encountering issues very similar if not identical to yours.

Re: Only getting Positive fuel trims
 

I checked that thread out and he just seems to be having the split blms like the title suggests, not so much them not appearing at all. Although he does use Solomon. Speaking of Solomon, the more I dive into this, the less trust I have in him. For example:

https://i.ibb.co/PMvMksM/solomon.jpg

On his websites he explains how to set the injector flow rate if you're running different injectors and/or a different fuel pressure. Well, in my car, the previous owner put a higher flowing walbro pump in it, and i've tested it and i'm usually getting around 46psi with no vacuum. He differentiates fuel pressure flow and fuel injector flow, which confuses me. If you follow his 2nd example which uses stock injectors with a different fuel pressure, i'd take 46/43.5=(1.057) and the square root of that=(1.028) times 24=(24.68) which is lower than than the stock value (making it run richer, which is the opposite of what you want with a higher PSI than stock) of 24.91. I've just always taken that 1.028 number times 24.91 which would put me at 25.61. Not Sure why he separates the two, or which way is right - if anyone can shed light on that.

Re: Only getting Positive fuel trims
 

He's simply saying there are two cases to consider:

1 - recalculating injector flow when the new injector was flow rated at a pressure different than 43.5 PSI.

and:

2 - recalculating injector flow of the same injector when the fuel pressure changes.

Referring to one as “injector flow rate change due to injector flow rating pressure”, and the other as “injector flow rate change due to change in operating pressure” would be clearer.

Not sure why he rounds the stock injector programming as 24 #/HR, rather than using the correct 24.91 #/HR. Maybe it just an “example”, or maybe he feels telling amateur tuners the real GM programmed value would complicate things with the decimal places. The rated pressure of the Ford/Bosch injectors is rounded off also. The rating pressure is 2.7 bar, which converts to 39.15 PSI.

On the other hand the impact of rounding the pressure is very minor. But rounding the factory flow rating causes a significant error.

Re: Only getting Positive fuel trims
 

I figured as much about the two cases. I happen to fall in the 2nd case with stock injectors at a different pressure - but like you said - I was confused as to why he was only multiplying by 24 instead of 24.91. I've just been multiplying it by 24.91 since that is what it is from the factory.

Re: Only getting Positive fuel trims
 

You are doing it the right way.