Most 5.3 trucks I've seen with fuel trims out this much are caused by failing intake manifold gasket/o-rings.
Could be a dirty MAF also.
I wouldn't TUNE it out if it's stock.
At the shop...we use a smoke machine to "smoke" the intake and look for the smoke leaking out.
Keep looking, you'll find it.
John
Originally Posted by 98 tigershark
here is a scan with my l.t.f.t. around 20% take a look let me know what you think.
2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...
Now own a 2015 1LE camaro
Can you re-log, but this time include MAF...
(if you have the LS1 PCM you can get 10 Samples/sec instead of 5 S/s if you reduce the pid channel count to 24 or less... remove some of the pids).
If there are no airleaks, then my estimate is either:
- PCM is calculating insufficient airmass (this leads to the next point...);
- insufficient fuel is being delivered;
maybe:
- MAF is dirty or low MAF reading.
- fuel pressure is dropping.
- fuel filter is dirty.
- injectors are dirty.
That was made simple, Nice, Very nice, Thanks!!!
Hey SSpdDmon,
Thank you for the link. That adds it up pretty well. When I tuned my car with the new motor, I crunched allot of numbers and spent allot of time asking questions and except for a few minor changes it is almost the same now as what I put on it then. The other day I took off the air filter to clean them. It is easier to take the maff off while doing so on my car. I was driving the car on the weekend and the maf and filter completely fell off away from the plenum (I forgot to tighten the Maf clamp). If a trouble light did not come on I would not have noticed as I was logging at the time. The maf is hooked up and does work. I also did the final tune on a dyno w my WBO2. I am not telling anyone to tune that way but I do crunch allot of numbers and I am surprised at how close you can get if you take the time and in my case allot of it. Converting the VE from % to G/S and watching (logging) the maf up to 4,000 rpms and reworking the VE in the G/S with the Maps from the scan and then using the IBPW formula for peak power for over 4,000 and make the maf and PE adjustments to match the IBPWs I want seems to get me very close with the fuel trims until they zero as well as the AFR. A WBO2 sensor is certainly the way to go but I was surprised at how little adjustments where needed on the dyno when doing the homework correctly.
I know you know how to build a base tune better than I but I do like the math involved. Did I explain what I do correctly (building a base tune with no WBO2 before the car is started))? and if so or not how would you go about building a base tune as your posts in the link was so clear I was hoping you might improve on the above. Thanks again.
98 tigershark
98 tigershark
L92/427 w/L76 CC'ed heads n upgraded springs
4.100 stroke, 4.068 bore w/ 11:1 comp
Cam, 591 int, 613exhst, 232-246dur@.050, 115*
LG headers, High flow cats,
RPM level 5 trans, RPM 3.42 gears, 2800 rpm trq convrt. .
Special Thanx to Joe and Bruce!
i cleaned the m.a.f sensor and also checked for leaks around the intake manifold, which came up negative.
2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...
Now own a 2015 1LE camaro
how can you get low m.a.f reading from a stock tune?
fuel filter has been replaced
used fuel injector cleaner as well
did not check fuel pressure. Would you think it could possibly a fuel pressure regulator issue? But wouldn't that make a mil light come on?
2001 camaro z28 ss vert with factory slp upgrades, Hooker long tubes, 3"y-pipe to a 4" muffler, ,airlid,s.s.r.a. ,t.c.bypass,descreened m.a.f. 232/234 .595,.598 +2 comp cam with ported and polished stock heads with .650 lift dual springs and a bowl grind. tuned with EFI Live. All combined to achieve 29 m.p.g. and 399 r.w.h.p. with 384 lbs of torque. sold...
Now own a 2015 1LE camaro
My math on base tunes is very simple. Find a car that had a similar setup and start from there. LOL "Free time" hasn't been a friend lately. So, trying to back into something like you describe isn't much of an option. Outside of fueling, it just comes with experience, talking to other tuners, etc. Wish I could offer more than that...but, it is what it is.
My regulator does not.
The fuel pressure regulator has no electrical supply. If you have one fuel line to the rail your regulator/filter is close to your left rear wheel. If you have 2 lines a feeder line and return as mine (suburban) does, than the regulator is in the fuel rail and the filter is back by the driver side rear wheel. There are no wires to the regulator or filter and if the regulator is a single line system it has the filter built into it. A new stock regulator/filter is around 50 to 60 bucks at an auto part store. The filter for the dual line system is around $20.00. It is not a bad idea to change the filter and or regulator/filter once in a while. The dual line with the regulator in the rail can also be replaced, but I have not heard of that regulator going bad before.
98 tigershark
L92/427 w/L76 CC'ed heads n upgraded springs
4.100 stroke, 4.068 bore w/ 11:1 comp
Cam, 591 int, 613exhst, 232-246dur@.050, 115*
LG headers, High flow cats,
RPM level 5 trans, RPM 3.42 gears, 2800 rpm trq convrt. .
Special Thanx to Joe and Bruce!
The time factor! a begged, borrowed or stolen base tun is the way to go!
I fully understand. I cannot tell anyone how much time I spent as there were no cars or tunes close to what I put into my car at that time. It was a fun but a very time consuming task. You are very wise to say get a base tune from a similar car. The math and experience involved is most likely not going to happen in a post like this. IBPWs are important to me and that is a time eating monster to get right math wise all by itself.
I worked very hard and put in long hours and could not even expect a tuner to put in that amount of time. Joe and Bruce gave me some very good comparison tunes but the geometry of my motor was very different and thus the time factor and money of course. So as the newer LS setups come out a begged, borrowed or stolen base tun is the way to go.
Thanx
L92/427 w/L76 CC'ed heads n upgraded springs
4.100 stroke, 4.068 bore w/ 11:1 comp
Cam, 591 int, 613exhst, 232-246dur@.050, 115*
LG headers, High flow cats,
RPM level 5 trans, RPM 3.42 gears, 2800 rpm trq convrt. .
Special Thanx to Joe and Bruce!
If MAF is dirty it can read low... leading to smaller airmass and advanced timing.
Fuel injector cleaner may or may not do the job... how many miles on your injectors...?
If the spring in the FPR has weakened, then the regulated pressure will be less... the only way to know is to test the pressure with a gauge.
We first want to rule out any physical problems first.
I take it you're sure about no leaks in the exhaust (anywhere between heads and 18" past front O2 sensors).
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