01transampower

iTrader: (9)

I'll try and make this sweet and short, the guy that tunes my car uses HPTuners. And we have been having a little problem with the car running lean. Now my stock fuel pump should be sufficent enough for the mods done to my car (check my sig). Now basically when going full throttle it will drop down to an a/f ratio of about 12.7 but then bounces back up to where it runs at idle and cruising while under full throttle. So basically i'm in the process of putting a Walbro 255 in my car to see if that helps but could this be a tuning issue and where can we find it on the software. Just so I have an idea of what to suggest. Or any problem solving.

ZL1Killa

iTrader: (17)

could you upload the tune so we could look at it? Do you mean it goes from 12.7 then back up to 14.7 or stoichiometric (idle and part throttle)?

is the car in closed loop with the MAF? whats the MAF curve look like? what is power enrichment table set to (PE table), any air temp sensor table modification?

01transampower

iTrader: (9)

Ill ask him if I can get a copy of it.
Yea it goes from 12.7 back up to the 14.7 area. Right now its running with the MAF off just running on speed density till the tunes done. zi'll be honest i know nothing about tuning but I trust what the guys on here have to say so i"m trying to do research to give suggestions to my tuner to see what we can work out.

redtail2426

iTrader: (10)

what wideband is he using,and where in the header is it located?try to get the tune loaded up on here.Maybe he didnt add enough to the ve table up top.

jimmyblue

iTrader: (11)

Misfiring will fool any O2 sensor. A jump in delivered AFR
without a corresponding change in the commanded AFR
would point at this.

Wideband sensors put too far forward in the exhaust can
get overtemperature and act kooky, but in my experience
this goes to dead-lean, not midrange readings.

If the air mass related tables (MAF, VE) are "under
construction" you might look at the air mass value vs.
MAP*RPM (in Excel or similar) and see whether you
believe the scatter-plot eyeball relation, or if something
kooky like a flat or negative slope is showing up which
would take away fuel by a wrong, low air mass calc.

01transampower

iTrader: (9)

Well today i got the new fuel pump in and took the car out. Got on the highway and did some pulls as well as some back country roads. Live in bfe lol. We'll in 1st and 2nd gear the car does still have the previous problem as stated before but it is better it doesn't climb as fast or as high. However if i am in third gear i can mash my foot in it and it will hold a 12.8 a/f ratio all the way up from there. So now could there be another issue? my clutch is slipping and is in the proces of being replaced with a monster stage 2. So could the clutch slipping in 1st and 2nd be part of the problem? I'm not sure how all this works but sunday me and the tuner are suppose to get together and get this done.

01transampower

iTrader: (9)

I have an AEM wideband in the car and its located about 4 to 6 inches from the header collector im pretty sure.

Old Geezer

iTrader: (3)

When the clutch slip comes in, what does the MAP reading do???

robstah

iTrader: (2)

I take it you looked at the fuel pressure go down before upgrading the pump?

As mentioned above, a misfire can read lean. I don't know how the AEM works, but check it's refresh rate. Having too fast of a rate can have the reading off a bit and that might be pointing you in the wrong direction.

got milk??

iTrader: (18)

If you can, connect the wideband to the HP tuners software that would be best for datalogging. It will show your AFR at every rpm, not just off the digi readout on the AEM gauge.

01transampower

iTrader: (9)

When we tune it we do have the wideband connected to the computer and use that for tuning. Its basically reading the same thing as the guage is. So we will see her in the next couple of days if it was the clutch causing the problems or the fuel pump or if its the tune. If its the tune there's no excuse and it needs to be looked at and fixed.