new to efi tuning, hesitation off idle on 4.8l

[JBURG]

I'm in need of some guidance here. Engine setup as follows: 4.8l with 00 camaro ls1 intake, TB and Injectors. Stock cam, stock heads longtubes only.

I changed the injection tables to match the 00 camaro as that's the tb, intake and Injectors I'm using. Just copy and pasted the tables. I have a really bad hesitation off idle I haven't changed any other tables yet. Other than injector tables is there something else I should be changing?

[joecar]

Which FPR do you have...?
Is it manifold referenced...?
What is rail pressure (measure it with reference hose temporarily removed)...?

What MAF plumbing do you have...?
Your MAF table might need to be corrected.

Your 4.8L now has a different intake and headers, so VE table would have to be corrected for this.

[JBURG]

I have a return less rail double regulated through filter and on rail 58 psi.
I'm using the truck 5 pin maf.

[joecar]

Ok, return-less (un-referenced) FPR, 58 psi.

Is your IFR table B4001 sloped or flat...?

Post your tune file.

Is the MAF plumbing (cold air pipe, filter) what came originally on this vehicle...?

[JBURG]

here's the tune that's currently in the car.18744

[JBURG]

Definitely sloped. I'm using the stock truck intake. Stock MAF but the Camaro TB.

[joecar]

Also post some log files showing the off-idle hesitation.

[JBURG]

I'll get those up shortly.

[JBURG]

18761

I not sure exactly what I should be logging. I'm new to efi.
If there's a particular PID I need to log let me know!

[JBURG]

18766

Here's the latest log file with what I thought would be the most relevant PID's.

Shows the hesitation I was asking about TP @ 100%

[joecar]

I'm looking at it...

[JBURG]

Any thoughts?

[joecar]

Looks to me to be due to spark timing dropping when throttle opens wide...

you have too many pids, the log is not capturing enough frames per second...

[joecar]

Log these pids (see attached, copy this file to Documents\EFILive\V7.5\PIDs, then start scantool, goto PID tab, open this pid file).

[joecar]

BTW: What transmission do you have...?

[JBURG]

Joe, thanks a million for your assistance! I'll have the new logs on Saturday with those pids.

I'm using a 4l60e from an '03 2wd. No special stall, stock converter.

[JBURG]

Sorry for the delay in getting the log. i"m bouncing between 2 different states,

18802Logged with the PID list you sent me.

[joecar]

No worries.

[joecar]

I see several things:

IAT is at 97F... where are you located, what is the outside ambient temperature...? I hope you're not pulling in hot air from engine bay.

ECT is pretty much stationary at 129F... can you verify if engine is actually coming up to at least 170F.

B1S1 NBO2 is not cycling sufficiently fast, could be due to exhaust gases being under temperature.
B2S1 NBO2 is almost zero, due to either massive air leak or to exhaust gases being under temperature.

I'm surprised that the pid FUELSYS reports CL at all.

ECT being so low is causing cylinder air mass to be too high, references wrong part of HO Spark table.

MAF is under-reporting, and it looks like it hicups when throttle transitions to open (i.e. tip in)...

I think the MAF is a big part of the problem, either it needs to be cleaned, or it is damaged, or the MAF plumbing is distorting the air flow to the MAF element (e.g. elbow causes air to follow the outside of the "turn", if this is too close to MAF then the airflow misses the MAF element).


Post pic of MAF plumbing in your engine bay.

[JBURG]

18809

I have the maf and airbox where I have an open spot to pull air from up front. Maybe My maf is on its way out?