Trims Bug after Cam Install

[crazyguy03]

I have a gen5 3.0/stock rockers again/full size IC/ 42s/N* and s1x cam

My issue is and has been the start up driving of my car. It will start , rev up and down for a few secs and settle in. Start to drive and the LTFT rises to 16.4. Sometimes this happens right after you put it in Drive or upon de-accel. Then at idle it causes a surge and sometimes stalls. Continue driving and its fine. NEVER comes back again. Trims go to 0.7 to -3.2 while accel and cruising.

i filled up my data logger to 71% with scan data, used eddies ( reset trims before and after) and my trims are tighter and tighter, but this fluke is still there

I went to Fuel>General>startup AFR vs ECT but I dont see what "decay" would do
SO then I went to Open&Closed Loop>and went to O/L AFR and dropped the AFR from 32* to 158*cells to 13.2 to see if it helps
Im probably not even looking in the right place

Its not a vacuum leak, I had my motor apart and did the lines recently myself.



Is this my o2? or something else?

I tried to add fuel during warm up but I think Im doing it wrong

[gn2beatu]

Have you tried less timing? My idle timing is only 14 degrees, yours is 26.

If less timing doesnt help, and its just at startup adjust your idle airflow by 10% see if it gets better. In similar situations, I have had to adjust as much as 20%. Hope that helps.

[oakleafresin]

Do you have a cat? If not, disable warmup spark correction with TinyTuner. My timing goes right to 27* once I start, no matter what temperature. Also, disable cat testing

This is a very easy problem to fix and diagnose. You are surging at startup for one or both of these reasons: you are rich, or your IAC cannot control idle. You claim that you don't have a vacuum leak, so you must be rich.

Realistically, you should have a wideband. But we can assume you are at least 11:1 depending on what rpm you are surging at. That's really rich...

You should put the tune (at least fueling) back to stock. Do you have a breather because of that IC? This is making the PCM think you have a huge vacuum leak.

Don't waste your time with closed loop. I run OL 24/7 and have ZERO issues with fueling ever. Fuel trims are fail imo, especially with that cam. That narrowband is hating the cam

If you deciede to go open loop (buy a wideband), let me know. I can get your shit running good lol

Those warmup fuel adders work like this: there's a table in the PCM that controls the AFR before closed loop. This table has desired AFRs per each increment of ECT. So lets say stock, at 32* the table (before the car enters CL) commands 12:1. Those adders kick in immediately, once key turns to run. So even tho the AFR table says 12:1, it then has to add the "adder" for that degree. So if the adder at 32* ECT is 1.2, then the final AFR that is commanded is 13.2:1.

[GPGTP]

If it were my car I'd hook my wideband up to it and see what's going on with the a/f ratio when the trims go positive. How does the car run in open loop?

Also, I notice when your trims go positive your O2's go super rich....strange.

I notice your trims start to level off between 160-170 degrees. You could set your closed loop to enable around that temp. Should get rid of the problem. If you do, you could lean out the base open loop table from 100 degrees and up.

[crazyguy03]

So I got my plx sm-afr up and running

Now when my trims go 16.4 it reads 11s and sometimes 10s

At wot, im hitting 11.6, so basically its the opposite of what I thought, its actually choking out from too much fuel


when crusing it switches very fast from 14s to 15s mid throttle 13s and then wot 11.2-11.6

soo now if I start tuning via wideband, should things be more stable, or will it still be very jumpy? I never ran a wideband with a cam before.

Also looking for info how to set this up to scan and tune with hpt

I bought this used, so I have no instructions
Thanks

[gn2beatu]

Google the instructions before you hook that wire up to HPT. You dont want to fry the tuning module from hooking up something wrong.

[crazyguy03]

So far it looks like I have to install a wire in the connector that allows wideband output. Then attach that to my hpt cable in spot "1"
But its how to get hpt to read it, scan it, and make histograms to tune it, is where Im lost

[Swiggles]

now i havent used the pro version, im using my egr for the wideband.

in the table on the scanner right click on with EIO Input you used for the wideband, its at the bottom of the table. then just select which wide band you have.

I have the same problem with my LTFTs going up 16.4 at idle. my WB says im dead on though, so i just ignore the LTFTs at idle since my WB has its own gauge on all the time.

[crazyguy03]

ok thanks swigs, Im gonna try that.

However my wideband reads a AF as rich at 10 at times when my trims randomly go 16.4 My only guess is that its a cat test. I just cant understand why I never ever saw this before I had the cam. It goes away then Im fine


So with this plx wideband, what else can I tune with it? My WOT locks nicely at 11.6 already, so is there a wideband program like eddies table modifier ?

or is it used strictly to tune 7k and up on the maf?

[murphinator]

this is on an 01 or newer car isnt it ?

I forget exactly what causes it on the newer l67 cars but it has to do with cat efficiency is my recollection... extra self test happening or something along those lines

[crazyguy03]

yup 2003

[Phantom]

I would do some Open Loop tuning at least in the idle region since the car starts in open loop and see if it helps any.

[crazyguy03]

open loop tuning ok

Is there a write up for that? Or is it histogram logging errors and multiply by half?

Guess I spent too much time learning maf tuning, and never found Regal related guides for wideband tuning

[Phantom]

A lot of people think that OL tuning is a wast of time since the 3800 does not use it (some 3800s use it in different situations but not a lot).

To do your basic OL tune you will need to do the following.
Set up a scan for MAP kPa, RPM, LTFT, STFT, and command AFR.
In your tune copy the high oct spark to the low oct spark. Set your PE TPS to 100% (I do not do this but I am NA and never go into PE). Flash the tune and disconnect your MAF and clear your trims.

Scan and use the histogram for VE vs RPM ve MAP with the PID being FuelTrims (here a LTFT+STFT can be handy) create apply the changes to the Primary VE table. I filter out decel and everything except for afr of 14.7.

Watch your KR when scanning. If you have problems with starting/idleing cold you might want to leave the MAF connected till the car is warm. If using a wideband it is the same but use %error instead of Fuel Trims.

I hope that helps and that I did not miss anything since I'm doing this by memory.