Timing Drop @ part throttle (-10* at 50%)

[deanh8]

Im trying to get the car to pass CA Smog, it failed due to the HC's being to high. I put the car all back to stock and loaded the stock tune back on and now its pulling timing at part throttle.

Here is a short scan of the issue, you see how getting on the throttle causes it to go -10* and then it seems like after 4k RPM its fine.

I dont know much, if anything about tuning. I use HPTuners to swap maps out and mess with timing tables depending on gas use. Im scared to touch any of the fueling tables until I learn more. I just dont see what the issue is. I mean its got the original tune in it with no mods.

http://www.scandepot.net/viewscan.php?pk=5008

[deanh8]

I also cat get the "catalyst" part of the smog check to come on, the LTFT goes to +16 when I do a WOT pass and let off the gas. locks in at 6.8 WOT.

Seems like anything under 4,400 rpm is negative timing, over that its fine but still low.

[Bill@HPTuners]

Im trying to get the car to pass CA Smog, it failed due to the HC's being to high. I put the car all back to stock and loaded the stock tune back on and now its pulling timing at part throttle.

Here is a short scan of the issue, you see how getting on the throttle causes it to go -10* and then it seems like after 4k RPM its fine.

I dont know much, if anything about tuning. I use HPTuners to swap maps out and mess with timing tables depending on gas use. Im scared to touch any of the fueling tables until I learn more. I just dont see what the issue is. I mean its got the original tune in it with no mods.

http://www.scandepot.net/viewscan.php?pk=5008

Torque management.

[deanh8]

what is making it come on? Like I said I loaded the OEM tune, it never drove like this before.

To much air? whats the deal with the LTFT going super high after letting off? 02 Bank 2 isnt reading also, I dont remember if it ever did though, on my Z06 it does. Is it because one has 2 and the other has 4? I thought I used to be able to read both front and rear 02's on this thing. Maybe thats why the catalyst check test isnt coming on.


The car is a 1999 Buick Regal GS BTW. Supercharged 3.8 L67

I attached another log to this post with a few WOT runs. Check how under 4,400rpm there is no Timing, and I have Traction control off.

Excuse my lack of knowledge on this, trying my best here to understand this stuff.

[murphinator]

hey Dean long time no see.

let me see if I can help with some of this for you. First off you are failing due to hc's (hydrocarbons) not nox (oxides of nitrogen) excess hydrocarbons are unburned fuel -rich , nox would be excess air (lean)


v6's only read one bank - the 02 sensor in your rear mani or headers if thats whats on the car which brings me to a couple ??

you say there are no mods as in to the tune or installed on the car ?

if you are trying to run a stock tune with airflow and exhaust mods its no wonder the numbers are off , let us know what is installed on the car for mods especially things like throttle body , maf , maf screen , cam ,rockers, headers ,pulley

how old is the o2 sensor ? is the egr functional/functioning ?

post your tune file so we can see what you have left for torque management in engine & trans tabs - Bill is probably right on as to your low timing if the TM is still all in place

was HC's the only thing noted on the emissions fail? did they give you the actual hc's vs. what is acceptable so we can see how close you are to passing ?

Bill , I know we are limited about what we can talk about in regards to emmisions on here is it only a problem in regards to defeating systems ? I wouldnt think trying to help a failing car get clean enough to pass would be an issue but please advise if it is and I can help Dean through other forums we are on

[deanh8]

I disabled torque management and its fine now. Here is my current tune and the most recent log. They have it on the rollers at 15mph and 25mph.

LTFT's are way off at idle it seems. Dont know what the deal is.

I had a 3.2 Pulley, headers Gen5 blower, 1.8 rockers, Gen5 LIM, Northstar TB, LS6 MAF, no cat, intake, no EGR, no PCV, 180* thermo.

@25mph HC was 45 (35 Max), C0% was 0.39 (0.46 Max), NO was 207 (max 706).

I recently put it all back to stock, stock blower, stock LIM, Stock TB, stock 195* thermo, stock MAF, working EGR, new PCV. Even loaded the stock HPT file I saved off the car when I first got it. It should have been 100% ready to go, all stock except for 3.4 pulley, smog legal togs, and the rockers. But it was way worse, now its..

@25mph HC was 87 (35 Max), C0% was 0.58 (0.46 Max), NO was 1241 (max 706).

I dont know what the deal is, Stock BIN, stock mods, functioning sensors, well maintained. I dont see how the NO goes from 207 to 1241 by putting stock parts and stock tune.

[murphinator]

I wish I had all your answers Dean - I hang out here a lot hoping eventually it will all rub off

what I did was open your attached file and a known stock file from my wifes 98 gs using the compare feature to see what major differences there were ** different years have slightly different tunes** so some of my observations may be nothing more than year to year differences

there is injector skew in your tune - I havent seen that in any stock 3800 tune I recall opening

injector flow rate is different
air fuel ratio corrections based on coolant temps are changed , especially at 194* axis - you are running a 195* t stat so its likely affecting you

your PE ( power enrich- added fueling) is set to kick in at 20% tps as low as 2400 rpm - any idea what gear/rpm they are hitting on the rollers ? kicking into pe would definately tank you !

you are pulling more timing at high iats than my stock file particularly at 102*-122* - on rollers inside a bay its likely you are seeing high iats and pulling timing , you have no kr in that scan according to your histograms so you could add some timing and it should give you a more complete burn I would think , your timing tables look low for a header rocker car too compared to what I am able to run

your fan on temps are considerably lower than my stock file , colder is better for power but warmer would help with emmisions provided the ect's end up higher due to changing the fans

ltft's show you are adding fuel - 02's are reporting lean

does this car still have 3.69 gears by chance ? this tune that matches my stock 2.93 gear tune ? I know you had 3.69's in one of your gs's

dont take me as gospel Dean as I am still in the learning phase of tuning , hopefully someone else with good 3800 tuning knowledge on here can take a minute to look at the items I have flagged and chime in an opinion

there seems to be a lot of changes from stock , what year is the car ? have you checked the repository for a stock tune for your year ? If not I am sure we can find you one to compare with - there may even be one in the tuning section of the old regal forum under subcategory bin file's

you havent mentioned a wideband , if you dont have access to one maybe get it on a dyno for a quick pull to verify if you are rich or lean in the rpm range they are in when testing your car

[LSChris]

I'm at work right now so I can't look at the scans so I'll just interject what's coming to mind right now.

Are you running completely stock timing tables? Lots of timing can result in high NOx (NO, Oxides of Nitrogen) because of increased combustion temperatures.

Are you still seeing +16 LTFTs? That can be a good indicator of a vacuum leak after the MAF or an exhaust leak that is upstread of the O2 sensor. +16 ltft means the pcm is adding as much fuel as it is allowed, which I suspect is what is causing the HCs (hydrocarbons) to be high.

[deanh8]

I wish I had all your answers Dean - I hang out here a lot hoping eventually it will all rub off

what I did was open your attached file and a known stock file from my wifes 98 gs using the compare feature to see what major differences there were ** different years have slightly different tunes** so some of my observations may be nothing more than year to year differences

there is injector skew in your tune - I havent seen that in any stock 3800 tune I recall opening

injector flow rate is different
air fuel ratio corrections based on coolant temps are changed , especially at 194* axis - you are running a 195* t stat so its likely affecting you

your PE ( power enrich- added fueling) is set to kick in at 20% tps as low as 2400 rpm - any idea what gear/rpm they are hitting on the rollers ? kicking into pe would definately tank you !

you are pulling more timing at high iats than my stock file particularly at 102*-122* - on rollers inside a bay its likely you are seeing high iats and pulling timing , you have no kr in that scan according to your histograms so you could add some timing and it should give you a more complete burn I would think , your timing tables look low for a header rocker car too compared to what I am able to run

your fan on temps are considerably lower than my stock file , colder is better for power but warmer would help with emmisions provided the ect's end up higher due to changing the fans

ltft's show you are adding fuel - 02's are reporting lean

does this car still have 3.69 gears by chance ? this tune that matches my stock 2.93 gear tune ? I know you had 3.69's in one of your gs's

dont take me as gospel Dean as I am still in the learning phase of tuning , hopefully someone else with good 3800 tuning knowledge on here can take a minute to look at the items I have flagged and chime in an opinion

there seems to be a lot of changes from stock , what year is the car ? have you checked the repository for a stock tune for your year ? If not I am sure we can find you one to compare with - there may even be one in the tuning section of the old regal forum under subcategory bin file's

you havent mentioned a wideband , if you dont have access to one maybe get it on a dyno for a quick pull to verify if you are rich or lean in the rpm range they are in when testing your car

Sorry the tune I posted isnt stock. The stock one was causing torque management issues and I had to take it off.