After hooking up my wideband 3 weeks ago Ive noticed my afr at idle is 10:1. This is rediculous for an LD9 with 310cc injectors and a stock FPR.

Now I am in the midst of considering an AFPR to fix this but I dont think the fpr is completely causing my problem. Im assuming that my afr is so rich at idle because of my spark gap and im wondering if this is possible. My car is a 99 (no hp tune) and currently has the rapid fires that come with the SC kit (didnt touch the gap when I got them). Before I had the 310cc injectors (rode on stock injectors for 2 weeks), my car burned too much gas already. In fact, both now and before the injectors a full tank would only get me 300km or 186 miles and thats without touching boost! N/A my car got 550km to a full tank.

So im kinda skeptic about using an afpr to solve my problem since I have seen other owners using the stock ones on an LD9 and still hitting near 14.7 afrs. So what do you guys think, do I just get the afpr and tweak it down? Should I gap the plugs higher or lower, if so whats best?

I really cant wait till the summer to get the HP tuners so that I could advance the timing and what not, but for now I cant stand the balls of black smoke that comes out when I ram my car!

One more thing, whenever im at WOT, whether im downshifting from 5th to 4th or going from 3rd to 4th at higher rpms my car seems to "bog", or it feels like its lagging. I dont really think its leaning out, im guessing this has to do with the spark or maybe it really might need a bit more fuel etc.. At WOT my afr is 12.7-13.2.

What do you guys think?

Heres a pic of the log file with the wideband. This starts from an 80km/h role in gear 3 (50mph), when I shift to gear 4 thats when you see a spike (6,16.5 on the graph) and then it spikes really high again cause I accidently hit the governor (only 2 shift points cause I didnt go to 5th). When I went from 3 to 4 my car lagged, can anyone see why by looking at the graph?

you seeing 5 psi now on the boost guage?

How you been Jake? Nope not yet still getting 3.6-4psi. Schools been keeping me away from my car but I did find this...the hose coming from the evaporative canister was rubbing on the SC belt. It cut a hole in it, enough to stick your finger in!! !Vacuum constantly runs through that hose along with fuel vapours, so im assuming theres my vacuum leak which is why I have an incorrect reading on the boost gauge. But anythoughts on my afr?

Do you have the GM reflash? Nevermind i didnt read you have a 99

Ok heres what you need to do and theres a thread on this in the tuning forum by Shifted
Here you go

There is another step that should be added to this process to get accurate data and that is disabling deceleration fuel cut off or DCFO , reason being is that while driving the moment you let off the gas the chart will show you as being lean cause your AFR drops to 19.9 AFR in DCFO mode and the hp tuners sees that as being different from the commanded 14.6 so it shows as a lean spot on the histogram

its always going to go back and forth be sure that the A is selected at the top of the histogram so your getting average values rather than min or max values, as long as your seeing 0 to -5 in the cells you should be fine


Follow the steps listed in that post and when your done making changes remember to reset the DFCO and closed loop, always make a backup of your stock tune before starting this process, I think if you follow all of this you will be just fine



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

Rodimus Prime wrote:Do you have the GM reflash? Nevermind i didnt read you have a 99

Ok heres what you need to do and theres a thread on this in the tuning forum by Shifted
Here you go

There is another step that should be added to this process to get accurate data and that is disabling deceleration fuel cut off or DCFO , reason being is that while driving the moment you let off the gas the chart will show you as being lean cause your AFR drops to 19.9 AFR in DCFO mode and the hp tuners sees that as being different from the commanded 14.6 so it shows as a lean spot on the histogram

its always going to go back and forth be sure that the A is selected at the top of the histogram so your getting average values rather than min or max values, as long as your seeing 0 to -5 in the cells you should be fine


Follow the steps listed in that post and when your done making changes remember to reset the DFCO and closed loop, always make a backup of your stock tune before starting this process, I think if you follow all of this you will be just fine

Bro that wasn't an HPT Screenshot that was from his Wideband logging software. he doesn't have HPT yet.

Sam - you need to consider this, the PCM is commanded to idle 252cc injectors @ 43.5 psi..... you have now put in 310cc injectors at the same PSI... the computer is still putting in the same amount of fuel in its mind but in reality you are dumping in 58 or so CC more of fuel.

So it runs rich.

So - should it run rich unless you decrease fuel? Yup. You can use an AFPR to do that if you'd like, you can use HPTUNERS... you can use a few different ways.

So if you want to put in an AFPR for more control and get the injectors to idle correctly for now that isn't a bad idea, it's still useable with HPTUNERS.... or alternatively you can live with the 10.5 afr until you get HPT.

Your choice Good luck bro I know what it's like to be too busy for this shizz.

-Chris-



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