I am getting ready to tune my 3800SC and am just making sure Im ready to start messing with fuel and such. The engine runs perfect at everything but WOT. At WOT I get a lot of misfires/spark blowout and my wideband indicates a very rich condition. Whenever I open it up the wideband pegs at 10.0 (the minimum) instantly which leads me to believe it is really much less than 10.0 AFR. I have done a boost leak test, checked that my fuel pressure behaves normally, and regapped my plugs to .055. Is it really getting that rich just because it needs tuning or do I have another issue going on?
Mods: 3800 series II 3.25 pulley ZZP short stack intercooler 4 inch intake 3 inch exhaust Autolite 104 plugs @ .055 180 degree thermostat ZZP billet aluminum fuel rails
[This message has been edited by Bfisher31286 (edited 04-29-2014).]
.055 is on the bigger end of the spectrum for the 104's
FWIW I use the 104's gaped @ .050 and I only have a 3.4" pulley ( ~9psi)
I'm not saying that is your problem, I think you just need to the the thing tuned, Fuel demand for a 3800 with an aftermarket pulley is much different than even the stock pulley.
I figured the stock tune would be able to match the AFR a little better. I thought the correct spark plug gap for the 3800 was .060 but since I increased the boost I gapped the plugs down a bit. I had the same misfire issue when I dropped the plug gap down to .045 as well so it seems to be fuel related.
According to Intense stock 605 plugs should be .055 (~6psi) 104's sould be gapped to .050 (~6-12psi) 103's should be gaped to .045 (12-18psi)
With a 3.25" pulley you should be around 12psi depending on how free your exhaust is, But that's like splitting hairs, the stock tune can't cope with a smaller pulley not even a 3.6" pulley. My car BARELY ran with with the stock tune and only a 3.4" pulley it even turned my bumper black just idling in my shop a few times.
I will try the plugs gapped down to .030 and see how that goes. How difficult is the HP Tuner software to use? Could I get away with tuning from a couple of pulls on the highway or am I looking at a full day on the dyno. I have done all my tuning in the past on piggyback computers which are a simple turn of a knob or a button or two.
The HP Tuner software is pretty pricey...is it a good idea to try and get a used package with some credits left or should I just buy it new?
If you are going to tune your self HP tuners is invaluable, if your on a budget, the ZZP 1.0 PCM isn't a bad option.
I have had HP tuners for years, but I only ever used it to adjust the spedo for customers with bigger tires (lifted trucks) and to turn off the rear O2's on cars with "high flow cats"
when I did my 3800 swap I just used a ZZP PCM $125 and 3 days later I was up and running.
You definitely need a tune. I've tuned with DHP powertunr and just picked up HP tuners. Based on my experince so far I would recommend that its much less time, cost, and risk to pay someone to tune it. I've got several swapped cars so I decided the time and money investment was worth it. Though, there is a ton to be learned and tuning can be time consuming and risky for a novice.
I wish I had bought HP tuners right away. If you have a good understanding of how an engine works and are eager to learn, the internet makes HP tuners not hard to pick up. Pick up greg banish's book first.
Ok so I got HP Tuners and I have been beginning the tuning process. I got my AFRs down to 11.1-11.9 through the RPM range and I am still having misfire issues. I tried upping the timing a few degrees and KR starts showing up around 13-14 degrees of logged timing at 3000rpm and up. It doesnt seem to make any difference to the amount of misfiring i get either. Should I be going any leaner on the fuel? I thought for FI cars 12 was getting lean at WOT. Should I really gap the plugs all the way down to .030? I am still at .055 and I figured tuning would help the misfires but it doesn't seem to be the case. What else should I check for?
Another thing to add...Ive got ZZP plug wires. Do people keep those metal heat shields on the wire boots with aftermarket wires? I have them on and am wondering if they ever cause problems.
From what I can tell the DTC for misfires is not disabled and in the VCM scanner it says "misfires n/a" in the readiness monitors. I have never gotten any codes for misfires even though I am getting a lot of them. Is there a specific way to set up a scan for misfires with HP Tuners?
[This message has been edited by Bfisher31286 (edited 04-28-2014).]
So I regapped plugs to .030 early this morning and took it out for a drive. I tried some half throttle and wot pulls and it seems the misfire is gone. The outside temp is low 40s so hopefully the misfires dont come back when it warms up. It seems all the KR I was getting before was false due to the misfires. Now I can get to some real tuning. Thanks for your help guys.
The stock tune I had was not that far off. I pulled the fuel back just slightly to keep AFRs on the wideband in the 11.1-11.9 range. What is the best way to smooth the transition from part to WOT? On my logs it shows once the TPS threshold is passed it pulls the fuel from 14.7 to 11.1 and the timing from like 25 to 15 and this causes a noticeable loss in power. What is the best way to start tuning the area just before and after power enrichment to get smoother power?
The stock tune I had was not that far off. I pulled the fuel back just slightly to keep AFRs on the wideband in the 11.1-11.9 range. What is the best way to smooth the transition from part to WOT? On my logs it shows once the TPS threshold is passed it pulls the fuel from 14.7 to 11.1 and the timing from like 25 to 15 and this causes a noticeable loss in power. What is the best way to start tuning the area just before and after power enrichment to get smoother power?
Stock PE is very generous, most tuners will turn down the transistions to make it richer and even less timing at an earlier TPS value. I wouldnt change anything if I was you.
Reminds me of a missfire that drove me nuts on my 3800sc^. Specifically, it would only miss at WOT, usually only towards the end of 2nd-3rd gear... It reminded me more of a "flutter". It slowly got worse until one day I had trouble accelerating on an on ramp. Everything was brand new except for the coils. Turns out 1 coil was causing it. Couple months later a different one croaked. I went ahead and replaced the last one just in case. Car was perfect ever sense!!! Just an idea.
