My preemptive tuning problems thread

**q2418130103p** · 09-24-2011, 11:32 PM

I just got my 550cc injectors installed this morning, planning on tuning with my (reflashed) neo tomorrow. I am anticipating loads of problems, so I figured I would just start my 'tuning troubles thread' now and get some of the baselines out of the way.

PTE 550cc injectors
hotwired supra pump
afpr (with gauge)
apexi neo (reflashed)
13t's
fmic (not a very good one, but it is still an fmic)
fresh copper plugs
WB o2 (which I can log in HHH)

Based on the team3s safc guide, I set my low throttle position to 30% and high throttle position to 85%. For initial corrections I did -30% for high throttle points and -35% for low throttle points.

So far I have only started the car, and let it idle (warm). This went fine, but I had to drop the correction to around -25% for the 1000rpm low throttle point to get the afr correct. The low fuel trim never dropped to 100%, but I am guessing I have to wait longer than a couple minutes to see that move.

So any suggestions, or 'plan of action' ideas considering my parts, would be appreciated, but I think 550cc injectors with the safc or neo have been discussed an awful lot. So I figure I will post an update after things go horribly wrong tomorrow. I am hoping that having a wideband tied into my logging data will make this a snap...

**q2418130103p** · 09-25-2011, 03:54 PM

Alrighty, it has begun.

First concern: The team3s tuning guide (Team3S- Dodge Stealth Mitsubishi 3000GT Owners Pages) attempts to get you to maintain 100% low fuel trim when tuning the low throttle points. This sounds good to me.. except that it seems to take forever for fuel trims to adjust, and the guide give the indication that it should be quick (this is a inference). In fact, I never actually see the trims change, they only seem to change after I turn the car off and on again.

Second concern: I am at -18% reduction at idle. The o2s cycle at around -25% or so, but I kept reducing to try and get the fuel trim to 100%. This seems like its way too little of a reduction for 550s. I am aware that some people have seen PTE injectors flow less then they are rated at. Perhaps I am not in the middle of the ECU's correction band, I assume this is why team3s has people shooting for 100% trim.

**RealMcCoy** · 09-25-2011, 05:31 PM

You need to step back and wrap your brain around what the all the trims mean, and what the low and high throttle points represent...

The fuel trims (low, med, high,) react to FTO2. FTO2 is a short term reaction to O2 sensor changes. The low, med, high, designations are for for airflow. They do not represent RPM or throttle opening. Your total trim is going to be whichever trim cell you're in + FTO2. so if you're driving down the road in the med cell, FTmed at 95%, FTO2 averaging 105%, your total trim is 100%.

If your state runs E10 as standard fuel, knock about 4% off your expected correction right off the top.

The fastest way to get a quick set, is to reset your computer, get all the trims parked on 100 (that's where they default on reset) then tune from FTO2 before the trims have a chance to move around.

You'll also find that the load tables are off in the lower rpms due to your airflow correction, and you'll have to run it REALLY fat in the lower rpm, high throttle sections to compensate.

**q2418130103p** · 09-25-2011, 05:55 PM

Ok, reset the ecu, trying to adjust off the ft02 right now.

**q2418130103p** · 09-26-2011, 12:51 AM

I believe I got the low points set correctly, so I went ahead and moved onto the fun part.

I went ahead and started doing 2nd gear WOT pulls. The first pull was pig rich at all rpms, no knock... not that it means anything in this case. I went ahead and started making adjustments, and doing more pulls. As I made adjustments, I started to get a bit of knock, but as I got the AFR closer and closer to the factory values the knock began to go away. The last run I did had a afr curve that looked decent, but the knock went back up, way up.

I have attached a picture showing two wot runs. The brighter lines are from the run with the 550cc injectors with boost set at 15psi. The darker lines are from an almost identical pull made yesterday with the stock injectors and the boost set to 9psi.

Compare.jpg

**q2418130103p** · 09-26-2011, 08:11 PM

Here is an AFR plot for the run (550s, 15psi). I also plotted the 'factory afr' estimate, which only has 500rpm steps, then I plotted a best fit polynomial to try and smooth out the 'factory afr'. I knew I was running it rich, but I didnt realize I was THAT rich... The factory table is obviously already conservative.