tune is very inconsistent could big injectors be the problem?
 

I can drive the car one day and the afr's will be great 14.7:1/vac and 11.5:1/boost and the next day it will ilde rich and be rich in boost, or another day and it will be lean to the point where the car struggles to idle, even though it never leans out past 11.5:1 in boost. My fuel economy is horrible about 20mpg, if I get the computer on it and fix it it will just be off the next day. the temps arent changing much and I always take the data when the coolant is warm (180f). its a Z6, I was contemplating using E85 so I went with precision 1000cc injectors they are low impedance so I am running a resistor box. I was told on PGMFI to mess with the injector offset but I dont know which colum to adjust or wich way or how much of an incriment I need to adjust it by and I dont want to do any dammage. ever since installing these injectors even if the afr's are perfect it idles rougher than it has with the 450's in.

Re: tune is very inconsistent could big injectors be the problem?
 

hmm i've heard of this problems using afc's but never with a chipped ecu

Re: tune is very inconsistent could big injectors be the problem?
 

Yeah i've been messing with the tune for about 2 weeks and if I make it right one day the next day its off again. Well I found some info on it on xenocron's crome writeup,

Re: tune is very inconsistent could big injectors be the problem?
 

what is your intake air temp ??

Re: tune is very inconsistent could big injectors be the problem?
 

Mine was doing that too, then it got real bad and ended causeing a misfire. It was only on cylinder 3. At first i thought i lost a spark plug wire or plug, so i did the easiest thing and swaped wire first then the plug and still no fix (note the 3plug was black and the others were fine, that should have been my indication of a rich condition and not a spark condition). Then i grabbed the injector wire and shook it allittle and the idle went back to normal. I noticed a bad connection, i thought it was a bad solder at my inline resistors, but still had the problem, i had overlooked the crap used dsm connector. The terminal was just barely to wide. The loose condition caused a super rich condition on that cylinder) I squeezed them together and fixed it and my AFR have been pretty dang constant now. Before it actually made a misfire, my afr were just not constant, i just thought that was the best it will get with an AFC. I was wrong, it got better but afc's still stink.

Re: tune is very inconsistent could big injectors be the problem?
 

My IAT is usually right around 110-115 if I'm in boost and if I'm just cruising down the highway it drops to like 100 or so it all depends on the day of course but I try and keep an eye on it and it stays pretty consistant.

I was wondering if this could be my problem because it does seem to be getting worse, when I let off the throttle between shifts it doesnt sound like it used to almolst like its still getting some gas, I had to cut a tab out of the injector's where the plug fits in they looked exactly like the dsm's, I'mm gonna try and bend the tabs a little to make sure its getting a good connection. I pull the plugs and they all look pretty close but thats after idling for awhile. When I first start the car and drive it misfires for half a mile down the road or so and I get quite a bit of blueish smoke, but I'm not using a drop of oil or coolant, once it warms up it doesnt misfire at all.

Re: tune is very inconsistent could big injectors be the problem?
 

jesus 115* ---- mine never goes above 100 but i got a fan on mine

Re: tune is very inconsistent could big injectors be the problem?
 

you have a fan on you're intercooler?? where are you're charge temps measuring from the stock sensor on the back of the IM?

Re: tune is very inconsistent could big injectors be the problem?
 

the fan is there a write up if not u should do it. do you use a geo rad fan or what?

Re: tune is very inconsistent could big injectors be the problem?
 

no i bought a indoor outdoor temp sensor at walmart for $6 and drilled my intake and put the sensor in there. my intake temp is usually within 5*-10* of what the temp is outside. the fan that is on there is off a cbr600 i think its small i got one on the intake side of the cooler and one on my radiator. both of them together dosent even pull what the stock honda one does

Re: tune is very inconsistent could big injectors be the problem?
 

nice, good idea thanks.

Re: tune is very inconsistent could big injectors be the problem?
 

that is sweet

Re: tune is very inconsistent could big injectors be the problem?
 

this may not be it but...in tuning some vw 4cyl turbo cars recently we found that with larger injectors, more spark is a HUGE benefit. we upgraded the stock ICM to the Mallory 6a with crane cams high output coil and it fixed the inconsistant AF ratios and allowed the cars to work very well..good luck man

Re: tune is very inconsistent could big injectors be the problem?
 

I got it figured out, I didnt change the battery offsets at all, just pulled fuel until it worked.

Re: tune is very inconsistent could big injectors be the problem?
 

Just an FYI, there is a script for Crome with injector offset tables for many after market injectors.

Good to hear you got it fixed.

BTW. Were you runningi open loop or closed loop with the inconsistency?

Re: tune is very inconsistent could big injectors be the problem?
 

I was running open loop, its still acting up but not as bad.

I know about that script for the injector offset tables I was reading about it on pgmfi, but I cant find where to download it

Re: tune is very inconsistent could big injectors be the problem?
 

Datalogging battery voltage is the way to tune the injector battery tables. If Crome doesn't support that yet, use a multimeter hooked up to the power pins on the ECU.

Turn on your headlights. Turn on your blower fan. Turn on your turn signals. Rev the motor up. Let it idle. Choke the motor to drop the idle even more.

Adjust the battery offset tables in order to get your AFRs to even out. Most of the time, you will be adding units to 10v, 12, 13.0v and significantly less adjustment at 14v and above.

I've yet to see any script with perfect battery offsets. Things like fuel pump, how pump is wired, battery being in trunk, which resistor box / inline resistors, etc. can make a huge difference.

Re: tune is very inconsistent could big injectors be the problem?
 

Thanks you very much for that Blunder.

:y

Re: tune is very inconsistent could big injectors be the problem?
 

I've noticed the exact same problem with my tune. I will be playing with the injector offset tables...

Re: tune is very inconsistent could big injectors be the problem?
 

Thank you very much for that, I've read that the best was is like you said.....use a multimeter but the whole reason for that is to find the exact pulse width at those certain voltages right? I've read dozens of threads on pgmfi suggesting the mutlimeter but I dont fully understand what i'm looking for, but you'd think that the company (precision) would know those exact pulst widths for there injectors at those voltages, but I guess like you said there could be alot of things affecting that.

So lets say I was going to start with the 10v, I just turn on accessories until I see 10v on the multimeter, correct? and then look at the pulse width in the datalogging window in crome, correct? and put that value under the 10v in the battery offset table, correct? then to do say the 12v turn off accessories until I get 12v across the pins on the mutlimeter and repeat the process, correct? Or am I all wrong, lol. I'll keep searching either way. The car has been put away for the winter, I will be pulling the motor breaking it down and checking it all out, maybe sleeve it. This is all great info thanks!!

Re: tune is very inconsistent could big injectors be the problem?
 

tune AFR vs. battery voltage.

You will not be able to put enough drain on the car to take it down to 10 volts unless you unplug the alternator while it is running (WARNING DO NOT DO THIS - IT IS DANGEROUS)

More often than not, you will be able to explore the voltage range 14 - 12v
Extrapolate the shape of the curve from there.