ALOT of misfires on cylinder 3...

[outtamymind]

jon, i would wait on that for a moment. i'm trying to find out how much a new one will cost me at my old parts store. btw which motor should i be looking up a 3500 motor or a 3400 motor ICM?

[3X00-Modified]

3400, or 3100, the 3500 the ICM and coils were a full integrated unit.

[outtamymind]

thanks. after everything that we've gone through with this car i can't wait to get this sorted out and start tuning.

[3X00-Modified]

Take it slow... the worst thing you can do with a boosted application is rush the tune and screw up something simple that costs you a block or a head.

[outtamymind]

thats why i want to get everything sorted out before we start tuning that way we know that everything is working properly and we can monitor it and adjust without thinking what if this part is bad and we're tuning it incorrectly.

[banzai92gt]

Best shipping method is jus normal usps...

Travis bettcher
156 dovercliffe way se
Calgary, ab, CA
T2B 1W7

[3X00-Modified]

I didn't get this till today, I'll have to drop it in a box tomorrow morning.

You should have the ICM tested at an autoparts store first though...

I'm guessing it does this cold or warm right? If so that eliminates the limitation of bench testing since they don't get as hot as on a car.

[outtamymind]

yes it does it cold and warm.

[outtamymind]

update****

changed out all the coil packs and ICM with one from another motor, misfires are still evident on cylinder 3 with some slight misfires from time to time on other cylinders. i did notice some slight knock but was under a degree each time (only happened 3 times).

no longer getting a flashing CEL indicating massive misfires but we are getting a run lean P0171 which is conclusive from the log, as the LTFT's are sitting way to lean as well as the wideband is reading lean. it drops down to about 10.1 under load but immediately leans right out as you progress through the fuel tables. anyways enough of my babbling, attached is the log from the run around the block. i've highlighted the 3 area's that showed some slight knock.

http://68.145.77.128/pictures/Tuning/UV ... %20PM.html

[3X00-Modified]

you have a major fueling issue... Go after the injectors or o2 sensor. with it reading +21 on the LTFT your just asking for something to break. I suggest not driving the car till you get that LTFT closer to zero.

What fuel injectors do you have? and whats the fuel pressure and what is the IFR in the ECU set for?

You have a lot of work to do before you should ever be hitting WOT and I don't know why you keep doing that. you need to work on the idle and part throttle fueling first and make sure you can control it, nevermind get rid of the misfires on cylinder 3. As soon as you see misfires shut the damn car off and take it apart again and try to find the issue, there is no point in driving it like this unless you want to replace a piston soon.

[outtamymind]

The commanded afr is set for 14.6, the o2 sensor reading looks to be working correctly. I'm gonna hook up my fuel pressure gauge to the rail and test the fuel pressure. I'm not sure on what injectors are in the car.

Where would you suggest I start woth everything?

[3X00-Modified]

Start with check the ohms on the injectors and see if they are all firing properly... With three misfiring as bad as it is its either a fuel issue or spark, and you've gone through the whole ignition system so fuel is left right now to check. Move Injector 3 to another cylinder and see if the misfires follow it... thats the quickest way to test the injector without having any special tools. I did that with my dads GMC Jimmy and the misfires it followed the injector to the cylinder I put it to.

And yes the AFR is 14.6 and the wideband is reading that, but ONLY after the ECU is correcting and adding 40% more fuel at idle... that's just insane, that engine is not breathing that much more air at idle that it should need that much table adjustment.

Try and find out what injectors are in there and check the IFR in the ECU and make sure that's set right. If they are larger injectors and it was set at stock then you would see a very large negative LTFT which leads me to believe that the IFR is probably set close to right or maybe way to low also (its milliseconds per gram for flow rate so the lower the number the larger the injector)... That could be another reason why the LTFT is so high.

[outtamymind]

i will test the ohm's first, do you happen to know what they should be at or is it brand specific. i think at this point probably the easiest would be to swap the injector around and see if it follows.

and what are you referring to with IFR? i've never heard this abreviation before.

[3X00-Modified]

Injector flow rate, its a value in the ECU that represents the physical ability of the injector. When you change the injectors you need to adjust this value approrately so the ECU knows what the injector flows for 1 millisecond of being open so it can calculate how long to keep it open in relation to how much air is coming in to hit a target a/f ratio.

As far as ohms go... you'd have to see if you can get a PN off of the injector then google it... Witchhunter.com may have some specs on it for what the range should be.

This is what I'm running and its a 28lb Trailblazer injector

[outtamymind]

ok i will take a look into that. i think we're gonna pull the rail and go from there.

i need to start reading more on tuning lol. this will be my first car to tune so if i ask alot of questions its because i don't want to blow it up lol.

as well i have a strong mechanical background as i worked as the equivalent to a second year apprentice for about 6 years. i still do mod's and such for most of my friends as well.