Alright so Im having a bit of an issue I cant seem to overcome. This isnt my car but the car that I worked on the motor and turbo setup for.

Its an 05 tc. Motor consists of 9:1 Wiseco Pistons and Carillo Rods. He originally was going to go with cams, so he had the head pnp'd and 1mm oversized valves installed - Im starting to think this head could be whats giving us the tuning woes. Just FYI - also the cams were never installed - so hes running stock cams, but with the built head. The car has deautchwerks 700cc injectors and a walboro 255lph fuel pump. Turbo setup is a 57 trim t3/t4 with .63 hotside. MAF is a blow-through setup in 2.5in piping. Were using the AEM FIC with boomslang harness. Resistors have been added to the cam/crank.

The car idles great, but when decelerating from a load it will stall if you engage the clutch. Often you can avoid it by decel in gear down to around 1000rpm than engage the clutch - than itll idle hunt but settle at a good idle. You can rev it all you want in neutral without issue. Also ive got the idle, cruise, and boost afr's and timing dialed in perfectly. No timing pulled under vacuum. Ive tried every injector response from 500us to 1.4ms. Going with the latter seems to help it but im worried about running out of fuel when we go to 14 psi and full throttle once the motor's broken in.

Im starting to think its possibly either the head or lt/st fuel trims. Ill be honest - right now I dont have a scanner that can read live values - but I ordered an ELM327 - so when I get it Thurs Ill be able to better diagnose this. Im afraid my idle looks good, but its due to the car creating st fuel trims to keep it in check, than when it hits open loop on the drop to neutral my fueling is way off. Ive taken about a million logs of it stalling, however it sweeps lean to rich - Ive tried going richer and leaner in my idle sells but I just cant seem to hit it. Ill post more when I get the scanner Thurs, but until than just wondered if anyone had any advice. Also FYI - Im running high level drive on the 02 map set to voltage with all 0's under vacuum.

 

just to get this out of the way, has a boost leak test been done?

 

Yep - no boost/vacuum leaks - isolated each vacuum accessory individually.

 

mine does this too with the fic

 

ok cool. Then im pretty sure its all in the tune. try getting the fuel trims in check and if needed redue your o2 map. Prolly start with setting it to voltage, place 3.2-3.0 in all cells that are 10psia and bellow. between 10psia and 14psia you want to tapper to 2.5-2.0 (cant remember off the top of my head), then from there you want to tapper even further to 1.0-1.1 for cells above 14psia.

this may help and it may not depending on your fuel map, just got to make your o2 map jive with your fuel map. good luck.

btw whats your maf map look like?

 

oh and are there any cel's?

 

Thats the weird thing, no cels. Ive tried the 02 map using 3.2 and 0 - some people had better luck using 0 with high level drive - thats why I tried it. MAF map is one written by someone quite awhile back, I also tried it with the maf map set to percent and zero'd out. (Basically avoiding maf voltage alteration all together)

 

YEP!

 

If you zero out your MAF map and you are not in % change mode for it, it will enter 0 output. I have seen this on the FIC. So, I would not recommend that.

 

yes i had the same problem untilll elevation tc tuned my car never happened to me again... said it was the o2 map or the maff setting's i don't remember one or the other.. but it would stall out when comeing to a stop and letting off the gas

 

When this was tried maf was set to percent, than zero'd out - such that maf in = maf out.

 

Maybe Mike will chime in here, Im really thinking it has to do with my fueling being slightly off and the st fuel trims correcting for it, but than when shifting to neutral I believe it drops back into open loop momentarily - causing it to stall. Hopefully Ill figure this out soon once the USB OBD2 hardware comes in.

 

btw is this a new boomslang harness being used? if so id check to see if your stuck in open loop all the time. They tend to put a resistor on the o2 leads. a scangauge will tell ya if your in open or closed loop at idle. I would think however that you would throw a cel for it but it may not.

 

Why the eff would they put a resistor on the 02 lead?????? Geeez, its funny all the fics ive helped troubleshoot are with boomslang harnesses - I wired mine myself and two other tc's - none of those have ever had issues lol. (*Knock on wood*). Ill def check that when I see the car again. Unfortunately dont have a scanguage - however when I get my elmscan in ill be able to do that

 

so far iv had to deal with that issue twice, first was on Kyle's car (HIX) then i got an fic and harness from another member who hadnt installed it but got it from another member on here. In my case it threw a cel after a couple of min, so im not sure this is your issue but id check just for the hell of it.





it had heatshrink tube around it and thats why i didnt catch it right off the bat.

 

now my first boomslang harness didnt have that resistor.
I get the gist of it but not sure its really the best thing to do.

 

Ill def be looking for that!

 

So we got the elmscan in today and were able to do some further testing. As suspected the lt/st fuel trims were way out of whack. I was able to dial the fuel trims in and the car feels much better, but it still has the stalling issue. Heres where it gets interesting... The car is throwing a P0012 - Camshaft Timing Too Retarted. So it looks like the car is slow, lmao TIMMMAAAAYY! Ok back to serious, I pulled the VVTI control valve and it functions properly. However I have not had a chance to pull the cam sensor and try a known good one (from my car) - ill be trying that tomm more than likely. Also I discovered his harness DOES NOT have the resistor fix done on the cam/crank wiring - Im wondering if this could cause this - however ive heard of that only causing a misfire issue at higher rpm. If we clear the MIL - the P0012 will come back by just sitting at idle - no need to put the car under a load. We have pulled the valve cover and verified cam timing twice over. Also something else really weird - at idle the car shows only 5-7* of timing advance - whereas on mine I show consistantly between 15-18* of timing advance at idle. Any ideas?

 

Also another guess of mine to through out there - something I overlooked when assembling the motor - the VVTI control valve has its own small oil filter on the rear of the block. This motor has been through hell and back before it was built - bent rods, spun bearings, you name it - so maybe that filter is clogged causing the vvti actuator to recieve insufficient oil pressure? I cant believe I didnt think to check that when I was assembling the motor - however I didnt do the shortblock assy - only the final assembly.

 

try putting a resistor only on the crank and not the cam...trust me do it i had the same code