No Idle, Low Vacuum, Missing on 6-8, WHERE to look now?
#1
No Idle, Low Vacuum, Missing on 6-8, WHERE to look now?
Ok, same story i've been posting about lately. My motor, as listed in sig., will NOT idle in open loop, although at one point in the past it did, with this motor, this tune, everything same. It used to even idle with a/c on fairly good, now there is just NO WAY. Ok, where I am at... IAC count pegged at 160 regardless of what I do. BLM's split cell 16, 147/162 or MORE on right side, steadily increases until it maxes on Right BLM's, AFGS of 11(when it used to run good would be closer to 13-14), map is around 70-80 jumps to almost 90 when it stumbles to die, 02 on left is about 450-500, right is 50-100. O2 sensor does respond and pickup when driving car down the road, only drops during idle! When I removed the 6 and 8 injector harness, it does not idle down, leaving me to believe I have a no fire on those 2. Every other harness I pop off will drop idle worse/kill motor. So here is where I am, EGR has blockoff plate from exhaust to intake,actual egr valve still on back of engine, only things pulling vacuum is HVAC, Brakes, and OPTI, everything else is capped off. Two ports on left side TB are capped as well. What I have checked, checked TB/IAC for proper operation, and not carboned up. Replaced all spark plugs. Checked 6&8 plug wires for spark, got a hot spark. Looked around intake for anything visual, sprayed starting fluid while running, no effects, removed and plugged each vacuum port causing no changes, datalogged 3 seperate times finding the same, tried slotting the TPS, and opening the blades more, IAC still pegged, fuel pressure is 45psi and runs on aftermarket regulator, removed all injectors, inspected, and replaced in different location to eliminate bad injector possibility, opti is newer, checked and swapped maf, cleaned airfilter, checked all header bolts, and visually inspected for leaks, checked valve clearances, checked torque on all intake bolts, checked plug wires for burns, with all of this I came up with nothing. Trying to run this situation in my mind, 2 cylinders not firing could be related to massive vacuum leak, IAC opens fully to try to adjust for the stumble, right bank reads lean, throws more fuel in, no fire situation, o2 reads unburned oxygen as lean and keeps requesting more fuel? Is this something like how the operation would work? I am throwing a code for map high, indicating could be a vacuum leak, but with a big solid roller that is what it is in my mind? So where should I be looking now? Its so hard for me to tell if these cylinders are missing when it runs down the road... it dosen't feel like its missing, but it could have been doing it for so long I may not even noticed? When I unplug injectors revving it under no load, I don't notice a difference, but like I said is under no load... Where should I be looking now? I keep having the intake gasket in my mind, and also this car has ALWAYS burned a little oil since the motor was put in, not signifigant enough for me to pull the motor... Anyone have some clues where I should be checking? I know its a long post but it is blowing my mind... I have looked everywhere obvious... and put alot of time trying to diagnose and searching the forum, but not getting anywhere. Any ideas would be appreciated!
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armedtrigger
LT1 Based Engine Tech
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02-24-2015 08:30 PM