Gentlemen,

I have an s5 TII that I am trying to get back to running. I pulled the engine out of my old frame after it got totalled and put it in a new one. While I put the new engine in, here is what was done to it.

Removed (blocked off and sealed where applicable)
Emissions - i.e. EGR and junk on the passenger side, above turbo.
BAC
Thermowax
Accelerated Warmup (on top of UIM)
ACV? (the solenoid on back of UIM)
Disconnected all vacuum lines coming from throttle body except fuel pressure regulator (secondary) w/ orange solenoid, and oil metering pump splitter. I did still leave the brakes hooked up lol. I also plugged the downstream ends on these to prevent leaks on their end.

Replaced
Secondary fuel injectors w/ 750cc RC Eng injectors
Exhaust - Straight Racing Beat split exhaust
Mass Air Meter - lost in crash
Coil Packs
Spark Plugs
Plug Wires
Intake Air Thermosensor (at throttle body)
O2 Sensor
Primary fuel injectors were cleaned and tested by RC Eng and replaced
Injector o-rings and spacers (all)
Throttle Position Sensors (and adjusted according to FSM)

Rotor Compression good. Stock turbo makes adequate boost. Stock N370 Computer

The problem I have is that it will not hold idle. The idle raises and drops, sometimes regularly, sometimes at random. Its almost like its flooded. You have to give it gas or it will lag out. I know most problems with these engines are I have hunted for vacuum leaks with a can of starter fluid like I was on safari and I'm pretty sure I got em all. It definitely will not hold steady idle below 1000rpm so I can time the thing with a light. Also, when starting from a stop, the engine will hop and jerk and kick until you mash the gas and get into the upper range. It runs just peachy in the upper range once the secondary injectors kick in but burns a ton of fuel and is obnoxious to drive around anywhere in town. One thing I have found is that after I run it for a while, and pull the UIM off, the tubes for the primary injectors (center 2 tubes) are wet with fuel. The plugs are dry and just fine, but both primary tubes in the intake manifold are wet, most of the way up to the throttle body. The secondary tubes stay dry and I dont have any problem in the upper range. What could cause this, and could it potentially be the source of my problems?

I realize this is a monstrously long post, but I have worked on this thing without any results except for a massive hole in my pocket book. I hope the devil is in the details and that I provided enough for you to help me out. I will be happy to provide pictures and video upon request to help straighten this out.

Thanks

 

welcome to the board.

i know you said you did this already, but i would go ahead and start simple by checking and rechecking for vacuum leaks. but ...
i'll try to make Aaron Cake proud and say this would be your next likely issue for the problems you describe.

 

Thanks for the quick response and I really appreciate the help. I will re-check for leaks. I am going to order a new inlet duct from mazdatrix that goes from the MAF into the turbo. and maybe those 2 elbows for the intercooler.

As far as the BAC being blocked off, why would that cause it not to at least stay running below 1k rpms? I am asking because I'm not sure what it does other than smooth the idle a little bit. Newbie question I suppose.
I got the engine running and the same symptom persisted whether the BAC was attached or not. I have tested the BAC both with a multimeter and batteries to ensure it functions. I also tested and it is receiving power from the wiring harness. The main thing the BAC did was help me raise idle with the screw adjust, but it still did the fluctuation, the fluctuation just gets worse as the idle state drops.

Could it be a possible grounding issue that would cause these injectors to flow more often than they are supposed to? I saw Mr. Cakes webpage and his technical section suggested regrounding and relocating some of the grounds. I was going to try that and see if it had an impact. The only other thing I can think of is getting 2 new primary injectors from RC

I will check your suggestions and look forward to hearing from you again soon. Thanks!