What fuel pump are you using? Are you able to watch fuel pressure at WOT? You may be running it lean... Just a possibility that the pump isn't keeping up with the demands of the engine.

 

My mind has travled that path too , I have the stock intank fuel pump and added the vortech 155L inline pump. I set it up so that the aux. fuel pump only comes on durring boost by grounding it to a hobs switch. I fabricated a bypass with a check valve so running it without the supercharger, it does not come on. I grounded it so it would come on to see if it made any difference...NOTTA

I'm thinking it was a wire that grounded? It felt like a cat was plugged then suddenly unplugged but I had both cat's checked. They turned out fine. Timming has been adj from 6deg to 12 deg initial and no real change either? It's gotta be a wire or something?

What wire could cause the car to run OK, just lack power? spark advance is working too? Like i said, my friends and I are stumped! I'm going to mess with it all day on Monday, recheck the valve lash but I know that's perfect so I may leave that for last. Tear down into the wires is a for sure thing.

 

You said that you went around a corner and it all the sudden opened up for a split second? If so you could have slammed all the fuel to one side of the tank and ran a little lean because the fuel pump couldn't pick up fuel fast enough. Remember that lean is mean You are running, ohh crap I cant remember which side of 128 is lean and rich. Its been so long since I burned a chip. If in fact you are on the less than 128 side and that is rich, you might wanna cut some fuel. Also hook your car up to a scanner! Check for and spark knock causeing the timing to retard itself. If I could get rid of my first gear only 14* of knock retard, I guarantee my first gear would be totally useless..... right now I hook up in 1st around 4000 rpm.

Tell us what kind of knock retard, spark advance, BLM's, WOT O2 readings you are seeing. Also How does the Speed Density setup like the boost? I know that running a MAF car with that much boost would be an exercise in futility for tuning.

 

The 128 is the perfect value, any value between 126 -130 is a good place to be. I'm there. As far as when i went around the corner, it opend up & stayed opend up till i blew a head gaseket and fuel psi regulator. Since the teardown and re assemble, it's running like it's plugged up again? It's about as fast as stock again? with and without the supercharger. When it did open up, the car running N/A was as fast as the stock engine with the supercharger! I only had the supercharger on for about two weeks, and when I got on it.......It was like driving on ICE.

No idea what ground would cause this?

 

One other symptom I am having in hot weather is the car seems to get really hot durriing stop and go traffic? The one thing that is different now is that i took the header wrap off my tes headers & i think that is the cause becasue durring normal driving conditions, it runs cool! New 160 themro and hoses.

 

what kind of boost are you running on what model of charger? You say that your fuel pressure runs up to 90 psi under boost. That is too high, maybe you have a problem with your fmu. You say that your pressure regulator and head gasket went at the same time, maybe what happened is that your FMU got stuck, which in turn ran your psi off the chart, which would no doubt overload your injectors and shut them down, and then your engine went lean because of this and blew out the head gasket. Do you have access to another FMU?

 

the 4/1 seems to work best for me, that's why my fuel psi is only 90

 

What do you mean only 90? Injectors are not able to run at 90 psi they shut down. What kind of charger at what psi are you running?

 

Sorry for the lack of info, running the paxton sn2000m @ 8.5psi. I have the ford svo 24lb injectors which can handle a bit more than the gm's. I have the plates so i can change my fmu from a 4/1 to a 12/1. It seems to run best at the 4/1 ratio. If i change to the 6/1 or 8/1, i can not tell much difference. I really need to build my wide band o2! I have a huge job interview on the 13th, after that, I'm a fixin a o2 wide band!!! I really think it is a wire some where? WHERE? What wire would cause this/?? I'm gonna do some digging tomorrow. I'll keep ya posted if I find anything. And if you have any more idea's.....PLEASE let me know!

 

sorry about the only 90 comment and quick comments. Have a 8mo old daughter who was demanding my time the otherday!

 

The only other question I have is when you were running your stock engine with the charger you would have had the FMU installed. When you changed over to your new engine and were running on motor only, did you still have the FMU installed as per the previous engine/charger combo, or was it removed for the N/A running time and then installed again once the charger was put back on? What you should probably do is pull the intake ducting off the paxton, disconect your drive belt, and reinstall the factory ducting to try and get the engine running properly N/A. Anyone who knows their stuff will tell you it is not a good idea to put a supercharger or any other mod for that matter on an engine that is not optimized in the first place. Once you get that thing running properly with out the FMU, and running on engine only, then take the next step. If you are insistant on tracking it down to a simple wire, the main culprit is usually the two ground wire bunches that attach at the rear of both cylinder heads. They are major grounding points for electrical components, and parts of your computer. If anything will cause a decrease in performance because of a bad connection, it would probably be those. Seeing as you have AFR's I doubt you painted them, but that is usually the main reason for bad grounding at those points. If none of this helps, it is time to find a wiser guy than me for info because I am tapped.

 

What engine temp do you run at?

 

Blownyellow, I thank you for all of your efforts, you too Redirocz! I tried to trace it down to the grounds, everything looks a ok? As far as the supercharger, I do not have it on. I am running it NA till i get thinks figured out? Ready to trash it and call the ins co, however, they would not give me waht i want for it so i guess i have to figure out the problem. One thing it is doing is at idle upon startup, its putting out water from the tail pipes. jsut condenstation i guess, no smoke or hesitation. Temps are about 180. I have a 160 stat. it does get warm during hot and go traffic in temps above 80 deg C. in town but once i'm on the road, it cools down. I took the header wrap off and think that's the reson why she gets so warm in traffic? And yes, i do have the FMU hooked up at all times even NA. I turned on the aux. fuel pump to see if that was the problem today also, notta?

As all of my buddies and i.......

got no ider's? HELP

 

Well I am happy to say we probably found your problem. Let's start by getting rid of the FMU in your cars N/A state. FMU's are designed for use with chargers, and even if it could work in a N/A engine, I am almost positive that it is the source of your problems. As hard as people try to make it sound like there is a ghost living in their cars causing a problem that is impossible to fix, there is always a solution. You have gone through every part of your cars operating system except the FMU and have turned up nothing. The one constant variable that is present and unconfirmed to be working is your FMU. I do not know if you were mistaking when you said that your psi was 90, but even if it was anything over 65-70 psi you have a problem in your regulatory system. An ideal FMU system should be reading 65 psi at max boost, by the sounds of it as I stated earlier, your FMU is not relieving pressure properly. FMU's have never been known to be reliable parts, and that is the reason why so many people are quick to discard them. Please, before trying anything else, take out the FMU, and run the car N/A, If I knew you better I would bet you 100 bucks that your car starts screaming afterwards. Again the FMU is not meant as a fuel system component on N/A engines, and it sounds like yours has taken a dump anyway because of the high PSI's. If the car responds after removal of the FMU, throw in some 42# injectors, and tune with the computer alone. You will realize better performance gains using injector size versus FMU psi manipulation anyday. Keep us informed and good luck.

 

Duck tape a fuel pressure gague to your windshield and make sure it's holding pressure under boost at high RPM. Not saying that's the problem but inadequate fuel supply is a major "head scratcher" gremlin. The FMU should make NO difference when running N/A if it's working right.

Now under boost..... I see you're running a 6:1 on the FMU (assuming 8 PSI). Have you tried something leaner like 4:1? Are you sure your WOT fuel mixture is correct? Also, running under boost with high pressures requires one HELLA STRONG pump. I agree with the above post to get some 42s and tune without the FMU, since you know how to do your own chips.

BTW- a 24lb SVO injector is like a 26lb "GM scpec" injector because they rate them at different pressures. (37 for Ford, 42 for GM). So you're gonna be running fat given that you are actually close to a 27lb injector but running a 24lb injector constant in the programming. I'm no programming pro, but I know to look out for that little gotcha from personal experience.

Is your distributor actually seeing the advance from the ECM?? If the timing wire was not connected that would make for lousy performance, but also a solid-lit check engine light.