Y have my times not improved?

I have no idea of what is up with my 92Z? With the stock engine and supercharger 8psi i ran 12.9. I rebuilt the engine with a ZZ3 cam, svo 24lb injectors, crane hi-6s ignition, SLP intake runners, TES headers with 3in cat back, AFR 190 heads and I ran the same et's and trap speed of 109mph...SAME:confused: Cat's are new too?

Last year after the rebuild, it ran like stock without the supercharger, then after 3 weeks, i was getting onto the freeway and it seemed to open up? Then it was really fast! I later put on the supercharger and blew a head gasket and fuel psi regulator. I replaced the gaskets and a new fuel psi set at 45. Now it's sluggish again. No vacume leaks, ignition and wires are correct, idles fine, sounds fine but seems like it is back to a stock engine again. I am stumped? valves are lashed at 1/3 lash and timming is at 6deg adv. I have moved the initial timming around but no change and i am at my whit's end!:cry:

Any Ideas?

if your 190 AFR heads are not ported then get them ported by a good porter like GTP. also try to scan your computer to see what is going on and go to a dyno shop to check your car's rwhp.

Get it scanned to see if any trouble codes are popping up.

Mike

BTW, this should have been posted in LT1 Tech.

Mike

no codes! Sorry about the location, however, i thought this could be considered advanced because I have no idea what is up and no one else i have spoken to does either? Good spark, fuel psi is @ 45 under load????

Osmosis, This should be posted in a regular tech forum, since you have a 92 ill get this over to 3rd Gen.

Thanks bud.

I think this all boils down to fine tuning and PCM calibration.

What injectors are you running? What PROM?

I would start by getting a good air/fuel ratio gauge and checking the base a/f ratio. The next thing is to put it on a scanner and check for knock retard. I think that if you're using the stock injectors you may be running lean and losing power. U really need to get it on a dyno and dialed in.

I burned my own chip and have 24lb injectors. No codes either? It was really wierd! After the rebuld, it was acting just like it is now for only 3 weeks, then i went around a corner onto the freeway and it opened up...BOOM like something was plugged up or a wire was not grounded? Now it runs like the first 3 weeks after teh rebuild but has not opend up? I plan to take it to a dyno soon.:cry:

anybody:bow: :think:

Are you running a FMU, or just 24# injectors at 45 PSI? Have you tried running the new combination with the stock programming? Your engine is not nearly modded enough that the stock chip shouldn't be able to produce good power, you obviously can make more power with a well tuned chip but that is if you have the skills to make one.

Yep, got the super FMU and burn my own chips. BLM's are between 16-128. It's strange because after i rebult the engine, it was similar to the stock power for about 3 weeks N/A. Then, it opened up?:confused: Do not know what the heck was going on??? Anyway, put the supercharger on, and blew a fuel psi reg and head gasket. After i fixed it, it's running like the first three weeks of the new engine? When I did open up, WOW! It was as fast with out the supercharger as the stock engine was with teh supercharger? Now, I have no idea what's going on? Currenlty making a wide band O2 but have work crap going on so it will have to wait a few weeks? Any ideas? :confused:

Was your stock engine with the charger running a stock chip or one of your burnt ones?

The stock engine I was running the stock chip except for the fact that i changed the injector constant from the 22lb to the 24 lbs and did 4 burns to get the BLMs in the ball park. And to turn the fans on @ 180ish. Other than that, i have yet to really tune the car via the chip due to this problem. I have tried to mess with the chip to see if that was the problem but nothing seems to work? So to answer your question, not really & still running the stock chip except for fans on @ 180deg and chaged the injector constant from 22 to 24. I'm stumped:confused:

What I was trying to get at is that your new combo is really not that far off of your old set up as far as the parts are concerned. You have a very minor cam, with higher flowing heads, neither of which would cause such a decline in performance if you kept the same programming as you had when you were running the old set up. Without the charger on that engine you could run in the twelves with a stock 305 chip. There are just too many factors to take in to account to make an acurate guess on what your problem is. Have you tried reverting back to the stock ignition? Whenever you have a problem that should be your first move. If that is Ok, this problem is probably going to be something that you have to go through step by step. If the engine is in proper condition, your chip is burned correctly, and your ignition is firing properly, then you must have missed something during the re-installation of your engine, be it a ground wire or whatever, you changed a variable that is going to be very hard to diagnose with out seeing the car. Also, if your psi is staying at 45 all the time your FMU is not doing it's job. You should see higher psi as your boost increases, what kind of charger kit are you running?

I agree! It is not too far off than stock and should be running 12's with out the supercharger! I know some one on TGO who runs mid 12's! The only difference is that he as a superram. He runs NA 12's! Anyway, I keep think Spark Air Fuel, my fuel psi is at 45 NA, supercharger and fmu is 90ish under boost. I have tried stock ignition, increasing fuel psi, no vacume leaks. Me and all of my friends are .... :confused: Lost on this issue. When it did open up that one time, it was like a wire grounded or a rock shot out the exhaust and it was running free? What wire could cause this? It Idles perfect! Sounds like it runs perfect? just lack of power.

Thanks for your help on this issue!

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? :confused: 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 :D 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. :confused: 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!:bow:

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.......:confused: :cry: :( :death:

got no ider's?:confused: 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.

BlownYellow,

I neglected to tell you that my fuel psi NA is 45 and under boost with the fmu gets up to 90ish. Maybe 80, its been a while since i have had the charger on. My next step is to omit the fmu, however, the car did wake up with the fmu connected. But I still plan to take it off and try it from there.
Damon, Thank you too! I did know that my svo's actually were rated @ aprox 26-27psi. I have them set as 24's via the chip. My BLMs show between 126-130 and 128 is the "perfect ratio" in the chip area so they are set ok. I have an aux fuel pump that runs off the hobbs swich. I have grounded it so i have max fuel psi, with intial set at 45. No change:( A few months ago i did get a code 32 egr, but i cleared it, and have yet to get a code since. I did check my egr via the vacume test and it was OK.

:confused:

Now what? I am going to have to wait till next week to mess with my Z becuase of a job interview I'm getting ready for. AFter that, Under the hood and making a Wide Band o2!

This may be too simple of a solution to your huge problem, but hey its worth a try:
Have you ever verified your CTS values? Just a possibility.

OK, I have a new thought on this issue. Is it possible that my timming chain may have jumped a tooth? That is the only thing i can come up with???

What would the sypmtoms be of a timming gear off a tooth or two?

I agree with the previous note, you may be running lean. You said your block learn is 16 and 128? You need to be at or near 128 on short and long term (block learn and integrator).
I have a 92 Z with a Paxton running 6-8 psi of boost. I had the stock inj. (23 lbhr.) and could not get this thing to run when the blower started boosting. I added an adj. regulator and the stock inj. will not open above 60 psi. I called Paxton and they suggested bigger injectors, 30 lb hr. I used a tech 2 to snapshot the run with 23 lb inj. and when the boost started my o2 vt went from .700v to .100 (way lean) and my engine fell on it's face. I added the 30 lb inj. and o2 vt stays at .900v all the way to 6000 rpms w/8lbs of boost. BTW the 30 lb inj. are Ford, they don't seem to mind higher pres. like the GM multech inj. My times went from mid 14's to 12.7 @ 108 mph.
I did put headers on and noticed a drop in power on accel. I did not have any driveability problems ie. misses, erratic idle, lean o2.
What I did find was a spark plug wire burnt on the header, dropping a cyl. under high load. I did not notice this until I tuned the engine up. Check your secondary ignition. Also, drop your plug gap about .010", when the boost comes on the ign. has a hard time jumping a bigger gap. This will not affect your low speed driveability. Let me know if this helps. If not, I'll see if there is anything else I missed. Good Luck

It sounds as if it's running in a "limp-mode", is there some value that's consistently way off?
The fuel management relies on tps,cts,iat,rpm,and o2 feedback,a flag on any one of these can get it to limp.
The BLM are jumping?What's the Intergrator doing?(adding or subtracting?)
Knock Retard is a silent power robber too.
If the timing/phasing was off a tooth you could blow boost thru the exhaust. Either way it would run like crap, noticably bad. Not to mention the timing mark would be gone when you look with a timing light.

Have you read your spark plugs? It's a great indicator of what's going on in there, look real close.
Any smoke under WOT?
Fuel pressure of "90psi" seems extreme! Most injectors are unpredictable at those pressures and possibility for failure, staying shut or locking open, is high. If more fuel is needed buy larger injectors. I'd have went with 30-36lbers with your combo.
But there is definitely something else at work here.

Sorry,

This an old post i brought back to life. The svo injectors can handle up to 100psi, the GM's go static above 90psi. I'm running the Z without the charger and trying to get it running right. Plugs show the car is running rich as the BLM's do. I am suspecting that the timming chain is off a tooth???

this may be dumb, but maybe you are running about the same time because you don't have enough traction to keep up with your engine?? Just a possibility.

NOPE! Definately not a traction issue.

I've went thorugh everything! spark, air fuel...The only thing I can come up with is the timming chain being off a tooth. I'm gonna check that before i put it on a dyno and do a wide band test. Open for any help!

I would go and check the grounds again. The one at the right rear of the engine is easy to not get tight.

Been there too! Just repalced my tranny and installed it myself. I inspected all the wiring to see if there was a missing ground, but found nothing out of the ordianry? The help is appriciated! Keep it a comming! I jsut got a piston stop today and plan to use the dial indicator in the next few weeks, when i get time, to check and see if my engine guy put the timming chain on correctly? I am at the point where i think the timming gear is off one tooth?

Chris Ja, where is exactly that ground at right rear? want to check it and where are the rest of the grounds? thanks :)

The grounds are at the rear of the passengers side head by the dip stick tube for teh tranny.

Well, if you think the chain is off a tooth;
Put the crank a TDC on the compression stroke.(valve cover off lokk for the intake valve closing)(or put a finger in the plug hole and stop when the compression blows it out, or air past it)You may turn it a little further to the mark ofcourse.
Now see where the rotor button is pointing?Hopefully directly at the #1 plug wire tower. If between 1&2 I'd say you're right.
Are both valves fully seated?

We had this similar problem with my buddy's GN, turns out he had a 30# chip with 36# injectors. He had a real rich mix and detenation from it at only 12psi.(small for a GN) It still sounds like a programming/ECM/sensor issue to me.

Test your FMU using regulate compressed air see if it sees and increases the fuel pressure at the rate you selected. 4:1 Or 4psi for every1# of boost. Also crossed fuel hoses on the FMU will hold the valves open. Also check the Hobbes switch to see if it sends power to the pump just after sensing 1# of boost, if it takes more than 1psi the pump will come in too late. Replace it. You'll need a fuel pressure gage that can be used while driving.