383 Runs very very poor
04-14-2003, 02:29 PM
#1
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Join Date: Jul 2000
Location: Carthage, MO
Posts: 9
383 Runs very very poor
Well, this summer I plan on spending some time getting my car running properly. About 2 years ago I dropped some serious money into it, in hopes of the car running really well. Seems my dreams went down the drain -- considering I have barely driven it since the upgrades.
Heres what I did (at least what I can remember):
Had the 350 block stroked to a 383
Installed a Crane Compu-Cam 2050. Has a .498 lift
Cam Description: "For 94-95 highly modified, aluminum head LT1 Camaros, Firebirds and Corvettes. High flow heads, headers and exhaust required. Manual trans recommended. Top end power with some low end loss"
Hooker Longtube SuperComp headers
3" catback, w/ Flowmaster exhaust
58MM BBK Throttle body - the intake was ported to match
Stock heads were port and polished
Mezier Water Pump
All the little items were replaces, such as the optispark, plugs, wires, coil, ignition control module, knock sensor, etc etc.
The PCM (took out the OBD-II, and replaced with an OBD-I) was tuned by Ed Wright, who I told of all my upgrades.
Using the stock MAF (got a new one of those as well) w/ a K&N CAI.
My car is a 96' Z28, M6, stock rear end.
Heck its been so long, i barely can remember all I've done to it. But now, I'm tired of it sitting there, and want to drive it again!
Heres the problem. It runs like @ss. Before all the upgrades, the car pulled a 14.0 @ 101mph at the track. After, 15.5 @ 95mph.
After dropping easily over 5k in mods, it was pretty depressing. The only area I haven't worked with, and hopefully someone will point at me and call me stupid for not doing, is upgrading my fuel system. Using the stock injectors, and fuel pump. Is it possible im starving my system of enough fuel to make this car run like it should?
The car has had all the emissions garbage ripped out from it as well. Inside the car, it throws no diagnostic codes. I've got brand new o2 sensors (at the time they were) as well.
Someone give me some direction here -- I was so pissed over the whole deal, i parked the car in my parents garage when I moved, and have my dad start the engine once a week or so to keep everything lubed up.
It sounds mean as hell, there is no backfiring, its extremely strong initial acceleration, roasting the tires isnt a problem (like it ever is in an lt-1), but when you hit 60+ mph it just doesnt have that POWER feeling that you wish it would.
1 more thing. It won't hold an idle. Have to keep bumping the gas so it doesnt die. I know that Ed set it down on purpose, but this once again leads me to think its being starved for fuel.
Help?
Heres what I did (at least what I can remember):
Had the 350 block stroked to a 383
Installed a Crane Compu-Cam 2050. Has a .498 lift
Cam Description: "For 94-95 highly modified, aluminum head LT1 Camaros, Firebirds and Corvettes. High flow heads, headers and exhaust required. Manual trans recommended. Top end power with some low end loss"
Hooker Longtube SuperComp headers
3" catback, w/ Flowmaster exhaust
58MM BBK Throttle body - the intake was ported to match
Stock heads were port and polished
Mezier Water Pump
All the little items were replaces, such as the optispark, plugs, wires, coil, ignition control module, knock sensor, etc etc.
The PCM (took out the OBD-II, and replaced with an OBD-I) was tuned by Ed Wright, who I told of all my upgrades.
Using the stock MAF (got a new one of those as well) w/ a K&N CAI.
My car is a 96' Z28, M6, stock rear end.
Heck its been so long, i barely can remember all I've done to it. But now, I'm tired of it sitting there, and want to drive it again!
Heres the problem. It runs like @ss. Before all the upgrades, the car pulled a 14.0 @ 101mph at the track. After, 15.5 @ 95mph.
After dropping easily over 5k in mods, it was pretty depressing. The only area I haven't worked with, and hopefully someone will point at me and call me stupid for not doing, is upgrading my fuel system. Using the stock injectors, and fuel pump. Is it possible im starving my system of enough fuel to make this car run like it should?
The car has had all the emissions garbage ripped out from it as well. Inside the car, it throws no diagnostic codes. I've got brand new o2 sensors (at the time they were) as well.
Someone give me some direction here -- I was so pissed over the whole deal, i parked the car in my parents garage when I moved, and have my dad start the engine once a week or so to keep everything lubed up.
It sounds mean as hell, there is no backfiring, its extremely strong initial acceleration, roasting the tires isnt a problem (like it ever is in an lt-1), but when you hit 60+ mph it just doesnt have that POWER feeling that you wish it would.
1 more thing. It won't hold an idle. Have to keep bumping the gas so it doesnt die. I know that Ed set it down on purpose, but this once again leads me to think its being starved for fuel.
Help?
Last edited by 96BlackZ28; 04-14-2003 at 02:45 PM.
04-14-2003, 02:37 PM
#2
Registered User
Join Date: Mar 2003
Posts: 27
Find a place that can take measurements for air/fuel mixture, ignition, and all the general diagnostic stuff. From what you said about it dying off at 60, it makes me think that your motor isn't getting enough fuel. Get an adjustable fuel pressure regulator, some new injectors, and other stuff like that. You might want to take the car to a dyno too. You can tell alot by your hp/torque curves.
Later,
Jason
Later,
Jason
04-14-2003, 03:41 PM
#4
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Join Date: Jul 2000
Location: Carthage, MO
Posts: 9
Don't get me wrong, it doesnt LOSE power at 60mph, it just doesnt have that level of pull necessary to achieve good 1/4 mile times.
I mean, it will still accelerate nicely, but its just not doing what its suppose to.
I mean, it will still accelerate nicely, but its just not doing what its suppose to.
04-14-2003, 03:59 PM
#5
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Join Date: Nov 2000
Location: Texorado
Posts: 227
How do the 1/8 times compare? Does it not pull like it should in high rpms or high speeds or never?
You definitely need to upgrade the fuel system with atleast bigger injectors, but I don't think that is your only problem. How about knock retard? It can take away a good bit of horsepower if its bad. Make sure your plugs and wires are ok, check all the little stuff.
You definitely need to upgrade the fuel system with atleast bigger injectors, but I don't think that is your only problem. How about knock retard? It can take away a good bit of horsepower if its bad. Make sure your plugs and wires are ok, check all the little stuff.
04-14-2003, 04:24 PM
#8
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Join Date: Jul 2000
Location: Carthage, MO
Posts: 9
http://www.cranecams.com/master/apps/chevy40.htm
Here is the website, its item #2
It will tell you better then I could sum it up here.
Here is the website, its item #2
It will tell you better then I could sum it up here.
04-14-2003, 05:22 PM
#9
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Join Date: Dec 1999
Location: Petersham, MA
Posts: 1,697
It's not the cam and it's not the fact that you're running out of fuel. Any F-body that traps 95 mph is making about 250 horse.
Time to verify proper secondary ignition, and I'd drop the exhaust to make sure there no collapsed muffler baffle or cat. Who built this engine? Perhaps the cam was not installed properly, or the valves misadjusted....the list can go on and on. But your car should be trapping 113-115 with those mods.
Time to verify proper secondary ignition, and I'd drop the exhaust to make sure there no collapsed muffler baffle or cat. Who built this engine? Perhaps the cam was not installed properly, or the valves misadjusted....the list can go on and on. But your car should be trapping 113-115 with those mods.
04-15-2003, 06:49 AM
#10
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Join Date: Jul 2000
Location: Carthage, MO
Posts: 9
Well, my car has no cats on it, just an offroad Y pipe that connects the headers to a flowmaster dual outlet muffler.
As far as the shop, they build very very fast cars, except they had never did a LT-1 before. They were confident about it, and said there were no troubles during the build.
If the valve adjustment is out of whack, is this something I can attempt to fix? As far as the cam being out of whack, that might be a little over me to fix ... not sure, never have pulled a cam before... .but I'm willing to try!
As far as the shop, they build very very fast cars, except they had never did a LT-1 before. They were confident about it, and said there were no troubles during the build.
If the valve adjustment is out of whack, is this something I can attempt to fix? As far as the cam being out of whack, that might be a little over me to fix ... not sure, never have pulled a cam before... .but I'm willing to try!
04-15-2003, 08:35 AM
#12
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Join Date: Jun 2002
Location: McAllen Tx. USA
Posts: 537
If everthing is mechanically ok, then it is something peripheral. It is practically safe to assume the shop did ok in setting up the engine. LT1 does not differ from the traditional small block chevy.
1.) Make sure you are not getting knock retard, are you getting any codes? It almost sounds as if you are running in limp-home mode.
2.) Check your fuel pressure at WOT, mine was going and I think it was the major source of my problem. What I have been told, is that it should go up around 3-5 psi at WOT. Mine goes down around 8-9 psi at WOT.
Let us know please.
1.) Make sure you are not getting knock retard, are you getting any codes? It almost sounds as if you are running in limp-home mode.
2.) Check your fuel pressure at WOT, mine was going and I think it was the major source of my problem. What I have been told, is that it should go up around 3-5 psi at WOT. Mine goes down around 8-9 psi at WOT.
Let us know please.
04-15-2003, 08:41 AM
#13
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Join Date: Jul 1999
Location: Winnipeg, Manitoba, Canada
Posts: 3,650
Start with the basics...
Make sure you have a new fuel filter on the car.
Tape a mechanical fuel psi guage to your windshield when you make a 1/4 mile run and watch to see if the fuel psi drops.
Are you auto or manual? If its auto does it shift at the redline or below it?
Did you put in a new throttle position sensor?
Make sure you have a new fuel filter on the car.
Tape a mechanical fuel psi guage to your windshield when you make a 1/4 mile run and watch to see if the fuel psi drops.
Are you auto or manual? If its auto does it shift at the redline or below it?
Did you put in a new throttle position sensor?
04-15-2003, 09:23 AM
#14
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Join Date: Apr 2003
Location: Rhode Island, USA
Posts: 6
Maybe if you have a laptop you could hook up some diagnostic tools to the ALDL port to check out the knock retard. The knock module for OBDII is different, and needs to be desensitized to work with OBDI systems.
04-16-2003, 03:51 PM
#15
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Join Date: Jul 2000
Location: Carthage, MO
Posts: 9
You know, that is one thing I never did replace, is the throttle position sensor.
What are the chances that it could all hinge on that?
My car is a 6 speed manual.
If my timing is off, how is it possible to adjust it? I don't have a way to adjust the computer.
I do have the cables and software that can monitor the computer, PCMRead (might be outdated by now) that i used to use to watch everything going on.
What are the chances that it could all hinge on that?
My car is a 6 speed manual.
If my timing is off, how is it possible to adjust it? I don't have a way to adjust the computer.
I do have the cables and software that can monitor the computer, PCMRead (might be outdated by now) that i used to use to watch everything going on.
Last edited by 96BlackZ28; 04-16-2003 at 03:54 PM.