idle problems on a blown 393

Strim91GT · 10-24-2002, 07:11 PM

I'm just working with getting my new 393 started, and i absolutely cannot get it to idle.... it will start up and rev to 3,000 and then just sputter and die... OR when it starts and revs i can keep giving it gas to keep it alive, but it will rev to 3,000 and stay there for about 5 or 6 seconds and then it will sputter and die but i can usually revive it by pumping the gas pedal. I can't even begin to get out of the car to start troubleshooting the problem because i can't get it to stay idling, it will always die if i don't give it gas. I have played around with fuel pressure, with timing, with the tps setting and the idle set screw. I have checked to make sure my idle air bypass valve tests okay, and the tps goes from .98 to 4.5 at wide open throttle with no breaks in the readings.... I am out of ideas, I am not sure if my eec computer is giving me problems since it is no longer a 302.... Any advice or suggestions is very greatly appreciated... it's a it's a dss 393 with afr 185 heads and trick flow injected intake with a complete aeromotive 1000 fuel system and 30 lb injectors plus a vortech S trim with a 2.85 pulley on it. I am totally out of ideas. I know it sounds underinjected right now i have the fuel pressure at approximately 60 psi to try to make up for some of that. thanks

BilLster · 10-24-2002, 08:11 PM

try removing your belt from your vortech and check for vacum leaks . with the blower removed lower the fuel pressure to about 50-44 and see how that works. the computer works ok on a 393

it sounds like a vacum leak or a injector going static. ?

what didi you change last ?

Hozer 88GTConv · 10-24-2002, 11:22 PM

I didn't notice your fuel pump specs?
255 lph in-tank and a nice in-line T-rex pump are minimum fuel delivery req's for your ride.
Sounds like a helluva combo once you get going.
oops...just saw the aeromotive 1000 set-up.

Good luck

Strim91GT · 10-24-2002, 11:31 PM

Well, the last change i made was to adjust the fuel pressure up a little bit.... i had a computer code that the O2 sensors were reading lean, so i thought i could overcome some of it with higher fuel pressure. The fuel pump i have on it is an aeromotive hp1000 with -10 line going up to the billet aeromotive fuel rails and two -8 lines feeding both rails individualy with -6 return to the tank with a granatelli -10 fuel tank insert. thanks for the info so farm i'll try removing the belt and see what happens... the cam is a comp cams hydraulic roller with 114 degree lobe seperation so it should idle fairly decently i would think.

Strim91GT · 10-24-2002, 11:33 PM

all my smog pump stuff from the 302 is eliminated if that makes any difference. except for the egr valve is still on and electrically connected, but no vacuum line going to it.

Hozer 88GTConv · 10-25-2002, 08:11 AM

I hate to be redundant, but you said you only had lean O2 codes...is that it?
Are you confident that your vacuum lines are connected or plugged as necessary?
I am sure you are thorough, people don't invest the time or money that you obviously have and miss the little things but it's worth a check. BAP/MAP? or under the intake vacuum line?
I'll call a guy around here too who might have an idea.

byrnech · 10-25-2002, 09:04 AM

What kind of mass air are you running? See how it runs with it disconnected. A friend of mine was having all kinds of idle problems, and drivability problems. Turns out his mass air was bad. It was a pro-m bullet set up for blow through. He returned it and got a univer. It has been running hard ever since. I know I am reaching here because his was a blow through mass air meter and yours is a draw through with the S-trim, but it's worth a shot. -Chris

Strim91GT · 10-25-2002, 10:27 AM

I'm not positively sure the vacuum lines are all plugged as necessary. I do however have the set of four vacuum lines plugged that comes from the fenderwell and previously went to all the emissions stuff. And i've been told that it's probably not the map sensor because it's a mass air car, but the guy who told me this isn't 100% possitive. The mass air meter is a pro-m 75mm for 30 pound injectors, and i beleive it's a universal meter. I put the 30lb injectors and meter on my 302 just before i blew a head gasket for the 5th time and decided to go 393 with the car. And the supercharged 302 ran awesome with that setup. I think i will probably try taking the blower belt off today and lowering the fuel pressure some and see what i can do, and try unplugging the mass air meter.

10-24-2002, 07:11 PM	#1
Strim91GT Registered Member Join Date: Jan 2001 Location: Kansas Posts: 59	idle problems on a blown 393 I'm just working with getting my new 393 started, and i absolutely cannot get it to idle.... it will start up and rev to 3,000 and then just sputter and die... OR when it starts and revs i can keep giving it gas to keep it alive, but it will rev to 3,000 and stay there for about 5 or 6 seconds and then it will sputter and die but i can usually revive it by pumping the gas pedal. I can't even begin to get out of the car to start troubleshooting the problem because i can't get it to stay idling, it will always die if i don't give it gas. I have played around with fuel pressure, with timing, with the tps setting and the idle set screw. I have checked to make sure my idle air bypass valve tests okay, and the tps goes from .98 to 4.5 at wide open throttle with no breaks in the readings.... I am out of ideas, I am not sure if my eec computer is giving me problems since it is no longer a 302.... Any advice or suggestions is very greatly appreciated... it's a it's a dss 393 with afr 185 heads and trick flow injected intake with a complete aeromotive 1000 fuel system and 30 lb injectors plus a vortech S trim with a 2.85 pulley on it. I am totally out of ideas. I know it sounds underinjected right now i have the fuel pressure at approximately 60 psi to try to make up for some of that. thanks

10-24-2002, 08:11 PM	#2
BilLster Registered Member Join Date: Oct 2000 Location: Ontario canada Posts: 446	try removing your belt from your vortech and check for vacum leaks . with the blower removed lower the fuel pressure to about 50-44 and see how that works. the computer works ok on a 393 it sounds like a vacum leak or a injector going static. ? what didi you change last ? __________________ 89 with 331 t3'/t4 hybrids. upr Suspention worked out finnaly . 9.89 144 mph .

10-24-2002, 11:22 PM	#3
Hozer 88GTConv Registered Member Join Date: Feb 2002 Location: Jacksonville, FL Posts: 706	in-line fuel pump??? I didn't notice your fuel pump specs? 255 lph in-tank and a nice in-line T-rex pump are minimum fuel delivery req's for your ride. Sounds like a helluva combo once you get going. oops...just saw the aeromotive 1000 set-up. Good luck __________________ 1988 GT Convertible 331 10:1 TW heads, GT-40 intake, MSD, TRW flattops, B Cam w/ 1.7's, MAC exhaust, 24's, 70 TB, 76 MAF, 3.73's, Pro 5.0, Koni's, Anderson PMS, Wideband 02, yatta, yatta... One week with new motor, two speeding tickets...joy

10-24-2002, 11:31 PM	#4
Strim91GT Registered Member Join Date: Jan 2001 Location: Kansas Posts: 59	Well, the last change i made was to adjust the fuel pressure up a little bit.... i had a computer code that the O2 sensors were reading lean, so i thought i could overcome some of it with higher fuel pressure. The fuel pump i have on it is an aeromotive hp1000 with -10 line going up to the billet aeromotive fuel rails and two -8 lines feeding both rails individualy with -6 return to the tank with a granatelli -10 fuel tank insert. thanks for the info so farm i'll try removing the belt and see what happens... the cam is a comp cams hydraulic roller with 114 degree lobe seperation so it should idle fairly decently i would think. __________________ vortech s trim,edelbrock 6032's, b303, cobra intake, 70mm tb, pro m 75mm bullet, granatelli alum. rad., accel 330+ digital ign., msd boost tim. ret., 30# inj., 190 lph fuel pump, t-rex pump, bbk, press. reg., tremec tko, ram billet flywheel, dual friction clutch, pro 5.0 shifter, 4.10 gears, aluminum quadrant, motorsport alum. driveshaft, hooker headers, off road h pipe, flowmaster cat back, subframes, megabyte jr lowers, heavy duty uppers, eibach springs drag springs, koni sport shocks, polished cobra r's, 85-86 taillights, msd pro billet distributor

10-24-2002, 11:33 PM	#5
Strim91GT Registered Member Join Date: Jan 2001 Location: Kansas Posts: 59	all my smog pump stuff from the 302 is eliminated if that makes any difference. except for the egr valve is still on and electrically connected, but no vacuum line going to it. __________________ vortech s trim,edelbrock 6032's, b303, cobra intake, 70mm tb, pro m 75mm bullet, granatelli alum. rad., accel 330+ digital ign., msd boost tim. ret., 30# inj., 190 lph fuel pump, t-rex pump, bbk, press. reg., tremec tko, ram billet flywheel, dual friction clutch, pro 5.0 shifter, 4.10 gears, aluminum quadrant, motorsport alum. driveshaft, hooker headers, off road h pipe, flowmaster cat back, subframes, megabyte jr lowers, heavy duty uppers, eibach springs drag springs, koni sport shocks, polished cobra r's, 85-86 taillights, msd pro billet distributor

10-25-2002, 08:11 AM	#6
Hozer 88GTConv Registered Member Join Date: Feb 2002 Location: Jacksonville, FL Posts: 706	codes... I hate to be redundant, but you said you only had lean O2 codes...is that it? Are you confident that your vacuum lines are connected or plugged as necessary? I am sure you are thorough, people don't invest the time or money that you obviously have and miss the little things but it's worth a check. BAP/MAP? or under the intake vacuum line? I'll call a guy around here too who might have an idea. __________________ 1988 GT Convertible 331 10:1 TW heads, GT-40 intake, MSD, TRW flattops, B Cam w/ 1.7's, MAC exhaust, 24's, 70 TB, 76 MAF, 3.73's, Pro 5.0, Koni's, Anderson PMS, Wideband 02, yatta, yatta... One week with new motor, two speeding tickets...joy

10-25-2002, 09:04 AM	#7
byrnech Registered Member Join Date: Jun 2001 Location: Anderson, TX. Posts: 166	What kind of mass air are you running? See how it runs with it disconnected. A friend of mine was having all kinds of idle problems, and drivability problems. Turns out his mass air was bad. It was a pro-m bullet set up for blow through. He returned it and got a univer. It has been running hard ever since. I know I am reaching here because his was a blow through mass air meter and yours is a draw through with the S-trim, but it's worth a shot. -Chris __________________ 331 10:1, AFR 185's, TFS-R intake

10-25-2002, 10:27 AM	#8
Strim91GT Registered Member Join Date: Jan 2001 Location: Kansas Posts: 59	I'm not positively sure the vacuum lines are all plugged as necessary. I do however have the set of four vacuum lines plugged that comes from the fenderwell and previously went to all the emissions stuff. And i've been told that it's probably not the map sensor because it's a mass air car, but the guy who told me this isn't 100% possitive. The mass air meter is a pro-m 75mm for 30 pound injectors, and i beleive it's a universal meter. I put the 30lb injectors and meter on my 302 just before i blew a head gasket for the 5th time and decided to go 393 with the car. And the supercharged 302 ran awesome with that setup. I think i will probably try taking the blower belt off today and lowering the fuel pressure some and see what i can do, and try unplugging the mass air meter. __________________ vortech s trim,edelbrock 6032's, b303, cobra intake, 70mm tb, pro m 75mm bullet, granatelli alum. rad., accel 330+ digital ign., msd boost tim. ret., 30# inj., 190 lph fuel pump, t-rex pump, bbk, press. reg., tremec tko, ram billet flywheel, dual friction clutch, pro 5.0 shifter, 4.10 gears, aluminum quadrant, motorsport alum. driveshaft, hooker headers, off road h pipe, flowmaster cat back, subframes, megabyte jr lowers, heavy duty uppers, eibach springs drag springs, koni sport shocks, polished cobra r's, 85-86 taillights, msd pro billet distributor

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