Car Missing Out Bad

bigbadtalontsi · March 26th, 2007, 09:51 PM

So here's the problem. My car has been doing some really funny things lately. About a week ago the car started missing out real bad to the point where it would not let me pull over 3000rpms. If i barely rested my foot on the pedal the car would raise above 3000rpm, but if i went more than 20% throttle it would act like it was running out of fuel. The car in the mean time would idle okay. I replaced the TPS,replaced the fuel pump with a walbro255,new fuel filter, and a new ajustable fuel regulator. I set the base pressure @ 39 psi. The car ran okay for about a day. Then the problem returned. I pulled the cap and rotor and gave them a good cleaning. That returned the rpms, but the car seems to have no power. When i floor it the car will buck real bad as if i am letting off the accelarator then smashing it back down. My mods consist of GT40 heads,explorer intake,b303 w 1.72s,full exhaust,73mm mass,walbro 255,fuel regulator,under drives,cai,65mm t-body,3:55 gears,.040 bottom end. Thats all off the top of my head. Somebody please help me!!!! I am in dire need the track opens up on 4/3. Thanks

Stangzilla · March 26th, 2007, 11:34 PM

What type of fuel regulator do you have? Might be a dumb question but you would be suprised.. You did adjust the new TPS right?

nolife · March 27th, 2007, 12:30 AM

You seemed to have checked everything fuel related so I'd move onto spark.

How about the ignition control module (attached to the side of the distributor). I do not know how to specifically check that but others have posted here in the past with similar issues and that was the problem.

Do you have cats? Could be clogged. Mine are toast right now but I get no real "bucking" but it does sound and feel like a random/bad miss and anything above 3-4 under load is useless. Idles fine. My cats made some awful rattling just before failure so it was easy to diagnose.

Tony_90fox · March 27th, 2007, 01:02 AM

Just a thought, maybe replace the cap and rotor instead of just cleaning. I had the same problem last year...I thought it was fuel related as well. Bought new cheapo accel cap and rotor and bingo, problem solved for me.

Just an idea, might not help at all.

Maybe some kind of vacuum leak.

bigbadtalontsi · March 27th, 2007, 06:16 AM

The regulator is a Professional Products piece. I will shoot and get a new cap and rotor.

dave0970 · March 27th, 2007, 07:22 AM

Same problem here, idling is not steady. The car run great, but when it stop RPM goes high and low. I gave a little gas it stable. Please help!

shurb125 · March 27th, 2007, 09:51 PM

Check the the tiny wires (maybe called diodes?) on the actual MAF sensor inside the actual MAF unit, could have trash on it causing it not to read corrrectly. I had the same problem and that's what it was. Hope this helps

dave0970 · March 28th, 2007, 06:14 AM

Thanks! But, the time that i replaced the original intake with the chrome, I deleted the AMF.

March 26th, 2007, 09:51 PM	#1
bigbadtalontsi Regular Join Date: Jan 2007 Posts: 60 iTrader: 0 reviews	Car Missing Out Bad So here's the problem. My car has been doing some really funny things lately. About a week ago the car started missing out real bad to the point where it would not let me pull over 3000rpms. If i barely rested my foot on the pedal the car would raise above 3000rpm, but if i went more than 20% throttle it would act like it was running out of fuel. The car in the mean time would idle okay. I replaced the TPS,replaced the fuel pump with a walbro255,new fuel filter, and a new ajustable fuel regulator. I set the base pressure @ 39 psi. The car ran okay for about a day. Then the problem returned. I pulled the cap and rotor and gave them a good cleaning. That returned the rpms, but the car seems to have no power. When i floor it the car will buck real bad as if i am letting off the accelarator then smashing it back down. My mods consist of GT40 heads,explorer intake,b303 w 1.72s,full exhaust,73mm mass,walbro 255,fuel regulator,under drives,cai,65mm t-body,3:55 gears,.040 bottom end. Thats all off the top of my head. Somebody please help me!!!! I am in dire need the track opens up on 4/3. Thanks

March 26th, 2007, 11:34 PM	#2
Stangzilla MM Fanatic Join Date: Aug 2006 Location: On my way to Baines's house!! Posts: 3,298 iTrader: 0 reviews	What type of fuel regulator do you have? Might be a dumb question but you would be suprised.. You did adjust the new TPS right? __________________ Rotating The Earth 1320 Feet At A Time!! Today, I found out that when I masturbate at night while watching internet porn I cast a huge shadow on the curtain and the entire street is able to see it.

March 27th, 2007, 12:30 AM	#3
nolife Hardcore Enthusiast 91GT, 88GT, 02GT Join Date: Dec 2006 Posts: 2,878 Blog Entries: 3 iTrader: 0 reviews	You seemed to have checked everything fuel related so I'd move onto spark. How about the ignition control module (attached to the side of the distributor). I do not know how to specifically check that but others have posted here in the past with similar issues and that was the problem. Do you have cats? Could be clogged. Mine are toast right now but I get no real "bucking" but it does sound and feel like a random/bad miss and anything above 3-4 under load is useless. Idles fine. My cats made some awful rattling just before failure so it was easy to diagnose. __________________

March 27th, 2007, 01:02 AM	#4
Tony_90fox Banned Join Date: Jun 2006 Location: Bowling Green, KY Posts: 3,831 iTrader: 0 reviews	Just a thought, maybe replace the cap and rotor instead of just cleaning. I had the same problem last year...I thought it was fuel related as well. Bought new cheapo accel cap and rotor and bingo, problem solved for me. Just an idea, might not help at all. Maybe some kind of vacuum leak. __________________ [SIGPIC][/SIGPIC] [B][U]MM Sapper Squad[/U][/B] [QUOTE=Regency 2007;1676187]MSO's stupidity has never stopped amazing me since the day he joined this forum.[/QUOTE]

March 27th, 2007, 07:22 AM	#6
dave0970 Newbie Join Date: Jan 2007 Posts: 16 iTrader: 0 reviews	Same problem here, idling is not steady. The car run great, but when it stop RPM goes high and low. I gave a little gas it stable. Please help! __________________ 1987 LX 5.0 Coupe AT

March 27th, 2007, 06:16 AM	#5
bigbadtalontsi Regular Join Date: Jan 2007 Posts: 60 iTrader: 0 reviews	The regulator is a Professional Products piece. I will shoot and get a new cap and rotor.

March 27th, 2007, 09:51 PM	#7
shurb125 Regular 1993 Mustang LX Vert Join Date: Nov 2006 Location: South Carolina Posts: 437 iTrader: 0 reviews	Check the the tiny wires (maybe called diodes?) on the actual MAF sensor inside the actual MAF unit, could have trash on it causing it not to read corrrectly. I had the same problem and that's what it was. Hope this helps

March 28th, 2007, 06:14 AM	#8
dave0970 Newbie Join Date: Jan 2007 Posts: 16 iTrader: 0 reviews	Thanks! But, the time that i replaced the original intake with the chrome, I deleted the AMF.

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