LT1-LT4 Modifications 1993-97 Gen II Small Block V8

weird miss and no throttle response

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Old Sep 21, 2009 | 11:14 PM
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Default weird miss and no throttle response

the car will start spuddering under part throttle and seems to have a miss. but when it does it the afr goes to lean. could this be a bad opti, or maybe a blown head gasket or something. im clueless. please help

i have changed computers, MAF, went to ac delco o2 sensors, e3 spark plugs. what else would u suggest
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Old Sep 21, 2009 | 11:30 PM
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opti maybe
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Old Sep 21, 2009 | 11:30 PM
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what codes is it throwing? what year car?
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Old Sep 21, 2009 | 11:34 PM
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Check your fuel delivery, put a pressure gauge on the rail. check your relay/pump/filter. Also, check to make sure your wires are all in and check the opti. also give the egr a check. did you check for codes?
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Old Sep 21, 2009 | 11:35 PM
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Keep in mind 96-97 have crank position sensors.
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Old Sep 21, 2009 | 11:52 PM
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Originally Posted by 93Z2871805
Keep in mind 96-97 have crank position sensors.
do u think this might be my problem?
the car is a 97 and it has a new fuel pump and injectors, and filter. all the wires are fine.
as far as codes i havnt got them checked since i put the new computer in but it was throwing a code for the maf and the speed sensor i think.
the car runs fine at wot, the afr goes to normal. except sometimes it will just spudder and die at wot
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Old Sep 22, 2009 | 12:06 AM
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To be perfectly honest it still sounds like fuel delivery, I went through 4 pumps before I got a good one. You need to check your rail pressure! You could have a bad fuel pressure regulator. You could be sucking all the gas from the rail and the regulator may not be keeping up, possibly a bad spring inside.
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Old Sep 22, 2009 | 12:09 AM
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Originally Posted by 93Z2871805
To be perfectly honest it still sounds like fuel delivery, I went through 4 pumps before I got a good one.
no kidding? that sucks. i hope its not the fel delivery part. that dange fuel pump is a pita. i have a walboro 255 in it now. the car usually runs perfectly fine on start up then if i open it up once it starts acting funny
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Old Sep 22, 2009 | 12:11 AM
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Originally Posted by 93Z2871805
To be perfectly honest it still sounds like fuel delivery, I went through 4 pumps before I got a good one.
Ouch.. hope you made an Access Panel..
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Old Sep 22, 2009 | 12:15 AM
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Originally Posted by the_merv
Ouch.. hope you made an Access Panel..
And you know this man!!!

I didn't even drop the tank for the first time, I cut that mother out first change. Made a nice *** cover for it too!
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Old Sep 22, 2009 | 12:31 AM
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Damn right..only way to do it..30 min Fuel Pump changes..
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Old Sep 22, 2009 | 04:23 PM
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We could have a fuel pump change race, cause I think I can go sub 20 mins! Sorry for sort of hijacking the thread with some f-body humor kalebm22. But seriously, I'd look to the fuel system for the problems. Try checking the regulator next because a walboro SHOULDN'T act up but who knows. Do you have an adjustable regulator?
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Old Sep 22, 2009 | 06:23 PM
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lean conditions dont mean spark issues. i had a walboro crap out in less than 3k miles and did the same thing. while i was changing the pump i also discovered it was losing voltage at the pump itself (fine at the relay) so until i correct that i will be going through fuel pumps every couple months.
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Old Sep 22, 2009 | 07:53 PM
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Originally Posted by stevo9389
lean conditions dont mean spark issues. i had a walboro crap out in less than 3k miles and did the same thing. while i was changing the pump i also discovered it was losing voltage at the pump itself (fine at the relay) so until i correct that i will be going through fuel pumps every couple months.
Did you go with the racetronix hotwire harness setup?
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Old Sep 22, 2009 | 08:44 PM
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no, just a drop in walboro 255 that i want to say was part of a granetelli (sp?) kit but i dont remember. the replacement came out of my 94 since the motor is in pieces now. gonna check for better grounds before i change up the wiring from the relay in the kick panel. anyway i just wanted to bring the experience as a possibility to the attention of the thread starter
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Old Sep 23, 2009 | 01:08 AM
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Originally Posted by stevo9389
lean conditions dont mean spark issues. i had a walboro crap out in less than 3k miles and did the same thing. while i was changing the pump i also discovered it was losing voltage at the pump itself (fine at the relay) so until i correct that i will be going through fuel pumps every couple months.
ya i didnt know if maybe the opti would make would make the computer malfunction and cause it not to spray as much fuel. but im not for sure what is goin on. where is the relay at, and wat voltage should i be running? i still have the stock regulator on it. does anyon know where a good place to get a replacement is?
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Old Sep 23, 2009 | 01:15 AM
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Autozone for a stock replacement (about $35-40). Go to summit or WS6store for an aeromotive adjustable (about $165). The pump relay is behind the drivers side kick panel right behind the hood release. I believe the voltage should be at 12.
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Old Sep 23, 2009 | 12:41 PM
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Originally Posted by 93Z2871805
Autozone for a stock replacement (about $35-40). Go to summit or WS6store for an aeromotive adjustable (about $165). The pump relay is behind the drivers side kick panel right behind the hood release. I believe the voltage should be at 12.
ok great, i cant thank you enough for your help. hopefully its just the regulator. but ill check the voltage as soon as i can.
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Old Sep 24, 2009 | 11:58 PM
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now this thread has some answers... thanks guys. have a similar problem as well.
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Old Sep 25, 2009 | 01:50 AM
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I would be willing to bet it is an ignition issue! Check to see if you have a wire arcing off of something, or maybe your opti is on its way out. Just cause the computer is saying its lean does not mean you have a fuel system problem. If the O2 sensor sniffs to much oxygen, it will tell the computer its too lean, even if there is raw fuel spilling out the exhaust pipe. P.S. when most opti's die, the first symptoms are backfiring, rough idle, and a miss under load.
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