hopefully you guys can help me figure out what's wrong.

This monday i finally finished putting my motor back together and cranked it (i was only using the jackson racing intank pump the 12:1 fmu and the rc 440 injectors). The car was idling fine(rich) although i had to turn down my fuel with the safc. but then if i gave it some gas it'd rev up to 4k rpm and then it's shot off. So i took the 440s out and put my stock injectors back on leaving only the intank pump and the fmu. Cranked the car back up and it idled fine (still rich) reved it up and the problem was gone it reved up fine without cutting off. So i decide to take it for a test drive(with the code scanner plug up the whole time just in case), i start driving not taking it higher than 4k rpm ( since it's a freshly built block) and sometimes it'll hessitate really bad and then gets going and then trows missfiring codes. For example the first time it threw 2 codes(missfiring in cyl #1 and #2) and the second time it was cyl #2 and #4 so it's pretty much missfiring ramdomly. Wat do you guys think this could be?? the only thing that i'm considering is since i haven't yet had the downpipe welded to the exhaust so my secondary O2 sensor is not getting a reading ( although it's not thowing a code for that and have no CEL) but i dont see how it would make it drive so rough. Please guys let me know what you think this could any ideas are very much appreciated......i'm really frustrated because i want to be able to drive the damned thing and BOOST!!!

 

Intank pumps will not pressurize fuel enough to use it with the fmu and stock injectors.Stock injector's are used with inline pumps and 12/1 fmu .Not having an inline pump with the stock injectors is why you are not getting enough fuel and misfiring. Put back the 440's and take out the fmu. Then use the s -afc or v-afc to tune out fuel so you can idle better.


[Modified by quickspoolin, 8:29 AM 7/19/2002]

 

Personally i would run the FMU and get an inline fuel pump and run the stock injectors. try this and let us know


Rob

 

ok....I will solve your problem because no one else did. A fuel pump is designed to push, not pull. It is always best to mount a fuel pump to the rear most part of the line so your ok with the pump. Your misfire code is the o2 sensor. Even though its not throwing that code...it throws the missfire code with a bad or missing o2, esp on obd2 cars.....Mike

 

thanks guys for all the replies i guess i'm gonna have to wait till i get the downpipe welded up to the exhaust to see if it was infact the o2 sensor i'll let you guys now what happens.