Hi I just put a brand new fully rebuilt motor in my car with lots of other new parts as well... Everything was running great for a couple days and now all of a sudden its missing very badly... Missing while idling and running through the gears.... not pulling at all most of the time.. and once in a while it will run right but not very often.

I did put on BBK longtube headers before we dropped motor back in the car... all the O2 sensors are hooked up no cats anymore though... What is the point of my O2 sensors now?? Are they even working right now??? What I dont understand is why would it run good for few days and now be running like ****?

The spark plugs are brand new... the only thing i can think is we had a bad fuel rail as soon as we cranked up the motor for the very first time... and wondering if the fuel spraying out could somehow go down into where the spark plugs may be and fouled them out that quick??? Is that possible to do???

We have gone over all the wiring harness looking for bad connections, pinched wires all looks good... Bought some new hoses and replaced some loose vacuum connections... Replaced a coil the other day cause one of mine was cracked on 2 corners thinking maybe it was arcing but still runs the same way.

More on O2 sensors... someone correct me if i am wrong... the back set just lets you know if your cats are working correctly right??? And the front 2 tell if the car is running rich or lean??
Well we were just experimenting seeing what would happen if we unplugged them thinking maybe they were causing issues since i have no cats anymore.... unplugged back 2 drove it did the same thing... then left them unplugged and unplugged the front 2 drove around again did the exact same thing.... ISNT the check engine light supposed to come on if they are unplugged????? My light didnt come on at all... Car still runs the same with the O2 sensors unplugged....

I dont know what else to do because change spark plugs again just to see what happens.... I just hate that i have to keepspending money on parts just to check and see if it fixes problem... and it keep running the same and i am out the money!!!

CAN ANYONE PLEASE HELP ME???

 

you are correct about the front O2s being the only ones thatreally matter.But the rear two unplugged should throw a code but might have to drive it for 50 miles or so. Seems like the CEL would be on if it is missing that bad. I would say to have it plugged into a computeratyour local shopand have them try to narrow it down by checking spark, air/fuel, each cylinder, etc.....

 

Do this.


Take off each coilover, one at a time, and look down the hole where the spark plugs sits and look for coolant/water/anything. If you dont see anything, the next think you should do is test EACH coilover to see if it is throwing a spark. I suppose you could do this with a screw driver and look for a spark... jut make sure your not holding a metal handel, haha. I would wait for somebody else to chime in on how to check that, but this is what you need to do. work from the spark plugs out.

oh and depending on how long your car has ran w/out o/2's, you CEL might not of had enough time to trigger yet. it usually takes 50-150 miles before it finally spits the code.

 

We had a mechanic bring over a scanner and hook it up but like 26 codes popped up and he said thats very strange and shouldnt be like that... and the scanner couldnt even run some tests because of it i think.

I have driven around all day yesterday and today with all 4 sensors unplugged still.

What is the CEL???

 

Yeah i have maybe put about 50 miles on it with no O2s hooked up right now... I have more spark plugs about to go outside right now and swap them to see what happens.... be back on here in a few minutes will let you know what happens....

 

Check Engine Light.


What year is this car? Is it the same motor that was in it before? Is it a new or used motor? Did you retrofit anything?

 

its a 1997

motor is the just rebuilt... everything brand new internally except rods..... bored 20 over... 3 angle valve job nothing much different from stock

 

check the coil overs. even before you change plugs. It would be useless to change ur plugs if its your coilovers that are not working.

 

are you still using the same plug wires?

 

well just swapped out the passenger side plugs and the car is back on 8 cylinders again big difference.... but still missing a little

can having one brand of plugs in one side and one brand in the other side affect anything as long as they are all gapped correctly??????

and yes im still using my old wires... they arent that old some MSD wires dont think there is any problems with wires.