LSGUN

Ok I have officially lost my patience with this car here are the codes that showed up on my scanner P0132, P0161, P0300, P1380, and P0303. finished installing a fresh rebuilt bone stock LS1 in my 98 c5 and ever since my car has been misfiring like crazy!! when I start the car it seems fine then after about a min of idling it starts to idle really really rough sounds like a tractor or a really big cam. then when I go to drive the car particularly at low speeds the car runs really slow and crappy unless I floor it in which case the car runs great as if it was brand new then as soon as I leave 3/4 to full throttle the car runs crappy again and misfires like crazy. when i am driving at about 60 down the highway it will go in and out of its misfire mode its driving me crazy and I cant figure out what the problem is I have researched this topic on the forum extensively and have tried all 8 coil packs swapped from my friends c5, installed new front o2 sensors, checked the coil ground lead at the rear of the drivers side head, installed brand new intake manifold gaskets, installed a different MAF sensor, and have replaced my plugs and wires with brand new ones and no luck please help me before I burn this thing to the ground

3boystoys

You check the valve springs, especially on Cylinder #3? I'd do a compression and leakdown test on all the cylinders just to make sure thae basic motor is OK.
What's you fuel pressure like too???

KOZ

I had a cracked plug from my header install that behaved like that.

LSGUN

Thank you all for the replies ill double check my plugs tonight and take the valve covers off and let you know what I find out

acroy

If the engine is OK, then something (probably simple) is wrong with ignition/wires/plugs... Best of luck!!

LSGUN

well I took my valve covers off and all my valves are in perfect working condition which is a good thing im looking at the positives and the plugs and wires seemed ok so I think next im gunna check my fuel pressure, hook her up to HP Tuners, and try injectors ill keep you all updated

cholmes729

I bet fuel pressure has something to do with it. Check for water or corrosion in the main cool connector.

martysauto

Lift the fuel rail assembly and cycle the key. See in number 3 injector is dripping. If so replace it. If not swap it to a cylinder on bank 2, clear codes and run it. If you rich code switches to bank 2 you found your problem. If not, install a noid light on #3 injector and run the engine. At low speed it should be a steady light flash. Check another bank 2 cylinder for a base reading. If the light intermittently gets very bright or stays on, you have shorted ground signal.

LSGUN

sweet thanks for the input ill give it a shot

LSGUN

fuel pressure is 58 psi wether its running normal or crappy

kcbc

have u look up all the codes definition yet..thats ur tell tales leads !

kcbc

p0132 is a heater code on O2 sensor
P0132 is an oxygen sensor code.....
so how do u check ur ground ?...just by cleaning it or using an digital
volt meter doing a voltage drop test when it is electrically loaded ? ...look up google and do a grd voltage drop test...remember !!!...any electrical system requires both pwr and grd to carry proper current in order to operate properly


also u mention car runs good on higher rpm .....sounds like a vacuum leak ....intake manifold vac is high at idle and it is low once the engine speed goes up the vac approach atmospheric as it move to WOT ....that's explain why it runs better on higher rpm .......
its all science ..... not luck

Mr. Jones

As noted the P0303 is cyl #3
P0300 or blinking cel light is multi misfires.
I just went thru a similar problem. New motor with misfires when it warmed up.
I usually use TR6 NGK plugs but this time I went with NGK Iridium TR6IX. checked coils, wires and plugs looked good. I had vibration, misfires and a knock from pushing a dead cyl I only got the blinking CEL at 2500rpm+ and it would go after the rpm's dropped.
Fuel pressure was 60lbs, valve springs new and inspected-they were good. So as a last chance attempt I put is a new set of TR6 plugs and problem is completely gone. I also found a stray piece of conductor sticking out of the spark plug boot (new GM performance wires) that would arc some times.
The iridum plugs show good fuel color on the base but the ground electrode looked to hot.
You should have a ground braid on the back or the drivers side head that goes to the frame. Header install can damage or break this braid. This is where mine is 2003 plus the battery to block on the pass. side.
Hope this helps

73Corvette

Not sure what seemed ok means... they can look new...in fact they can be NEW and still be bad... lots of problems with MSD wires...

kcbc

I agree a 100% ...there are no way to count on ignition component by visual. Ignition wave is a good alternative without removing parts and be 100 % fail safe for defective parts

ZZ06

Don't get me started 73Corvette. will be purchasing so GM Red wires this upcoming weekend to see if it rectifies my low rpm misfires

73Corvette

Good choice from what I've seen on the forum... should eliminate that issue