having a hell of a time with this car,

car has a misfire once in a while first thing in the morning codes that come up are P1316 ( ususally the one that causes the freeze frame ) p1187 and p0306.... it happens when the RPM is at about 700rpm short term fuel trim -24% both banks long term +24% both banks, new wires and plugs installed all OEM, new 02 sensors installed , compression is good, fuel pressure is good, temp sensor is new

anyone with help it would be greatly appreciated

peter

 

you got something causing you to run lean, when you start it up you should be dumping fuel to help the warm up, but since youre already dumping fuel to compansate for the lean condition, you end up way too wet in the cyls. what you need to do is figure out why your long term is at +24, could be a vac leak, bad mafs, exhaust leak or many other things... now that i think of it, you said oem wires... do they have the cyl number printed on the wire, or is there a little white sticker/sleeve that has the number??? the ones with the sticker are notorious to have too large of a opening for the plug contact, if its loose that can also cause a mis

 

its the wires with the sleeve number, but the problem was exactly the same before the wires got replaced, no vacuum leaks i smoked the system, i was going towards a MAF but its so hard to do it when its so damn expensive , i read somewhere that a crank sensor can cause a misifre when its cold and get better as it warms up, but that wouldnt really have anything to do with the car running lean, a misfire would make the car run rich due to all the unburnt oxygen getting dumped into the exhaust, hmm which it is when it misifres the short term fuel trim was at -24% @ the time of misfire, what i dont understand why the #6 cylinder only, i heard these cars are notorius for carbon buildup but iv been told that this car had heads done 2 years ago, could it have buildup already??..

 

whats your mass air readin at idle... on the 4.0 you should be seeing about 16-19 without ac on...the 1187 code is for a open circuit in an upstream sensor, so if this is only happening at startup you need to check them, both the sensors and the wiring, it sounds liek you know what youre talking about, so ohm out the heater side of both front sensors, if ones way off, replace it. as to the carbon, that will usually present itself under a load, and just cus the head gaskets were done, doesnt mean the valves were cleaned or their guides were reamed. however, seeing as how both banks are running lean, i think youre looking at something on the intake side of it, unless you just have some bad o2s