LasC3

After spending a good amount of hours reading threads on this and other forums, I'm at a loss ....
Picked up our 2002 Roadster at the end of last year .... it had a slight flutter with medium amount to throttle increase ... started the investigation almost immediately ..... starting with cleaning the sensor at the intake ..... then checking all of the grounding points ..... including the coil grounds on the head ..... changed the fuel filter .... plugs and wires ..... including a couple of bottles of Injector cleaner (Techron) ..... all with no gain or change of any kind ....
Seems to be getting more apparent with time .... and get worse with the increase in engine temp.
Currently at idle .. in gear (auto) the drop out is quite noticeable ... again more so as the engine warms up.
We had our local LS tuning guru plug in ... and reported seeing spark drop out .... and all over the map ..... can happen on either bank ... and cylinder .... one time it will be in #1 ... then #7 ... then #4. Not consistent in time .... nor any particular pattern ....
There is no noise ... other then a bit of popping at WOT .... again inconsistent .... oh yeah .... and no codes !!
So now where to go from here ..... thoughts ?????

gMAG

iTrader: (1)

Let me preface this comment by saying that I'm not a guru here.
With that in mind, could your crank sensor, or the crank sensor lead(s) be opening, intermittantly?
I'm trying to reason how this could be so, without throwing a code.

poltergeist 02

iTrader: (65)

i have seen crank sensors go bad without throwing a code. this could be your issue.

gMAG

iTrader: (1)

If you pursue this avenue, I would start out by proving the crank sensor wiring...beginning at the wiring on the sensor side of the plug/connector, and hotwiring (bridging) at the other end of the wires at the computer. Keep in mind that because you would be bridging the wiring, that this test can be skewed if one or more of the existing sensor wires is already crossed with the car frame, or is shorted to something.
If this doesn't fix it, you can try the crank sensor. imo

LasC3

thx for posting up guys ...... will go the direction indicated ..... and will post up results either way ...... these are furstrating issues .... but ya gotta love these motors ..... (( and C5s ))

chrisfrost

iTrader: (8)

Have You checked voltage going to PCM power wires and as stated already the integrity of the wires to and from crank and cam sensors . My Moms' Cadillac started throwing a code for the cam sensor wiring so I pulled the sensor and 1 of the wires was in bad shape at the plug / fixed wire and re-installed and since then the problem has gotten worse in that the engine at idle is dropping down and up 500-700rpm's and intermittently throws the same code . Before it was interm also . So I will probably buy a new sensor and recheck wiring and go from there .

gMAG

iTrader: (1)

Just a couple of thoughts before any wire-swapping or electronic troubleshooting.
Because of the intermittant nature of the spark loss, try nudging the crank & cam sensors & assoc wiring, while the engine is running. See if this creates more spark loss.
Due to the inaccessible nature of the crank sensor connector, a 4 ft long, non-conductive cord can be tied around the crank conn & wiring. Start the engine and then gently tug on the cord.