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Put in a mild cam and trick flow heads in my 2001 c5, and after driving and restarting the car doesn't want to idle well. Thought it was a tuning issue but did some logs with HP tuners and it seems it is the camshaft position sensor.
On cold start the car runs fine and you can drive around idle etc and the camshaft position count is increasing and the rpm readout on hp tuners is ok. Upon turning the car off and immediately restarting (warmed up) the car does not idle well, the cam position count is froze and the rpm readout is frozen causing all kinds of issues since all the tables are based on rpm.
I don't think this is a wiring issue, and it seems it may not be the sensor either, as it works fine running hot until you cycle the vehicle. Anyone have any ideas? Wanted to ask before i change this sensor, it's hard to get to on the back of the motor.
Tim,
The CMP sensor is not needed to start and operate the engine but you will have a longer than normal crank time with a bad one !!…is it just running rough ??…like all driveability issues you would want to look at MAF, MAP, fuel trims, O2 sensors…I’d look at these…also KOEO what does your MAP read ??…should be around 103 kPa or 14.9 psi (30.4 inches of Mercury)…what numbers are you seeing..any misfires ??..and MOST important is to get your battery checked and load tested…the cars modules (PCM, BCM) require a good voltage to operate at 100% !!…car may start OK but the voltage to these modules must be 100% or you will have driveability issues !!
Hey thanks for the reply. The o2's look good at wot but are lean at idle and part throttle. I am pulling about 7.5 psi manifold pressure. Long term trims are about + 10 There are misfires at idle when this problem happens but none when driving around. I noticed the other day as i was logging on the first start all is fine looking at the 02 table log rpm vs kpa. Then i restarted and i was stuck in the 800 rpm zone on the table while driving around as there was no rpm input. Whenever i have this problem there is no RPM input, if the rpm input is working everything is fine. I know i need to fatten up the low end, but came upon this issue while actually logging to tune.
At WOT the O2 should go full RICH…800mv or higher…at +10% you are running lean…increase the RPM to about 3000 for a few minutes….if long terms decrease you have a vacuum leak…if long terms increase you have a fuel delivery issue (fuel pump/injectors) or dirty MAF !!…I would spray and mixture of baking soda and water on the ignition system and see if you see a lightning show underhood…inside a dark garage is the best to see these.
That’s something I really don’t graph RPM vs MAP…I always check MAP KOEO just to make sure it’s not skewed !!…and looking at those fuel trims…skewed MAP will affect MAF reading…you should normally see the displacement of the engine as grams/second so a 5.7 liter you should see anywhere from 5.7-6.2 grams/second or so !!
I was displaying that table so I could use it to adjust the ve table. I am getting atmospheric pressure before starting -is KOEO key on engine off? Low map would indicate WOT.
Camshaft position sensor
