help me out guys, just put a new 360 in my truck went with a little bigger cam, and advanced it 4 degrees per comp cams suggestion, the truck already had the kegger mod, hughes plenem plate kit and a hypertech tuner, installed the engine today, it wont idle at all have to keep my foot on the gas, runs very rough and has no power what so ever i have checked and or replaced all sensors, iac is new and throttle body is clean, new plugs wires, cap, rotor, crank sensor, pickup coil...i have checked the distributor drive gear three times and it is dead on. i am about at wits end with this thing any info will be greatly appreciated

 

is fuel delivering?

 

yupp checked that first runs at 49 psi

 

ususally the pcm has to relearn the idle when the batter has been disconnected. when i replaced my tranny my truck wouldnt idle for a good 15 minutes and kept stalling. after that 15 minutes though it idled beautifully and has ever since.

 

The fuel sync should be reset with a capable scanner. Also maybe the cat is clogged. Unscrew the front o2 sensor and let it hang, and see how it runs.

 

Bingo. This is the root issue. If and when changing motors, depending on the CKPS to CPS relationship, the PCM will need to be reprogrammed for the new engine- especially with a new cam. Not only the fuel sync but< there's also the CPS to CKPS offest parameters that may need to be timed as well.

To that post above on not idling for 15 MINUTES after BAT disconnect: that is not right and is indicative of a reset gone south. Anytime I've disconnected the source, and after changing the IAC, MAP and TPS sensors, the engine will fire up and idle within seconds. When cold, it runs on preset parameters thus, not using nor adjusting them and, it is supposed to run fine.

Now, what ends up happening is, if the reset was not successful or, there was data corruption in memory or, a sensor was swapped out for another without reset - the PCM data used will not correlate with the sensor output thus, putting the entire EFI system out of whack then, what ends up happening is, it takes way longer to relearn every sensor and, to overwrite all the data in memory. This takes a lot of time and, it takes approximately 10-20 minutes to do this. It is creating a new baseline at the PCM level.

So, to prevent that from occurring, there's a certain method of resetting that alleviates this from happening.

CM

 

took o2 sensor out ran the same, would a snapon modis be able to reset the fuel sync?

 

some Snap on tools will have that feature yes but, not all and, some are very costly. in my opinion, they are good tools but, not worth what they charge for them PLUS, those are usually tied into multi vehicle programming thus, why they cost so much.

I am not familiar with that model that you've mentioned but, one thing I always do is to call tech support or application engineering to find that out for sure.

Here is an option for you to consider trying or, at least looking into. Most speed shops have those tools to do that. If you ask them if they can do this, they may offer a low price to plug it in and set it up for you. Plus, they may even have a scope as well. In my opinion, one needs to see what is going on at all levels within the different systems in order to get a clear picture of exactly at which system the issue is rooted.

Now, let me ask you this: on your CPS and CKPS (master sensors one and two of three for the EFI timing system) are these OEM or after market?

Next question: CAM: does the cam selected require a custom tune or, did they tell you it requires no tune? The reason I ask is, I seem to recall a similar case on here that involved a CAM change to which, a custom tune was required to make it work timing wise.

CM

 

the sensors are borg warner, got them from o reillys they told me the were the oem replacement, and as far as the cam goes it is a comp cam but its set up for towing and i was told i wouldnt need a tune for it but that my hypertech would enhance it a little bit

 

BW stuff is not very good if at all sad to say. I wouldn't be surprised one bit to find those sensors problematic thus throwing the master clock off right from time KEY <ON> event is initiated.

Let me explain this in detail. The sensors that OEM dealers sell are FULLY tested to unsure a working sensor in all environmental conditions. The ones that do not pass or, do not meet ALL tests, are sold off to brokers who, in turn, sell them to third party stores across the country.

There's also other parties that produce sensors that look a lot like the OEM version and, they will tell you that it is a direct replacement and not to worry.

Well, again, when it is made with junk materials inside, it is not going to work reliably if at all under full temperature ranges that automotive applications are subjected to.

I recommend having those removed and replaced with OEM Mopar sensors. I went through multiple after market sensors until finally getting mad enough to do some research and replacing them all.

CM