Hi i have a brand new 350 tbi with a mild comp cam and headers with true duals. Starts and runs great but shutters at idle very bad and being on the highway for about 15 minutes my engine light comes on. Code reader is saying its my knock sensor put a new one in didn't fix it. I was told it could be my cam setting off my knock sensor. I was told theres a computer chip that advances the timing differently and could stop my problem but i really am out of ideas. Any help is appreciated thanks.
Dave

 

Make sure the ign. timing is on spec, make sure it advances when you rev it.
Did you upgrade to 350 injectors? Tee into the vacuum hose that goes to the map sensor, the reading should be 18-21" at idle, with a smooth needle.

 

What are your engine spec. Mild camshaft can be interpreted in many ways. TBI is a speed density system and relies on MAP sensor (and other sensors) to deliver correct fuel and spark. For near stock calibration a cam with LSA of 112 deg and duration of 210deg (0.050) is probably a much as you can get away with.

Which chip do you have?? ECM part number??

Did you set base timing correctly - i.e with EST connector open. Most TBI calibrations use either 0 deg or 6 deg BTDC for base timing.

//RF

 

Can you locate a laptop and put winALDL on it(free) or TP-RT and buy build a ALDL cable? It will tell you what the sensors are seeing.

 

Hi and thanks for info. Yes timing was set to zero with wire unplugged. Cam is 206 duration @.050, lift is 425 and 110 lobe sep. I need to check my vacuum still for my idle problem but i am more worried about engine light than i am about the idle. Knock sensor only goes off over 80 km/h at over 2000 rpm. thanks again

 

Are you by any chance running headers with a single wire O2 sensor???

 

Yes i am. single 02 with headers. with that screw up readings?

 

NBO needs to be above 600 F to function correctly. A cold NBO will read low voltages ( low voltage = lean mixture) thus causing ECM to add more fuel when engine does not really needs it. People with shorty headers have mixed results running single wire NBO. This is especially a problem at highway speeds as there is a lot air rushing by headers removing heat that is needed to keep NBO operational! To remove this degree of uncertainty it is better to setup 3 or 4 wire NBO (use search for a setup ) and not to worry about this ever again. A little DIY takes care of this problem.

//RF

 

Back to the winALDL comment. It will confirm the erratic function of NB RF is refering to.

It will also show the KC's as they appear. Could very well be mechanical. Not sure if excessive KC sets an error code. I get mechanical KC's in every log I do. Pull timing did not help. Most likely my exhaust.