Why would my car big down?

[Cochise]

It doesn’t always happen, but sometimes after starting my car back up it bogs down and dies. It will start no problem and “stall” so to speak. It also sometimes happens when comping to a stop. Like a red light or stop sign.

I can occasionally prevent it from dying by giving it a little throttle, but obviously doing that regularly isn’t ideal.

For background,

107K miles
New timing chains, tensioners and stage 2 cams at 106K.
FRPP intake with trick flow plenum.
Tuned.

It’s weird and inconsistent. For instance, my car has been idling in the parking lot just fine for the past 5 minutes while I type this.

Thanks in advance.

 

[RAU03MACH]

what is the idle at what is the tack at

 

[ttocs]

any chance it is happening at a specific temp or range of temps when you try to start it? While it is tuned it might need a slight adjustment to the IAC at that temp for starting to allow more air in.

 

[Cochise]

what is the idle at what is the tack at

any chance it is happening at a specific temp or range of temps when you try to start it? While it is tuned it might need a slight adjustment to the IAC at that temp for starting to allow more air in.

The tach lives around 800 on idle.
When it dies it drops below 500.

Unfortunately there is no regularity to it. It does it on occasion hot or cold and also at different times of the day whether hot or cold.

 

[07GtS197]

Your best bet is to datalog while going driving and see if you can catch it. Something should come up on the log.

 

[ttocs]

well it is always a good idea to start simple. One small problem I discovered on my car while tuning was that a clip on my TPS harness broke off. As tight as the other one held it I didn't care just slapped it back on and it must be good right? Well what we discovered while tuning(data logging) was that the throttle was starting to show 4-7% throttle when the car was at idle and I was not touching the pedal. I assumed the sensor was bad and replaced it only to find the same problem next time, once I soldered a new harness on it the problem was fixed. Get under the hood and disconnect, inspect the contacts and clean where necessary and when you put them back together give the harness a good pull/tug/wiggle and make sure it does not move at all. You should be able to give it a pretty good yank and not have it come off, if it does come off or even wiggle a little bit replace it.

A lot of the sensors under the hood use resistance for readings. For example the tps is a variable resistor that changes as you give it gas, the ecu reads that change and knows you are on the throttle. If the harnesses start to get loose they will change that resistance reading and mess with the ecu's tuning.