start then stall

[youngk]

in the mourning or when my car has been sitting for more than 5 hours i have a hard time starting the car. it starts stumbles and dies. i have version3 k pro ,full bolt ons with rdx injectors and cams. the problem only started happening after i installed my im and tb. i double checked and made sure i dont have a vacuum leak. ive tried adjusting the cranking trim and havent had any success. im trying the method below but still no luck. any suggestion


Joined: Sun Apr 09, 2006 8:12 am
Posts: 226
You will have to tune this over a series of days when the engine is cold - (this is not easy for a beginner and 2nd you need to track changes to cranking pulse, decay rates and ECTc at diffrence warm up temps)

First tune your warms ECTc with a wideband. Only then (the next day with a cold engine) tune your cranking pulse and decay rate.

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STEP 1

If car wont fire, go to step2 , then come back to step 1

Warm up Fuel - This is what I am doing currently Turn OFF closed loop and richen/lean out the mixture at each ECT until the engine stumbles, then use the mid-point. Jumper the service connector to remove the delay in ECU response to changes in ECTc Then enable Cloop. Note the HO2/STRIM only kicks in when the sensor is warmed up to 600 C (approx 30+ secs post start).

Use a Wideband and ensure it is heated up before firing the engine and data-logging the whole warm cycle - approx 10 minutes

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STEP 2 - TUNE YOUR Cranking Pulse and Decay Rate

Cranking TRIM - try depressing the gas, while cranking - engine fires (rpm>500), your crank trim is too rich. Try adjusting the Cranking TRIM at 10% steps then narrow down to 5%/3%.

If your engines fires and stalls, the inc/decrease the decay rate - cold engines initially need more fuel ( to compensate for fuel which get stuck of the cold manifold/port walls) which is tapers off over 30 seconds. The decay rate is to tune this. It is important to have tuned your open loop ECTc first, to eliminate this as factor.

if the cranking and ECTc are tuned right, its the decay rate.

the ECTc can be tune on a wideband - the crank pulse and decay are by trial and error

Also be aware that after firing (>500 to 1100 rpm) what load cells your engine is hitting (normally 9-10, 6-7, then idle load) - useful to have a Wideband to log the warm up AFR (make sure the WB is to heated up, before the datalogging the start & warm-up. Assuming those cells are not way out