Originally Posted by ronjenx
Are you saying the starter stays engaged for 5-6 seconds AFTER the engine fires up and is running on its own?
That's right Ron. For tip start to work properly several things must happen. One you must have a valid crank signal(CKP). Two you must have a valid cam signal(CMP). When I say valid I mean within 2-3% variation of the learned trigger wheel or the PCM will reject it.
Then you must have CKP - CMP synchrozation, the relationship between the CKP and CMP signals. The CKP - CMP synch is a PITA for tuners and engine swappers alike. I believe it is leftover from the K car timing belt days so when the T-belt slipped the engine would stop running to prevent damage. Chrysler puts a lot, to much weight into the CKP - CMP synch IMO.
Then after this valid CKP and CMP signals are received and verified synched the engine must pass through a predetermined rpm and so many milliseconds later the starter is disengaged.
That is why if the CMP sensor or trigger wheel(timing gear) is damaged the engine continues to crank after it is already running. The PCM will look for a valid CMP signal for several seconds until it determines the signal is corrupt or missing then it stops looking and reverts to the CKP sensor for engine operation.
An interesting side note, the A/C, charging system, cooling fans, Tip start and many other functions are disabled until a valid CKP - CMP is reached or the CMP signal is rejected.
The tachometer will not read until the above conditions are met; therefore, does the tach work while it is overcranking?