97 Larson with Merc 5.7 TBI

[Insanegtp]

Takes a bit to start (3-4) seconds or crank time. sometimes starts and dies right away, some times stays running a few seconds, sometimes stays running fow a while and surges, idles goes up to 2000 and back right away, even in forward, if we are just cruising same thing.. New plugs, wires, coil, cap... any ideas??

 

[Glastron_V210]

Re: 97 Larson with Merc 5.7 TBI

Check for a vaccuum leak...or the IAC could be dirty or malfunctioning. (IAC= Idle air control valve...I'm not totally sure if you have one...I'm more of a car injection guy).

The IAC controlls the amount of air to the engine in idle/low throttle settings and could account for the problem as well. Sometimes it's the rpm feedback to the ecm (The ecm controlls the engine rpm to a target rpm via the IAC).

Try hooking up a vaccuum guage to see whats' going on when you have the rpm excursions.

Chay