Experiencing a miss-fire underload when supercharger is boosting, doesn't happen when engine is cold, fuel filter has been changed. It's a 1999 lightning, no mods, and has covered 16,000 miles.can it be plugs already? or are people having problems with coil packs or fuel pressures, this truck is driven in England and I have no diagnostic equipment, so any ideas would be appreciated.

 

i have a 99 L with 76,000 miles...original coil packs..I had a misfire for a while....It could possibly be time for a plug change..Any mods? My problems was at WOT throttle my truck would have a pause during the downshift... Well I recently put a 4lb pulley on but while I was waiting for a friend to install it I took my chip out and disconnected the battery...When He installed my pulley and put my plugs and reset my PCU the problem went away... Try changing your plugs, resetting your PCU and if that doesn't work I'd say its your coil packs

 

Hesitation or stumble during acceleration:

1. Ignition system(coils?) not functioning properly.
2. Dirty or clogged fuel injectors.
3. Low fuel pressure --It's a well known problem with 1999 Ls. One of the fuel pump hoses can come loose........
4. Fuel injection or eng. control systems malfunction.

Dan