tntmonstertrucks
New member
any help will be greatly appreciated. recently bought a 99 donzi zf with twin 99 250 efi. all of which has less than 500 hours.ran great for few months then started noticing the port engine would stall as soon it was put in gear to pull out of the slip. would start right back up and run fine up to full throttle with no issues,problem started getting worse i was told the fogging oil can gum up the spark plugs,replaced them and the engine ran great for a few more trips with no issues. checked the throttle position sensor and was out of spec. adjusted the .95 at idle worked fine for another few trips. same issue happened i check the throttle specs and was off but no more adjustment left on the slots bought a new sensor set it and ran great for another couple trips. has injectors out and cleaned new iac new plugs swapped coil packs and both computer boxes from engine to engine and not one big of difference. all compression is at 95 psi on the dot.. it idles like it has a dead cyl or 2.. one thing i noticed is at an idle i can unplug the top 4 coil packs while its running and not one bit of change is noticed. if all 6 are plugged in and i unplug either of the bottom coil packs it will stumble and shut off.. its driving me nuts to say the least. could this be a stator issue? i was talking to a merc guy yesterday and told me certain years have a high and a low side ?..