engine hesitation

I have a 98 vortech 7.4 liter that stumbles at 1/2 throttle or so. plugs & wires didn't help neither did a tps. no check engine light but idles a little rough also. Maybe someone han help. I sure would appreciate it.

Hi Chris, welcome to the forum I am sure Hobbist will know what to do....

theirs a possible chance that a vaccume line may be leaking.check your fluids through the week.and see whats disappearing.check your oil for white foam.check you coolant for oil.have some start the engine stand by tail pipe and see if their and smoke ailke:

1:white steam or vapor is coolant.
2:blue, dark gray is oil.
3:black raw gas.

the reason you may or might have leaking head gasket.
or your might have a fuel injector playing games.
or fuel regulator is not cutting back when engine is not under load just driving along and loading up engine.throttle position sensor you already changed but causes this.make sure temp is correct on coolant.guage may read wrong.ignition module may no sensing cam ,crank position correctly use scan tool to check.

if this engine has a coil on each cyclinders one coil could be bad.

also check your gas station and see if they have had a problem with water.take a sample out of your tank and see if moisture has intered your system.

Post edited by: hobbist, at: 2008/05/19 14:58

Thank you Hobbist, for your reply. The engine does not smoke at all., and has awesome power at high end. I am leaning tward a injector problem like you sugguested. I am in Mississippi doing hurricane work and my snap on mt2500 is in Wisconsin. Do you think it will help? should I at least check the injector time on/off? And also didnt hear any vaccum leaks. and i have ran 40 tanks of fuel from different stations across U.S. thanks again for your reply.

i do not think it has anything to with time. fuel injectors fail like leaking in off condition or they get pluged. i have only seen one dead injector in last two years.my olds delta 88 3.8 has had a skip at low idle hot. but in over drive theirs not skip on hard pull my gas mileage has not been lost so i dont no what else to tell you.i do not want to fix a 91 auto 200.000 miles on it. i am just driving it till it quits then junk it.i have a code 41 says cam sensor malfunction installed two new ones . still have code.on wiring diagram shows both cam and crank sensors is wired through ignition module.problem is maintance manual says the engine should not be running so my conclusion is part of my ignition module is not receiving or amplifier is not reading sensors.

Post edited by: hobbist, at: 2008/05/20 13:25