goldhunter_2

ok I am still trouble shooting the problems with my 1984 944 Porsche, it at one time ran pretty dang good but now days it feels more like riding around a old run down work truck that has seen its better days if I am in town the only time it feels right is when I get on some back roads and can really wined it out . Don't get me wrong it starts and drive ok but rough especially driving in town (not pushing it) or the lower end of every gear.

Just to recap what I have done to try to trace this problem down so far while attempting to trace the problem down.
*replace fuel tank
*replace fuel tank screen
*replace fuel pump
*replace fuel filter
*had injectors rebuilt
*replaced fuel pressure regulator
*I have check for vacuum leaks visually and by spraying either around with no RPM changes at all
*replaced timing belt and Balance belt
*replaced plugs, wires rotor cap , rotary button

I am wondering if possibly the thremo vacuum valve under the intake goes bad on these old Porches and if it would cause a issue like I have??????? what do ya'll think?

dontnow

Have you rechecked the balance shaft belt alignment. I understand it is easy to get the shafts out of alignment.

944Ross

Are you saying it has vibration, but fires evenly? Have you done motor mounts?

Or is it firing erratically causing roughness in power delivery?

goldhunter_2

yes I have double checked the balance belt I originally replaced it thinking maybe it was stretched then went back after replacing the belt and double checked it was right

goldhunter_2

yes it fires evenly no cross wires or anything like that, yes I have replaced both motor mounts also which reduced a little vibration but that was not the issue with the motor running incorrectly


maybe I am not wording this right but the car runs , but rough up and down at ideal and in the bottom of each gear it feels like it is lugging the engine spit and spudering. if I have my son drive it and stand behind the car exhaust I smell excess gas fumes during the rough running spots of the engine

944Ross

I wonder if it's a problem with the speed and reference sensors being on the edge of acceptable, or maybe marginal on gap? Have you checked the connectors at the rear of the head?

goldhunter_2

no , I would have to look them up in the book I have never messed with them.

oh I did also check the airflow box , it did have the two tracks but after doing it there was still no change

goldhunter_2

can the thremo vacuum valve cause this type problem or no?

laco996

Swap the sensors,in the bell housing,and you have to swap the plugs at the connectors.

laco996

Thermo switch only operates Idle, and wouldn't afect the runing

laco996

Pinch the hose and drive it