Join Date: Jun 2005
Location: I would rather not say
Re: 156 jerking problem, I need Help
I had this problem (jerking/rough when cold) but only solved (or nearly solved) it after changing lots of stuff. New thermostat, temp sensor and cleaning throttle butterfly helped idling and sorted weird temp readings. However, it was not until I changed the MAF, the air intake stuff (check that the concertina-like ducting after the MAF hasn't perished - this seems really common), the air filter and plugs until it really improved.
I'd check air intake rubber piping first. The MAF (air flow meter) is fairly expensive. Mind you, the lambdas are much more expensive, but probably aren't responsible for the bucking when the system is in open-loop before the lambdas are hot (and system goes closed-loop). Could be wrong about this though!
If you temp doesn't stick at 90deg when the engine is warm, do the thermostat and temp sensor. The ECU needs to know that it is cold for the electronic choke to work (enrich the mixture).
I think some roughness in the TS when cold may be "normal". Maybe this is part of the ECU cold start program.
P.S. I see you have the V6. It is not very kind to push beyond 3000rpm when cold!