Hey all, I'm hoping someone can point me in the right direction with this.. I have a 2001 s60 2.4T that starts up rough when its been sitting for awhile. First start of the day is almost always rough, but it also gives trouble if its been sitting for more than an hour or so. Upon first turnover, it coughs and hiccups as your turning it over, and then the motor will catch like its trying to run but cant decide if it wants to or not. It usually only does this for a handful of seconds before it'll finally catch and start running. If you flutter the gas as its doing its thing at startup, it seems to catch and start running at idle just fine. Once the motor does seem to 'catch' and it starts running, it runs great, both at idle and while driving(aside from the occasional minor hiccup at idle where the rpm will drop a few hundred for a second). ***Edit*** It doesn't always start up rough though, even when its sat for awhile. Its gotten more frequent in the last week, but it still doesn't do it all the time.

Any advice? It had a rough idle there for awhile, but cylinder 1 was misfiring so I replaced the spark plugs and the ignition coil on cylinder 1 and that resolved the idle issue. Haven't had any problems with the idle since. The plugs and coil are the only work that has been done it in the recent past. I have read alot about the jacked up or dirty throttle modules, and I thought about trying to clean it myself, or have it done. Could this be the issue?

I also got a code that the fella at autozone said was probably being caused by low coolant or a bad thermostat, but the coolant in the overflow tank is full, and I figure the car would overheat if the thermo was bad? The temp gage is always low, and rarely gets up to even halfway on the dial where most normal cars run. I was told this could be the temperature control/read sensor?

Anyhow, I appreciate any help and/or advice anyone can give me before I foot a huge bill sending it in to the dealership for a diagnostic/repair.

 

well replace the coolant temp sensor and clean the throttle body

what happens is when the car is cold the computer uses a basic program operation to run the engine, you get lacked power and fuel efficiency. but when the engine warms up all the other sensors kick in and relay to the computers what the car is doing and the computer modify's the variables to allow the car to run properly.

so in short it could very well be the temp sensor(s) and its so easy and cheap to clean the throttle body i say do it, just read up on a how to for the first time.

 

Thanks for the advice, I think I will do both