1990 Volvo 240 Rough Cold Start

[Ryoku75]

When I try to start my 240 in the morning it'll start up okay but the idle will gradually drop, the engine will shake like its running on 3 cylinders, and just today it'll whine like a belts slipping. If I keep the gas going in it'll eventually sort itself out and run good all day, and start back up just fine.

I've replaced the battery, replaced the sparkplugs, replaced the coils and dist cap, removed the airbox pre-heater hose and capped the hole, installed a new air filter, installed a new MAF, cleaned up the flame trap (going to replace it soon), and cleaned out the IAC.

I'm guessing the issue is a vacuum leak at this point, a lot of the smaller hoses are getting brittle. The hose to the air pump check valve had a good crack in it so I cut the tip off and reconnected, seems to have helped but not entirely fixed my issue.

Could it be a vacuum leak? And does anyone know where I can find a new check valve?

[93Regina]

new MAF

MAF (AMM) must have all air pass by it...vacuum leaks, especially in winter months, screw the pooch since fuel mixture is leaned out.

With Volvos I get, I

1. Install new intake gasket
2. Install new injector o-rings
3. Check all vacuum hoses
4. Clean up flame trap
5. New Air Filter

That said, a defective brake booster will suck outside air, so I remove hose, and plug inlet vacuum port. This can be done, blocking inlet ports, on smaller hoses, one at a time.

>air pump check valve

I'm not aware of that critter...unless that's an emission item.

[Ryoku75]

If anything it seems to run to rich, like its getting too much gas and not enough air.

[lummert]

Did you check the engine temp sensor?