2003 Volvo C70 RPM feels like car will stall

REBLYN

MEMBER
2003 VOLVO C70

Noises problem
2003 Volvo C70 6 cyl All Wheel Drive Automatic 58, ooo miles

Check engine light not on, but when I come to a stop RPM needle moves down, car shakes an pings, but doesn't stall. Rough start and then needle will jump from 1 1/2 to 2 1/2. I will get to my destination then get back in car no problems at all, like it never happened. What could it be?

1 Reply

JIS001

MECHANIC
3,411 POSTS

Your throttle could have carbon build up and you will need to clean out the throttle and the pcv system. Usually the coolant nipple on the vacuum side gets plugged up as well. Here is a service bulletin that tells you what you need to clean. Hope this helps.

Carbon deposits can form in the coolant nipple (vacuum side), located on the underside of the intake manifold, and the Electronic Throttle Module (ETM) bore on cars frequently driven short distances. This residue can cause idle speed to become uneven and noticeable to the driver especially with the increased load produced by the air conditioning compressor cycling on and off. This Tech Net Note describes how to clean the coolant-heated nipple in the intake manifold and the ETM bore.

Remove the intake manifold
Disconnect the hose (1) from the nipple.

Blow the hose clean using compressed air (2). Loosen hose from opposite end and ensure air is flowing through hose. If the hose is blocked, use a welding rod (approximately 250 mm) to clean the hose (1). Clean the nipple using a 2 mm drill bit (3). Install the hose on the nipple.

3. Preparations, ETM Cleaning

Remove the ETM from the intake manifold

4. Cleaning the ETM

Warning! Use a fume hood or ensure that ventilation is good. DO NOT submerge throttle unit in cleaning solvent. ONLY use cleaning solvent recommended in this bulletin.

Important! Do not scrape or use a rotary wire brush to clean the unit.

Clean the ETM bore using cleaner H (P/N 1161436-9) and a soft bristle brush. Ensure that all the residue is removed from the surfaces shown in the illustration.

5. Carefully wipe the bore clean on both sides of the throttle plate.

6. Flush the ETM bore using cleaner H on both sides of the throttle plate.

Check that there is no residue in the bore or on the throttle plate. Any remaining residue can promote new residue build up.

Repeat the procedure if necessary.

Install the throttle body (TB) on the intake manifold using a new gasket.
7. Intake manifold, installing

Install the new gasket for the intake manifold. Lift in the intake manifold. Install the banjo bolt with the new sealing washers