Engine Surging While Braking

Post by **zulu-v40** » 26 Oct 2011, 12:08

Okay guys, my 2003 V40 is still driving poorly. The engine has been surging as I slow down, or come to a stop. Is there a recall on the ETM for later years? Should I be replacing or cleaning the throttle body? Something is not right.

claymore850 · Post by **claymore850** » 26 Oct 2011, 22:06

Check the throttle and clean it, also take a look on the brake booster, look the the vacuum check valve for leaks..

Post by **zulu-v40** » 27 Oct 2011, 07:30

Thanks for the advice. Not sure where the brake booster or vacuum check valve are located, but I'll check those out. I'll definitely clean the throttle body. After reading around this site and others, I think it might be the throttle position sensor.

Post by **zulu-v40** » 29 Oct 2011, 09:49

After more research, the V40 does not have an ETM, but an "accelerator cable" that opens and closes the throttle plate. I knew that already, as I've cleaned the throttle housing a couple times now, seeing both the cable and throttle plate in action. I get the difference between the ETM and cable assisted throttle now. Can anyone chime in on whether or not the throttle position sensor is a likely culprit for engine surging? I'm not hearing a vacuum leak. I've sprayed carb cleaner on the hoses and there's been no idle fluctuation. The problem is worst when driving the car from a cold start. After driving a couple of blocks in the morning, without fail, the engine will surge about 500 RPM as I brake for the stop sign. This is happening at slow speeds, not highway speeds.

draxcam · Post by **draxcam** » 30 Nov 2011, 13:27

Had identical problem and the Engine Coolant Temperature sensor was the culprit. i also replaced the thermostat while I was working in that area anyway. BTW, did u notice any erratic readings on the temp gauge while the engine was surging?

Post by **zulu-v40** » 01 Dec 2011, 18:38

Draxcam, I was still having the surging problem after replacing the Coolant Temperature Sensor and Thermostat. The computer threw up a CEL for the thermostat, but I never had erratic temperatures. Even after replacing most of the rubber vacuum hoses on the engine with silicone from boostcontroller.com, including all three lines to the Turbo Control Valve, the engine continued to surge when first started. Yesterday, I replaced the Fuel Pressure Regulator and o-ring. The V40 now starts up like a charm and the engine surge is gone. After starting the car, I still see the tach jump around a little bit when coming to a stop, but nowhere near the level of surging that was going on before. It might hop up 100 rpm, but it is very subtle. I've been posting about this problem for months, about as long as I've been a member here. It feels good to have finely solved the problem!!!