poor acceleration after cold start Topic is solved

freewalk · Post by **freewalk** » 15 Dec 2017, 12:37

My 2000 S70 non turbo, with 174,000 miles has a problem when the car is dead cold and the temp is below 30 deg. F. It will start fine, but as you start to accelerate it will not go over about 10 miles per hour. It feels like it has no gas, and pumping or flooring the accelerator does nothing. After about 4 or 5 minutes the acceleration starts to come back and in 10 minutes it is normal. No codes, no CEL, VIDA shows no codes. Electronic Throttle Module is in spec in VIDA. Car has a white sticker etm. After 10 minutes car is fine. No further problems on restart until engine has cold soaked back to dead cold below 30 deg. F. I would appreciate any input

Post by **RickHaleParker** » 15 Dec 2017, 13:02

Could be several things.

A good place to start is the type/brand of gasoline you use. Fill up with a high grade fuel, see if it makes a difference. When was the last time the fuel filter was changed?

It could be a slow O2 sensor that needs to warmup before the air/fuel ratio is adjusted. You can try unplugging the front O2 sensor and see if it makes a difference.

bobray12 · Post by **bobray12** » 09 Oct 2018, 07:36

i am having the exact same problem could you please let me know what you did to fix your volvo
after mine warms up it drives fine. thanks

Post by **abscate** » 09 Oct 2018, 08:44

If the gas pedal has no effect that points to the ETM pretty strongly.

VIDA should show the commanded and actual throttle plate position - do they match?

If neither changes with pedal action - the pedal sensor is suspect

WhatAmIDoing · Post by **WhatAmIDoing** » 16 Oct 2018, 09:05

The fuel pump relay can fail when cold to a "barely functional" state allowing engine to idle poorly. Press the gas and nothing happens. Once the relay warms up from use/engine heat, it begins to work properly again. Same thing can happen if relay gets too hot. When this begins to happen, total failure is near.

Jump the relay next cold start and see if your issue is still present. If she runs fine, buy a new VOLVO fuel pump relay.

I also agree with the above that you should run high test gas and change the fuel filter if mileage is unknown.

freewalk · Post by **freewalk** » 29 Oct 2018, 20:04

SOLVED: Thanks you got it. It was the fuel pump relay. Swapped out to an 850 relay 103 and all is well. I don't understand the failure mode, but fail it did. Thanks for the tip.