Stutters when giving gas/selecting D or R at cold start Topic is solved

[Woolf75]

Hello, my first post

Volvo S80 T6 1999.

At cold starts: starts directly, good idle. When I select R or D to start driving, the engine stutters and almost stalls, so when I put in neutral or Park it stabilises again. When I rev the engine in Park or Neutral the engine almost stalls.

This lasts maybe for a minute, then drives normally. So I let it idle for a minute. It is like the engine can't handle any load the first minute or so. No problem when engine warm.
What could this be?

Any suggestions appreciated!

[matthew1]

Welcome to MVS, Woolf. Can you tell us where your S80 is for maintenance?

https://www.matthewsvolvosite.com/stage-0/ use that as a guide. For your case we're not interested in brakes, etc., only engine/fuel/spark/air.

[Woolf75]

Hello and thank you!

I have not had it for so long and have almost no history on it. My son bought it from someone who didn't drive it at all for four years, all tires were flat etc...he brought a new battery and fixed the wheels and managed to drive it home surprisingly enough it started easily (!!)
We found several vacuum hoses detached

What I/we have done:
- New spark plugs
- new vacuum hoses
- cleaned throttle body
- cleaned MAF
- changed VVT
- some kind of "engine clean" my son did and new oil/filter
(and other stuff like replaced all other fluids)

Runs well, I have gone on a 4 hr trip without problems.
We have not changed air filter or fuel filter. We have a code reader that can read Volvo - specific codes, no relevant fault codes come up. Oh - and one thing: quite smokey at startup and maybe exhaust smells "rich" but I am not sure

[matthew1]

Air filter and fuel filter have a high benefit ÷ cost for problems like this. That's where I would start (continue).

[scot850]

How cold is it where you are just now? The older Volvo P80 cars 93-00 years in turbo form can have a problem when really cold with the intercooler freezing. This causes the engine to run really rich. If you open the hood, look at the intercooler hoses and see if they are collapsing inwards.

Do you have or use a block heater on the car?

If this is the issue, then driving with cardboard over the hood grill can help reduce the intercooler freezing as the engine cools. Starting and letting the car idle for 5 minutes before leaving may also help.

It could be other things but easy stuff to start!

Welcome to MVS!

Neil.

[Woolf75]

Replaced air filter, problem persists.

Neil => it is not that cold, same issues actually when I start from a heated garage. Idling is ok, but as soon as I give gas (or select D or R) it begins to stutter. Confusing.

I will go on by replacing fuel filter

I see now that the intake air sensor is fastened by previous owner with a cable tie. The "clips" that should hold it in place I have to check if possibly there is an air leak there. But then there should be a problem all the time not only first minute..?

[Woolf75]

...and this is how it looks. Plastic broken, the small metal wires seem intact but with some dirt on them. It seemed secured air tight though

Found the sensor on the web : Air Charge Temperature Sensor - 9445153
I will order one of these anyway since it looks a bit unhealthy, but might this explain my problems..? I have not had any related fault codes (my scanner also presents Volvo specific codes)

[Woolf75]

Solved!

I replaced the ABS module and the cold start problem is gone! I replaced it because I suddenly had ABS and STC warning lights intermittently, also the lambda warning light. I don't understand how the ABS module could make the engine stutter when cold, but problem 100% gone! What is the logic behind this?

[BlackBart]

Unless somehow you bumped or pulled a vacuum hose off in the process and didn't notice it?

- new vacuum hoses

- some kind of "engine clean" my son did

What sort of cleaner was this? Something sucked into the engine intake?

[matthew1]

Yes, this is very strange. Maybe you bumped a vacuum hose back on by accident while you were working on ABS?