Diagnosing 1998 V70 N/A slow cold start

[dynamaniac]

I have a 1998 V70 N/A, 135,900 miles on it, and lately it's been struggling to start cold. Once I've driven the car at all on a given day, it starts immediately for the rest of the day. First start of the day never sounds happy and always takes ~2 seconds.

Some backstory:

The car had some more severe issues with inconsistent starting and rough idling a few months ago, and I took it to my mechanic knowing he could diagnose it faster than I could (with a trip to Lake Tahoe approaching). He traced the problem to corrosion in the distributor cap and rotor, and replaced those, as well as the spark plug wires, but not the (relatively new, clean) spark plugs. He also replaced the original fuel pump relay. Normally I'd want to do these sorts of replacements myself but it was a good opportunity to give him some business, as he's given me advice for free in the past.

These fixes cleaned up the car's rough idling, but while the car hasn't failed to start since then, I've noticed it has begun to require more hard cranking to start cold in the last few weeks. I haven't seen the CEL at all over this time, and I'm hoping to borrow a friend's code reader soon to see if any codes have been thrown unbeknownst to me. Also, I recently replaced the car's battery, and cleaned the MAF sensor with MAF cleaner. Also also, I've noticed some very minor RPM wandering at idle (when it's cold it idles at 1k, warm closer to 850, but wanders between 800-900 - I might be reading too far into this but it's noticeable to see RPM change with my foot off the gas). At times the idle sounds rough again, too.

I'm set to replace the timing belt, and also replace the PCV system using a kit, in the next week or two. I was wondering if anyone here could point me towards any diagnostic checks I might want to do to address an increasingly slow cold start, while I'm taking apart these parts of the engine. I'm still a bit new to taking care of Volvo's but I do have some experience thanks to this site (like heater core, timing belt and water pump swap, etc). I'm thinking of checking things like the battery wires, throttle body and idle air control valve, maybe the engine coolant temp sensor? Any tips on what I can look for before deciding to replace any of these?

Thanks for your advice!

[theWIFES_S70]

Sounds like a fuel pressure issue. Is there any difference if you crank the engine after you let all the chimes stop, or when you turn the key to the on position a few times before cranking on the engine?

There's a check valve near the fuel filter that helps hold some pressure.

Could be a clogged fuel filter, or fuel pump screen attached to the fuel pump...

Is your fuel pressure damper original? Could also be that...

I would only worry about this if your crank starts to take longer and longer (which would mean your fuel pump is on the outs...).

[dynamaniac]

Thanks! No difference when I let the chimes stop or repeatedly turn the key to ON before actually starting. Once I've driven around for a little, and I shut it, it always starts up with no issues. I will check out the fuel pump/check valve, fuel filter, and fuel pressure damper, and maybe the tank lock ring seal, based on this: viewtopic.php?t=79994

Related: can I damage my engine if I keep starting the car hard like this until I'm able to actually resolve the problem? I probably can't get around to this for a few more days...

[scot850]

When was your battery last replaced? My brother recently had the same issue with his 97 850 NA and it was just the first signs of the battery going. He took it to Autozone (or someplace like that) and they tested it and it had a bad cell. Once warm the car would start fine. New battery and all is good again.

Neil.

[dynamaniac]

I recently replaced my battery (I had left an interior light on, and the six-year-old battery couldn't be jumped, so I replaced it). I'll need to dig through a few starting components and fuel line components to figure this out, I think... I've also read that old battery wires can cause issues like this, too.

[scot850]

Old cables can cause the issue as can bad earth connections on the various engine earth wires. It takes some time to work around them but worth cleaning them up to start.

The next thing you could try is to have the starting system checked at Autozone or where ever. They might have the tool to check the current draw on the starter. It could be it is worn out or has a bent Bendix. When I have removed the starter in the past on old P80's I have found them to be totally worn out and dry. One had the inner plastic plate crumbling and cracked. Replacing the starter made a huge difference.

When you say hard cranking, do you mean the engine struggles to turn over, or you have to crank it for a long time?

If it is the latter, it could be low fuel pressure (should be 43 psi or higher) or a bad ECT sensor (the temp sensor below the thermostat). It is worth carefully checking the connection to that on the power steering pump to make sure the connections are good and clean. There is a resistance check you can do with the ECT sensor to make sure it is good. There was a right up on that recently in this forum.

Neil.

[Klausc]

Take a close look at the exhaust pipe while cranking the starter during cold start. If you see a puff of black smoke, your fuel pressure regulator may have gone on vacation.

The 1998 has a hard line from the FPR to the front of the intake manifold. You could disconnect the line at the manifold and see if you can get any vacuum pressure. If any gasoline drips out, the FPR is dead and you are now getting the same pressure as if you had the gas pedal on the floor.

Long cranks will not hurt the starter.

[cn90]

At that age of 135K miles, with slow cold start, think ignition department:
- Spark plugs (I use NGK copper $2/each)
- Cap/Rotor: Bosch only
- Bougicord should last > 150K.
- ? ECT (info in forum I posted a while ago). My ECT failed at 110K.
- Thermostat should be replaced anyway.
etc.

All of those things are in forum.