• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

S/V/C Odd cold start issue

Bready

Bready

board deviant
Joined
Nov 23, 2002
2001 C70

A bit odd - not infrequently at a cold start the car is getting no fuel, if I give it a few seconds it starts, starts even more quickly if I use the accelerator.

Problem started when I did my engine swap, at that point it was just a brief hesitation and it seems to have gotten progressively worse.

Changed out the fuel filter figuring that was the issue but it hasn't resolved the problem.

Fuel pump? Other thoughts?
 
Do you know for sure that it's not getting fuel? Can you check the fuel pressure?

Does an '01 C70 have an IAC valve? I know my '01 S40 does.
A dirty IAC would have been my first guess.
 
Pretty sure it's a fuel issue. Had a complete no start last week thought I was stranded pumping the heck out of the accelerator got it to start after no start cranking for five minutes.

Haven't had it get that bad since, and changing the fuel filter may have helped. But after it's been sitting overnight it's a pretty consistent issue, typically need to pump the accelerator a few times to get it to turn over completely. It will crank and not start or turn over and bog down to virtually 0 RPM before stabilizing once I hit the gas.
 
swedishiron.com said:
Take the Coolant Temperature Sensor (CTS) off the old motor and re-try.
Click to expand...

Too late old motor is long gone. Why would that be an issue - it turns over normally unless its been sitting overnight even after sitting for a few hours.
 
That was a common symptom of a failing cam sensor on the old M4.3/4.4 stuff. The cam sensor on those was only used during cranking, for injector sequencing until it lit off and pulled from the crank sensor. I haven't read up on the ME7 stuff, but if they do the same thing, that might be worth a look. Also wouldn't hurt to toss a noid light on it, see if it's getting injector pulse on crank. If so and no fuel, pump issue. If not, engine management issue. Same thing for a fuel pressure gauge. At least it would be a starting point.
 
I am not at all knowledgeable about white block engines; but, I presume that it is still just port injected? If so, have you confirmed that the fuel system is going through its prime cycle when you do key on power up? Most port injection EFI systems have two activities at start up. When first powered up you will hear the fuel pump run for a couple of seconds to prime the fuel system and then shut down (prior to starting to crank the engine). When the pump is priming the system it typically fires the injectors briefly to wet the intake manifold to help with a quick start. Once you start cranking the engine it will start firing the injectors at a pulse width based upon a temperature based look up table. A few things can screw this up:

If your fuel pump is weak and does not establish base pressure the priming pulse and the cranking pulses will not flow sufficient fuel and starting will be problematic. There is no closed loop control during start up to correct the AFR.

The fuel system has a check valve in it to maintain pressure when parked. This facilitates priming and starting if you don't give the pump a chance to run through its prime cycle before cranking the engine. If the check valve gets sticky or the FPR gets leaky the system will lose stored pressure which messes up the start cycle. Check to see if the system is losing resting pressure. If it does, allowing the fuel pump to prime the system twice (key on, key off, key on) before starting cranking can sometimes help.

As noted, the fuel pulse width during cranking is determined by a coolant temperature based look up table. If your coolant temperature sensor is out of spec, it may be providing too much (reading a low temperature) or not enough (reading a high temperature) during cranking.

As an observation, if the start problem is caused by over supply of fuel, do not pump the accelerator. Push the accelerator to the floor and hold it there while cranking. Most EFI systems detect wide open throttle during cranking and put the system into flood clear mode. This only applies during cranking. Once the engine transitions the cranking to running threshold you are on your own in terms of what you do with the accelerator to keep it running.
 
Bready said:
Too late old motor is long gone. Why would that be an issue - it turns over normally unless its been sitting overnight even after sitting for a few hours.
Click to expand...

The reason is that these fail quite often but are easy to replace. When they fail, they flood the engine on cold starts. That's why you have to floor the accelerator to get it to clear out the fuel that's washing down the cylinders.

Check your oil / dipstick - if it's very gassy, this points to a bad CTS.
 
That's easy enough to check with either an OBD dongle and app on your phone (I use Torque Pro), or a DVOM. Definitely valid points on it being super rich as well, but that will usually also have drivability side effects.
 
gsellstr said:
That's easy enough to check with either an OBD dongle and app on your phone (I use Torque Pro), or a DVOM. Definitely valid points on it being super rich as well, but that will usually also have drivability side effects.
Click to expand...

Once the engine heats up it usually goes away.

JB - does the replacement engine have an Electronic Throttle Module?

If so, that could also be a potential culprit.

I'm with Gary on this one. I'd like to see what the codes are.
 
swedishiron.com said:
The reason is that these fail quite often but are easy to replace. When they fail, they flood the engine on cold starts. That's why you have to floor the accelerator to get it to clear out the fuel that's washing down the cylinders.

Check your oil / dipstick - if it's very gassy, this points to a bad CTS.
Click to expand...

I'll check the dipstick but I think the issue is exactly the opposite. I don't have to floor it to get it to start just pump the accelerator during a long standing cold start - so I think the issue is probably more along the lines of what 142 was presenting.

Appreciate all of the helpful input.

:wave:
 
Bready said:
Too late old motor is long gone. Why would that be an issue - it turns over normally unless its been sitting overnight even after sitting for a few hours.
Click to expand...

CLT sensor tells the computer it's cold so the computer knows to inject more fuel.
 
Honestly since this is a 99+ volvo I'd recommend getting vida to scan it rather than just guessing. You'd be able to check all kinds of things and values while the car was running too so you'd see if it was a bad pump by watching the fuel pressure value. I wouldn't own a 99+ volvo if bootleg vida didn't exist.
 
Kind of odd - the problem has largely diminished.

Old fuel filter causing air in the line - perpetuated for a while when swapping out the filter, eventually purged after a week or so?

:e-shrug:

It still "coughs" very slightly but none of the "no-start" tendencies seem to remain.
 
Just updates here.

So the issue became more severe during cold starts after the car had been sitting over night - really had to pump the pedal, had my mechanic check it fuel pressure was definitely dropping steadily. Had him replace the fuel pump (last thing I wanted to deal with in a C70 Cabrio) but that didn't fix the problem. Did find if I put the key in "start position" about 3 or 4 times in a row the system pressurized enough to start.

So I swapped out the injectors and had a very odd result - the cold start issue went away completely. But now it will be intermittently difficult to start after driving for a while and letting it sit - say an hour or so once in a while.

FPR? Can't quite figure out which FPR this car has or where it's located, I think on the left side but for the life of me can't find the correct part number for a 2001 HPT C70. I think that's the last thing I need to swap out to address the issue.
 
Bready said:
really had to pump the pedal
Click to expand...

One person suggests getting a new battery: HERE

Just hold the pedal down say 3/4 way down...if more air is needed to start, this might suggest a rich mixture.

So I swapped out the injectors and had a very odd result - the cold start issue went away completely.
Click to expand...

Disconnect the cold start injector (electrical plug). Was battery disconnected when injectors were replaced?

Can the voltage at the TPS (throttle position sensor) be monitored?
 
swedishiron.com said:
Take the Coolant Temperature Sensor (CTS) off the old motor and re-try.
Click to expand...

Annnnnd you win! :bouncy:

After replacing the fuel pump, fuel filter, injectors and coil packs - finally diagnosed as a CTS issue.

Swapped out and issue seems to be resolved.

Appreciate the council there - you were spot on.

Not that there was anything wrong with replacing the other components - the fuel pump and filter had over 300K and 100K miles on them each.

The injectors, though low mileage were off a motor from 2004. Coil packs 1 and 3 were showing up as issues on the code so a fresh set was a good call anyway.

Thanks guys - and especially SI (and ovlov) - appreciate the thoughts and direction...

:wave:
 
Bready said:
Annnnnd you win! :bouncy:

After replacing the fuel pump, fuel filter, injectors and coil packs - finally diagnosed as a CTS issue. Swapped out and issue seems to be resolved.

Appreciate the council there - you were spot on. Thanks guys - and especially SI (and ovlov) - appreciate the thoughts and direction...

:wave:
Click to expand...

NicE!
 
You must log in or register to reply here.
Back
Top