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Hard Cold Start/Rough Idle then Smooths Out??

L

Lolvo940

New member
Joined
Oct 16, 2019
Hello members of TurboBricks!

I currently own a 1994 Volvo 940 wagon, non-turbo. Every morning after the car sits over night it has a long crank with my foot down on the gas to get it to start. Once it starts the engine idle is very choppy and blows white or blue smoke out the tail pipe (can't really tell if its white or blueish). After a few minutes with my foot on the gas so it doesn't stall, the car returns to normal idle and smooths out. For the rest of the day it will run completely normal.

I replaced the pressure regulator, 02 sensor along with a new exhaust, new cap and rotor, fresh oil change, new spark plug wires, and I changed my spark plugs last Spring. Again, I am still learning but I think there may be a vacuum leak somewhere?

Any help or ideas would be greatly appreciated!
 
It could be coolant from a blown head gasket. Get a coolant pressure tester on it, pressurize the system and look down the spark plug holes with a cell phone borescope and inspect for coolant in the cylinders.
 
ZVOLV said:
It could be coolant from a blown head gasket. Get a coolant pressure tester on it, pressurize the system and look down the spark plug holes with a cell phone borescope and inspect for coolant in the cylinders.
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I had just replaced the head gasket a few months ago though.
 
ZVOLV said:
Even more reason to suspect the work done. Are you loosing coolant? Is the coolant bottle overpressurizing?
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I am not loosing coolant as far as I know I check my levels regularly. The work done on my head gasket was done by a friend of mine who is a Volvo expert and master mechanic so I don't think it could be the head gasket. However, I will still keep it in mind and test for it just in case.
 
daniels740 said:
I think I have the same problem. Do you also hear a ticking/ slight knocking noise that goes away when the engine smooths out?
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Right before the engine smooths out my RPMs will rise and I hear a sound like metal rubbing against metal. not sure how to describe it. More like a high pitch vibration, then it smooths out to normal RPM and run completely fine.
 
Lolvo940 said:
Right before the engine smooths out my RPMs will rise and I hear a sound like metal rubbing against metal. not sure how to describe it. More like a high pitch vibration, then it smooths out to normal RPM and run completely fine.
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Strange. If you do find the cause of your problems please tell us what it was in this thread so I can try that as well. Best of luck to you.
 
I'll open a new thread for a similar problem I have with my 1990 240. May be we can figure this out. My car's been sitting at my local Volvo dealer with the same issue. After throttle body was cleaned and gasket replaced, new spark plugs, and new OEM injectors installed, issue still there. Running rich and hard to start when cold. Nobody knows what's causing it. I want to try a different MAF sensor to see if there's any change.
 
Lolvo940 said:
I am not loosing coolant as far as I know I check my levels regularly. The work done on my head gasket was done by a friend of mine who is a Volvo expert and master mechanic so I don't think it could be the head gasket. However, I will still keep it in mind and test for it just in case.
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You mentioned the HG was replaced.

a) what was original reason for replacing the HG ?
b) was the head inspected/cleaned/resurfaced/etc ?
d) how does the oil look ?
 
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If it's a very small leak, it would not show smoke or in the oil. You can rent an exhaust gas in coolant tester from most auto places. I had to buy the fluid for like 10 bucks. But it was nice having the peace of mind.
 
Mbeas96 said:
If it's a very small leak, it would not show smoke or in the oil. You can rent an exhaust gas in coolant tester from most auto places. I had to buy the fluid for like 10 bucks. But it was nice having the peace of mind.
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same person as Lolvo940(helper) ?

I've had several redblock cars but never had a blown HG that wasn't related to overheating, and each case the head was either replaced or inspected/cleaned/resurfaced, but those were my experiences. ;-)
 
No...

I had a rough idle only on cold start for a long time, eventually it just kind of went away...I still wait a minute or two before driving off because it just feels different.

Checking for exhaust gases is what I was told to do. After sitting overnight coolant may pool in the cylinders and cause a rough start. After a minute or so, it clears up and smooths out.
 
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