My 1995 Volvo 850 with Turbo, 210,000 miles lags when I hit the gas - like a half to one second - almost stalls. It also seems to lag when I make a hard right turn. The fuel filter is about 1.5 years old. It also seems to be very finnicky about the gas I put in it - hard to start with cheaper gas. It's been doing this for months so it's not a bad tank of gas. Sometimes it lags so bad it almost quits. Wondering if one of my injectors is clogged. It's getting poor gas mileage. It also doesn't have the power it used to.

 

1~1.5 sec turbo lag is normal on many turbocharged cars due to inertial drag (turbochargers are a miniature version of centrifugal jet propulsion). Some cars try to compensate turbo lag by installing two smaller chargers.

Your 850 seems like it needs a good tune-up. Do you have a full maintenance record? The fuel filter probably isn't an issue.

See what others have to say.

JPN

 

I don't think its the turbo that's lagging. It seems to be related to fuel. The whole car seems to get no gas.

 

Are you able to retrieve fault codes from the ECU? Your 850 may have both OBD-I & OBD-II; under the coin holder in front of the shifter. Autozone used to do free OBD-II diagnostic but not sure if they still do.

If no codes are stored, then the engine may need a good tune-up or the fuel pump/pump relay is about to give in. You could try a bottle of Techron fuel system cleaner or Lucas fuel system conditioner as a cheap trial, but if the injectors are so dirty then they need to come out and mechanically cleaned, preferably by a professional.

JPN

 

If you don't have a mechanical issue you can also try adjusting the wastegate to bring boost on sooner. Just don't go crazy with it.

http://www.matthewsvolvosite.com/for...hp?f=5&t=28239

http://www.matthewsvolvosite.com/for...hp?f=1&t=37163

 

Check your distributor for moisture. It is 3 torques (T25 or T30, cant remember) bolts and it will pull off. Use a flashlight and peak inside. ANY moisture or oil of any kind will make your car run crappy and sensitive to gas. But it will often seem to not effect performance above 4k RPM. If their is any moisture blow it out, wipe it out, make it as dry as you can, re install, and drive. Judging by your description this is very likely your problem. After drying, if this problem comes back after a few days, or even hours, you have a bad cam seal. Cheap and pretty easy to replace with general DIY mechanic knowledge. If you have not pulled the valve cover off a OHC volvo before, DO RESEARCH on how to take it off correctly, or you could break the grooving for the cam seal. You will also need to re time the car if the valve cover has to come off. Don't forget to us a TINY amount of gasket sealer (volvos dont use a valve cover gasket) and correctly re torque the valve cover. Torquing this valve cover is extremely important as it holds your cam in place. Let me know what you find. Hope this wasnt to confusing.

 

Forgot to add; disconnect the plumbings to the turbocharger and make sure it spins freely as you spin it. Also, make sure there is no blockage in the exhaust system.

JPN

 

All the info above is good. I'd like to add that a lot of people have problems when they try to accelerate hard, the intake tube collapses, especially under WOT. That is the first thing I would check. If it accelerates fine with driving normal or softly, I'd suspect the intake tube.

Then I would focus on the fuel delivery, like the relay and check fuel pressure. If that is fine, move to ignition parts, plugs, plug gap, wires (age), cap, rotor, etc.. If you have oil in the distributor you can replace the cam seals without pulling the cam cover. The cover only needs to come off to change lifters, change valve stem seals or remove the head.

 

Yeah that makes sense. The gasket can just slide in. I never thought of it that way because any time I've dealt with the cam seal I was just replacing it cus I had the head off. Good call!

 

Thanks for all the helpful input.
1. I listened for the fuel pump and heard it.
2. I used the paper clip in the relay slots - car drove the same.
3. I replaced the distributor cap and rotor (not wet or oily) - car drove the same.
It does accelerate fine normally or softly, but if I punch it a little it lags for about 2 sec and then jumps in.
Where is the intake tube? I have a Haynes manual and didn't find it readily in there.

 

Next to the red arrow is one of the intake tubes and I think it's the one they are talking about.

All the tubes from the air filter to the throttle body are actually intake tubes but that one is more likely to collapse from what I've come across on here.

You do have a good clean air filter in there ??

 

In addition to previous advice, I would ck the engine compression. If that's good, then look more closely at fuel pressure.

Should see around 43 psi at idle, and it should go up a few psi when you blip the throttle. That latter part is critical; if it doesn't move when you blip the throttle, then there's a problem with the fuel pressure regulator and/or the vacuum line to it. That would give you exactly the symptom you described.

 

Check here:


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