Hi I just picked up a 1989 Volvo 740 Turbo. I have always admired these cars and I was somewhat eager to get behind the wheel. Maybe a little to eager since I did not notice the acceleration issue during the test drive.

It starts out real smooth and strong but around third gear it seems to lug down and loose power. I shift to fourth gear and then overdrive and I can manage to get it going 50 mph and even 60 mph once but it lugs down to 40 and I have to switch gears and get the rpm back up to get going 50 again.

The seller provided receipts of the work recently done including a new fuel filter, fuel pump, fresh air hose and radiator. I assume that he knew about this and will not be assistance in getting it diagnosed.

I have a limited mechanical background so my description of what is going on may not be clear. My guess at this point is cat converter. Are there any known issues with this year and model to do with acceleration? Any insight is appreciated.

To be honest I am still tickled to be cruising around at low speeds. This thing is sweet

 

Well I have some good news... I think. After driving around for a good part of the day I have figured out how to get the car going.

When the turbo gauge hits the yellow that is when it bogs down. As long as it does not touch the yellow section then I am fine. It is still peppy and I can drive on the Freeway at 75 mph. If it hits the yellow though it chokes out.

I assume that this is not normal but I am glad that I can at least drive my new found treasure. If anyone has any ideas of why it is bogging down when the turbo gauge hits the yellow please let me know.

Thanks for reading my post...

 

I'd go through all the stuff on here, Engine Tune and Performance

 

Wow what a great resource. Thank you for the link. After reading around in there I have the idea that my turbo bogging down could be related to a leak in a hose.

I had a look under the hood to try and find a loose hose and this is what I found...



The hose that I highlighted does not have a clamp on either side. I can remove and replace it very easily with just my hands.



Here is a close up of the side closest to the front of the car.



... and here is the other side. Note the the hose kind of covers the part that connects but hopefully you get the idea.


Any idea if that not having this hose clamped on could be the cause of my problem? What the name of the clamp/hose is so I can buy them? I am currently tracking the fuel mileage so I am not sure if I am getting what I should. I should know that in a week or so. I really only drive a bout 50 miles per week but since I got this I have been cruising a little more

Thanks again for the link and any ideas would be appreciated.

 

Just to clarify, it is this hose right here.

 

that 1" foam covered hose that comes out from under the intake manifold and crosses over to the intake hose between the AMM and the turbo is the crankcase ventilation. I'm not sure it being disconnected would cause the symptoms you describe, but, when the turbo is sucking hard, it could certainly allow some air into the system that hadn't gone past the AMM, causing the EFI to underestimate how much gas is needed.

That end in your last picture end goes to the oil trap on the block under the manifold. Note that hose is actually a plastic pipe that has a foam cover (why? I dunno), the cover ends a bit before the end of the pipe.

since your problems start with positive boost pressures, I'd be looking for holes/leaks in the air plumbing AFTER the turbo.... My 745T had a severe power loss at full throttle high RPM which turned out to be the intake hose on the output side of the turbo being improperly clamped and under high boost was letting too much air out. but in my case, this caused the turbo boost needle to flap wildly as the power cut out.

 

Well it ended up being the turbo hoses. I drove with the stutter for about a month until it got so bad that it would not drive any further. I got the new hoses and then I finally felt what this thing can do.

Actually other then the turbo hoses and a universal exhaust, that's all the work that I have had to do. Its a little slow on the starts. Someone said that I need a new fuel regulator but it does start every time after a little bit of cranking.

I am happy with my 1989 Volvo 740 Turbo Inter Cooler. Thanks for the advice.