acceleration problem

lee0623 · Post by **lee0623** » 28 Dec 2003, 17:25

I just bought my first volvo, a 1988 760 gle turbo. Great looking car and with all the options working. It even had a r143 retro fit down last year. There is one problem though that I can't seem to figure out. If I press the accelerator down about half way, it accels just fine. But if I press down further, the car hesitates and blows out black smoke from the exhaust. Can any one help? I would appreciate it.

lee0623 · Post by **lee0623** » 29 Dec 2003, 16:51

I noticed today that my vaccum canister had no vaccum. I disconnect the two vaccum lines at the throttle body and there was no vaccum. I tried some other vaccum lines near the intake and there was vaccum there. Any ideas?

Volvord · Post by **Volvord** » 30 Dec 2003, 11:51

Vacuum will only be available on the lines after the throttle plate. The line you might have been checking, was it in front of the throttle plate? If so it would be the port that senses turbo boost levels and will be read by the turbo gauge.

lee0623 · Post by **lee0623** » 30 Dec 2003, 16:58

thanks volvord, you were right. There was vaccum there when applying gas. So, let me try to explain the original problem. While accelerating, the car starts to hesitate around 3000 rpm and smoke starts coming out of the exhaust pipe. If I depress the accelerator less than halfway, the car accelerates (but slowly) up to speed. It's when I depress it abruptly that the hesitattion occurs. I am thinking vaccum leak somewhere. The cruise control doesn't work and the a/c fan cuts in and out during acceleration. Any ideas? Thanks for the help.

Volvord · Post by **Volvord** » 31 Dec 2003, 10:19

I would be looking for a leak in the intake air system. The air quantity is metered by the MAFS connected to the aircleaner box, the ECU uses this reading to determine the amount of fuel to add to that amount of air. If there is a leak between the Turbo and the throtle body less air will be seen by the engine and a rich mixture will result.

Carefully check all of the intake hoses and connections from the turbo to the intercooler and from the intercooler to the throttle body for leaks, cuts, breaks, or holes. This is a fairly common problem and I am sure you will find a hidden leak in one of the large rubber intake hoses.

Guest · Post by **Guest** » 02 Jan 2004, 09:26

Turns out that the fuel pressure regulator was bad. I bought one from a salvage yard until I can order a new one and it comes in. Now it accels straight on up and shifts better Thanks for all the help. Thanks volvord, I did find some vaccum hoses that were burnt enough to seem air in. I replaced alot of hoses and now my cruise works again. I look forward to talking to everyone again soon.

Post by **matthew1** » 02 Jan 2004, 10:17

Please disregard this post...
I'm marking threads for use in a planned beginning-to-end repair 'database,' and this one will be included, thus this message. There's no other way to mark threads save posting to them.

Thanks!