850 t5 hessitates during hard acceleration

csdrcallum · Mar 3rd, 2010, 22:36

hi chaps! new to the volvo scene, just brought my 850 t5. the car is brilliant although it hessitates during hard acceleration in 3rd/4th and 5th gear. the problem does not occur in 1st or second.
i am unsure wether it is ignition or mechanical. it just seems like it cant hold boost for long without "cutting out". then restarting power again, then cutting out again.

anyone else had this problem and what do you reckon it could be? cheers

Merc85 · Mar 6th, 2010, 22:23

Hi, sounds like it's over boosting, My 850 t5 estate has no cat and is running a mbc manual boost controller, in cold weather it boost's more and the ecu cut's the power at 13 psi......

On a warm day she will be fine runining about 12.5psi, there is only one way to stop this and that is get the ecu remap.

Peteodell · Mar 7th, 2010, 17:53

I would try changing the plugs first... I know it sounds a strange one, but mine was doing very similar and changing the plugs sorted it....

Cheers Pete

Mar 3rd, 2010, 22:36	#1
csdrcallum New Member Last Online: Oct 25th, 2017 22:06 Join Date: Mar 2010 Location: farnham	850 t5 hessitates during hard acceleration hi chaps! new to the volvo scene, just brought my 850 t5. the car is brilliant although it hessitates during hard acceleration in 3rd/4th and 5th gear. the problem does not occur in 1st or second. i am unsure wether it is ignition or mechanical. it just seems like it cant hold boost for long without "cutting out". then restarting power again, then cutting out again. anyone else had this problem and what do you reckon it could be? cheers

Mar 6th, 2010, 22:23	#2
Merc85 Premier Member Last Online: Apr 19th, 2024 12:58 Join Date: Dec 2009 Location: Harwich	Overboost Hi, sounds like it's over boosting, My 850 t5 estate has no cat and is running a mbc manual boost controller, in cold weather it boost's more and the ecu cut's the power at 13 psi...... On a warm day she will be fine runining about 12.5psi, there is only one way to stop this and that is get the ecu remap. __________________ HLM304, Forge unos 17.5psi at 3.8 bar, 18t, Me7 Manifold, Blues, Walbro, De-cat, Ported n Polished Head, 3" Dp stainlesss exhaust, Carbon Air intake, Polly Bushed thoughout.

Mar 7th, 2010, 17:53	#3
Peteodell Member Last Online: Nov 14th, 2015 17:37 Join Date: Feb 2010 Location: Portishead	I would try changing the plugs first... I know it sounds a strange one, but mine was doing very similar and changing the plugs sorted it.... Cheers Pete __________________ Used to Own a Highly Modded 855 T5.... Now Own a standard S80 2.9 SE 1998 Model with a S80 Plate

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)