Hi!
I have a problem with my 1995 850 GLt. The problem seems to be there only when the engine is hot. It hesitates and strongly shudders when I press the accelerator from 1500 to 2500 rpm. The problem is worse when the accelerator paddle has not been pressed for some time (more than 5 sec, like waiting in front of a traffic light, long decelarating in gear with fuel cutoff). The problem is also gone if I accelerate very slowly with the gas pedal pressed only 1/5th of the way down or less. From 2500 and above there is no problem.
The problem is there irrespectable of gasoline content in the tank and seems to be getting worse with each kilometer.
There is no "check engine light" on. The MAF sensor is 6 months old. Air filter new.

Can you please help ? Thanks!!

First place I would try is the dis cap and rotor.
Have you done stage 0 lately?

Good luck!

Read your post again, start to think you MAF could be on my list too.

Ignition cut or blow out would make the engine puff. I would look more at the fuel filter or pump. It could be MAF but thats an easy check with a meter. Or just go wide open throttle. If it still does it then its not the MAF.

I assume your idling is good at below 1,000 rpms.

I am not sure about the ignition cut as mentioned by Volvospeed, but fuel delivery issue is very possible. If you have a clogged fuel-filter, accelerations can be a bad experience given lesser fuel reaches the starving combustion chamber.

I agree to look at the fuel filter and the fuel pump. In addition, clogged injectors can also give that headache, as also a weak/dying Fuel pressure regulator (Relay 103 - PINK) in the fuse-box.

Thanks so much guys, I agree with you - the problem is most likely in fuel delivery. If it was electrical it would get worse in damp or rainy and cold days.

Wide open throttle gives the same jerking and hesitation.

I don't know what stage 0 is?

The MAF was changend unnecessarily 6 months ago - after the new one had been installed , the Check Engine Light came back again and no the engine was still very weak under load (50% power or less). I found out later that the air intake hose after the MAF had a large hole in it (for my thumb) and that was the problem. Now I think it's fuel pump or filter.

I'll check that out and let you know!!

Thanks again!

Stage 0 is the common maintenance parts that have a scheduled periodic life, in essence. just check on these items for instance, to ensure they are working properly. Things like:-

1) Distributor cap (some serious players change this on a yearly basis! some even LESS than that...)
2) Distributor rotor arms
3) Spark plugs
4) Spark plug cables
5) Ignition coil
6) Power stage
7) MAF sensor (cleaned, no need to replace unless faulty)
8) Air filter
9) O2 sensor (cleaned, no need to replace unless faulty)
10) Injectors and seals (cleaned, no need to replace unless faulty)
11) Fuel pump
12) Fuel pump controller (relay)
13) Idle air controller valve (cleaned, no need to replace unless faulty)
14) Throttle-body (cleaned, no need to replace unless faulty)
15) Intercooler (cleaned, no need to replace unless faulty)
16) Intercooler Hoses
17) ATF
18) Vacuum Hoses

and a few more i think. Cant remember everything right now.

The idea is to get your car on stock-standard base, which is basically a very good tune-up already, if you ask me, before you start modding for more power.

Cheers.



This post has been edited by ampangbear: Aug 13 2008, 02:49 AM

http://volvospeed.com/vs_forum/index.php?showtopic=100165


Good thread discussing it for various cares based on age.

Ah yes, i forgot the ATF, the intercooler and hoses, and the vacuum hoses.
:)

And list edited.

Hi guys!

Just solved my hesitation at accelaration problem!
It was fuel filter - full of dirt.

Thanks for all your advices!

Thanks for the update.

:)