1998 v70 petrol coughs on highway at steady speed

[MattGat]

Hello I m Matthieu from France ,
Sorry for my english.
I have a very special symptoms on my V70 2.4 petrol 1998 with 250 000 KM / 155 000 Miles . she coughs on the highway at a steady speed and when there is a slight climb it is even worse.
In all other situations it works perfectly.

I have change:
- catalyst and exhaust,
- lambda sensor
-pvc system
- ignition harness
-spark plug
-water sensor
-petrol filter

i have have check all hose of petrol and depression she's looks good
The preasure fuel is 42 psi in position II and 36 psi at engine idle.

I will check the injectors with a machine this weekend to see the spraying and the flow rate are good.

Maybe the fuel pump is not working in this situation?
because no problem starting or idling.

i don t have error code with OBD II

Thanks for your help.
I would like to find the problem because it is a good car that works well but this problem prevents me from traveling

[scot850]

Have you checked the MAF (Mass Air Flow sensor)?

What about the Fuel pump relay?

You might have to find a way to check the fuel pressure while you are driving the car to check if it holds pressure when you are putting the engine under load.

Neil.

[wizechatmgr]

When was the last time the fuel filter was replaced? The reason I ask is if they end up full of gunk, sometimes the car will run fine at slower speeds but start having issues at higher RPMs.

[MattGat]

Thank's Neil.

I had forgotten the mass air flow is new.

Fuel pump relay 103 appears correct.

Yes I will try to check the pressure while driving. The tube is long enough to put the pressure gauge in the car.

If the pressure drops on the highway I'll change the gas pump.

I'll be back at the beginning of the week after the tests

Maybe an other idea?

thank's

[MattGat]

the fuel filter have 6000 miles but replace with a cheap brand i will replace it

[abscate]

Bon jour, Matthieu

When was the last time the distributor cap, rotor, and spark plugs were serviced? These items need inspection every 3 years / 50,000 km and usually need replacement.

The copper parts of the cap and rotor should be shiny and clean

[MattGat]

Hello abscate,
i have replace all of this parts the last and check this weekend they look good.

I have clean and control all injector, change filter and seal nothing changes on the highway.

I noticed that the exhaust gases were very very hot at the exit. I do not know if it's normal

[scot850]

Is your fuel pump relay a Volvo one or aftermarket? We have had a lot of issues raise by the KAE brand relays over the years. My buddy has just had an issue with his 00 V70 NA with fueling issues, lack of power on steady throttle and he finally traced it to the fuel pump relay. He swapped in a spare and 2 weeks later all is still good. While I don't recommend it long term, jumping the fuel pump relay for a short run may help figure if it is good or bad if you don't have a spare to try. This means the pump is running all the time so short run only!!

Neil.

[MattGat]

I have an error in dignosis set is no signal to coolant temperature (N°135) but i replaced her and I have my temperature level on the dashboard.
I think the error happens when it is hot