Intermittent Acceleration, MORE INFORMATION
 

Alright so i posted about this before, but I have noticed more about the issue, so here is more information about the problem i face.

i'm having a really annoying problem with my 2000 S70 N/A B5244S. (automatic trans) this has been happening since i got it a year ago. After sitting all night, starting it and it drives fine. but after a few hours of continuous driving, if i turn it off and if it cools even slightly below operating temperature, it refuses to go up hills or under load.

So i've been leaving it running even when i'm away from it. and that worked, until its been getting colder outside and cooling the engine while it sits, also it seems the cooling fan has been staying on when its running and well below operating temperature.

the hesitation is not a misfire, and not a catalytic converter issue, i have catless side pipes. it's just simply a hesitation. it just stays at speed or even decreases when its screaming at 4k+ rpm, sometimes full power would kick back in for a second and then go back to hesitating. and i have a few examples here


ALSO. Last night it was consistently having this problem as it was cold. But i noticed, when i let off the throttle from the hesitation, a blue flame would come out every time.
I'm on my last nerve with this issue.
Any suggestions would be greatly appreciated.

explain "blue flame would come out every time"?

Unplug the connector to the Mass Air Flow (MAF) sensor, by the air filter housing. It will throw a check engine light so you will need to get it cleared but drive it with the MAF disconnected for a bit and see if that helps. I'm leaning toward a dying MAF causing the issue.

I am testing that now, have an hour and a half drive to Clarksville I'll see if it starts acting up, if not... I'll be ecstatic! Then I'll get another MAF sensor. Updates coming soon.

Wow! So far it seems okay, the real test will be tomorrow when I am in Nashville doing deliveries all day. So far it seems like it has definitely helped. Got another MAF sensor at a junkyard and put that on. Updates will come tomorrow but thank you so much for the suggestion

Unfortunately it didn't help. I just didn't drive it like I usually do. Any other ideas?

Possibly a bad coil or wires causing a weak spark at higher RPM?? When is the last time the car had a complete tune up including fuel and air filters??

I have replaced all coils, plugs, fuel pump, air filter, all air sensors except for idle air control

Is the check engine light on? If so can you get the codes so we can see what is up with the computer.

Just re-read the original post and I see the cooling fan has been staying on and the problem is getting worse now that it is turning colder. This sounds a LOT like a bad temperature control sensor. I know you said you replaced all the sensors, but this is the sensor located in the thermostat housing just below the thermostat. IF this sensor goes bad it can cause symptoms just like yours.

Oh! I was unaware there would be one under there. I'll see what I can do, also, my CEL Codes need to be cleared and redone because I've unplugged a lot of things and codes have appeared. Would that temperature sensor be a coolant or air temperature? Is it the one screwed in directly to the thermostat housing

Yep, still acts the same after I swapped the coolant sensor :/
Oh another problem has recently popped up as well, sometimes I'll be driving and the speedometer just goes to 0 and my odometer and trip counter just has lines where the numbers go. "-----------" and the lights like before you turn the car on come on like abs brake park brake etc then eventually it goess back to normal

Ok.....Well, my best advice right now would be to get the codes cleared and then see if any come back so we can get a clue as to what may be going on. The dash thing sounds like it may be a ground issue. We had an old 850 that would intermittantly do the same thing (it had over 300K on it) but my son sold it before I could dig into that issue. One other thing you could try is what I call a "hard reset". WIth the car off, remove the two computer modules and re-install them. They are located in the square black box in the front of the engine bay and are easily removed and reinstalled..

I took out the engine and trans computers and it still ran the same, also found a new symptom about the odometer, speedomersp, brakes, abs and trip counter all turning off, when I turn on my headlights usually that makes it all come back on. Sometimes they stop again when they're on, so I turn the headlights off for a second or 2 and then back on and it usually 99% of the time gets it all working again, but it doesn't fix the stupid acceleration problems that I still can't figure out

Ok, the issue with the odometer, speedometer, etc.......sounds like either a bad ground under the dash panel, or possibly the ABS module. When we had a similar issue on an older 850, it was looking like the ABS module but I never got around to checking it out before my son sold the car, Do a foum seasrch and there are a lot of posts on the issue. As for the accelreation issue, since you have a 2000 model, it has an electronic throttle system. They have been known to cause similar issues of going into a limp mode when they get too hot or start to fail. Again, search for ETS issues on the forum as there are tons of posts. I hope this helps,