2001 S60 5MT Base Pulse/Jerk During Acceleration

WarbirdPilot91 · Post by **WarbirdPilot91** » 13 Nov 2014, 11:09

Hello, fellow Volvonians.

My 01 S60 5MT has been treating me great, however, I have recently run into a weird problem. Coincidentally, this exact thing happened this time last year to my old Honda Civic. Regardless, here's the issue...

Car starts and runs fine @ idle. When I go to accelerate, the engine runs strong (no drop in RPMs), however in each gear (shortly after shifting), the car seems to pulse/jerk/stutter for a bit until more RPMs are added. This sensation seems more apparent at low speeds and higher gears, such as 5th Gear @ 30mph, 2-4 at 15-30mph. The car is showing no codes either on my OBD-II scanner.

To me, it feels like the brakes pulsing on their own, I hear a "thumping" pulse kind of noise (if that makes sense.) I've made a list of all the possible things to check (CV, wheel speed sensor, ign coil, etc.) However, I really want to see if there is a known issue with this particular model. What do you guys think could be the issue? She is going into my mech. next week, as this feels a bit above my level.

Thanks!

draser · Post by **draser** » 13 Nov 2014, 13:07

Clutch judder?

WarbirdPilot91 · Post by **WarbirdPilot91** » 13 Nov 2014, 13:40

It jerks when clutch it both engaged and not engaged

Post by **chrism** » 13 Nov 2014, 21:54

When it stutters, does the the tach jump up and down like the engine is missing?

WarbirdPilot91 · Post by **WarbirdPilot91** » 14 Nov 2014, 08:03

chrism wrote:When it stutters, does the the tach jump up and down like the engine is missing?

It does not, which has me puzzled...lol. Would it help if I got a vid of it?

Post by **chrism** » 14 Nov 2014, 08:29

After I asked that I realized you have a manual trans. So any engine missing probably wouldn't have a big effect on the indicated RPMs, as long as the clutch is still engaged, like an auto trans would.

I would be tempted to rig a fuel pressure gauge to the injector rail and tape the gauge to the windshield so that I could see, real time, if there's a drop in pressure that correlates with the stuttering. At least then you could either realize a problem in fuel delivery or eliminate that possibility which cuts your diagnostic effort in half. That's how I diagnosed a bad fuel pressure sensor that was causing a miss but wasn't triggering the CEL.

How old are the spark plugs? For about $12 you can pop a set of new copper cores in there. A bad spark plug tends to rear its ugly head when the engine is under heavy acceleration and not so much when it's sitting there idling.

Post by **oragex** » 14 Nov 2014, 09:25

was the fuel pressure sensor replaced? (recall)

may also inspect spark plugs as mentioned, fuel filter (if plastic gas tank), spark plugs, clogged injectors, vacuum hoses

WarbirdPilot91 · Post by **WarbirdPilot91** » 14 Nov 2014, 17:48

chrism wrote:After I asked that I realized you have a manual trans. So any engine missing probably wouldn't have a big effect on the indicated RPMs, as long as the clutch is still engaged, like an auto trans would.

I would be tempted to rig a fuel pressure gauge to the injector rail and tape the gauge to the windshield so that I could see, real time, if there's a drop in pressure that correlates with the stuttering. At least then you could either realize a problem in fuel delivery or eliminate that possibility which cuts your diagnostic effort in half. That's how I diagnosed a bad fuel pressure sensor that was causing a miss but wasn't triggering the CEL.

How old are the spark plugs? For about $12 you can pop a set of new copper cores in there. A bad spark plug tends to rear its ugly head when the engine is under heavy acceleration and not so much when it's sitting there idling.

Good idea on the fuel pressure tester, I will explore that option! The plugs are about 2-3 months old, I recently replaced them along with ignition coils. I could check to see if any are faulting, but the last time one did, the CEL engaged (hence the reason why I changed everything, LOL.)

WarbirdPilot91 · Post by **WarbirdPilot91** » 14 Nov 2014, 17:50

oragex wrote:was the fuel pressure sensor replaced? (recall)

may also inspect spark plugs as mentioned, fuel filter (if plastic gas tank), spark plugs, clogged injectors, vacuum hoses

I will check the fuel pressure, the fuel pump was replaced before I bought the car last May, but I do not know if they did the filter as well. Which vacuum hoses should I check/how? (Pardon my ignorance.)

WarbirdPilot91 · Post by **WarbirdPilot91** » 14 Nov 2014, 18:08

Here's a crappy vid of it, lmao. Anyhow, anytime the camera shakes or you hear that rattle noise, that is the jerking/pulsing I am referring to. Notice the RPMs seem steady, nothing erratic.