Gokul

Hi guys,

Been noticing this problem for sometime on my ML320. It never has caused performance issues but has now started occurring a lot more frequently giving me a little worry.

The symptoms are -

1. When the car starts, typically before the engine gets fully hot at 80C, the car begins to sputter when there is no accelerator applied
2. The sputtering can be mild or severe
3. Problem does not occur as soon as I start the car, but typically within 1-2 minutes when I stop at a signal outside my condo (engine not fully warmed up)
4. The sputtering is very random, sometimes occurs, sometimes not, but mostly occurs within 5 minutes of staring up the car
5. During the sputtering, pressing the accelerator does not cause any acceleration, rather the car just sits there sputtering
6. The engine never shuts off, just feels like there's not enough power to move the vehicle (maybe fuel shortage?)
7. After about 5-6 seconds the sputtering stops, irrespective of whether I tried to accelerate or not
8. I've noticed this sputtering occur more frequently in the summers, and hardly ever in the winters

Any ideas what could be causing this?

khomer2

Any CEL?
Scan and post any saved codes.

When warmed up, any acceleration issues? rough or lumpy idling?
Could be a number of issues:
MAF
FP FF
Cat /O2 sensors

From what you stated, it seems you have had previous issues, however, now, it's more prominent and noticeable, affecting normal driving.
Point 8 is irrelevant right now based on your present real-time situation.
No mention of starting problems.

Gokul

Hi Khomer,

Thanks for the reply.
There are absolutely no other symptoms of the problem, the car runs as smooth as the first day I got it.
No starting trouble either. Turns on the first turn of the key, every time.

I haven't scanned it though, do you reckon doing that would be helpful in this case?
What is this FP/FF problem you're talking about? Never heard of that one before....

khomer2

It's always a good idea to scan for any saved codes.
You can still get error codes without a CEL coming on.
FP=fuel pump
FF=fuel filter (when was the last time you changed? present mileage?

Simple things first.
I would clean the MAF first and see how it runs after cleaning.
Also, check of vacuum leaks - on these older suvs, the lines get brittle, break crack etc - inspect carefully or do a smoke test with a DIY smoker.

Gokul

I haven't changed the FP or FF since I got the car.
She's done 235000 kms.
I took out the engine air filter the other day and cleaned it, I'll also try cleaning the MAF.

khomer2

Engine filter - you mean replace it, correct?

Speaking of filters, if you havent yet, replace the cabin filter too.

Gokul

Nope, I'd changed the engine air filter and cabin air filter about 12000 kms ago.
I took the engine air filter out yesterday to check if it was dirty, but it wasn't so I just vacuumed it and put it back.
I'll get to the cabin air filter later. :-)