S Max 2.5st poor running mind boggled

Hi guys,

im absolutely mind f*#:ed with my S Max 2.5st running problem, im praying one of you guys may be able to help me. I’ll try keep it short and not boring.
so…what started as a slight stutter/misfire (felt more like engine flooding) when sat idling in traffic for anything over approx 20mins. I live in London 😞

This went on for a long time, not really getting worse but very annoying. I could generally get rid of it by giving some high reving out of gear, or switch off for a bit.

eventually thought I’d treat myself to a stage 1 map, praying this would fix it and always wanting it so thought sod it.

Although I’d already changed plugs thinking that was the cause a while ago, I did them again with new Coil Pack, MAF Sensor, Air Filter, Oil & Filter change ready for tuning.

I chose to go with SuperChips. When they first came they plugged in and said my ECU has to be Hard Wired (said that’s the only way with my model car), so sent another guy  with correct equipment. He got under the wheel arch and went to work. 90mins later he was done. 
I went for a test drive and OMG, the acceleration and torque, especially from 2nd gear and up put a permanent grin on my face, she even wheel spins in 2nd. So, anyone thinking of having a map done, do it… you won’t regret it.

anyway, what I did notice was a very faint blip on initial foot down (about half a second) but nothing else. However, as happy as I was the main problem remained.

Now, 6 months later everything is going to *****. (No, I haven’t been ragging her,lol. Just nice to know power is there if you know what I mean)

Over a very short period she’s gone from random stuttering/power loss, then normal. To one day driving down motorway with horrible stuttering on slightest touch of accelerator, put on cruise control which helped a bit, hoping I could complete my journey. Then that was getting worse so I eventually pulled in to next services and called breakdown to take me home.

The following weekend I took her round the block and she was responsive again but still with the slight blip which was now a little worse. Weekend after that I tried again which after 100yards went into limp mode. So switched off, restarted (came out of limp mode) gently drove back and so here I am..

Im looking hard for any air leaks etc but I may be missing them or completely something else.

She will always start and idle, sometimes stutter when I rev, sometimes rev normally like nothings wrong. I can’t blind trust a garage anymore as been fleeced for a few grand before when I did it (blind trust) with my previous car to this ML350. I actually enjoy getting my hands dirty and working on my car so that’s not a problem, my trade is building.

I have a nice Atoto stereo fitted with an OBD2 adapter that gives real-time info through the stereo. I’ll upload a pic of this to show running information that may point something out to you guys.

If anyone out there can help me, please please please do…..

Cain

Edited December 31, 20223 yr by Cain