118TSI MAP sensor wierdness

[cme2c]

2009 118TSI. Engine replaced at 40, 000, now 150000, Recent new coils and plugs after scan showed random misfire all cylinders. Fine when it's cold, but when it warms up it will randomly jerk, like a momentary stall, then come back. Most annoying and disconcerting, like running over bricks! It was back to get the DQ200 preeure accumulator recall redone, and the dealer scanned it. Random MAP and vacuum codes. So, I got a cheap eBay OBD2 wifi dongle and on my iPad, the MAP sensor readout jerks when the engine does, and the fuel flow momentarily goes to zero, then back to something sensible. I am going to try cleaning the MAP sensor, then replacing it if that doesn't work. No check engine lights! Wierd.

[Lucas_R]

Some good info in this post relating to the 118TSI misfire: Golf 118 TSI Engine Failures and Service Campaign 24S4

VW revised the software for the 118TSI engine (and DSG) several times to try and cure the issue these things have with blowing themselves to bits. Would be a good idea to check you have the latest version of the software.

Also remove your spark plugs and check their gap. Gap to 0.7-0.8mm. If they are gapped at 1.1mm then this will be contributing to misfires.

Otherwise i suggest you check/replace the cam solenoid because when these get old they fail to operate smoothly and cause the engine to intermittently die (for like 0.5-1.0 second) which feels like a big misfire (my Subaru has this issue at the moment and i just purchased 2x new cam adjuster solenoids to fit). I also had to change this part on my Mk6 GTI a few years back.

Also check/replace your fuel filter, because if this is dirty/clogged then it could temporarily starve the engine of fuel at certain times causing a misfire. And while you are checking fuel related items, might be a good idea to check your fuel pumps (the in tank low pressure pump as well as the high pressure fuel pump (HPFP) driven off your intake cam).

And lastly, make sure you are running the engine on 98 octane premium fuel. You could probably get away with 95, but for the extra $1 it will cost you to fill up with 98 I wouldnt risk it.

[cme2c]

Some good info in this post relating to the 118TSI misfire: Golf 118 TSI Engine Failures and Service Campaign 24S4

VW revised the software for the 118TSI engine (and DSG) several times to try and cure the issue these things have with blowing themselves to bits. Would be a good idea to check you have the latest version of the software.

Also remove your spark plugs and check their gap. Gap to 0.7-0.8mm. If they are gapped at 1.1mm then this will be contributing to misfires.

Otherwise i suggest you check/replace the cam solenoid because when these get old they fail to operate smoothly and cause the engine to intermittently die (for like 0.5-1.0 second) which feels like a big misfire (my Subaru has this issue at the moment and i just purchased 2x new cam adjuster solenoids to fit). I also had to change this part on my Mk6 GTI a few years back.

Also check/replace your fuel filter, because if this is dirty/clogged then it could temporarily starve the engine of fuel at certain times causing a misfire. And while you are checking fuel related items, might be a good idea to check your fuel pumps (the in tank low pressure pump as well as the high pressure fuel pump (HPFP) driven off your intake cam).

And lastly, make sure you are running the engine on 98 octane premium fuel. You could probably get away with 95, but for the extra $1 it will cost you to fill up with 98 I wouldnt risk it.

All very sage advice. The car was scanned after the last DQ200 accumulator recall and came back up to date. I exclusively use 98, V-Power or Ultimate. My mechanic tells me there are 2 part numbers for the spark plugs with different gaps and the ones he used have 0.8mm. Only 2 phasers on your subi? My wife's 86 has four of them! Anyway, the old Golf is running fine now, but thanks for the tips!

[Lucas_R]

All very sage advice. The car was scanned after the last DQ200 accumulator recall and came back up to date. I exclusively use 98, V-Power or Ultimate. My mechanic tells me there are 2 part numbers for the spark plugs with different gaps and the ones he used have 0.8mm. Only 2 phasers on your subi? My wife's 86 has four of them! Anyway, the old Golf is running fine now, but thanks for the tips!

It could also be carbon buildup on the injectors and intake valves - carbon buildup causes misfires and is common on all direct injection engines no matter which brand of car. Some injector cleaner should help clean the injector tips but suggest looking into a proper carbon clean (several methods can be used, but the most common is blasting the intake valves with crushed walnut shells and they come up like new. Then the intake manifold and injectors are chemically cleaned).

And yes, only 2x cam phasers on my Subaru (its a 2008 model Liberty GT to not exactly a modern engine). They arrived in the mail yesterday so will be fitting them sometime this week.

[cme2c]

I used Liqui Moly intake and upper engine cleaner. It seems clean enough and I don't really want to take the convoluted intake apart ATM as it's running fine now. Check out Car Wizard on YouTube. He got the intake and valves perfectly clean on an Audi V10 with cleaner and compressed air! I was watching as he did it and still couldn't believe it.

I hate to sound like a fanboi but,honestly, the Liqui Moly was just something to try before the walnut shells.So far, so good. I did also use some injector cleaner. It's smooth, has its power back and uses less fuel.