To MAF or Not To MAF

[99PBATR]

Hmmm I need a bit of advice. I am a new HSV Monaro owner and I have had some interesting advice on here. I have an 06 plate HSV Monaro with a Harrop HH12 supercharger and intercooler. One of the previous owners at some point clearly must have deleted the MAFF as the dyno plot suggests a MAFless tune.

Here is the thing though....the car when I bought it definitely had and still has a MAF fitted...but all is not well as it seems to have a slight misfire and is not good at all from cold. Having stuck an OBD tool on it, its reading a fault with the airflow suggesting the airtemp is very high and dense, which I was wondering if is caused by the MAF on it.

It was suggested to me that I should do away with the MAF as these are often deleted on supercharged cars. What therefore goes in it's place in the tube between the throttle body and the air filter? What are the consequences of dumping the MAF and if it is to be deleted, why would someone go and get one fitted to it again?

I am a little confused so advice would be appreciated all

[99PBATR]

Cheers for the replies. Mine is fitted with an aftermarket K&N huge cone filter, which sits inside a custom made housing inside the left front engine bay to the front of the car.

It says in one of the invoices I have that its a Wortec CAI but after investigation the pipe leading from the throttle valve appears to be made by Harrop, as I contacted them and it looks the same as one of theirs. Needs replacing as its a bit old and slightly perished due to the heat. A new one is £200 from Harrop

Can't say i'm particularly impressed with it, as it seems to be a bit cobbled together. So if I read previous comments right, it would be best to disconnect the MAF or at least unclip the sensor wiring which is currently plugged in? Issue is that whilst it has been clearly mapped in the past, whether it has been mapped since to take the MAF is something I am unsure of. If I remove the MAF will it not play havoc with the airflow that the engine sees and cause issues? To be fair it seems to run crap from cold and has a slight misfire, which I am wondering if is caused by the MAF. I guess I can disconnect it and see how the engine runs without it? I can only assume someone stuck MAF on to get through a MOT for emissions. It's in at Walkinshaws in 3 weeks for a health check and a really good once over but the misfire is really bugging me.

[99PBATR]

Cheers for the advice. Personally I couldn't give a fig about dyno numbers. According to the dyno plot I have that came with the car it managed 578BHP with a mafless tune. I will disconnect the MAF later and see what difference it makes to things. All being well it will improve my misfire....let's wait and see

[99PBATR]

Well that didn't go as planned. I disconnected the sensor wire and connector from the MAF and immediately the engine coughed almost died and then came back but with the engine warning light symbol and buzzer and the screen reading TRAC? Im not sure why this would come up but I assume that has nothing to do with the traction control. I can't see how it could. I'm just not used to this car so sorry if I sound dumb...every day is a school day

[99PBATR]

Cheers fella for the recommendation...it's in at Walkinshaws at the start of next month, so I'm hoping they can tell me all it's faults and we can start correcting them..I feel an anaemic wallet coming on

[99PBATR]

Nice one. I have never been too impressed with the crappy CAI pipework on mine and I did also wonder if there was an air leak in the system somewhere, which will throw everything out.

I also suspect it was a MAFless tune but perhaps now isn't. Now try and explain this one..I put a brand new MAF on it sometime ago and it would not hardly run at allSupercharger was having none of it and car backfired terrible...So I can only assume it's been mapped somehow to the current MAF and that has been modded in some way. The new MAF was a genuine LS2 MAF

[99PBATR]

My guess is that you are absolutely right. When I put a standard one on it, the car misfired and spluttered something chronic, leading me to believe you are bang on. My only guess is that I have a high flow MAF that was either mapped to my car for emissions and perhaps has gone faulty and/or there is an air leak somewhere in the CAI system causing a fault and the OBD to see too high an air temperature. This may or may not cause the ECU to be causing the engine to miss slightly...either that or I am talking total bollo* and its a problem coil pack perhaps on one of the cylinders.

In others experience what common faults cause the LS2 to miss most?

[99PBATR]

Thanks for the reply. The air temp we were seeing was reading in excess of 70c and it was throwing up 4 fault codes when using the OBD tool, so our assumption was that this was not right.

The Dyno plot that came with the car notes a 1 BAR maff tune and a 2 BAR maffless tune. By the looks of it, it made approx. 540BHP @ 1BAR tune at approx. 6400RPM and 578BHP on the 2BAR maffless tune at 6300 RPM. Max torque was 518.5 FtLb

My guess is that based on what I have read that I have perhaps a modified MAF on mine to suit the supercharger? Problem is I don't know much about supercharged cars but I do know it's not running quite right. We will see what the guys at Walkinshaws say when it goes in. Just want to get it running as right as it can be.

Judging by the raft of receipts, Monkfish supplied a lot of the parts for the car inc the Harrop Supercharger as they did for most of the cars on this forum

Edited by 99PBATR on Friday 21st September 10:23

[99PBATR]

wormus said:

Indeed. See the post above ^ he’s the man who supplied them.

I figured that might be the case....the clue being in the name