Thread: Maf being economical with the truth

Looking at the recording the first thing I noticed is that the map appears to be wrong for your engine.

The map then engine is running is designed for a 4 wire AAP used in the EU3 engines, while you have a EU2 engine with a 3 wire AAP. This will cause the ECU to read an ambient pressure of around 10kpa lower than actual. This means the waste gate will open at a boost level 10kpa lower than it should. It's not a huge amount but the ECU will behave as if the boost levels are 2psi higher than they actually are, which will effect the way the engine is fuelled.

What ECU do you have in the D2?

The other thing I'd note is the engine is running a little bit hotter than what I'd consider optimal. A cooling system in good condition should run around 88-92.

I'd recommend hooking up wastegate modulator, the engine will be a bit more tractable and it won't effect maximum boost levels.

Otherwise nothing really stands out as seriously wrong. The airflow does look like it's down slightly but that is possibly due to the incorrect map.

cheers
Paul

The ecu is a remapped msb from trs, it does go better than the original it had in it but not as much as I would have thought,they took it for a drive before it was fitted and agreed with me that it runs very well but does not seem quite right for some reason that they could not pinpoint.

Just checked the ambient pressure now with engine off and it is about 95.8 at 435m alt,( which I calculate to be pretty accurate) either the aap is faulty or I have a intake restriction somewhere,the snorkel I have on it does restrict a bit , but even without it hooked up it still is lower than I would like,the reading varies but sometimes its worse than others for some reason,

Initially the car was running way too cold, about 75 degrees max, I fitted a new "aftermarket" thermostat and it is now always about this hot, I would not recommend an aftermarket one after seeing this, I am not particularly happy about this and would have changed again except its a terrible job.

I will hook up the wastegate controller again, I just forgot I had unhooked it.

Was it just the aap readings that make you think the map is wrong?


cheers james

Originally Posted by shack

Was it just the aap readings that make you think the map is wrong?


cheers james

Yes it's usually a good indicator of using the wrong map on the NNN, but if it's an MSB ECU then you should have be right. Looking at the BOM site the stations at Eudunda and Clare are at 395M and 415M and have readings in the range of 1000-1010hpa today.

I've got a spare three wire AAP you can borrow to check to see if it makes any difference.

cheers
Paul

Well that's very decent of you ,

just went outside and re checked the altitude and its about 411 metres on a different gps , not what i wrote before, however I'm not sure how accurate it is, will be near the coast soon so will check what it reads then, may take you up on the sensor though, thanks

cheers james

edit: just checked my 2 barometers, first one is reading 1010 hpa, the second is reading 1012, should this be a direct comparison over to kpa as might seem logical to me, to compare to the aap on the car?

Originally Posted by shack

Well that's very decent of you ,

just went outside and re checked the altitude and its about 411 metres on a different gps , not what i wrote before, however I'm not sure how accurate it is, will be near the coast soon so will check what it reads then, may take you up on the sensor though, thanks

cheers james

edit: just checked my 2 barometers, first one is reading 1010 hpa, the second is reading 1012, should this be a direct comparison over to kpa as might seem logical to me, to compare to the aap on the car?

The AAP should be pretty close to atmospheric pressure with the motor switched off and the engine cold. It's also worth checking the manifold pressure is reading close to same value as the AAP sensor with the engine off.

cheers
Paul

Just checked both readings this morning cold, the aap is 95.65 and the manifold is 88 , something would seem to be amiss, I have already tried a different map iat sensor as well but didn't take an ambient reading but the car does not behave any differently with this one.

edit: just checked again, now the ambient temp has warmed up and now the aap is 95.8 iat/map is 93, so switched to a different iat map and that one read 96, so plugged back into the original now that reads 96 as well,

I think the prince of darkness has paid me a visit

James,

Just had a thought. The BOM pressure figures are adjusted to Mean Sea Level, so still need to be adjusted for altitude. The sensors will be reading about 5kpa lower than sea level at 400m, so 96Kpa is not unreasonable. 88Kpa is a bit wonky.

cheers
Paul