Bosch v 5AM and barometric pressure / temp

[TVR Beaver]

Have been playing over the last few months trying to get rid of the last few bit’s of ‘hesitance’ at 1800 RPM… more for fun than need, as it’s not bad at all now… (but not as good as it was!);)

When we changed a few things last year, as well as the Cam and induction etc, Mark Adams suggested I go for the Bosch MAF and Red Top’s (standard upgrade so I hear)

Anyway.. I was out in the car last weekend and it wasn’t great in town.. a bit hesitant around 1800 and I could also feel this in 5th on the motorway at 50 mph a tad… that said it was 20 deg plus last weekend but for sure, you didn’t get pushed back in your seat as much as other days..
Last night it was cooler (8 or 9 deg) with no doubt thicker air and the car was a different animal.. very smooth and went like a rocket!.. and it was about this temp when Mark set it up last year..

Now I know air temp etc will contribute greatly to how an engine carberates and combusts the gasses, but I thought the MAF meter accommodated this to some extent?.. obviously it can’t make the air cooler or thicker, but may be adding a bit more fuel to compensate?.. I’m not sure how it would work but Mark argues this is the advantage of MAF systems over the others.. for sure my set up does appear to go weak when it’s hot.

Question is, is there anything else that could be showing the same symptoms?.. fuel pressure / temp may be.. ECU temp take-off?...
The old 5AM didn’t appear to suffer this (to the same extent anyway) so again is it something with the Bosch that’s not quite as good as the Lucas??

I’ve mailed Mark on this in the hope it’s something he can address in the chip but he appears to be missing at the moment.. probably over-seas.. but has anyone else seen this in their cars (Bosch or Lucas)?
Must say when on the rollers, how would you set up for this unless the rollers were in a temperature controlled room?.. however I’m sure there must be base map’s to cover this sort of thing in the chip… May be mine just needs a tweak

Cheers!!

[blitzracing]

The Lucas AFM does take care on the change of air density and temp automatically by the use of two sensors, one heated wire thats cooled by the passing air volume / rate to give a resistance change, and one temp sensor for the air thats not heated, so it reads the ambient, so its output should relate directly to the amount of available oxygen to burn. I dont know if the Bosch is the same, but id supect it does, as it would be seriously flawed with out this system.

[wycoller]

blitzracing said:

The Lucas AFM does take care on the change of air density and temp automatically by the use of two sensors, one heated wire thats cooled by the passing air volume / rate to give a resistance change, and one temp sensor for the air thats not heated, so it reads the ambient, so its output should relate directly to the amount of available oxygen to burn. I dont know if the Bosch is the same, but id supect it does, as it would be seriously flawed with out this system.

the Bosch also has 2 sensors probably for same reasons, i am going to record my AFM outputs against intake boost pressure, hopefully Mark Adams should have some data, i am looking for data that may confirm i am loosing boost on overlap due to wrong cam etc.
i also wish to check if prob is due to prob on intake to SC etc.
John when you finally sort that Griff out etc etc when i was out in it i thought the engine was very smooth and pulled well

[TVR Beaver]

Cheers Guy's... I am only playing with the last bit of annoyance now and it is slight, thats why it's not been obvious whats going on... but having twigged it, it is now!
I sure the bosch works in the same way (although you do cut a wire fron the ECU plug when you fit it and instead give it a voltage supply?).. but I guess if it don't conform to the std map then there is no way of knowing... you can only set for the feedback on that day.
As said, I've mailed MA and I'm sure he'll have the answer....
.
Good luck with your readings James.. It will be a monster when you get it sorted...

Cheers

[wycoller]

TVR Beaver said:

Cheers Guy's... I am only playing with the last bit of annoyance now and it is slight, thats why it's not been obvious whats going on... but having twigged it, it is now!
I sure the bosch works in the same way (although you do cut a wire fron the ECU plug when you fit it and instead give it a voltage supply?).. but I guess if it don't conform to the std map then there is no way of knowing... you can only set for the feedback on that day.
As said, I've mailed MA and I'm sure he'll have the answer....
.
Good luck with your readings James.. It will be a monster when you get it sorted...

Cheers

cheers do not hold ya breath with MA for me getting the readings thats easy part, finding out if the data is related to data MA has etc may be prob, i never got a response from Colin Harvey on my thought process, Ian at TvR thinks its a logical step
i agree with what you are doing as monitoring , etc tunes you into the car
etc i,d love to get too that point by sorting it myself.

[TVR Beaver]

That's interesting... There are 5 connectors on the Bosch MAF (4 wires going to it).. the first one is 'not used'... it's refered to as Temp sensor!... so is going Bosch a backwards step in this area?.. the connector on the 5AM also uses 4 wires and some pins are not used in the plug so may be this also didn't use the temp bit, or may be with the PCB in this unit, It didn't have to??
Just hope again that a few extra BHP has not been gained at the expence of drivabuility...
Will see what MA say's when he replies... Cheers

[blitzracing]

The 5 AM has 4 wires, 12v, ground, output and CO trim (not used on catalyst cars), so any temp sensing is part of the output signal. Cant pass comment on the Bosch however.

[TVR Beaver]

Hi Mark... On the Bosch they are:-
1 Air Temp
2 +12 volt ignition
3 Signal ground
4 +5 volt referance
5 Airflow signal

and as I say '1' is not used....
You do trim on install a voltage depending on cat or pre-cat giving I think 1.8 volts (Co trim).also using a variable resistor... but looks to me like the air temp is not used.

The Lucas unit has a PCB and trim within it.. but the bosch does not have anything here... so may be the Lucas one works this out and as you say, compensates accordingly??

I suppose though as there is a pin for this, if you understood what was going on here, that you could rig up an air temp compensation feed.. not sure what you'd go into or the IO's required??.. again.. may be MA can comment?

[daxtojeiro]

This problem is more than likely related to the ignition advance as opposed to fueling. I would imagine that the fueling is on the edge for the advance you have so when the incoming air is warm its just enough to make the issue raise its head.

Gain control over your ignition and I feel this problem will go away.

Gain real control of fuel and ignition and it will go away
Phil

[wycoller]

[quote=daxtojeiro]This problem is more than likely related to the ignition advance as opposed to fueling. I would imagine that the fueling is on the edge for the advance you have so when the incoming air is warm its just enough to make the issue raise its head.

Gain control over your ignition and I feel this problem will go away.

Gain real control of fuel and ignition and it will go away
Phil on fully mapped fuel with sequential etc coil packs and getting rid AFM done properly you put to bed all these issues with TIV RV8,s shunting etc thats a done deal is it if so what type you recommend and what cost
cheers jim

[daxtojeiro]

wycoller said:

daxtojeiro said:

This problem is more than likely related to the ignition advance as opposed to fueling. I would imagine that the fueling is on the edge for the advance you have so when the incoming air is warm its just enough to make the issue raise its head.

Gain control over your ignition and I feel this problem will go away.

Gain real control of fuel and ignition and it will go away
Phil on fully mapped fuel with sequential etc coil packs and getting rid AFM done properly you put to bed all these issues with TIV RV8,s shunting etc thats a done deal is it if so what type you recommend and what cost
cheers jim

To get fuel and ignition control in wasted spark (coil packs) and fuel in batch fire (the same as the Lucas) then you need:

MS2 ECU, bare ended loom, comms lead, 2x coil packs, HT leads, 36-1 crank wheel, crank sensor, air temp sensor at £610, see my site for more options, I dont know if Im allowed to link to it so I wont, but its in my profile.

You can also have the same with semi-seq fuel for a little more and I've just finished testing the MS3 in full sequential mode which will give you sequential fuel and ignition, cost is yet to be sorted as we havent had many driver boards built as yet.




Surely by the time youve paid for chips and rolling road runs, etc, your better off going a different route than the Lucas, especially if the issue is the ignition, which is where I suspect it is in most cases,

Phil

Edited by daxtojeiro on Tuesday 1st June 06:59

[TVR Beaver]

Hi Phil... I've taken my vac advance out to come in at 2K (by moving the takeoff) but not sure when the weights start?.. you could be right although it's as strong as an anything at all other times.... It's just around the 1.8K mark and worst with warm thin air?
.
I've been looking on your site... Is there any issue with type approval on after market systems? I know the bike world is getting a bit tough here now with insurance etc?... It does look like a good system.... and could give hours of playing I would of thought?.. May be something to consider longer term but I did want to keep the car as standard as I could....
There must be a way of cracking the 1.8K issue!.. they all do it to some extent..

[daxtojeiro]

TVR Beaver said:

Hi Phil... I've taken my vac advance out to come in at 2K (by moving the takeoff) but not sure when the weights start?.. you could be right although it's as strong as an anything at all other times.... It's just around the 1.8K mark and worst with warm thin air?
.
I've been looking on your site... Is there any issue with type approval on after market systems? I know the bike world is getting a bit tough here now with insurance etc?... It does look like a good system.... and could give hours of playing I would of thought?.. May be something to consider longer term but I did want to keep the car as standard as I could....
There must be a way of cracking the 1.8K issue!.. they all do it to some extent..

Hi,
there are Plug-n-play solutions offered by V8D that allow you to gain full control over the fuel, if you dont want to go for coil packs, theres also a wasted spark option in the PnP stuff which would give you spark control too, but you will have to add a 36-1 crank wheel and coil packs so it wont look quite standard with that.

A lot of people fit these to kit cars that have to pass the SVA/IVA test and they don't have issues. I've also had people tell their insurers and they didn't ask for type approval, I would guess its treated the same as fitting anything thats not direct from the OEM,
Phil

[TVR Beaver]

So looks like the Lucas system does adjust according to the air temp coming in.... But it's not used on the Bosch??.. Still awaiting a reply from Mark on this one....

Extracted from the Rover Manual:-

The hot-wire air flow sensor is mounted on a
bracket attached to the left hand valance, rigidly
connected to the air cleaner and by hose to the
plenum chamber inlet neck.
The air flow sensor consists of a cast alloy body
through which air flows. A proportion of this air
flows through a bypass in which two wire elements
are situated: one is a sensing wire and the other is
a compensating wire. Under the control of an
electronic module which is mounted on the air flow
sensor body, a small current is passed through the
sensing wire to produce a heating effect. The
compensating wire is also connected to the module
but is not heated, but reacts to the temperature of
the air taken in, as engine intake air passes over the
wires a cooling effect takes place.

The electronic module monitors the reaction of the
wires in proportion to the air stream and provides
output signals in proportion to the air mass flow
rate which are compatible with the requirements of
the E.C.U.

[Mark Adams]

Hi John

Although I rarely look at Pistonheads these days, I've just spotted this. I'm sorry for the lack of response to all my Clients, but I am simply swamped with messages and enquiries. I get around 20-30 messages a day, and most of them need very detailed individual answers. There simply aren't enough hours in a day to cover them all, so often you need to be persistent.

I have answered over a dozen e-mails from you on this subject, but I am running out of ways to say it. I'm not meaning to shoot you down here, but there are a number of relevant factors here that the readers of this thread would not be acquainted with.

When I set this car up on the rollers before, it had a camshaft variant with a very narrow Lobe Centre Angle. This gave it a great top-end, and very nasty manners low down exactly as you would expect.

However the behaviour you are now noting is after a change of camshaft and fitting of a plenum spacer, but still running on the old setup. You cannot draw any conclusion from the current behaviour until the car has been set up again - it is not an indictment of the AFM at all.

An engine is mapped for efficiency – if it was 100% efficient there would be no need to map it because it would become a linear function. The camshaft has a profound and massive effect on efficiency.

To answer your original question about the airflow meter, all hot wire and hot film AFMs respond to changes in air density, temperature, humidity, etc. The purpose of the AFM is to measure the true Mass of air entering the engine.

This is also the reason why Mass airflow measurement is the most accurate way of metering an engine's fuel requirements, for engines where the fuel is injected into the inlet port. The term "Air Fuel Ratio" (AFR) is actually expressed in terms of mass, and represents the chemical proportions necessary for complete combustion.

The particular variant of the Bosch meter used in this conversion does carry a separate air temperature sensor, but this is used by the Bosch system for the control of ignition timing. Air temperature has a specific effect on the ignition process, which is very different to fuelling requirements.

On another note Daxtojeiro (Phil), I'm quite surprised at the somewhat blatant plugging of your own products as in this thread. I'm even more surprised that the moderators are happy about it, and it's not something I ever do as a trader of some repute. The behaviour on this particular vehicle is actually due to a combination of camshaft and port characteristics, and not specifically ignition timing. However there are certainly gains to be had with mapped ignition - a point I have made many times before. This conclusion is backed up by thousands of dyno hours, and not just a feeling.

[spend]

Mark Adams said:

The particular variant of the Bosch meter used in this conversion does carry a separate air temperature sensor, but this is used by the Bosch system for the control of ignition timing. Air temperature has a specific effect on the ignition process, which is very different to fuelling requirements.

Can you spell out the difference with the 5AM Mark? I thought the original question was that the 5AM had a temp sensor wired to the 14CUX or am I confused.

PS Agree with the 'plugging' but we'll just be labeled as grumpy old farts for that times change...

PPS Surprised at your proclamation on cam + ports, V8D did all Johns car with a cam and manifold+trumpet base+ plenum IIRC, their own parts combination that they must have used 100's of times successfully. That I thought was the major source of Johns frustration, but I may be behind the times on this?

[TVR Beaver]

Hi Mark.. the only change is the Cam.. the plenum spacer was on there before you set it last year....(I've only had 2 mails from you this year... More last year when we were setting it up.. Have I missed some?)
As I've said.. it's a totaly differant car now and I'm only playing with the last bit of 'hesitance' around 1800 RPM... but in being so slight now, it has become more obvious when it happens.

When it's a cooler day there is no isuue around this RPM and the car goes very well.. but as the air temp increases on hotter days, it tends to get a bit wooley at 1800 rpm. I did read up on how the Bosch worked (my mate who works at Wabco got me the data sheets) and it struck me we weren't using the Air Temp sensor. I'm sure the fueling is not too far out as the MAF should take care of the cam change (not spot on I agree but Rob said it was okay), but wondered if somehow the 'Air Temp' output could be used may be on the timing side (or do you have map's to cover this?)?

So I assume the output you use takes into account the Air temp / Pressure and Humidity.. (For my interest only.. but obviously these things are complex..a little knowlage and all that ). Just want to get it as good as I can before we have another go at setting it up..

Cheers... John

Edited by TVR Beaver on Wednesday 2nd June 15:59

[spend]

It doesn't need any of those corrections AIUI John, the AFM is telling the ECU you have XXX oxygen molecules to fuel for (mass)

The only reason we worry about keeping temps down and pressure up is to try and squeeze more of the little blighters in

[blitzracing]

I do wonder if humitity comes into the equation somewhere, more than simply the free oxygen content.

[spend]

Steam & petrol engine all rolled into one?