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MAP resolution

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Hey guys,

I'm wondering whether I'm getting a normal sort of map resolution reading from my map sensor? Seems to be all over the place/not very stable? Is this normal?

20v blacktop with open stacks, map is running off the vac port on the intake manifold. OE map sensor. Link gave me the input values in a custom table for the input. Only other port being used is brake booster. It just seems erratic but stable in rare sections. Is this normal?

I'm new to tuning, only my 5th or 6th time out trying to dial in some power after watching some of your tutorials

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Is the port on a single runner? Have you got a pulse damping chamber/filter or something in line? ITBs have significant pulsation which is why they are other tuned TPSxMAP or TPS with map modifier. For fuel/load calculation there will usually be significant signal damping in the software if there isn't a physical balance rail/chamber/filter. Some systems use the single throttle pulse waveform as a 720 reset instead of a cam sensor.

Look up sampling frequency and aliasing, you may find that is where your smooth/rough observed data is coming from.

I've got the map reading off of the oe port on the back of the intake manifold which I believe has runners from each throttle into the 1 exit port, into a filter chamber then into the map sensor itself.

It's currently tuned using tp on the main fuel table with map on the ignition table as this is where I found the best results with the tune so far. I was just wondering if my map resolution should be reading more stable or if this is normal for an itb engine with open throttles. I may change the ignition table to tp aswell but with both tables using tp would that not make the map sensor redundant? I'm running link g4x with the traditional fuel equation setup

As I mentioned to you on the Link forum it is normal to have a relatively noisy MAP signal on these engines. You've only got 3 or 4kpa of noise which is not going to cause you any difficulties. You can increase the MAP filtering in the software but I typically wouldnt for this level of noise. If you have an idle valve then you are best to keep the MAP sensor as this is the easiest way to compensate for the air that the idle valve bypasses around the throttles.

No idle valve, idling fine using tps. Only vacuum running off the intake manifold is the map. Brake booster is after so it doesn't make a difference am I right?

Brake booster will still take air that your "TP" tells the ecu is going into the engine, MAP will compensate for this but it is so little it wont make any difference. The MAP signal you have is perfectly fine/normal. 3-4kpa noise at idle and almost none as soon as the throttle is open any more than about 5%. What is the actual problem that you are trying to solve?

I was trying to fix a problem where i was getting some advance at low rpm when accel but it's because my load axis on ignition was set to map. I obviously need to change this to tps.

In this case is it correct in saying that the map sensors only function, if my fuel and ignition tables are set to tps, is in the fuel equation? load=map

I was trying to fix a problem where i was getting some advance at low rpm when accel but it's because my load axis on ignition was set to map. I obviously need to change this to tps.

Its a bit hard to tell from just a very zoomed out pic but your map appears to reflect engine load from what I can see. Yes for an NA engine it would be fine to use TP as the load axis on the ignition table.

In this case is it correct in saying that the map sensors only function, if my fuel and ignition tables are set to tps, is in the fuel equation? load=map

Yes, when fuel equation is set to "load = MAP" it is used as a multiplier on injector PW. So it tends to flatten out the shape of the fuel table. MAP may also be used for some lockouts such as idle control, knock control, closed loop lambda etc but is not specifically needed, and if you have a fuel pressure sensor it is used as part of the differential fuel press calculation. You can set fuel equation source to Load = BAP if you want to take MAP out of the fuel equation altogether - fuel table will need doing from scratch however.

Cheers, Adam. Yeah, I had tried to change the fuel table to BAP=load but like you said it put me back to square one on my fuel table and I felt as though I had a pretty decent tune at that point so I didn't try to build a new table. Do you recommend Bap as a load for my setup or just keep it as map if I'm getting decent results? Do you think I'd get more accurate results using bap for my accel enrichment as that's where I feel like my tune needs work.

Another issue in the interim, my alternator has gone, but just prior to this my wideband started showing error codes, 16 - overheating. I've since replaced the alternator but now getting a new error code, under-voltage for 3 or 4 seconds then changes to the same overheating error. Is this due to my alternator going? Could it have cooked my sensor? Was only a month old or so?

And thank you, I do appreciate your time answering my questions mate.

Leave it at MAP, I dont see any advantage in changing to BAP in this case.

Do you think I'd get more accurate results using bap for my accel enrichment as that's where I feel like my tune needs work.

Accel enrichment cant use BAP, BAP is typically static unless you drive up a very big hill. Accel mode should typically be set to TPS.

I've since replaced the alternator but now getting a new error code, under-voltage for 3 or 4 seconds then changes to the same overheating error. Is this due to my alternator going? Could it have cooked my sensor? Was only a month old or so?

Error 16 is "Heated too long", this means the sensor isn't heating at the expected rate based on the duty cycle being sent to the heater. This error has 2 main causes - Either the power wires are too small or its circuit is not capable of supplying the required current, or possibly another inductively noisy device connected to the same power supply can mess up the heating rate measurement (something like an idle valve or ignition coil could do it). If your power/ground wires are ok size (~18AWG), then try moving the relay supply to a "cleaner" source (ie battery) or you can try adding the capacitor as per the alternative diagram in the quick start guide.

Error 16 is "Heated too long", this means the sensor isn't heating at the expected rate based on the duty cycle being sent to the heater. This error has 2 main causes - Either the power wires are too small or its circuit is not capable of supplying the required current, or possibly another inductively noisy device connected to the same power supply can mess up the heating rate measurement (something like an idle valve or ignition coil could do it). If your power/ground wires are ok size (~18AWG), then try moving the relay supply to a "cleaner" source (ie battery) or you can try adding the capacitor as per the alternative diagram in the quick start guide.

I've just puled it apart again and the Can H and Can L wires are both spliced out as a power and earth on the loom I have, so can H is power and Can L is Ground, maybe vice versa. This is how it came from the MRP patch harness and it was working for maybe 3 weeks or so. That's not how it says to wire it on the link diagram

No, you have that wrong. The ECU is receiving the error message so there was communication. For there to be communication there must have been 12V & ground and CAN H & L on the correct wires. There is no way it would work with 12V or Gnd spliced to either of the CAN wires.

I'll rewire the car with a link loom

I've rewired the can lambda as per the diagram preferred method on the quick start. still reading error code 16. Faulty sensor? WHat else can be done to troubleshoot this before I rewire the entire loom?

So the relay goes direct to the battery now? Is it grounded to the battery as well? It is a fairly simple device, I wouldnt consider rewiring the whole engine just to solve the lambda power issue assuming everything else works.

Direct power off battery to relay thay I've ground to the chassis. Do I need to ground the relay to the battery?

No there's a few other wiring things that are quite rummy that need to be sorted it was running a 20v ecu originally so there's joint wires from connectors and shit it would just be good to buy a 5m loom and start again I think.

I mean the ground wire for the CAN Lambda to battery.

Battery to relay

Relay ground to chassis

Ignition source and lambda power on the other pins.

Can lambda ground is just ground to chassis. It was spliced to the main ecu ground but I took it off and ground it separately. That splice was on the mrp loom, just trying everything to get the thing going again. I've got a 22f capacitor now or whatever it's called i'm going to try splice that in on the power and ground and try again. Alot of people have had success with this method it seems.

Battery to relay

Relay ground to chassis

Ignition source and lambda power on the other pins.

Can lambda ground is just ground to chassis. It was spliced to the main ecu ground but I took it off and ground it separately. That splice was on the mrp loom, just trying everything to get the thing going again. I've got a 22f capacitor now or whatever it's called i'm going to try splice that in on the power and ground and try again. Alot of people have had success with this method it seems.