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Megasquirt accel enrichment problem
clairetoo - 9/7/12 at 07:09 PM

I've just spent some time getting my throttle bodies balanced on my Mx5 V6 project , but I have been having problems with the accel enrichment cutting in at tickover , with the fueling and revs going all over the place
The only thing that stopped it was disabling the accel enrichment . I remember having the same thing on my Fury - but that was four years ago , and I cant remember how I cured it (plus that was in Ms1 , and the Mx5 is running Ms2)

Can anyone help - I now have a steady slow tickover , `bodies balanced , allmost ready to drive ............ but this has me stumped

MakeEverything - 9/7/12 at 07:25 PM

I had that too.

Check;

Earths to the ECU are common and to the same point
Earth to the engine is good
Connections within DB37 are good and that the plug is connected properly (fitted tightly)
Check Hall (VR) Sensor is ok and that its lead is undamaged and screened.

Sounds like a 'Noise' problem causing the RPM to jump which is then causing the Accell Enrichment settings to cut in.

[Edited on 9-7-12 by MakeEverything]

coyoteboy - 9/7/12 at 07:30 PM

TPSdot or MAPdot?

clairetoo - 9/7/12 at 07:36 PM

quote:
Originally posted by coyoteboy
TPSdot or MAPdot?

Its running AlfaN so I guess TPSdot ?

Its not that it revs and then accel cuts in - at tickover , throttle position (on the laptop) isnt steady , and injector duration goes up and down , which then causes the tickover to waiver .
With accel turned off - no problem at all .

matt_gsxr - 9/7/12 at 08:35 PM

With MS2 you may be running mapdot or tpsdot, or a blended version of both.
This is independent of whether you are running alpha-N or Speed-Density.


How noisy are the MAP and TPS? Maybe show a screen shot that includes MAP, TPS, MAPdot and TPSdot.

The "mapdot threshold" needs to be above the noise level of the mapdot signal, and the "tpsdot threshold" needs to be above the noise level of the tpsdot signal. My values for mapdot and tpsdot are 100 and 80 these are on the high side from what I have read.

If MAPdot or TPSdot is really noisy then you can adjust the percentage "Throttle position vs manifold pressure ..... %" to 0% or 100% which will mean it uses all of MAPdot or TPSdot and so it takes no account of the other one.


Decreasing the noise on the MAP and TPS lines is always a good idea if possible. You can reduce the noise on the map signal by increasing the volume of the tube (and partially blocking it at the TBI end) if that is your problem. ALso you can reduce the noise on these signal lines using "Basic settings, General, lags" if the values are 100 then there is no smoothing, lower values smooth out the noise more, 50% is a fair amount of smoothing for MAP and TPS.

Hope that helps.

Matt

BaileyPerformance - 10/7/12 at 12:53 PM

quote:
Originally posted by clairetoo
I've just spent some time getting my throttle bodies balanced on my Mx5 V6 project , but I have been having problems with the accel enrichment cutting in at tickover , with the fueling and revs going all over the place
The only thing that stopped it was disabling the accel enrichment . I remember having the same thing on my Fury - but that was four years ago , and I cant remember how I cured it (plus that was in Ms1 , and the Mx5 is running Ms2)

Can anyone help - I now have a steady slow tickover , `bodies balanced , allmost ready to drive ............ but this has me stumped


Hi Clare,

Make sure the ECU grounding is good (normally ground to the block)
Make sure the engine is earthed to the chassis with a large cable
Make sure the battery is connected to the block/chassis with a large cable

We always use screened cable for the TPS as MS2 does seem more susceptible to noise on the TPS, you can get way without screened cable on an MS1.

Normally, if you have the engine tuned spot on in Alpha N very little accel enrichment will be required as you can afford to set the threshold high to avoid unwanted shots due to noise.

clairetoo - 13/7/12 at 09:02 PM

I'm pretty sure its noise on the TPS signal - the wireing does run fairly close to the coil , and just pushing it away as much as space will allow makes a difference .
So now I'm after about a meter and a half of three core shielded cable.........and the time and weather to get it sorted