From Performance Oriented Dyno Map to SMOG able map

Hi All,

New to tuning here just finished going through the courses, I have a performance oriented dyno tuned map it is tuned by a local garage which is no longer here. I am trying to build a SMOG able map out of this by adjusting the AFR.

I managed to get it under SMOG requirements at idle by adjusting the AFR/Lambda Target Table (1.0x to match 14.7:1 s. value) however when I move onto the next stage getting it up to RPM (3000RPM) all hell brake lose. The digit jump from 0.04 to x.xx for CO and 005 to 1000 for HC.

What else should i look into other than fuel table and AFR/Lamba target table? I see the map have open loop lamba table activated and uses traditional fuel equation. I have 2 x Euro IV CAT on my exhaust for SMOG and use the factory ECU to pass SMOG previously but it has since died.

For emission test by running close to 14.7:1 the HC and CO reduced to SMOG acceptance level at idle. HC target below 10 and CO below 0.05.

Vehicle: Custom build 4AGE engine 9.5:1 compression ratio, 35cc chamber volume with 262 intake and exhaust cam 9.0mm lift

ECU Link G4+ Thunder ECU

Anyone shed some light, much appreciated.

Cel

The first thing you need to do is get us some more background information.

What kind of emission test does the UK use? I'm trying to find something online. Here in the USA we have a few different types of tests depending on where you live. Some just measure idle CO%, some measure idle, 10mph steady on a dyno, and 30mph steady on a dyno measuring HC CO and NOx. Some have an actual driving cycle the inspection station has to follow that involves accelerating, braking, etc.

You said it passed before on stock ECU. Can you post the results? Did it fail once already and now you're trying to get it to pass? If it's failed before, please post a picture/scanned image of the failure paperwork. It should indicate what the emission limit is and what you measured. I attached an example, which is my Rx-7 passing steady state California emission testing.

If you have to meet NOx emission you have to be careful with just leaning it out. Also, are you running closed loop with a wideband? There are also other tricks you can do with spark timing for example but it depends on the nature of the test.

Hello,

I am living abroad, excuse for the country information. The standard is quite straight forward at where I am located:

Idle 30 sec measurement:

HC below 150

CO below 0.8

Steady rev to 3500 RPM for 30sec for measurement:

HC below 100

CO below 0.3

The stock ECU (4AGE MR2 MK1) passed with following results:

Idle:

HC: 2

CO: 0.02

3500Rpm

HC: 2

CO: 0.02

I have attached the AFR/Lambar target table (I added 0.10 to the dyno map to meet aforementioned idle emission requirements) and Ignition map (No change). THE HC and CO values just increased to like 1000 and 2x.00 respectively whenever I rev the engine to 3500RPM, come to think of it could it be the ignition timing?

Cheers

Cel

Ok. So they don't run it on a dyno (no load at all, just free reve) and you don't have NOx standards. That makes it easier.

If your CO is going up then you are going richer than Lambda=1. CO% is directly related to AFR. In fact, in the old days before wideband o2 they would often just look at CO% to determine how rich the engine is (you can also calculate lambda from all the emissions too, it's a complicated formula). See attached image. Can you take a log of the engine running at 3500rpm (recreating the test condition)? The actual lambda should match the target assuming your closed loop control works.

For spark, retarding spark will reduce emission as long as you don't push it to the point of misfiring. That's why old cars used to have spark retard solenoids for their distributor.

So my advice is,

1. Make sure the ECU is achieving target AFR. This is probably the root cause. You need closed loop o2 sensor control and it needs to be working right. Maybe your o2 controller gains are off.

2. Retard the spark table 2 to 4 degrees. This is probably not necessary though.

3. Make an emissions map that you load in there before you hand the keys to the emission inspector that includes the spark retard.