Celica ST165 Distributor with TST185 Link ECU

[RecceRS]

Hi everyone! I'm using the Link (TST185) made for the ST185 on a complete first-gen ST165 setup through a jumper harness. Both these engines share the same equipement as far as the critical components go (injectors, etc) but I was aware that there might be differences between the distributor from the ST165 and the ST185 as far as the trigger signals go though. Anyway, the timing was correctly set at 10 BTDC at idle with the factory ECU before switching to the Link ECU. All pre-start checks and calibrations were made. Now timing is way off (idles between 35 to 45 BTDC) and idles rough and super rich (around 0.65-0.66 lambda). The trigger calibration tool was used again at idle and at 2000 to 3000k but didn't change the result. I'm assuming that it would be difficult to properly map such a distributor signal, unless someone has done it before on this model? I'm looking into acquiring a complete ST185 distributor, if all else fails.

[Vaughan]

If you take a trigger scope that will confirm the trigger pattern. Regardless of whether or not the timing was set correctly on the factory ECU you need to get a timing light on it with the Link ECU and calibrate the timing in the ECU software.

[Adamw]

7 hours ago, RecceRS said:

idles rough and super rich (around 0.65-0.66 lambda).

Adjust the master fuel value to get the mixture somewhere in the ballpark.  

[koracing]

For sure the distributor trigger is the same with ST165 and ST185.  I've actually changed the connector on the harness of a 165 and run the stock ecu with the 185 distributor as the 165 distributors are long gone.  The trigger scope function should be able to look and see if your signals are good at least.  It likely wouldn't run if you didn't have something close to right, but you also likely need to adjust the thresholds.  If you aren't getting timing to sync up then you perhaps aren't pressing enter on the trigger adjustment/offset when making changes in the timing calibration window which catches a lot of people out who are new to link. 

[RecceRS]

Indeed, thanks everyone! The biggest hurdle is always to correctly set things up but I managed to get things going on the right track now!

[RecceRS]

I now have a bit of a mystery on my hands! MAP remains constant at 187 KPA from 4,000 RPM all the way through 7,000 RPM, however from 5,000 RPM to 7,000 RPM I had to gradually remove 14% of fuel to retain my AFR target (that target is the same in the effective full boost area).

This means that the engine is actually losing 14% VE in the 5 to 7k RPM range while the MAP remains constant... I'm not sure how or why? The engine does have bigger cams fitted so I'm wondering if they are the cause of this due to too much valve overlap? If that's the case, they're actually detrimental or am I missing something?

I'm attaching the log file.

PC Datalog - 2023-11-8 11;38;51 am.llgx

[koracing]

VE will be the highest at peak torque - so it isn't necessarily unheard of to see the VE drop off with increasing RPM.  More overlap would tend to improve higher rpm VE and decrease VE at lower RPM.  What are your cam centerlines set to?

[RecceRS]

23 minutes ago, koracing said:

VE will be the highest at peak torque - so it isn't necessarily unheard of to see the VE drop off with increasing RPM.  More overlap would tend to improve higher rpm VE and decrease VE at lower RPM.  What are your cam centerlines set to?

They were set at the same position as the factory ones

[Adamw]

Most likely EMAP is running away.  

[RecceRS]

1 hour ago, Adamw said:

Most likely EMAP is running away.  

You're talking about exhaust manifold pressure, correct? So you mean that I'm getting too much backpressure thus VE is dropping although the turbo is maintaining its boost constant throughout the high RPM range? Wouldn't what you're suggesting actually make the boost and MAP readings drop? Because it didn't for me, MAP stays steady around 187 KPA from 4k to 7k and turbo boost doesn't drop at all, but VE drops dramatically from 5k-on. But you also may be suggesting that, although the turbo can maintain its boost pressure, there's just too much backpressure and the engine can't "breathe out" enough past 5k thus reduces VE?

[Adamw]

Yes, EMAP = Exhaust Manifold Absolute Pressure.  If you think of the engine just as an orifice or restriction, air flow through it is relative to the pressure on the intake side Vs pressure on the exhaust side.  If you increase pressure on the exhaust side while keeping the pressure on the intake side the same then air flow decreases.   As the compressor and turbine move further outside of their peak efficiency island you will see the pressure ratio (MAP/EMAP) increase dramatically. 

[koracing]

On 11/8/2023 at 1:13 PM, RecceRS said:

They were set at the same position as the factory ones

So you verified the intake and exahsut centerlines with the OEM cams using a degree wheel before going to aftermarket cams, and with adjustable cam gears set the centerlines to the same values?  Or do you mean you simply put OEM cam gears on the new cams and set them to the OEM timing marks? 

Aftermarket cams *rarely* line up with recommended centerlines buy installing them "straight up" with non-adjustable gears on the 3SGTE.  Almost always the exhaust cam needs to be retarded for optimal performance, and really a cam degree wheel should be used to set up the cams properly on these engines.

[RecceRS]

The cams already were installed by the previous owner. I simply noticed that they were at OEM position. I will be removing them since I don't think they will be any good for my mild setup anyway. Thanks!