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Basic cold start questions

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I watched the Tuning Cold Start video and really liked it. I am getting ready to start practicing on my own car and some of my friends.

How do you see what your actual A/F ratios are when you initially start the car? Most wide bands don't come online until 20-40 seconds after start-up or at least that's my understanding. Do you just key on for a minute and let them heat up before you try and start the car so that you can see whats happening? I have a basic grasp on what I want to do just not sure where to get the feedback from how the engine is doing do make proper adjustments ? :)

Also, I have a CANBUS wideband setup on my car with a Haltech Elite. For cold start could I not give it +/- 25% control and have it start control instantly and just let it handle all of it?

Thanks!

The easiest way of reading AFR during startup is to power the wideband directly from the battery instead of the ignition circuit. This means it can remain powered up during the cranking and starting cycle.

You could allow the Haltech wideband to help handle the correction, however if you are relying on it then there is a good chance that you will either be too rich or too lean at some point. It also won't be able to help until it comes on line and starts reading. You're always best to do the work in the main and correction tables and then allow the wideband correction to pick up any remaining error. This will give you the best results and the best driveability.

... you still need to figure out what "target" AFR's you want. And like you said.... the O2 sensor doesn't come online until its heated up sufficiently by exhaust gas. So i definitely wouldn't try to use it for closed-loop control for post-start running.

About cold start on Haltech Platinus series:

1) During watching cold start webinar based on Motec M1 ECU, I noticed that VE values in cells of the base map that refer to cranking are around 60-65%. Why is this so? I see manifold pressure between -5 or -7 kPa during cranking at very low speed, I always thought that there should be around 90% VE.

2) The Lambda ratio choice for -5 degrees of ambient temperature on New Zealand winter is clear, about 0.87-0.9. How are things with ambient temperature about -35 degrees?

3) The Haltech PS has basicly the following tables that are related to cold start Cooliant temperature table, Post start table and Prime table. Am I right that the cranking amount of correction is kept in 0s column of post start table?

4) What should like the injector timing? We should aim at open or closed valve?

5) What is the procedure of tuning that tables? The first one would be cooliant temperature table for sure, and after that? Why I am asking - there is no opportunity to sit in cold car when the ambient temperature is below -35 degrees trying to find adequate procedure and basic values in tables. The notebook display even doesn`t want to work))) Last winter I discovered that I run maximum 100% of post start enrichment and it soon not enough to start engine on first 10 seconds of cranking. Raising values in prime pulse table above standart 145 ms on 1000 cc injectors quite dangerous job and could cause engine flooding.

Any advice?

No advice?

Definitely inject fuel when valve is open, when cranking. Im pretty sure "Post Start" enrichment has no bearing on cranking-fueling. Thats all in your "cranking" table.

You need a LOT of fuel to start an engine at -35 air/coolant temp!.

There is no cranking fueling

Here's some answers to your questions:

1. It's not strictly possible to tune the VE accurately at 0 rpm as obviously we can't hold the engine here. It's a balancing act between the VE value in these cells and the cranking enrichment value as well. The ECU uses both and we could effect the startup by altering either. Normally I will maintain a regular shape to the VE map below where I can actually access/tune.

2. Regardless of temperature, I wouldn't aim for a lambda value richer than around 0.85 as this can result in fouled plugs over repeated cold starts.

3. You can enable a 'Cranking Table' in the Haltech PS series ECU from the Settings/Advanced/Fuel Corrections menu. I would strongly advise this.

4. In a cold engine particularly I would be targeting OVI. At the sort of temperatures you're talking about there will be no heat in the port wall and valve to help the liquid fuel evaporate if you use CVI.

5. Start by making sure your main fuel table is correctly tuned and the warm idle lambda is correct. From here you can attempt a cold start and check the performance. It depends how much time you have with the car and how bad the ambient conditions are for you (pretty bad I'm guessing). In the perfect world you really want to move backwards through the tables and start by optimising the coolant temp table, then the post start and finally the cranking enrichment table. Understand that each will influence the cold start performance. Cranking only has effect during the cranking portion. Post start will then effect the next 10-30 seconds of running and then the performance is solely down to the coolant enrichment table.

I hope this helps you. Let me know if you have further questions.

There is no cranking table in non PRO Platinim Sport/Sprint ECU and that makes me really confusing (

Attached Files

LOL!... no cranking?!.... im never buying Haltech!.

In a Haltech the prime map in the menu allows for adding the fuel at 0 rpm at first revolution of the crank, therfore this would be your "cranking map". To my experience this works quite well in combination with a post start map and 2D or 3D coolant map. The technique followed is the same as that of the cold start Webinar. Just use these maps to mimic the Link functionality as good as you can.

in Haltech language, the cranking table is called prime pulse table.

actually, once everything is dialed in, that table is set up pretty quick

Our experience at this point is limited to the Haltech Platinum Pro Plug-In for our Z33 350Z and this ECU definitely has the option for a cranking map as pictured.

I can't comment specifically on how Haltech deal with the prime pulse table. This sounds similar to a pre-crank prime table which isn't uncommon. This sort of compensation though is quite different to a cranking enrichment. I'll contact Haltech today for some clarification and come back to you :)

Attached Files

No news from haltech? )

Slipped my mind sorry. I'll touch base with the guys today :)