Cold Start Parameters

Hello,

A beginner level question. I have a truck with a ViPec V88 ECU installed. It is (mostly) tuned and ran fine in Los Angles weather. I have since moved to Central California, and the temps here in winter are quite a bit lower. I have the truck parked at a farm while we get settled. I tried to start it one morning when the ambient temp was probably about 45 deg F, though it had been much colder during the night (Around freezing). It cranked fine, but would not start, not even a cough.

I am wondering where to begin with modifying the cold start parameters. There are several options, injector prime duration, first crank enrichment, general crank enrichment and hold time. Maybe they should all be changed. But how much? I do not want to instantly flood the engine.

Not looking for exact answers, just some guidelines if anyone has them. Thank you - Gustave

Here are my existing parameters:

I would go to that Crank Enrichment table and on the entry for the current coolant temp (which could be quite a bit below 45 degF), add 10% at a time, until it starts. I would then look at the shape of the curve and extrapolate it out to colder temps.

Alternately, you could just try increasing the value in the Prime table. See which one works for you. Unfortunately you only get one or two shots at cold starting per day. Keep notes...

I haven't tuned cold start on that ECU, but I have 175% - 200% fuel compensation for the first few crank cycles at 0-20 degC.

BTW -- I'm in Paso Robles -- where are you on the Central Coast?

Thank you David for that advice. That gives me something to hang my hat on.

Funny thing, I am also in Paso. On the West Side of town, Oak Street and 3rd.

My truck is at a sheep farm on the way out to Lake Nacimiento. Do you run a tuning business in the area?

Gustave

I am facing the same problem with my Vipec i88. The first cold start its about 5 seconds of cranking. When the engine shuts down by me and restarted immediately everything is much much easier. Have spent hours and hours of searching , everything.

So I would say that it might not be a problem with fuel values ONLY but all things might make things worse each by its own way. For example if you are having a low resolution cam and crank signal this with the fuel atomization with the engine cold etc etc will make things worse. It has to do with the spray pattern, combustion chamber shape etc etc.

What fuel injectors are you using and what injection pulsewidth ?

I might give you mine cold start settings wich is pretty spot on on AFR 's till the end of Warm Up Enrichment

If you are planning to use the function of pre crank prime use the option engine on and not key on. With the second you might flud the combustion chamber and foul the plugs. Every time you turn the key on off with out cranking the engine the fuel injectors spray. So use ignition on and not key on if you are planning to use that option.

Dr G.

I'm located 3 mi east of Paso. Here is our website with contact info: Veracity Racing Data

Give me a call, or stop by sometime.

Thank you for the advice Lewis.

I am facing the same problem with my Vipec i88. The first cold start its about 5 seconds of cranking. When the engine shuts down by me and restarted immediately everything is much much easier. Have spent hours and hours of searching , everything.

I have found that it always takes a while for my engine to start with the V88. At least 3 seconds of cranking, always, regardless of conditions. I have assumed that it was taking a while for the ECU to figure things out. My engine is an old school Ford V8. Single cam, nothing fancy. I converted an MSD distributor to act as a crank and cam position sensor. So 6 teeth for crank speed and a single tooth for cam position. I suspect that if I installed a toothed wheel on the crank that things would improve.

What fuel injectors are you using and what injection pulsewidth ?

I'm sorry but it has been 8 years since I set this all up. I'll have to dig through my records on the injectors.

I might give you mine cold start settings wich is pretty spot on on AFR 's till the end of Warm Up Enrichment

Thank you for that offer, but I would guess that our engines are not very similar, so that may not help very much.

If you are planning to use the function of pre crank prime use the option engine on and not key on. With the second you might flud the combustion chamber and foul the plugs. Every time you turn the key on off with out cranking the engine the fuel injectors spray. So use ignition on and not key on if you are planning to use that option.

This is excellent advice. In fact my pre-crank prime is indeed setup for key ON. So I will try to change that.

Gustave

I'm not as familiar with the Vipec. Does it let you log the cam and crank syncing indicator to see how long it takes? Besides that, a general approach is: if it's cranking and not even firing, add cranking fuel, and consider advancing cranking timing to see if that helps. If it's firing and then dying, it's basically post start and warm up enrichment. This is assuming your basic VE table and other engine parameters are close enough.

I can log crank and cam syncing.I have went from 10% till 200% crank enrichment and the outcome was the same. I have also played with the values of advance at cranking zone(0-300rpm)The outcome is the same.

One friend suggested me to set my cranking advance at 0 and that is what I will try out tomorrow morning

The first start up is difficult If I turn off the engine and fire it up immediately then it starts almost fine despite the environment temperature.

Generally cold start values, warm up enrichment, decay etc etc are spot on. My only problem is the first start up which takes 4 to 5 seconds. Not happy with that.

I should probably tow my truck home from the sheep farm and get it on the driveway. That will make things a lot easier in terms of trouble shooting.