A little experiment, Ljet cold start Options

[Porschef]

After all the trials and tribulations by some of the Ljet crew and their struggles with cold starts, it came to me in an early morning haze this morning that maybe I should try bypassing the AAR valve and rigging some sort manual one. I figgered if inadequate air was creating the low idle at start situation, then maybe this would be a way of seeing that an increase in air would remedy that.

Ok, so I pulled the AAR, and set out to get what I needed. Well, here’s where a little laziness took over, I thought before I through that, may I’d see if a total bypass would work…



Here’s one of the AAR hoses going from the plenum directly to the intake boot.

So being diligent on startup as to not allow a potential crazy high idle, I gave it a shot.

Wouldn’t you know, while it was a bit balky to start, when it did the idle shot right up, and I shut it off. Knowing what to expect on the next attempt, it went up to just about 2k rpm, then crept up more. It was enough to convince me that inadequate air is getting into the engine with the stock AAR (which functions perfectly) and that a slightly larger one like VanB has installed will probably be the ticket.

Thanks to @Van B @StarBear and @Wonkipop for their quest for perfection (IMG:style_emoticons/default/beerchug.gif)

[Porschef]

Ok, fellow Ljet brethrens,

@Van B
@StarBear
@Wonkipop
@emerygt350
and anyone else...had some time to read through the extensive thread Van started back in Nov ‘21. Lots to see there, but I’m gonna try to remember the questions I had plus a couple comments.

It’s encouraging to see the effort and research there, I don’t know what happened but I left this thread at some point and never caught up. So, first comments-

Emery, that valve you rigged was very cool and even elegant. Great idea using that garden unit, had I seen it earlier it would have been the way to go instead of a quarter turn unit like I was gonna try till laziness took over and I just went for the straight bypass. It does confirm that there’s not enough air getting through at cold start.

The search for substitutes for both the AAR’s and TTS’s is great. Options are a beautiful thing.

The TTS is the only part of the system I haven’t checked yet. Would like to find one that sends the signal at 95° instead of 55°.

The metric system is great, especially if you can do close conversions in your head. But temps are better in Fahrenheit than Celsius IMHO, allow for more precision if you ask me.

Installing a 123 is the best thing I’ve done to make the car run better.

I’ve adjusted both the dynamic spring and static setting in the AFM to meet the needs of the 2056 as best as I can. Readings from the Innovate wide band shows 14.7 at idle and low 13’s at cruise. It’s very happy there. Hard acceleration drops down to low 12’s.

Ok, enough of my blabbering, here’s a couple questions...


Van, I know you replaced your AAR with the BMW unit. Was your original one fully functional? If not, do you feel a good unit would have made your cold starts the same as what they are now? I saw your pics with them open, it didn’t seem to me that they were drastically different. I also saw that you replaced some of the hoses that were improperly sized, do you think that would have made a difference with the original AAR?

Emery, I watched your cold start and warm running videos this morning. Engine sounds great. That’s how my Djet started and ran when I first got the car until the engine dropped a seat the following year. Been running the Ljet since. Are you still using that garden valve as part of your warm up procedure?

Wonk, have you changed your’s? Loved the couple SAABs I had, the 900 turbo was pretty bulletproof, and the 9000Aero was the best road car I’ve ever had. A six hour trip felt like 90 minutes...


Ok, I think that’s it for now. I know these are silly little problems in the grand scheme of life and I’ll probably have a couple more, but they do provide some welcome distractions from the 600 pound gorilla in the room or however that saying goes... (IMG:style_emoticons/default/beerchug.gif)

Thanks all

Joe