Stalling Issue!! Need advice & theories.

[Rowie94]

Explanation in video here.

Basically, if i clutch coast to idle rpm while cruising, from anywhere above 3K, it will hit idle rpm, hesitate, and stall.
Between 2500-3000, it will fall to 1000, then drop to about 500 usually before coming back to normal rest.
Normal idling, and clutch coasting from 2300 or lower is completely normal.

Any clues as to what may be causing this?

98 legnum with facelift engine, running EFlex on E85 tune at 15 Psi through 650cc injectors.

 

[pretzil]

You are running (caltex) eflex??? That car is tuned for united.

Have you disconnected the battery lately?

 

[pretzil]

I have a stock bov you can chuck in at the carwash meet if you would like to try, its pretty easy on these cars, especially yours with rock crawler spec.

 

[Rowie94]

Rock Crawler spec
Yes I'm using caltex eflex. The dual maps don't work yet so I can't just run 98, and the closest e85 united's are bald hills, and loganlea. given that i live in upper mount gravatt, and work in thornlands, there's no way I'm going so far north or south out of my way to get the real stuff. I'm under the impression that running a lower mix of ethanol like eflex just makes it run rich?? Or am I mistaken and doing my car harm?
Also, yes, the car is still running the atmo BOV that sam had on it.

 

[pretzil]

I would expect it not to be too bad, going the other a way and running lean would be worse, but maybe @TME_Steve has some input.
I have been told by others that you need to stick to whatever you are tuned to.

Having the VTA will also cause a rich condition on shifts, maybe doubling up is causing an issue?

 

[TME_Steve]

Yes its tuned for e85 and is running e70ish. The dual maps are written but when Sam loaded them in they didn't work. We suspect that the wrong pin is being earthed (I'm going pin b11 yeah? And Sam is like oh. Um i don't think i did that one....) anyway. So with the 70, yes it will run rich. And it will have too much timing so we suggested disconnecting the 3 port to reduce bist as an interim measure. Certainly wouldn't advise running an e85 tune flat out with e70 fuel.
I would think that this problem is quite possibly to do with that. At 3500rpm to 4000rpm is where the map is starting to get richer at light load points than it is at say 3000rpm. Backing of the throttle induces a slightly rich condition while the maf/injectors catch up with the transient change in airflow. Same as when you open throttle we have to add fuel to avoids leaning it and stuttering from a lean condition. So I'd think you're just going slightly over the threshold of it wanting to run. I count 3 things at work here that could be or add up to the cause.

Vta bov isn't ideal for this problem as the air keeps running longer causing the transient problem to be increased

Its tuned for a fuel requiring more flow so running rich and it's winter and e flex runs slightly less ethanol in winter than summer so the problem is likely worse again.

And it's only occurring at the point of the map i would expect it to be where the problem would start. Add some 98 and if guess that dip from 3000 may become a stall.

 

[pretzil]

@TME_Steve, if he wants to run caltex, are you able to make a slightly adjusted map using the same interpolation you will be applying for flex?

 

[TME_Steve]

We can make a guesstimate. Flex is not as simple as interpolation. Its interpolation with adjustment of the interpolation curve.

That said if you recall. I guessed your fuel value and it was spot on

 

[Rowie94]

Ah, should've mentioned I am indeed running the car with the 3 port disconnected and on waste gate pressure, as per steve's recommendations. Okay, so basically a culmination of a bunch of things, resulting in the issue, mainly caused by the richness of the fuel. Thanks
I'd prefer a recirculated bov, I think rick offered to test fit one for me tomorrow? On that note, in terms of fitting a flex sensor and tuning accordingly, easy or massove expensive pain in the ass?

 

[pretzil]

Flex isn't a thing yet, hopefully in final stages of testing, once it is done it should be worth the effort.

Will bring the shitty plastic OEM recirc valve to try tomorrow.

 

[TME_Steve]

Flex is in the middle stages of testing

 

[Rowie94]

Good to hear! Unless united put e85 in eight mile plains, it's 98 or flex for me. Once that's ready to go, what do you think a flex install and tune would be worth, Steve?

 

[pretzil]

My mate runs united in his skyline, he lives in my gravatt, I'll check what united he uses.