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Ive had an on going issue with idle quality with my vehicle since fitting my d1sc.
When warmed, idling in park, more often than not, a rev of the pedal and it will die, or stumble and surge. And sometimes stalls around corners and pulling up to lights.
Has good idle vacuum around 18/19in, with a stab of the pedal raises to 5-10in. Not sure if its normal, this is my first procharged vehicle.
My ideas-
Proflow valve isnt operating correctly/cant flow enough for idle conditions. other than compressor surge, are there other sign its too small. im using the procharger supplied vacuum header, pulling reference from there, maybe length of vac source too long.
First tuner told me injectors were slightly too big and idle had to be raised to close to 900rpm. Never did stall with his tune but there is a whole different story there. So injectors too big? or fuel system issue?
Or have i got some random electrical fault somewhere, the ecu has been moved, ive fitted a second hand set of ls2 coils to fit Holley valve covers, i dunno thinking outside the box here.
The new shop has had a couple of goes now, doesn't seem to do it as much as first but still there, and its getting annoying now. i have personally checked with a scanner and it doesn't throw codes on the factory ecu.
Otherwise the new shop are good guys, do have ls1 and good e85 experience having some of the fastest stock bottom end 1/2j vehicles in the country, a friend included. But im considering it could be the tune itself.
Open to fresh ideas here.
Hope this is the right area. Didnt have these problems until i had forced induction haha.
First thing to do is fix any mechanical or electrical problems. You can't tune a car if it's got issues with the build.
Once you sort out those problems, get a tuner who knows what they are doing, and you'll be fine.
For reference, I'm running a 416, with an F1A, with a TiAL blow off valve that is closed at idle. I too have ID1000s, and tuned the car myself, and it idles fine at like 650-700 rpm.
Im pretty certain there are no mechanical or electrical issues, just thinking outside the box in some regards. Its a low mileage, well kept vehicle that has turned to crap since the original shop put the blower on.
Ive organized for them to have the car for a few days to nail it down. Lets see what happens.
As said, if no mech. issues and a stock cam, should idle fine.
Most of the time your vac. will keep the BOV open at idle, lose
of vac, WOT, valve stays closed-I have seen dias. get a hole in
them and create problems-I would look at the tune, see what is
going on-you could disc the line to the BOV and see how it acts,
might surge at low speeds, but would eliminate flux.
Vac at cruise will be higher than idle vac, normal, boosted or NA
With the high vac. you have, I would think the valve is staying open
pretty solid until WOT
what is likely happening is, you rev the engine and release -> it creates a vacuum signal strong enough to open the bypass -> maf will see air leaving the bypass as air entering the engine -> ECU adds fuel to compensate for air leaving the bypass -> engine goes 10:1 rich and dies.
what is likely happening is, you rev the engine and release -> it creates a vacuum signal strong enough to open the bypass -> maf will see air leaving the bypass as air entering the engine -> ECU adds fuel to compensate for air leaving the bypass -> engine goes 10:1 rich and dies.
That would only be the case if he had his maf on the inlet to the blower, which chances are, if he is still on a maf, it's still before the throttle body, so the bypass valve being open wouldn't change anything.
super charger BOVs have like a -2 psi spring. so the BOV should be open right up until 8-90ish kPa. Then it shuts and you move onto positive pressure. it shouldn't be closed at idle or you are wasting a ton of energy compressing air between the blower and throttle body. The engine will always idle in vacuum.
your MAF before or after the blower? The MAF is a 1bar device, so it should be before the blower if you kept it.
Its mafless tuned since the blower went on, or i think you guys call it speed density?
Bypass is definitely open on idle. My main concern if the actual open size was large enough to bypass enough air. Its only the proflo valve, and i'm running a touch more that the standard kit.
Is that the small black BOV, I have run a bunch of boost with one and never a problem-Orig it was a used one, and the dia. had cracked, but Procharger had replacement dias. so I rebuilt it
what a week its been.
got the car back friday, stalled 3 times on the way home. worst its been.
got home from work today, decided to reset the pcm and relearn the idle.
It worked so well, it don't want to stall, it was cruise controlling itself, maintaining speed with not throttle and pushing on the converter at lights.
Got home, adjusted the throttle body closed. reset pcm process again.
And now it seems really good, no stalling, stable idle, no hunting or surging, no stalling after a rev in park.
Im wondering if they have never checked TPS voltage or reset the pcm, a touch to high.
Maybe it still had pump fuel learnings in the pcm, and had never been reset changing to e85. i cant think of a time the fuse was pulled or the battery off long enough to drop power to the pcm.
Maybe more of diagnostics ending, but, perhaps something to keep in mind when switching fuels.
Curious, did you switch to E85 after installing the Procharger, or were you running it before the switch
Sounds like you know more than the people you were paying to tune the car, lol-sounds like your on to the problem, good info
Did the swap to e85 at the same time. And generally had some sort of idling problem since.
I'm pretty surprised how much everything changed once i reset the pcm.
Decided on a cam swap with a different shop, with a lot more LS experience. Not exactly sure whats happened but i didn't loose any boost with a Crane 224/228 .551 114lsa cam, and with no pulley change, maybe had some piping leaks? But a making a solid amount more power.
06-21-2016, 06:14 AM
Ideas for stalling and surging - LS1 D1SC 
