Intermittent Low Idle, Stalling
Intermittent Low Idle, Stalling I have an LS2 with Maggie TVS2300 in my 68 Chevelle. Recently I've been having a fluxing RPM issue where at a stop light, it will go from 900 RPM to 500 or less, often times stalling. Sometimes, it holds rock steady at 900 RPM and all is well. This happens with the AC on or off.
I've read a lot about IAC issues maybe causing this, but I've also read that the LS2 throttle body has an integrated IAC or that it's electronically controlled and you can't just remove it to clean it.
I haven't taken the time to pull the throttle body and clean it yet, but I do plan to.
This car was dyno tuned about a year ago. No CEL's. I don't have HP Tuners and nobody local does tuning (I moved from where it was previously tuned)
Other than that, any thoughts?
I've read a lot about IAC issues maybe causing this, but I've also read that the LS2 throttle body has an integrated IAC or that it's electronically controlled and you can't just remove it to clean it.
I haven't taken the time to pull the throttle body and clean it yet, but I do plan to.
This car was dyno tuned about a year ago. No CEL's. I don't have HP Tuners and nobody local does tuning (I moved from where it was previously tuned)
Other than that, any thoughts?
So I pulled the throttle body and for all intents and purposes, it was pretty clean. Had a little bit of carbon around the butterfly. I sprayed with throttle body cleaner, wiped it all away, put it back together. It's still doing the same thing. Where else can I look? Anyone?
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Can you explain how a VSS would affect an idle issue?
Does the rpm drop while sitting at a light, or does it drop when coming to a stop? If you dont have a VSS signal going to the PCM, basically what happens is the PCM gets used to the engine running at a cruising speed then when you stop, it doesnt know the car has stopped and can cause it to stall. If its fluctuating while already stopped and nt when stopping I wouldn't think its a VSS problem. Maybe a vacuum leak or something. Have you verified your fuel pressure isnt dropping off at idle? Maybe the pump is getting weak?
It happens as soon as I put the car in neutral and while coasting to a stop...it then continues to happen while stopped. Sometimes it levels out and steadies at 900 RPM, other times it continues to flux from ~400 to 900 RPM...at times dying out.
If it is a VSS issue, what is the resolution?
I will also look into a possible vacuum leak. I only have one vacuum line that's running the brake booster. Other vacuum ports are capped off.
I have not verified fuel rail pressure, I need to put a gauge on to check that, but that's a very good suggestion to look at.
If it is a VSS issue, what is the resolution?
I will also look into a possible vacuum leak. I only have one vacuum line that's running the brake booster. Other vacuum ports are capped off.
I have not verified fuel rail pressure, I need to put a gauge on to check that, but that's a very good suggestion to look at.
Some additional info: anytime I start the car fresh when it's cold...it starts right up immediately.
If the car stalls as a result of the surging at idle issue, it's a little difficult to get the car started again. Like it's taking much longer than usual to ignite and get going again. Would that be an indication more towards a fuel issue?
If the car stalls as a result of the surging at idle issue, it's a little difficult to get the car started again. Like it's taking much longer than usual to ignite and get going again. Would that be an indication more towards a fuel issue?
It happens as soon as I put the car in neutral and while coasting to a stop...it then continues to happen while stopped. Sometimes it levels out and steadies at 900 RPM, other times it continues to flux from ~400 to 900 RPM...at times dying out.
If it is a VSS issue, what is the resolution?
....
If it is a VSS issue, what is the resolution?
....
Funny how we get used to fancy EFI and forget how shitty carburetors could be...LOL
Andrew
Can someone check me on a fuel pressure test? I hooked up a gauge, turned key to on position and I get about 55 psi or so but then it immediately bleeds down to near zero. Then I start the car and the pressure is pretty much pegging the gauge out around 90-100 psi (no fluxing RPM at this time). Then I shut the car off and it bleeds down very quickly again.
Reminder this is an LS2 with inline filter/regulator and no return line.
Is there something wrong with this test?
Reminder this is an LS2 with inline filter/regulator and no return line.
Is there something wrong with this test?
Yes, the stock filter/regulator combo. Keep in mind, I've been driving the car the way it its for nearly two years with zero issues until recently. It was dyno-tuned with the way it is and pulls over 600HP to the rear wheels. The filter is hooked up property without question. The real question is did the fuel pressure test fail because it didn't hold pressure at all and could it possibly be caused by a bad filter/regulator or something else? The car operates extremely well most of the time...until it doesn't.
Others have mentioned that loss of fuel pressure immediately after the pump is turned off could be a symptom of the pump itself leaking inside the tank. I'm just wanting to know if my idle issue could possible be caused by this fuel pressure issue....especially being so intermittent.
Something else that came to mind...every now and then when I really want to get on the throttle, if i punch it, the engine will rev up quick...then almost immediately will kick back like it choked...then pick up again and go. Almost like misfire of sorts. This is also intermittent.
Something else that came to mind...every now and then when I really want to get on the throttle, if i punch it, the engine will rev up quick...then almost immediately will kick back like it choked...then pick up again and go. Almost like misfire of sorts. This is also intermittent.
