Need Help!!!! Please!!!

M

mystro9876

Active LVC Member
Joined
Aug 27, 2005
Messages
128
Reaction score
0
Location
Newark, NJ
Terrible:

I was just driving home from work with no problems in sight. I decided to stop at the ATM by my house to get cash for the week.

When I go to turn my car back on, it turns on.... then immediately TURNS OFF!! It's like the engine isn't getting enough juice for it to stay on. The car goes very low on the RPMs, then turns off. I tried it again.... rev the engine, and within seconds, the RPMs go down and stalls. I said F--K it, and was able to make it home by keeping the car revved after turning it on. It did stall once because I had a stop sign, but I wasn't leaving my car there.

Why would by car immediately go off after it turns over?

WHAT CAN BE CAUSING THIS?????

THANKS!
 
If your car is a gen I, then I would guess that maybe your IAC (or idle air bypass valve) has failed. I think that's about a $70 part.
 
It's a V8 (LSE).....Would the check engine light be on for that piece? I have 76 Miles until empty.
 
Do you think it could be my battery? I've had problems lately with my battery dying relatively quickly (door open for 5 minutes and I have to jump it). I think I definitely need a new one regardless.
 
Actually, I take that back, because it does turn on......Maybe the engine isn't getting enough fuel.....Would that cause the check engine to go on (fuel pump/fuel injector/fuel filter)?
 
yep, sounds like a fuel pump or clogged fuel filter. confirm this by measuring your fuel pressure on the fuel rail. i believe we are 30psi at idle and 40 at full throttle? if you're lower, then its probably one of the following issues...
start with the filter since its cheap and could probably use it anyway.
if its the pump, there are a few threads that describe how to do it yourself if you're comfortable with going into a gas tank.
use common sense and ask questions if you need and you'll save a lot of money.
 
Okay, do I not understand the issue here?
I thought that your problem was that it is stalling at idle, but it runs when you keep your foot on the gas? Is this true? If so, then it is not a fuel flow problem. A fuel flow problem would be the other way around. It would run at idle, but then stall when you press down on the gas.
 
You got it. If I keep my foot on the pedal, it would go, but as soon as I let go of the pedal it would stall, pretty much immediately. It seems like it can't hold a RPM. If I were to just start the car without revving the engine, then it would stall immediately as well.
 
My warranty just expired 200 miles ago (75k) too and I brought it into the dealership right before the 75k. If I bitch to the dealership, do you think I can get it covered still? I hope it's not something they saw or could have seen and just didn't want to fix.
 
mystro9876 said:
You got it. If I keep my foot on the pedal, it would go, but as soon as I let go of the pedal it would stall, pretty much immediately. It seems like it can't hold a RPM. If I were to just start the car without revving the engine, then it would stall immediately as well.
Click to expand...

Fuel flow problems show up when the engine is using the most fuel, not when it is using the least. Your problem is an air flow issue (not enough air at idle). This is almost always due to the failure of the IAC. Usually, they get dirty and stick closed. You may be able to get it going again just by tapping the IAC a few times with a hammer. You may also be able to get it to work for a while longer by removing and cleaning it. My experience has been that replacing it is the most reliable option.
 
Take off your air intake tube. the piece it's connected to on the engine side is your throttle body.

The IAC valve is like a bypass of the throttle plate, so your car can still draw air when you're not stepping on the gas. If this passageway becomes dirty/clogged, or if it malfunctions, your car will either have difficulty running, or stop running all together while at idle, since3 not enought air can get through. This is the reason why when you step on the gas, it will stay running (because the throttle plate opens when you step on the gas).
 
joegr said:
Fuel flow problems show up when the engine is using the most fuel, not when it is using the least. Your problem is an air flow issue (not enough air at idle). This is almost always due to the failure of the IAC. Usually, they get dirty and stick closed. You may be able to get it going again just by tapping the IAC a few times with a hammer. You may also be able to get it to work for a while longer by removing and cleaning it. My experience has been that replacing it is the most reliable option.
Click to expand...

at idle, the pump makes less pressure. if your trying to push fuel through a clogged filter, it will stall. the pressure will rise with throttle increase and may force enough fuel through to keep it running- the pressure will still be low. maybe the pump is on its way out and requires more voltage to flow enough fuel to run properly (done so by pressing on the gas more).

its just a thought and an easy thing to rule out with a fuel pressure test.

when you find the issue, please post back.
 
What year is your LS?

On the gen1 V8 (2000-2002), the IAC Valve is bolted to the front of the throttle body.
 
02LincLS said:
at idle, the pump makes less pressure. if your trying to push fuel through a clogged filter, it will stall. the pressure will rise with throttle increase and may force enough fuel through to keep it running- the pressure will still be low. maybe the pump is on its way out and requires more voltage to flow enough fuel to run properly (done so by pressing on the gas more).

its just a thought and an easy thing to rule out with a fuel pressure test.

when you find the issue, please post back.
Click to expand...

Fuel pressure is electronically regulated on the LS. The LS electronics can run the pump at full power (if needed) at idle to produce the needed pressure. (In other words, if it can produce enough fuel for the running condition, then it can certainly make enough fuel for idle.) Your comment might be correct for the old days of carburetors and mechanical engine driven fuel pumps.

Also, fuel pressure is regulated past the filter, so filter restrictions would be automatically regulated out by applying more fuel pump power. Eventually, of course, it wouldn't be possible to maintain pressure, but that would happen first at road speed, not idle. You are correct that fuel pressure is lower at idle. This is because engine vacuum is high at idle, so the computer reduces fuel pump power to keep the fuel pressure relative to manifold pressure the same. [note that it would not reduce fuel pump power if the pressure were low, it would keep it running full out] That just makes my point that fuel flow/pressure problems show up at road speed, not at idle.

I suggest that you do some research on modern fuel systems. The LS's (like many 2000+ cars) is a returnless system. However, even studying the older return style fuel injection system would show you that your reasoning is wrong here. On the return style systems, the fuel pumps run a full power all the time, even at idle. The pressure regulator just returns more fuel to the tank at idle. The only fuel system that I know of where the fuel pump can't pump at full power at idle is the old mechanical engine driven fuel pumps.

There is one fuel system related problem that could cause a car to stall at idle, but run with your foot on the gas. That would be if the fuel pressure was too high. It would cause the engine to flood and stall. However, that is not what the OP is describing here.
 
I ran out to take a pic. IAC is circled:

IMG_7276.jpg
 
pektel said:
I ran out to take a pic. IAC is circled:
Click to expand...

Yep, tap it a few times with a hammer and see if that unsticks it for a little while. I had two Grand Marquis that did this a few times. The hammer trick worked each time, till I changed out the part. The gen II LS doesn't have an IAC, the main throttle is used for idle control on them (if anyone was wondering).
 
guys, you don't understand how much I appreciate your help. Thank you so much. I will let you know what happens when I try the hammer trick
 
mystro9876 said:
and looked what I found!!!!!!!!!!??????????? looks to be an easy fix..
Click to expand...

Yeah, I guess that would do it too. You were getting enough air at idle, but since it was not being measured by the MAF sensor, your engine didn't know it.
Glad that was all it was.
 
You must log in or register to reply here.

Members online

No members online now.
Total: 283 (members: 0, guests: 283)
Back
Top