Topic: Car dies off at idle, starts up every time, runs with gas pedal down, no codes

[edwardmorris]

So life continues doling out lemons, my car's acting very strange .

2001 Chevy Prizm. I drove it 60 miles yesterday trouble free. Then took it out today, drove a 1/4 mile and parked at the grocery store. When I came back, it started right up but wouldn't stay running. Starts right back up each time, just won't idle and dies. If I push the gas pedal down a bit, it stays running, but dies right off at idle. I managed to drive it back home by not letting go of the gas,  but again, as soon as I parked, it died off. What could be happening?

[CBJoe]

So life continues doling out lemons, my car's acting very strange .

2001 Chevy Prizm. I drove it 60 miles yesterday trouble free. Then took it out today, drove a 1/4 mile and parked at the grocery store. When I came back, it started right up but wouldn't stay running. Starts right back up each time, just won't idle and dies. If I push the gas pedal down a bit, it stays running, but dies right off at idle. I managed to drive it back home by not letting go of the gas,  but again, as soon as I parked, it died off. What could be happening?

No Check Engine Lights?  Usually you will get something if there is an issue with the intake/Idle sensing circuit.

Easy Checks are the Air Filter and MAF Sensor.  Make sure some small furry animal didn't stuff a bunch of stuff in the airbox.  Also check the tubing to the PCV Valve.  If you have an air leak in the intake it can wreak havoc on starting and idling.

Cheers, Joe

[754]

Stuck EGR valve did that on a nineties Chevy truck I drive sometimes..had to brake torque itat lights to keep it running.
 Local neighborhood car guy slapped it around a bit with a brake adjuster prybar, and its fixed for a while..

[eigenvector]

Really depends on the vehicle.
On my pickup for instance there's a sensor at the throttle plate that has in the past failed and that wrecked the idle. 

Simple fix - replace the sensor, it threw a code though.  Your car does have an error code - just a matter of getting it.

[jgger]

Get it scanned someplace that can check pending codes, then write down the exact "P" code. NEVER LET THE PARTS STORE JOCKEY TELL YOU THAT NEW HEADLIGHT FLUID OR SOMETHING ELSE IS THE FIX ALL. A sticky/dirty throttle body will do that too, or low fuel pressure. First step is get the codes read, throwing parts at it can be expensive.

[Steve F]

I've seen things like that on my truck, and it was a vacuum leak on the intake.  New gaskets and all was well again.

[edwardmorris]

Back on the road, thankfully it was simple. This is purely my neglect. Started with the intake system as advised, and found out that the cause was a clogged up air filter and a gunked up throttle body. Changed the filter, cleaned the MAF sensor, throttle body, and the sensor right at the TB. Runs and idles buttery smooth again. The air filter wasn't due for a change for another 1K miles, but its possible that dirt and pollution have gotten worse in the area. I used to clean the TB, sensors and other electricals (in fact the entire engine) once a year, but have slacked off in the last few since I got busy with the CBs. I took it in to my buddy's shop to have them closely inspect all the hoses and so far they're all good.

The car is pushing 235K and I really ought to get a newer one, but I can't get over it. It is the one constant that has failed me the least over the past decade. Just not ready to give it up yet. As always, thanks a bunch friends, advice here has always proved invaluable.

[CBJoe]

Back on the road, thankfully it was simple. This is purely my neglect. Started with the intake system as advised, and found out that the cause was a clogged up air filter and a gunked up throttle body. Changed the filter, cleaned the MAF sensor, throttle body, and the sensor right at the TB. Runs and idles buttery smooth again. The air filter wasn't due for a change for another 1K miles, but its possible that dirt and pollution have gotten worse in the area. I used to clean the TB, sensors and other electricals (in fact the entire engine) once a year, but have slacked off in the last few since I got busy with the CBs. I took it in to my buddy's shop to have them closely inspect all the hoses and so far they're all good.

The car is pushing 235K and I really ought to get a newer one, but I can't get over it. It is the one constant that has failed me the least over the past decade. Just not ready to give it up yet. As always, thanks a bunch friends, advice here has always proved invaluable.

Good Deal!  Glad it was simple

[eigenvector]

Glad to hear you figured it out.

MAF and TBS will get you every time

The MAF can be a tricky one.  I know plenty of guys who fiddled with it and ended up giving themselves all sorts of grief. 

MAF, DPS, and the TPS are all basically the sensors your car uses for proper fuel/air ratio (Mass Air Flow, Differential Pressure Sensor, Throttle Position Sensor)

[Duke McDukiedook]

The trick with those sensors is if they go south and you have to replace you need to be careful about what you replace it with. On a Nissan Pathfinder I was fixing for my father-in-law you either had to go with an OE part or from the dealer. If you went with the cheapy Chinese part they usually wouldn't work properly on the TPS and the MAF sensors. Some parts are worth shelling out the extra dough to save grief.

[chewbacca5000]

I have a 97 geo prizm rusting to pieces, but runs like a beast!  Sound like one too.  With all the noise it makes I like to pretend it is a Porsche or something.

[Jerry Rxman Griffin aka MuthaF'er]

Curious, did you hook up a code reader to determine no codes or just no dash light? Places like Advance Auto will let you use their reader. I bought a cheap Chinese blue tooth reader for $6 shipped and installed TorqueLite software on my phone. Plug the reader into the computer port and have at it. Read the code and reset the computer to turn off the dash light.

[edwardmorris]

Yep, no codes, and all hoses are intact. After the intake, hoses were next suspect, but I had replaced almost all of them about 85K miles ago.

[RAFster122s]

Sometimes new parts fail long before they should if the manufacturing process was not tightly controlled.  Add the general quality of much of the parts coming out of China that are "cheap" (and sometimes expensive) There is no guarantee a new part will hold up.

David

[evinrude7]

i had a stalling problem and low idle issue with my truck.  no codes.  racked my brain for days trying to figure it out.  my wife said check the plugs.  sure enough 1 of the 16 plugs was loose.  it was at the back of the engine.  super hard to get to.  i must have forgotten to put a wrench on that one last time i did the plugs.