car starts but won't idle

socalover · Post by **socalover** » 06 Oct 2015, 18:52

Here I go again. My car starts but dies with seconds. I can hear the fuel pump relay and the fuel pump engaging. The thing I know that needs to be fixed is the iginition switch. I need to tap it sometimes for the lights to come on or to take it out park. It would nice if this is the issue but I'm guessing it's a long shot.

Recently replaced:
MAF
AIC
ETC
Vacumn lines

The short period that is runs there are no codes. Any ideas where to start?
Thanks in advance

sk55 · Post by **sk55** » 06 Oct 2015, 19:27

fuel filter --- maybe check the pressure at the rail...
fuel pump...
plugs
coils
yes you should fix your ignition switch...
it could be the ETM....

i think u can start it without the MAF connected...

does it die when press on the gas once its started?

just a few ideas....

socalover · Post by **socalover** » 06 Oct 2015, 19:31

It dies even if I give it gas. I had my neighbor watch the throttle cable and it's moving fine.

socalover · Post by **socalover** » 06 Oct 2015, 19:32

Forgot to add that hear the fuel pump engage in the back of my car. Since it's a wagon it's easy to hear.

Post by **Ozark Lee** » 06 Oct 2015, 20:29

sk55 wrote:fuel filter --- maybe check the pressure at the rail...
fuel pump...
plugs
coils
yes you should fix your ignition switch...
it could be the ETM....

i think u can start it without the MAF connected...

does it die when press on the gas once its started?

just a few ideas....

From his sig the OP has a '96 so it has no ETM and only one coil with a distributor and ignition wires.

To the OP,

Fuel pressure is a good starting place and unplugging the MAF is also a good test. When you replaced the MAF sensor what did you use? Most of the aftermarket brands and the "rebuilt" MAF sensors have been very problematic so if it wasn't a new Bosch then try the unplugged MAF test for sure. If the car starts and idles OK with the MAF unplugged then that pretty much confirms a MAF problem.

...Lee

Post by **abscate** » 07 Oct 2015, 04:52

Is seconds like 10'seconds or 1-2 seconds?

The latter is the symptom of anti-theft shutting your car off

socalover · Post by **socalover** » 07 Oct 2015, 09:49

It runs for less than 5 seconds. I thought about the alarm so I locked and unlocked with key three times. Is there another way to check? Can I disable it until I can get it fixed if that's the problem?

Post by **Ozark Lee** » 07 Oct 2015, 11:41

The immobilizer on a '96 only kills the starter, not the ignition so that isn't it. It can be easily bypassed but if it cranks OK then there is no reason to do it.

...Lee

socalover · Post by **socalover** » 07 Oct 2015, 15:15

I'll check the car out on Friday. For now just gathering info. Question about MAF. I've read different theories. If it started going bad would it run poorly before causing this issue? I'm not sure of the brand since a friend put it in at his shop.

I also just remembered all my fuel injectors seals were replaced when one was going bad about 6 months ago.

Post by **Ozark Lee** » 07 Oct 2015, 17:37

There isn't really a definitive answer to the MAF question. It depends on how they fail.

As they get dirty the car will begin to lose performance and mileage. The ECU tries to compensate for that and it actually does a pretty good job of hiding the problem until it gets so bad that the ECU can't deal with it anymore.

There can also be a sudden failure where the sensor just up and quits so it would give no warning at all. The sudden failure is the one that is the toughest for the car to deal with since it has "learned" a starting offset over time and suddenly the values are no where close to that preset offset.

The offset values are being constantly learned and the offset values will change over time as the sensor outputs change. It finds a "new normal" all the time but that normal range has to fit in a prescribed window that is programmed into the software. Once the value is outside the window the ECU disables the out of tolerance sensor and uses the other sensors to make a best guess so as to try to keep the car running. It can't always do that.

Another sensor that can cause the car to stall out is the ECT sensor. If the ECT sensor is bad it can tell the car that the engine temperature is -20 degrees or so and give it an extremely rich mixture, so rich that the car will stall out.

...Lee