Quote:
Originally Posted by lindemandude
Engine wise the car is pretty much stock with about 90k manual trans.
MAF sensor is below value
O2 heaters are below value
Did an oil change and tuneup a few weeks ago but is unrelated as this issue has happened in previous years (pretty much since I moved).
I’ve tried giving the car gas as well as other changes when starting. Rising in RPM is just the sweep as the car starts. Obviously a normal start would crank, start, rise in RPM, then settle at idle.
Instead of settling to idle the RPM just drops and the car dies. Same result after clearing codes, starting again, gas/brake combinations.
The codes seem largely irrelevant given the same codes have been present long before this issue started happening. Also the fact that the car still starts and drives normally any other time with the same codes still present.
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So first your codes are very relevant.
Your MAF sensor (Mass Air Flow sensor) is one of the sensors used to tell the DME how much air is coming into the engine. From this the DME then knows how much fuel to add to that air for proper combustion.
If the values are out of spec. your going to be running to rich or to lean causing your catalytic converters to burn up or plug up over time. Also over time other issues will begin to arise.
Like the engine dying issue your having. The DME/ECU simply doesn't know how much fuel to mix with the incoming air at all times.
O2 sensors.
If the heater on an O2 sensor is not working. it has to heat up from the exhaust if it even works at all.
They need to reach around 650 degrees F before they begin to work.
Their job is to report feed back information to the DME about fuel air mixture.
If they are not working or take to long to heat up and begin working.
What happens is your car stays on cold start fueling longer. (overly rich fuel air mixture). Which damages your Catalytic converters. Fouls your plugs and does other damage over time.
So you need to deal with any code related issues. letting them go does damage over time and you get more problems.
When you get codes they need to be dealt with. I can't stress that enough.
The following is just a guess.
But your car has an "IACV" (idle air control valve) on the throttle body. It controls the idle by controlling the butterfly position (air intake) in the throttle body. Your rise in RPM and then dropping of and dying at start up could be due to a dirty, stuck or failed IACV.
They are simple and not expensive to change.
They can also be cleaned and that (at times) works just as well as replacing them.
Use the search function here on the forum and do some research on them.
Just type in IACV.
So your MAF sensor issue or an IACV issue.... or both are most likely to cause your problems.
But you also need to fix any and all the code related issues or your going to have more and more issues and expense over time.
When you get sensor codes that say below value that can be a sensor issue or an electrical issue.
"below value" meaning low current or low electrical signal so there is excess electrical resistance for what ever reason.
Keep us posted on the out come.