Olds alero 2.4 idle fuel pressure

1999 Oldsmobile Alero Stumble and Loss of Power 3000rpm

www.2carpros.com/.../oldsmobile-alero-1999-oldsmobile-alero-stumble-...
Sep 28, 2008 - Engine Performance problem 1999 Oldsmobile Alero 6 cyl Front ... Hey All, Had a very rough running Mazda 626 on LPG, engine code FP.

1999 Oldsmobile Alero High Idle Fix - YouTube

? 1:47
www.youtube.com/watch?v=xBV9BmjFZVs
Jul 4, 2010 - Uploaded by GrindTimeAuto
1999 Oldsmobile Alero High Idle Fix ... How To Fix Or Prevent Stalling, Surging Or Rough Idle, Cleaning Throttle Body and MAF Sensor ...

1. Fuel delivery problems (bad fuel pressure regulator, bad injectors, clogged fuel filter, etc.);
2. Defective idle bypass (Idle Air Controller);
3. Bad Throttle Position Sensor (TPS);
4. Defective Engine Control Computer;
5. Demonic purple gremlins from space (don't make them angry).

Check the BROWN ground wire where it attaches to the throttle body by a 10mm headed bolt.. Audi used a thread sealer here and it makes poor contact.

Check the fuel pressure. Should be 55 psi dropping to 25 psi or so when engine off after 30 minutes. If fuel pressure drops to near zero, warm engine start will be hard. This is caused by a faulty fuel pump check valve or accumulator ( Grey looking can under rear of car with two hard fuel lines to it.) Pressure should be checked before the fuel distributor.

The warm up valve ( WUR ) can also cause hard starts. It is on the side of the engine with two stainless braided hoses going to it. It can be rebiult by Larry at CIS FLOWTECH.

CIS FLOW TECH LLC19225 County Road 13
Fairhope
AL 36532-3687
Phone: (251) 929-0190
Category: Fuel Systems and Parts, Motor Vehicle


The intake trunking has a habit of cracking open between the folds and admitting false air as engine moves. .

Low pressure from fuel pump, when the pump is cold the pressure increases, as it warms up the pressure drops (this happens in a pump that is going out) the normal pressure should be at 40 with the key on and engine not running, when started the pressure should stay around 36, any less it won't idle and may run as long as you hold the pedal down. The injectors are opened electronicaly, so as long as there is fuel flow the engine gets fuel to run.So check the fuel pump, soundslike you need a new one

hard start is AM is most commonly caused by a defective fuel pump pressure check valve, the other stall is issue is covered by the following procedure.
Here are some of the causes of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Here are the most common causes of surges, stalls at stops, low erratic idle speed, rough idle and engine hesitation, it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

oil pump might be going bad

I'm sure you have installed a fuel pressure gauge and monitored the fuel pressure while the problem is occurring?Another diagnostic tool which is easy to do,is while the problem is occurring,unplug one sensor at a time beginning with the Mass Air Flow first,.if it uses one.Many times,not always,depending on the sensor,if the sensor is taken out of the picture as far as what the PCM is seeing,like unplugging the MAF,the PCM will substitute the missing sensor output with a generic value that will allow the engine to at least run,and if unplugging for example the MAF,the engine idle speed returns to normal,you know you're onto the problem.You didn't mention if the engine ran ok other than the idle problem.As far as checking for vacuum leaks,i use something like brake cleaner or WD 40,more of a liquid,and it does sound like a vacuum leak.Plastic intake manifolds do develop nearly invisible cracks that open up more with heat.Revsisit the possibility.And as for the PCM,it is possible,but more likely a mechanical problem.Lastly,remove an O2 sensor or two before the catalytic convertor,run the engine and see if anything changes.Cheap way to verify the catalytic convertor is flowing and not restricting engine airflow,as i have seen bad cats cause misfire codes and strange problems.Good luck.

intake manifold has a vacum leak or other vacum leak hose etc.

The two most likly causes of your Idle problen are, low fuel pressure. try installing a new fuel filter. Or the other one is the Air Idle control valve, can cause the exact problem you discribed with a cold engine. Fuel Injection engines do not have a choke like carburated engines do. So the idle is computer controled thru the Air idle control valve.