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Discussion Starter · #1 ·
Hey all...I have a 2003 Chevy Malibu LS with the 3.1L engine. It has trouble starting after sitting for between 1.5hrs to 6hrs after cooling down from being hot. No theft lights on the dash, no check engine, it'll just crank and crank and crank and then start. It does always start, but takes a LONG time of cranking.

Here's the list of parts that have been replaced on it:

Fuel Pressure Regulator
Fuel Pump
Fuel Filter
Fuel Injectors
Spark Plugs
Spark Plug Wires
Ignition Module
MAP Sensor
Coolant Temp. Sensor
Throttle Position Sensor

Also, the car drives normally.
If anyone has any ideas at all, please let me know. I've stumped a few garages and dealerships...Thanks!!
 

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Hi kyleabrams

The hard starting issue with the malibu is not always engine related and there are a few things you will need to check. The first thing you will need to look into is the security module. The module has to be re-set in order for the engine to start and sometimes this doesn't happen causing the problem. To work around it because it is such an expensive part to replace, disconnect the battery for a several minutes and allow it to reset, then reconnect the battery. When you attempt a re-start, press on the gas pedal very lightly and then crank the engine. Keep in mind that constant cranking will flood the engine causing more problems, so if it doesn't start on the first 2 or 3 cranks stop immediately and repeat the process.

Another key issue is that the ignition key has also been noted to develop carbon deposits on the switch contact points. This problem relates to the engine's inability to turn over at all. To rectify this, use a piece of emery cloth to clean the points but to get access, will require you to have specialized tools and mechanical knowledge to take the steering column apart because there is a small linkage within it that gives out quite often.


Good luck !
 

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Also check the vacuum lines for leaks, trust me you have a few of them in places you wouldn't think you have them.
My Malibu is a 05
 

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When you first turn the key on can you hear the fuel pump run a second.This can lead you in one direction Also when cranking do you get a spark at the wires.The crankshaft position sensor can play this sort of game.hence the interest in spark.Are the plugs wet after cranking a while.If not try a little starting fluid down the intake.Does the check engine light come on with the key just in the on position.All part of trouble shooting.
 

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Discussion Starter · #5 ·
I pulled the key assembly out and found a TON of carbon. There was about 100ohms of resistance across the starting terminals. I cleaned it all up and measured about 0.3ohms afterwords, however it still does not want to start all of the time :(

I do hear the fuel pump prime. I've tried in the past to cycle the key a few times to let it build pressure, but it does not help. I pulled a plug and it is sparking during a hard start condition. Did not check the plug to see if it was wet, but I would imagine it is not if it is sparking? I will check this when I get a chance. Check engine light does some on until the engine starts, then goes off. I've checked it for codes with a scan tool and did not find any.

I'm starting to think that it is not pulsing the injectors properly. Is this done by the Cam position sensor? I'm assuming that the crank sensors are OK since it's sparking. Is this a correct assumption?

Also, no flashing anti-theft light, it's on solid until the key is turned to start, and then it goes out. So i'm guessing that passlock 2 is not a part in this..
 

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Discussion Starter · #6 ·
And I also both sprayed carb cleaner around the intake and throttle body and also tried propane and the idle did not seem to change.

I did notice something yesterday will idling it for a long period of time - the hotter the car got, the rougher the idle. Seems like a sensor is breaking down during heat-soak...just not sure which one :)
 

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The crank sensor tells the computer that the piston is at TDC and the cam sensor gives a signal to the computer telling it when to fire the spark at the coil(s). The injector pulse width is controlled by the computer. Since the engine fires up, there's nothing wrong with the cam or crank IMHO. If the injector does not pulse properly, the most common fault is a leaky injector or an electrical problem which is a loose or broken ground wire from the harness which is fastened to a thermostat housing, intake manifold etc. These types of wires are grounds that are directly to the computer, and they need to be periodically inspected. If you suspect an injector, you will need a stethoscope which has a steel probe at the end, these are are super cheap to buy and you can find them at any auto parts or tool supplier. To check for a bad injector, take the probe and point it on the injector body, you should hear a clicking noise at a very fast rate. The clicking noise is the injector turning off /on at a specific time in seconds. If there is no click but a hum sound, then the injector is shorted or open internally. You will need to do this to all injectors to be sure all are working, but that is not the only method to test them. By removing the injector plug and reconnect it while the engine is running, you can perform a cylinder balance test by visually see how the engine responds.
A bad injector when the engine is hot can cause the rough idle, the only way to determine this is to take the injectors internal resistance both engine hot and cold by using a DVOM and check your spec sheet for the appropriate values.

post back your findings.
 

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You sprayed propane into an engine? Why? I always though propane could explode if the engine backfired through the intake or if there was a electrical short somewhere
 

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Discussion Starter · #9 ·
I sprayed it around the intake VERY CAREFULLY. I didn't think it was a good idea myself, but someone said to try it on another forum so I gave it a shot. I didn't lose any limbs or anything so I guess it works lol.

octaneman: is there an easy way to unplug these injectors without taking the intake off? I'm thinking that it's not going to run too well without that..

If not, can I use a heatgun on the injector and then get the resistance to simulate a hot engine? These are "new" re-manufactured injectors (actually a second set of them because I thought the first set was the culprit and sent them back).

Again, thanks for the help!!
 

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I was always told o use soapy water around an intake. but if propane didn't blow up on you then I guess it did the job :)

You should be able to remove injectors without removing the intake, they should just be held in by an "O" ring
 

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The heat gun generates too much heat for the delicate internal windings in the injectors. If there is a shroud that covers the injector plugs, just remove it to get access it may be held down by alan screws or something similar.
 

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Discussion Starter · #12 ·
Well if I remember correctly when I changed the injectors a few months ago, I had to take the upper intake off (the piece of aluminum that says 3100 on it on the top of the motor). After that, the fuel rail needs to come off, and then you can get to the injectors.

I did notice something odd when cranking during a hard start last night. The starter sounded like it wasn't getting full voltage - it was cranking fine and then started to slow down. Also the headlights were dimming majorly during each crank. I shut the key off, cycled again and it cranked and cranked normal speed and started. Should I do a resistance check on the starter? Also, could it be a bad battery? I'm not sure of the age of the battery, but this car does startup fine in the morning cold (about 29F) first try.
 

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Knowing Chevy's like I do I'd say check the starter, the battery terminals the starter relay and the starter solenoid
 

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kyleabeans


On my previous post I mentioned that to do a cylinder ballance test you only disconnect/connect the molex connector plug on the injector, not removing the injector completely off the rail.
 

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Discussion Starter · #15 ·
I just looked up the procedure for removing the fuel injectors-

Remove or disconnect the following:

Negative battery cable

Fuel supply hose from fuel rail

Upper intake manifold

Main injector harness electrical connector

Fuel injector electrical connectors

Injector wiring harness from the fuel rail

Fuel injector retaining clip

Fuel injectors



There's really no way to get to the molex plugs on the injectors without removing the upper intake manifold...am I missing something?
 

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My book covers 2004-2007 so I can't be sure, but even though my engine is a 3.5, the procedures listed in my manual are the same as what you posted, and from looking at the picture of how the fuel injectors hook up to the fuel rail I'd say that what you posted is the only way to access it. Like I said though mine is a 2005 with a 3.5, so keep looking around If you find a different way to do it post in on here, please:)
 
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