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A friend of mine has this 2004 malibu that sometimes struggles to turn on, but mainly the problem shows when you try and put it in drive or reverse. What happens is that the rpms drop down real low, almost like the engine is going to stall but then they go back to normal. A local mechanic told him that it was the fuel pump, but I’m thinking something more along the lines of fuel filter, maybe idle control sensor? Also the car tends to jolt when put in either reverse or drive.
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Hi OrangeBoi,
A couple quick suggestions. Check the voltage on the battery before starting, as well as while the car is running. Want to make sure you have a good battery, as well as ensure that your alternator is charging well. Ideally the battery voltage before starting should be between 12.4 – 12.6 volts. (75 -100% of the battery). While running, the battery should should be around 13.5 – 14.5 volts (as a general rule).
Check the air filter and make sure it is clean. A severely clogged air filter could provide similar symptoms.
How many miles are on the vehicle? How old are the spark plugs and how many miles are on them?
A fuel pressure guage would help identify if you have proper pressure in the system.
Is there any CEL (Check Engine Light) or codes currently?
Sounds like the vehicle is struggling due to a lack or either air, fuel, or spark. Keep us posted.
Not sure how old the spark plugs are but I do know that the battery is in perfect working condition. Its got around 150k miles on it but no there’s not a CEL light or any codes right now. I’m gonna try to see if I can get someone to check the fuel pressure but not too many reputable mechanics around here where we live. Do you know if it costs much to get someone to check the fuel pressure?
Quoted From BigC:
Hi OrangeBoi,
A couple quick suggestions. Check the voltage on the battery before starting, as well as while the car is running. Want to make sure you have a good battery, as well as ensure that your alternator is charging well. Ideally the battery voltage before starting should be between 12.4 – 12.6 volts. (75 -100% of the battery). While running, the battery should should be around 13.5 – 14.5 volts (as a general rule).
Check the air filter and make sure it is clean. A severely clogged air filter could provide similar symptoms.
How many miles are on the vehicle? How old are the spark plugs and how many miles are on them?
A fuel pressure guage would help identify if you have proper pressure in the system.
Is there any CEL (Check Engine Light) or codes currently?
Sounds like the vehicle is struggling due to a lack or either air, fuel, or spark. Keep us posted.
This is great stuff and excellent advice. I would add however that most idle issues are mixture related so I don’t think fuel pressure has anthing to do with it. I think your time would be better spent looking for vacuum leaks instead but I actually suspect an issue with the IAC valve but perhaps not the valve itself but rather it’s not getting the signal that you put it in gear. I know you say you don’t have a CEL but I would recommend checking for codes anyway as there could be one stored.
Keep us posted.
Just thought I’d chime in on my fuel pump failure experince.Had two vehicles that had strange idle and stalling and non-starting issues.Not sure if this would help.My vehicles did not throw actual fuel pump codes.Not sure if newer vehicles do.Had 89′ olds that starting to idle rough and almost stall and the check engine light would flicker on and off.Was able to retrieve a lean mixture code.Figured it was the 20 year old fuel pump and it was.Also, had an 93′ Ford bronco that would act weird.It let me sit and after about an hour it started.Sometimes it would start and run so rough I thought the engine would shake out.Ford dealership could not find a problem and he said(just like Eric) I should have the IAC replaced among other things that would cost a fortune.I also had the fuel pump pressure checked at an independant shop and it checked good, but car was running good.After a week of idle issues and determining the car would idle crazy after sitting for about 15-20 minutes and restarting I drove to the dealer and demanded the same tech come out in the lot and look at it running crazy.Lots of codes came up so he grabbed his pressure gauge and I had very low pressure.This was only happening mostly after it would sit for awhile after driving and restarting.He ended up replacing the pump and pressure regulator.Fixed my problem.Hope this helps.
The first method of diagnostics would be to check for codes.
If the Malibu your working on is a V6, i believe that vehicle is equipped with the drive-by-wire system. The throttle is all computer controlled and so too is the idle.
There is a relearn process you could try on this particular design but a scan tool may be necessary.
If you have a 4 cylinder, the IACV is replaceable. However, you could try cleaning around the throttle plate if it is gummed up, providing it is a 4 cylinder.
Hope this helps.
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