Question about Cars & Trucks
When I first start the car, it chugs or hesitates. Once I drive a mile or more (very slow, easy on the gas) it smooths out. However, in that mile if accelerating like you normally would, it chugs hard and it will almost stall. At work they thought I might have got bad gasoline. I put a bottle of HEET in. It's been a few days, and during start up it's a bit better. Sprayed down with carb cleaner. New air filter, changed the oil, checked the plug connections, and using mid-grad gas from Shell. But this morning's commute if you hold a steady 40-45 it will chug and shudder some. On the highway 55-60 steady it really shuddered a couple times hard, if I slowed a bit and returned to speed. This car does not like to do over 60. Could this be a trans thing and not a fuel line thing? A failing valve? Replaced the EGR last year, but not the IAC. Thoughts? Appreciate any and all suggestions! new stuff since summer 2012... plugs, cables, fuel filter, EGR, tires, water pump, thermostat. I have used FIXYA to bring this car back from the dead, THANK YOU all!!!
EGR is typically not employed at high loads because it would reduce peak power output. This is because it reduces the intake charge density. EGR is also omitted at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle. The EGR valve also cools the exhaust valves and makes them last far longer (a very important benefit under light cruise conditions).
Since the EGR system recirculates a portion of exhaust gases, over time the valve can become clogged with carbon deposits that prevent it from operating properly. Clogged EGR valves can sometimes be cleaned, but replacement is necessary if the valve is faulty.
Posted on Jul 11, 2013
Testimonial: "Right, got that all about the EGR. We replaced it because the diaphragm was no longer working. Do you have any diagnosis beyond that? I greatly value your help."
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Posted on Jan 02, 2017
SOURCE: 99 olds alero 2.4
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.
Posted on Dec 04, 2008
The plenum problem should not affect compression tests. It allows oil to get sucked into the intake and will cause carbon buildup, plug fouling, and pinging. If you have zero compression on a cylinder, it is usually a valve problem. Even a burned piston will make some compression, unless it has a big hole in the middle.
Sorry, but if your compression results are to be trusted (and it seems they are), then you have to tear a head off to find the problem, or at least get a borescope in it.
Posted on May 20, 2009
check all of the vaccum lines and check for leak at the fuel injection unit and for leaks at the intake manifold also make sure the spark plugs are at the right gap and change the fuel filter and here is a couple of website to checout www.autozone.com and www.alldatadiy.com and i forgot one www.taurusclub.com and i hope i have been some help to you Michigan Man.
Posted on May 20, 2009
lower control arm, rubber bushings worn, common problem, can be intermittent
check wheel bearings as well.
Posted on Feb 02, 2010
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