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Can a bad EGR valve cause a high rpm misfire?

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Yes it can, at least on my 97 saturn SL2.
You can remove the EGR value and check for carbon built-up.

The carbon can build up on the intake valves and cause misfires.
The carbon lowers the octane level of the gas and also partly burns some of the fuel.

How I do a valve cleaning:

  1. Buy engine de-grease for the outside of the engine
  2. start engine when it is cold.
  3. remove the pcv hose
  4. spray into the throttle body for 30-60 seconds or stop when the engine chokes
  5. turn engine off
  6. wait 30 mins
  7. start engine, white smoke will appear
  8. have oil change since the cleaner will thin the oil
I use Lucas Upper Cylinder Lubricant to keep the valves clean for the type of engine below.
http://www.lucasoil.com/products/display_products.sd?iid=26&catid=8&loc=show can a bad EGR valve cause a high rpm misfire? - 3ec0aad5-8a21-4065-85b4-cbad634920da.jpg

Posted on Jun 06, 2014

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I have a 2003 ford expedition and when you set and it idles for a bit like at stop light or just sitting in traffic it like sputters and feels like the whole engine is gonna fall out. Please help


hot or cold engine, or both? key,
key fact too, can you save the stall or low RPm with fast right foot action??????
that is misfire, can be caused by 50 things,
most things are in engine, like cracked valves or pistons,etc.
but in physics its just 3 (assumes battery is at 13.3v to 15v running)
stalls or near stalls.
when the engine shook, was RPM below 800 RPM
at below 500 all engines shake, that is normal for idle speed control failure.
ever service the engine? at every 60,000 miles,? do the listed things
in the operators guide? at the least spark plugs and filters.?
tune up parts are those parts that never last the life of an engine, 300k.+
no engine option stated. there are many.

800RPM hot misfire is another matter.
that will be (compression good all cylinder) bad spark on any ,bad fueling or egr stuck open (egr will cause dropping idle, if extreme leak)
no engine stated so cant look up if it has EGR. some engines dont
the use a detuned CAM to do same thing.
its and older truck some have huge mileage after , 11 long years. huge. (unstated )
oh all old cars or high mileage a compression test and leak down test
are the 1st step by me.
you cant burn fuel well with flat compression.

Jun 10, 2014 | Cars & Trucks

1 Answer

RUNS ROUGH AT MID RPM


Need to be more specific here. Runs rough...like misfiring? or vibrating excessively at about 1500, and again about 3000 rpm? If it's the latter, chances are your engine's balance shaft is not timed correctly. This causes a heavy high-frequency vibration/buzz throughout the car, at the aforementioned rpm ranges. If it's more like a misfire/stumble, look into your ignition system, or possibly a sticking EGR valve. (This will cause a mild surge/bucking under light accel, peaking between 45-50mph. Good luck!

Apr 07, 2014 | 1997 Honda Accord

1 Answer

My 2000 Ford Expedition 4.6l had a manifold seal blown and was leaking fluid in the sparkplug sockets. Seal replaced and spark plugs changed, now I am having to change coil packs because Im getting...


Faulty EGR valves do not cause "false" misfire codes. An EGR valve that is not closing properly can cause misfires (and misfire codes) but they are REAL misfires when this happens.

To understand this, you need to understand what a misfire is and what kinds of things can cause them. It is a very LONG list and I do not have the time or space to get into all that here.

You will also need to understand this if you are going to properly diagnose your misfire codes without wasting a whole bunch of money on parts that you do not need. MANY things can cause misfires other than spark plugs and ignition coils.

I do not know what EGR code you are getting, but I will tell you that in the 37 years that I have been diagnosing and repairing cars, there has only been once that I can remember that I have ever replaced an EGR valve on a Ford engine because the valve itself was faulty. Most EGR codes on Fords are caused by either clogged-up EGR ports or a bad DPFE sensor. Every so often you will find a bad EGR control solenoid or a broken vacuum line, but it is extremely rare that the EGR valve itself the cause. With the exception of leaking vacuum lines and on certain engines, clogged EGR ports (Like the 6 individual EGR ports in the 4.2L engine), none of these causes for EGR codes will cause any misfires.

Also, most of the time when people pull the trigger on the ignition coils on the 5.4L and 4.6L engines, all the thing really needs is new spark plug boots. They get contaminated with oil and water and can cause carbon-tracking on the spark plugs and/or arcing into the spark plug wells instead of sending the spark through the spark plug. It is pretty much the same thing as having bad spark plug wires on a conventional ignition system. You don't throw the coil and distributor away on a conventional system because it needs new wires. Neither should you replace a coil on a COP ignition system that just needs a boot. Some auto makers do not make the boots available seperate from the coil. Ford at least had the insight to understand that people cannot afford the cost of replacing all of their coils just because the boots are defective.

Mar 24, 2012 | 2000 Ford Expedition

1 Answer

Idel problem on 5.7 1995 silverado


You engine is TBI, It uses a MAP sensor check the vacuum line for crack and make sure yo have a good seal, The distributor also check and make sure the pick up does not have corrosion which causes the relutor to stick. As for the EGR it would cause a misfire, and yes the do fail. I am sticking with the IAC as a problem its a stepper motor and has a high failure rate, chack also the ECT (engine coolant temp sensor) for corrosion that gives false reading.

Mar 05, 2012 | Chevrolet Silverado Cars & Trucks

1 Answer

No Idle - dies. Truck has been sitting for six years. Had 2nd cylinder miss and rough Idle. Replaced plugs, hoses, adjusted TPS to Spec, and adjusted timming. I had to take vaccum line from Cruise...


I would check the EGR valve diaphragm to see if it will hold a vacuum. The VSV associated with the EGR valve is controlled by the computer and is probably what is kicking in at 1700 rpm. When the VSV opens, a leaky EGR diaphragm will let air into the intake manifold just ahead of the throttle body. This air will not be measured by the mass air flow meter/sensor and the resulting mixture will be very lean and lead to misfires.

Feb 25, 2011 | 1986 Toyota Pickup 4WD

2 Answers

On a 2003 Buick Rendevous the computer keeps coming up with a code of P1374. Have check both of the crankshaft sensors, the 24x has an input of 11.15 instead of the suggested 12 volts. Nothing else obvious...


Timing Reference High Resolution Signal A ( No Pulses) This is a misfire code so try this info. This info is where your mechanic would be following.

The following info comes from a code reference guide for troubleshooting.


Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
A random misfire code usually indicates a vacuum leak or bad gas.
a misfire in a specific cylinder should lead you to check the spark plug, fuel injector and compression.

Jan 24, 2010 | 2003 Buick Rendezvous

2 Answers

Idleing high and low on my engine.


Check your codes, you might get an EGR code, Fords are notorius for bad breathing,
clean your throttle body also

Sep 10, 2009 | 2003 Lincoln Navigator

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