02 4.2l surging bad at idle
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02 4.2l surging bad at idle
Hey everyone,
Newbie here, I am having great difficulty trying to figure out why my truck is surging so bad in park or in gear at idle. I have to mat the brake while in drive to prevent me from ramming the car in front of me. It all started when I replaced the air filter. Everything I've read leads me to the EGR valve, but that has been bypassed.
Can anyone try and shed some light on this situation for me?
Newbie here, I am having great difficulty trying to figure out why my truck is surging so bad in park or in gear at idle. I have to mat the brake while in drive to prevent me from ramming the car in front of me. It all started when I replaced the air filter. Everything I've read leads me to the EGR valve, but that has been bypassed.
Can anyone try and shed some light on this situation for me?
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Joined: Mar 2014
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From: southern maryland
check the air filter be sure you installed it right and did not damage anything in the process what type of filter did you use. also do you have a check engine light on it would be a good idea to get any codes sounds like you caused a big vacuum leak weather it be air filter or something like this
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I asked a local mechanic and he said it was probably the egr. Yes I have propane. The codes were p0102 and p0136. I checked the mass air flow sensor and it looks bran new.
I cant find or hear a vacuum leak anywhere.
I cant find or hear a vacuum leak anywhere.
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From: Baltimore, MD
When you replaced you fuel filter you probably disconnected your MAF sensor. Since you probably don't have a scanner to watch the sensor voltage, which would be ideal, you have to physically look at the sensor and wiring. Make sure the harness clip is fully engaged and undamaged and that the wires are in good condition. Unplug the clip, check both sides and reconnect it, reset the code (or disconnect the battery if you don't have a code reader). If that doesn't solve the problem, you can try running it with the MAF disconnected to see if there is any change.
While it is possible that it is a completely different system, it is not likely. EGR issues generally set EGR codes and the fact that you were working right next to the MAF and now have a MAF code indicates something probably happened during the repair. Be sure you are checking the MAF and not the IAT also, the IAT is a much smaller sensor in the intake system.
While it is possible that it is a completely different system, it is not likely. EGR issues generally set EGR codes and the fact that you were working right next to the MAF and now have a MAF code indicates something probably happened during the repair. Be sure you are checking the MAF and not the IAT also, the IAT is a much smaller sensor in the intake system.
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The MAF has not been disconnected, I double checked it and wiggled the wires and pushed on the harness to make sure it wasn't. No change in doing that. What kind of scanner are you talking about? The MAF is the one closest to the filter with the 2 wires and the other one your talking about is further in and is a little red bulb right?
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Fleet Mechanic
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From: Winnipeg
Assuming this surging happened immediately after the install, first I'd remove the filter again and check the MAF wiring for being pulled by mistake. I would check all the tubing from the MAF sensor toward the throttle body for cracks and or improper reinstall. If not installed correctly or damaged, unmetered air can be drawn into the throttle body.
If the filter was plugged solid you might want to remove the cable from the battery for a couple of minutes so the Adaptive learning is reset.
If the filter was plugged solid you might want to remove the cable from the battery for a couple of minutes so the Adaptive learning is reset.
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From: southern maryland
take your propane bottle and lightly release it around anywhere that deals with air starting with the air filter if the engine rpm changes or stalls then you got a good idea were to look. try unplugging the mas air with the intake duct off and see what the engines response is
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I tried the propane and nothing noticeable happened. I unplugged the MAF and nothing changed either. I also disconnected the battery and that changed nothing. Now it only seams to be doing it bad when the truck is in gear, as soon as I put it in neutral or park it calms down and is a subtle surge. I also noticed that when the headlights are on and its surging the lights keep dimming like its about to stall. Do these clues shed any light on the problem?
Is there any way to test the IAC?
Is there any way to test the IAC?
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From: southern maryland
your truck should have a solenoid type Idle Air Control while the engine is running dis connect the valve and see if the engine stalls. looking at the codes it sounds like you have air fuel issues dealing with mas air flow and oxygen sensor circuits that being said if the engine is not running correctly due to an initial air pick up then it will kill the whole air fuel ratio as to what the engine needs. i would be wanting to see weather or not the engine is adding or taking away fuel and at what rate is it lean rich is it a fixed lean or rich oxygen sensor or what have you. And take the air filter out and start the engine see if it has any change.
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The engine stalled when I unplugged the IAC, so I'm assuming that means it's working fine? Nothing changes with the air filter out. So seeing that there doesn't seem to be any vacuum leaks, chances are its the MAF or the o2 sensor gone bad? Which one should I change first?
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You have 2 issues as verified by the codes.
.
LOOK ...at the codes and work form them.
Code 102 is Mass Air sensor circuit low (open).
You likely pulled a lead out or opened the circuit close by.
Motor will not run right with the Air Meter open circuited.
At least remove the connector and replug it.
.
Code 136 is the OX sensor circuit passenger side rear is open.
Harness, sensor plug or heater is open.
This sensor is the Cat monitor so it won't affect idle.
Good luck.
.
LOOK ...at the codes and work form them.
Code 102 is Mass Air sensor circuit low (open).
You likely pulled a lead out or opened the circuit close by.
Motor will not run right with the Air Meter open circuited.
At least remove the connector and replug it.
.
Code 136 is the OX sensor circuit passenger side rear is open.
Harness, sensor plug or heater is open.
This sensor is the Cat monitor so it won't affect idle.
Good luck.