I have a 1994 Pathfinder SE (VG30E engine) with 214K miles on it. It experiences hesitation when under load at low rpm. The most common item mentioned in the posts (including this site) and manuals i read was spark plugs. After changing the plugs the situation improves but is still not solved completely. My next guess is the oxygen sensor. Any thoughts out there regarding this? Or anything else for that matter.
The process I am using here is the same process the Nissan Mechanics use; replace parts until the car runs good.
No error codes show on the computer. This computer is the older one where you read the blinking lights.
Engine Hesitates under load at low rpm
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davidrberg
- Posts: 7
- Joined: Sun Jul 24, 2016 10:09 am
- Car: Nissan Pathfinder 1994
Nissan Xterra 2009
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davidrberg
- Posts: 7
- Joined: Sun Jul 24, 2016 10:09 am
- Car: Nissan Pathfinder 1994
Nissan Xterra 2009
Engine Hesitates under load at low rpm - update
Update ...
Repaced the oxygen sensor - no change
Replaced the plug wire set - very slight improvement
Replaced the distributer cap and rotor - very slight improvement
Replaced the EGR valve - no change
Performed a vacuum pressure smoke test using a 1 gallon paint can with incense in the bottom of the can (see utube posts on vacuum testing) using 5 psi
Detected a leak on one of the 1" hoses on top of the left valve cover
Fixed/replaced leaking hose - improved idle issue - it is now idling ok but a bit low
Now the computer is finally putting out an error code - number 32
Number 32 is the EGR so I am going to replace the EGSR solonoid valve as it is the next thing to replace after the EGR valve itself
More to follow ...
Maybe the Nissan Mechanics can come over to my house for their next training session ...
Repaced the oxygen sensor - no change
Replaced the plug wire set - very slight improvement
Replaced the distributer cap and rotor - very slight improvement
Replaced the EGR valve - no change
Performed a vacuum pressure smoke test using a 1 gallon paint can with incense in the bottom of the can (see utube posts on vacuum testing) using 5 psi
Detected a leak on one of the 1" hoses on top of the left valve cover
Fixed/replaced leaking hose - improved idle issue - it is now idling ok but a bit low
Now the computer is finally putting out an error code - number 32
Number 32 is the EGR so I am going to replace the EGSR solonoid valve as it is the next thing to replace after the EGR valve itself
More to follow ...
Maybe the Nissan Mechanics can come over to my house for their next training session ...
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atraudes
- Posts: 1106
- Joined: Thu Jan 10, 2013 7:46 pm
- Car: 2001.5 Infiniti QX4 4WD
- Location: Sammamish, WA
Re: Engine Hesitates under load at low rpm
Careful, it's a slippery slope! I've replaced just about everything on my car too. I've spent a small fortune, but it's running like a top! At least, it will when I get this one last thing done... 
Change your fuel filter and clean the throttle body if you haven't already (good ideas anyway) and check your fuel pressure. Otherwise it sounds like you have a pretty firm grasp on it
Let us know how it goes!
Change your fuel filter and clean the throttle body if you haven't already (good ideas anyway) and check your fuel pressure. Otherwise it sounds like you have a pretty firm grasp on it
Let us know how it goes!-
davidrberg
- Posts: 7
- Joined: Sun Jul 24, 2016 10:09 am
- Car: Nissan Pathfinder 1994
Nissan Xterra 2009
Engine Hesitates under load at low rpm - solved
Replaced EGRC solenoid valve. This fixed the computer error code number 32. Been driving the pathfinder now for a couple of weeks and the hesitation and idle problems are pretty much solved! Good enough for a 214k pathfinder at least. Took the car down to get the emissions tested and it passed CA regulations - YA HO !!!!!! In retrospect the only wasted money was the oxygen sensor and the EGR valve.
The most fun thing to do was the 1 gallon paint can smoke test, to find the vacuum leak. Took a gallon paint can and drilled two holes in the lid. Took some 3/8 inch copper tubing left over from a plumbing project. Cut one at 10 inches; to push the air in to the bottom of the can. Cut one at 4 inches to take the smoke out the top of the can. Put washers on both sides of the can lid, on each tube, and held it all together with silicone seal. When it dries it is air tight. When you connect the can up to the air compressor set the regulator to as low as it will go, in my case about 3-5 psi. Even that low psi will make your paint can lid pop off, so you need a buddy to stand on the paint can lid for you. I had some leftover vinyl tubing that i used to connect the can up to the air compressor, and to one of the vacuum tubes on the car. You also need to put a plastic bag over the rubber air intake tube. I used a ziplock and repurposed the existing clamp to hold the ziplock in place. When you fire this contraption up smoke will come out someplace. That is your vacuum leak. There are lots of (useless) u-tube videos on this stuff, but I can tell you that this approach works.
The suggestion regarding the throttle parts. I looked at that and it must have been cleaned by some previous persons as it is already very clean. Obviously not 214k worth of dirt on it.
As for the fuel filter, A clogged filter will not let the fuel flow; which is more evident at the higher engine speeds, not so much at idle. I had this exact problem on another vehicle, replaced the fuel filter, and was good to go. A good suggestion, as this is a pretty cheap part.
The most fun thing to do was the 1 gallon paint can smoke test, to find the vacuum leak. Took a gallon paint can and drilled two holes in the lid. Took some 3/8 inch copper tubing left over from a plumbing project. Cut one at 10 inches; to push the air in to the bottom of the can. Cut one at 4 inches to take the smoke out the top of the can. Put washers on both sides of the can lid, on each tube, and held it all together with silicone seal. When it dries it is air tight. When you connect the can up to the air compressor set the regulator to as low as it will go, in my case about 3-5 psi. Even that low psi will make your paint can lid pop off, so you need a buddy to stand on the paint can lid for you. I had some leftover vinyl tubing that i used to connect the can up to the air compressor, and to one of the vacuum tubes on the car. You also need to put a plastic bag over the rubber air intake tube. I used a ziplock and repurposed the existing clamp to hold the ziplock in place. When you fire this contraption up smoke will come out someplace. That is your vacuum leak. There are lots of (useless) u-tube videos on this stuff, but I can tell you that this approach works.
The suggestion regarding the throttle parts. I looked at that and it must have been cleaned by some previous persons as it is already very clean. Obviously not 214k worth of dirt on it.
As for the fuel filter, A clogged filter will not let the fuel flow; which is more evident at the higher engine speeds, not so much at idle. I had this exact problem on another vehicle, replaced the fuel filter, and was good to go. A good suggestion, as this is a pretty cheap part.