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Discussion Starter · #1 ·
I have posted this question on another thread, but was kicked off. so for all of you V-6 owners, here we go again! :waving::waving:

1994 SE V-6 4X4. She starts and runs with only this one quirk. It is costing me fuel economy and performance. I live in the Ozark Mountains so there is alot of uphill driving, and shifting gears. Therein lies the problem.

Every time the rpms drop down to 2400 the engine lugs and vibrates, untill you get the rpms back up above 3000. :wtf:

This happened last year about this same time. But after poking around and running a few cans of fuel treatment through her it cleared up until last month.

Here is the list of what I have tried thus far: Wiggle and jiggle all wires and
harnesses and connectors.

New Throttle postion sensor
new spark plugs
several cans and brands fuel treatment
check codes. just knock sensor. Duh!
check all vacuum lines, replaced ends of some.
ALOT OF CURSING!!!

So, I am hoping some of you folks have had a similar problem with your V-6 and can shed some light.

A search of the forum turned up a similar problem but with a much older engine. Sooooooo.

thanks folks
crystal :confused:
 

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Discussion Starter · #3 ·
zanegray, thanks for the reply. I did what you suggested with the Battery cable and got the "no malfunction" code. I will do it again, after driving this weekend.

Why stop using the treatment??? Curious?

Cooland Temp. sensor??? How will that help?

Here is a new thing I noticed, When I start the truck after is has sat for awhile, I notice a fuel smell. There are no leaks. But it seems to be dumping or not burning gas
on start up.

Ideas?
 

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Discussion Starter · #10 ·
The one that feeds the ecu (oem pt# 22630-51E02)
ok speedo, it is starting to make a little more sense to me now. MY question was more , which sensor as in where on the engine.

I am begining to see the light a little. Let us look at the evidence so far,,,

I had this same issue about the same time last year. Weird, but ok.

There is a fuel smell on cold morning start ups.

It lugs under a load after changing gears, and starting from a stop.

This reminds me of a carb with the choke stuck closed or partially closed.

So do you think the temp sensor is telling the computer that the engine is cold all the time and it is pulsing too long or sending too much fuel through the injectors so I am getting a fuel "dump"or too rich type of situation??

Or,,,, is the evidence just circumstancial and we are making it fit the symptoms???

PLEASE HELP ME OUT GUYS!!! THE EXTRA FUEL AND THE VIBRATIONS ARE KILLING ME.

ALL THIS BRAIN POWER AND WE CANT FIX IT?????
 

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My truck has lasted forever, by driving slower. Ease it around, and enjoy life. The thing might not be running perfect. but it will continue on like that (running) forever.

Mine is an 88, so you might have the more modern fuel induction system. I would start going through it and make sure that everything is clean. Consider that about 75 bucks a month in maintenance is very cheap transportation. If you have to spend 800 bucks on new injectors (for example) you will be back to even money after maybe 10 months.

Air filters, air flow sensors, injectors, o2 sensors, distributor and ect.. All this stuff is cheap enough and you won't regret having new parts. Clean and replace, and slow it down for awhile and enjoy life. :)
 

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NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
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Since it appears that the engine is running rich, the first thing I would do is check to make sure the vacuum hose is attached to the fuel pressure regulator at the back of the engine and then test the fuel pressure with a fuel pressure gauge to make sure it is within specs and not excessive. Also, make sure the coolant gauge needle is about in the middle when the vehicle is at normal operating temperature. If it is sitting at the lower end of the gauge, near the "cold" range, you may have a thermostat stuck open that needs to be replaced. If all is good at this point, definately look at the ECT sensor and make sure it is reading correctly and the circuits are good.
 

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Discussion Starter · #13 ·
Thanks for the replies.

I have checked the vacuum hose. It is good. I don't have a fuel pressure guage.

I am just a lady who like to work on her own stuff. I have been messed with too much at auto shops. Shops will quote me one price, and my brother almost half as much for the same work on the same truck!!

Anyway, I am planning on replacing the thermostat this weekend, and perhaps even the water pump as well.

I have to replace the crank oil seal cause it is almost pouring oil out of the lower timing cover. Since I will be right there with the radiator, shroud, fan, belts pullies, etc. all pulled out, I may as well put all good stuff up there so I won't have to worry about it later.

I was thinking on replacing the temp sensor as well.

BTW. what is the other wire go to right there with the temp sensor???

Thanks. I will let you know.

Not much on taking it slow and easy. Plan on doing 90mph sliding to a screeching halt and yelling "what a ride" into my grave!! LOL

Crystal
 

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NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
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If it's a single wire switch, it's likely the temperature sender for the coolant gauge. A fuel pressure gauge might be available through a loaner program from your local parts store. Simply tees in between the top of the fuel filter and the fuel filter hose. Turn the key "on," and you'll see the pressure raise on the gauge. Start the engine and it should be around 34-36 psi. Disconnect the vacuum hose from the fuel pressure regulator and plug it off, the pressure should raise up to somewhere around 45 psi +/-. If the "regulated" pressure is higher than 36 psi, you may have a lack of vacuum to the regulator, bad regulator or a restricted return fuel line. Excessive fuel pressure will push more fuel through the injector than should, causing the engine to run rich.
If you are doing a water pump, check out the "Gates Timing Componant Kit w/ Water pump" at Rockauto.com. It gives you the timing belt, water pump and tensioner along with instructions and a mileage sticker. Good quality parts at a very reasonable price (and usually a lot cheaper than what you can get the same parts for at the local auto parts store or dealer). I use them a lot on the VG engines. I would recommend you get the front cam and crank seals, as well as the thermostat, from Nissan. If you are replacing drive belts, I would get them from Nissan, as well.
 

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Discussion Starter · #15 ·
good info. Thanks.

I will check with the parts store about the pressure guage.

Why Nissan on the seals and belts?

Is there that much difference in the seals? the belts?? Gates have always been pretty good belts.

Just curious.

crys.
 

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NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
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My experience with drive belts on Asian makes is that some of the belts from Gates and Dayco are just a little bit longer or shorter than the original belts and tend to put the accessory drives close to the end of their adjustment brackets or go on a little tight. Also, Gates and Dayco make several types of each size, so if you do go with either of them, make sure you get their "premium" belts made with EDPM. A lot of aftermarket belts seem to have issues with squeeking not long after they've been installed. The original belts on Nissans are usually made by "Bando" or "Mitsuboshi" (not "Mitsubishi"). Bando brand belts can be had on the aftermarket from part stores like NAPA and Federated Auto Parts, but often have to be special ordered. So, if you go with aftermarket, I would recommend you get the Bando. There usually isn't much difference in the price of genuine Nissan belts and premium aftermarket belts, so it just makes sense to stick with genuine Nissan. As far as the seals, the Nissan cam seals have external grooves that make them install a lot easier then some of the aftermarket seals. Also, they sell the crank seal individually. A lot of times when you try to get a crank seal in an auto parts store, you have to buy an oil pump reseal kit to get the crank seal, which makes it more expensive. Genuine Nissan seals are often cheaper than aftermarket seals, as well. So, it just makes sense. You didn't mention it, but aftermarket thermostats, while considerably cheaper, seem to run a little colder than the original Nissan part and I've seen some be faulty right out of the box. The genuine Nissan thermostat usually puts the needle of the coolant gauge dead center, or just a hair below dead center. I've had some aftermarket thermostats put the coolant gauge needle about 1/3 of the way from the cold mark. Nissan, like most Asian makes, can be a little tricky when it comes to replacement parts. On some parts, aftermarket if fine, if you know what works and what doesn't. On others, the only way to go is genuine Nissan, or at least the OEM supplier of those parts to Nissan (companies like NGK, Hitachi, and Akebono).
 

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Discussion Starter · #17 ·
I was changing the crank shaft seal and discovered that the right cam timing mark was one tooth off of the timing mark on the block.

Could this one cam being one tooth off be the lugging problem??

Weird that there is no backfiring, dieseling, or hard starts.

Thoughts???

crys.
 

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I have the same 94 V6 SE 4x4 truck that Crystal has, and a very similar problem that just developed this past week: Severe lugging/lurching in lower gears. It is apparent in 3rd and 4th gears as well, but not as noticeable as there is proportionately less torque transfer. The problem seems to happen only after the engine is warm - 5km or so from a cold start (that's about 3 miles - sorry, I'm Canadian). I notice it when the truck is idling too - it runs fine for 20 seconds or so, then almost stalls and revs back to normal idling speed.

Fuel delivery checked out fine. This feels electrical to me. I can't find any hints for how to diagnose the ignition coil in the service manual. Suggestions would be much appreciated - I am the second owner of this truck (we are both Engineers and good friends, and I want to keep it in the family so to speak). It has only 160,000 miles (not km; it was imported from California and modified for Canada).and has been a real workhorse.

Crystal, if you are still there, I am wondering if you were ever able to resolve this problem? On a side note, I too smell fuel when starting the vehicle on cold winter mornings. I know what causes that - the seals on the fuel injectors stiffen with age and shrink with temperature, so a bit of fuel vapour leaks out. Once the engine is warm, the seals expand and do their job properly again. I heard this diagnosis first from Click and Clack on NPR's CarTalk about ten years ago, and that was it for me. They said this is not a serious or safety issue, and you can safely ignore it if you choose.

Thanks - Trevor
 

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NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
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I have the same 94 V6 SE 4x4 truck that Crystal has, and a very similar problem that just developed this past week: Severe lugging/lurching in lower gears. It is apparent in 3rd and 4th gears as well, but not as noticeable as there is proportionately less torque transfer. The problem seems to happen only after the engine is warm - 5km or so from a cold start (that's about 3 miles - sorry, I'm Canadian). I notice it when the truck is idling too - it runs fine for 20 seconds or so, then almost stalls and revs back to normal idling speed.

Fuel delivery checked out fine. This feels electrical to me. I can't find any hints for how to diagnose the ignition coil in the service manual. Suggestions would be much appreciated - I am the second owner of this truck (we are both Engineers and good friends, and I want to keep it in the family so to speak). It has only 160,000 miles (not km; it was imported from California and modified for Canada).and has been a real workhorse.

Crystal, if you are still there, I am wondering if you were ever able to resolve this problem? On a side note, I too smell fuel when starting the vehicle on cold winter mornings. I know what causes that - the seals on the fuel injectors stiffen with age and shrink with temperature, so a bit of fuel vapour leaks out. Once the engine is warm, the seals expand and do their job properly again. I heard this diagnosis first from Click and Clack on NPR's CarTalk about ten years ago, and that was it for me. They said this is not a serious or safety issue, and you can safely ignore it if you choose.

Thanks - Trevor
Crystal's last activity on this forum was back in 2014, so I wouldn't expect to hear back. A lot of stalling (especially when hot), no start and/or hesitation issues on VG engines are caused by bad distributors. Often it's the optical sensor, but sometimes the shaft bearing will fail and/or shaft oil seal. That could also cause unburned fuel at start-up, which would explain your gas smell. Ignition coil component test is in the engine control section of the 1994 factory service manual for your vehicle, on page EF & EC-134. If you do determine it's the distributor, I highly recommend getting a genuine Nissan reman rather than an aftermarket unit.
 

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Thanks so much for your prompt response, smj
!
The truck is at my Nissan dealership right now, but they lost their service manual and OBD tools for this model year/engine, hence why I am researching and soliciting opinions. Their first thought was fuel delivery, but it tested fine (at my cost). My first thought was distributor/ignition coil intermittent - so it is good to receive your second opinion. I will run the diagnostics and see what sorts of error codes appear. I downloaded the service manual and found the ignition coil tests you mentioned - thanks for the specifics. Here in Canada it can be hard to source old parts. Do you have any idea what I should expect to pay for a new ignition coil assembly? I will follow your recommendation for a genuine Nissan part - thanks for that. Regards -Trevor
 
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