Help Me Identify A Problem Oppo

"Denver Is Stuck In The 90s" (denver80222) 09/11/2016 at 20:38 • Filed to: None

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So My Girlfriend’s Boss has a 1988 Nissan Pathfinder V6 4x4 Manual, Its misfiring, the exhaust smells of unburnt fuel, the exhaust rattles and its blowing black smoke out the tailpipe. It drives like it has an artificial limiter at 3k rpm and it stalls out at idle. the issue gets worse once hot.

The Good:

New Fuel Pump

New spark plugs

new wires

new cap and rotor

new fuel pressure regulator

10 year old cat

The bad:

original throttle body and injectors

original intake and vacuum lines

original AB valve

350k+ miles

150k Mile timing belt (at least, hes never done it as long as hes owned it)

Im thinking either its got a pretty severe timing advance that is forcing the ECU into “limp mode” at 3k or its got a clogged cat. What say you oppo?

JQJ213- Now With An Extra Cylinder! > Denver Is Stuck In The 90s 09/11/2016 at 20:42

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Honestly that sounds like mutliple problems, not just one...

My friend’s XJ Jeep needed a new throttle body when it wouldn’t rev over 2500 rpm. but it didn’t have any other problems like you listed.

Denver Is Stuck In The 90s > JQJ213- Now With An Extra Cylinder! 09/11/2016 at 20:44

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Maybe, also keep in mind this thing has throttle body injection

NostalgicCarLife > Denver Is Stuck In The 90s 09/11/2016 at 20:44

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What do the spark plugs look like? Black smoke usually mean running too rich.

Denver Is Stuck In The 90s > NostalgicCarLife 09/11/2016 at 20:45

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Havent gotten em out yet, going back later tonight

dogisbadob > Denver Is Stuck In The 90s 09/11/2016 at 20:50

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an injector?

If the injector isn’t delivering fuel properly, that could result in unburned fuel.

Maybe a MAF problem

Can you figure out which cylinder(s) is/are misfiring? You can probably readd any CEL code there may be, even though it isn’t as easy as on a newer OBD2 car. Probably some key dance method or jumping wires somewhere.

My X-type is too a real Jaguar > Denver Is Stuck In The 90s 09/11/2016 at 20:54

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This'll sound strange but could be a bad temp sensor. When these fail the engine thinks it's below freezing and dump lots of fuel to the engine.

Denver Is Stuck In The 90s > dogisbadob 09/11/2016 at 20:56

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Oh I forgot he replaced the MAF a few years ago too, and it has no CEL, also OBD 1...

I was also thinking injector, as far as I can tell there is only one injector in the TBI, but I second guessed that when he told me it runs fine after its been sitting all night, but once it warms up all hell breaks loose

Denver Is Stuck In The 90s > My X-type is too a real Jaguar 09/11/2016 at 20:57

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huh... maybe... Its a long shot though

My X-type is too a real Jaguar > Denver Is Stuck In The 90s 09/11/2016 at 21:01

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Happened to my 98 Saturn it was the last part I replaced and the cheapest.

BJ > Denver Is Stuck In The 90s 09/11/2016 at 21:01

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RacinBob > Denver Is Stuck In The 90s 09/11/2016 at 21:07

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I assume it’s fuel injection has a common rail with a bypass pressure regulator. Sometimes these regulator diaphrams fail and the gas goes straight to the intake manifold. It’s a long shot but it’s easy to check, If you take the vacuum line off (smaller line attached to top of the regulator) and there is any indication of gasoline liquid in the line, that is it. The regulator is below.

Denver Is Stuck In The 90s > RacinBob 09/11/2016 at 21:08

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Regulator was replaced yesterday

Forge Crown Victor! > Denver Is Stuck In The 90s 09/11/2016 at 21:12

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This is a classic temp sensor. When it goes into open loop the ECU thinks its -60F water temp and just dumps the fuel.

bob and john > Denver Is Stuck In The 90s 09/11/2016 at 21:14

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mis-fire, fuel smell and black smoke are all probably the same issue.

Id do the vacuum lines, AB valve, and check the fuel system to make sure nothing is clogged.

brianbrannon > Denver Is Stuck In The 90s 09/11/2016 at 21:24

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Pull the distributor cap and clean the oil off the optical timing wheel

gmporschenut also a fan of hondas > Denver Is Stuck In The 90s 09/11/2016 at 21:29

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I wouldn’t 100% rule out “the good” list. In regards to the bad, skipped maintenance kind of scares me.

Things I would check first, vacuum lines and maybe temp sensor.

My 914 had a vacuum leak, and a bad temp sensor. which would cause it vary the amounts of fuel at both warm up (bad temp sensor), and then super rich on higher RPMs (vacuum leak) causing it to enrich the mixture.

the temp sensors are often “cheap” thermo-resistors that decrease resistance as they heat up. the benefit is that they can be measured with an ohm meter.

http://www.nissanpathfinders.net/forum/topic/25…

When in doubt, check vacuum lines. and if 18 years old, replacement is a good idea anyway.

gmporschenut also a fan of hondas > gmporschenut also a fan of hondas 09/11/2016 at 22:02

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read 1988 as 1998. Yeah I would say those vacuum lines are well past their expected life.

His Stigness > Denver Is Stuck In The 90s 09/11/2016 at 22:22

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No need to bother because black smoke and when you smell unburnt fuel, that means there’s unburnt fuel.

V8Demon - Prefers Autos for drag racing. Fite me! > Denver Is Stuck In The 90s 09/11/2016 at 23:32

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Just because there’s no check engine light does not mean there aren’t any codes with OBD-I. Hook up a test light and check.

MAF is a possibility as is a stuck open injector.

Pull codes first.

Denver Is Stuck In The 90s > V8Demon - Prefers Autos for drag racing. Fite me! 09/11/2016 at 23:42

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When I said there is no CEL, I didnt mean no active light on the dash. I meant there is no check engine light, as in no socket or bulb or cut out on the gauge cluster

Die-Trying > Denver Is Stuck In The 90s 09/12/2016 at 09:00

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are the plug wires in the correct order? sometimes people pull them ALL off, and lose track of where they go.........

what do the plugs look like????