# 99 nissan quest



## BUDFAN8 (Apr 11, 2007)

this van at start is idleing like it has a single misfire it gradually gets worse the warmer the engine gets. at cold temp the van has full power and drives fine except the feel of a slight miss. at running temp it is terrible has lost all power and dies when a load is put on the motor.

only engine code i got was for the knock sensor i have read alot of online topics on the knock sensors and i dont think the sensor is the culprit here.

another thought was the cat. converters but not getting the rotten egg smell and the exaust dosent seem to have any blockage from the amount escapeing the tail pipe.

i have already tried the fire test (pull the plug wire off while running to listen for engine change) to each cylinder all seem to be working fine.

will be testing compression in the morning and will also try the remove the O2 sensors to make sure the cats. arent the culprits. i will update on those when i can.


if any are familiar with these types of vehicles your advise will be apreceiated as im not too familiar with them. thanks in advanced.


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## cardoc (Apr 15, 2007)

HI budfan8
I take it that is a mitsubishi Universal v-6 under that hood.IF it has a distributor (I forget what year they went to DIS.) the first thing I would do is to change the cap and rotor.
When the rotor goes bad it grounds out to the metal insert where the lock down screw is.
A very hard to see problem,it's an internal ark, always worse when warmed up.If on a scope you would see the spark kv raster just disappear and the engine dies untill the load is removed.Spark takes the easyist path to ground.As always could be a lot of things but I've seen this one mess up some very experianced techs.You may get a knock sensor code from a out of time misfire (dist cap or rotor) or engine noise.If cats are clogged you usually have good idle but no power,may also sound like a vacuum cleaner under load.
Good luck and keep me posted.
Cardoc


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## qldit (Mar 26, 2007)

Good Morning Gentlemen, I also would agree the problem most likely involves the ignition drive system and in that it is engine temp related most likely is an under the bonnet problem in the hot components area.

I also have struck this kind of problem with distributor models and after a lot of head scratching just replaced the distributor completely and fixed it.

That symptom is generally good running when cold, maybe an occasional odd miss, but when the engine is hot the miss worsens and is especially evident under power conditions like when gear shifting happens at the bottom of the range, hesitation, severe misfiring and foot off throttle helps to improve the situation.

The cost of distributor sensor components was greater than a wrecker's complete distributor assenbly charge.

Pulling these distributors apart to replace components is a real challenge and should be avoided, they can be a real box of worms!

It is not a good idea to disconnect spark leads with a running engine, the high voltage has nowhere to go and can damage other upstream ignition components.

If the vehicle doesn't have a distributor I would be closely investigating the coilpacks, spark leads and the electronic drive system that operates them.

I would suggest obtaining a Haynes type manual specific for that vehicle from your auto supermarket.

As cardoc suggests it may be a rotor or cap, but I am never so lucky.

Others will have different ideas.

Cheers, qldit.


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## BUDFAN8 (Apr 11, 2007)

well the distributor cap and rotor button didnt help looks like ill be hunting for a distributor.


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## cardoc (Apr 15, 2007)

One last simple thing.Try disconnecting the mass air flow sensor while its acting up.It "may" put in it's own value a straighten out a bit.Were you able to scan system for temp sensor values etc.
Good luck,Cardoc


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## BUDFAN8 (Apr 11, 2007)

temp as in tempature or temporary? the tempature went up in the 190s but it never got hot when i had the code reader looking at live data. i dont know alot of the specifics i was looking at with the reader. only one that looked a little odd was 1st O2 sensor was only getting a 480 top value no matter throttle pushed or idle. 

ill try the MAF disconnect and let you know if any change.


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## cardoc (Apr 15, 2007)

Coolant temp looks ok.O2 sensor reading lean either as a result of your problem or faulty sensor (possible but not likely).You could try riching the mixture with a spray of carb cleaner into intake or vacuum line to see if O2 sensor spikes higher.Is sensor stuck at 480mv or is that just it's highest reading?Stuck would indicate a bad sensor or wire with ECM putting in it's own value but should throw a code.How is your fuel supply?
Cardoc.


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## BUDFAN8 (Apr 11, 2007)

maf disconnect had no change still same problem. 

fuel supply seems good i havent gauged it yet. 

480 was the highest reading.

ive sent request to salvage yards waiting on prices of distributors looks like thurs before i can order one so no new news til i get one i guess but as soon as i install it ill update. you guys have been very helpful thanks.


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## cardoc (Apr 15, 2007)

Goodevening BUDFAN8
If your going the distributor route you can order a NEW assem.for Autozone or Carquest for $300.A healthy investment but not actually a bad price.
Good luck
Cardoc


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