I have problems, many problems

[Paffphinder1989]

I will find the code thread and print it out, I had it at one point, so I should be able to find it again. I will pull codes tomorrow and try to get pics of the spark plugs up.

 

My problem seems to be associated with hot humid days, on cooler days it seems to run much better.

 

I will check at checker auto the next time I am in Grand Forks and see if I can loan a tester out, because I really need to know if it is a head gasket or anything major.

 

I will try to make a more informative post tomorrow or friday, with pictures and everything because I have got to get this figured out. I am really leery about taking it to a garage though because I think I will get screwed.

 

Thanks Again!

Edited July 25, 2008 by Paffphinder1989

[Alkorahil]

Idles like a 2 cycle and puffs black smoke

Kills sometimes when put in reverse

RPMs drop and raise back up

Kills occasionaly while I am driving

Has difficulty (struggles) to shift at times

 

My problem seems to be associated with hot humid days, on cooler days it seems to run much better.

 

based on these quoted points I vote IVAC-ACC Valve and/or regulator.

[Paffphinder1989]

based on these quoted points I vote IVAC-ACC Valve and/or regulator.

 

What exactly is an IVAC-ACC Valve/ regulator and what does it do?

 

I googled it and I could not figure out what it is.

 

That could very well be what is causing my problems, but I have no idea what this valve or regulator would look like or even where it is at. I left my Haynes Auto Repair Manual down home, 5 hrs away!

 

Thanks!

Edited July 25, 2008 by Paffphinder1989

[Slick]

have you checked to see if your rad cap is old/not pressurizing anymore?

[Paffphinder1989]

Sorry it's been so long, I am trying to add some photos to this post, so tell me if it works or not!

 

I have some pics here

 

Click for pics, should be 3-4 pics

No I have not checked my rad cap, but I would assume its fine?

 

In the pictures you should see the exhaust tip, the pulley that I found a leak under, and the big puddle of coolant that my truck whizzes out every day...

 

With the leak, it is really inconvenient (sp?) for me to pull off the fan shroud or the skid plate etc. to look for the leak thoroughly yet, as I am moving it home on a flatbed in 2 weeks. So it could really be anything.

 

I know it is leaking from somewhere on my engine, hopefully this is a good sign...

 

THANK YOU!

 

Please read the captions on the pics too!

[Alkorahil]

What exactly is an IVAC-ACC Valve/ regulator and what does it do?

 

I googled it and I could not figure out what it is.

 

That could very well be what is causing my problems, but I have no idea what this valve or regulator would look like or even where it is at. I left my Haynes Auto Repair Manual down home, 5 hrs away!

 

Thanks!

 

The IACV regulates idle speed, raising and lowering it as needed. It does this by opening and closing a "trim" valve to allow more or less airflow into the intake manifold when the throttle is closed.

The adjustment we make on the IACV is for setting the "base idle". By unplugging the TPS we tell the ECU to completely close the trim valve in the IACV. When this happens, the idle airflow comes completely from a needle valve - the one you can adjust when you turn the screw on the IACV body.

 

If everything in the fuel and intake system is operating properly, the idle speed will not be able to drop below this setting. A few things can cause the base idle speed to go out of adjustment.

 

First, the needle valve can become clogged with dirt or carbon, reducing or completely blocking off airflow through the needle valve. This would reduce the airflow through the needle valve and cause the ECU to rely partially or fully on the opening of the trim valve in the IACV to maintain target idle. This would mean that the idle could possibly fall below 750 before the ECU could intervene.

 

Second, the trim valve within the IACV could be rendered partially or totally inoperable, either through blockage or failure. If this valve is blocked open, idle speed would be high unless the needle valve's opening was reduced to compensate. The result of this may be the inability for the ECU to compensate for all idle conditions - base idle would be set for Y percent trim valve opening, leaving only X-Y percent of the operating range of the trim valve for ECU adjustment. If the trim valve is not blocked open but the passage to this valve is partially clogged, it would require the ECU to open the valve farther than normal to allow a given amount of airflow to pass. This would also reduce the amount of compensation the ECU can apply to idle speed.

 

 

To sum it up, there are two idle speed adjustments to control idle on our cars. First is the manually adjusted base idle setting, which determines the minimum airflow through the IACV (and minimum warm-idle speed). Second is the ECU's control over the "trim" valve within the IACV, which compensates for hot and cold idle and engine loading (power steering and A/C operation).

 

 

Now, there is one other factor in this equation, the IACV-Air Regulator. This valve is in parallel with the IACV-AAC valve. This valve is what supposedly makes the car idle fast when the it's cold. The FSM gives the following description of the IACV-Air Regulator.

 

"The IACV-air regulator provides an air by-pass when the engine is cold for a fast idle during warm up. A bimetal, heater and rotary shutter are built into the IACV-air regulator. When the bimetal temperature is low, the air by-pass port opens. As the engine starts and electric current flows through the heater, the bimetal begins to turn the shutter to close the by-pass port. The air passage remains closed until the engine stops and the bimetal temperature drops."

 

 

Here is the diagram:

 

Note the IACV-AAC valve is under the intake plenum, back by the fire wall. you have to remove the intake plenum to get to it.

[Red87Path]

The IACV regulates idle speed, raising and lowering it as needed. It does this by opening and closing a "trim" valve to allow more or less airflow into the intake manifold when the throttle is closed.

The adjustment we make on the IACV is for setting the "base idle". By unplugging the TPS we tell the ECU to completely close the trim valve in the IACV. When this happens, the idle airflow comes completely from a needle valve - the one you can adjust when you turn the screw on the IACV body.

 

If everything in the fuel and intake system is operating properly, the idle speed will not be able to drop below this setting. A few things can cause the base idle speed to go out of adjustment.

 

First, the needle valve can become clogged with dirt or carbon, reducing or completely blocking off airflow through the needle valve. This would reduce the airflow through the needle valve and cause the ECU to rely partially or fully on the opening of the trim valve in the IACV to maintain target idle. This would mean that the idle could possibly fall below 750 before the ECU could intervene.

 

Second, the trim valve within the IACV could be rendered partially or totally inoperable, either through blockage or failure. If this valve is blocked open, idle speed would be high unless the needle valve's opening was reduced to compensate. The result of this may be the inability for the ECU to compensate for all idle conditions - base idle would be set for Y percent trim valve opening, leaving only X-Y percent of the operating range of the trim valve for ECU adjustment. If the trim valve is not blocked open but the passage to this valve is partially clogged, it would require the ECU to open the valve farther than normal to allow a given amount of airflow to pass. This would also reduce the amount of compensation the ECU can apply to idle speed.

To sum it up, there are two idle speed adjustments to control idle on our cars. First is the manually adjusted base idle setting, which determines the minimum airflow through the IACV (and minimum warm-idle speed). Second is the ECU's control over the "trim" valve within the IACV, which compensates for hot and cold idle and engine loading (power steering and A/C operation).

Now, there is one other factor in this equation, the IACV-Air Regulator. This valve is in parallel with the IACV-AAC valve. This valve is what supposedly makes the car idle fast when the it's cold. The FSM gives the following description of the IACV-Air Regulator.

 

"The IACV-air regulator provides an air by-pass when the engine is cold for a fast idle during warm up. A bimetal, heater and rotary shutter are built into the IACV-air regulator. When the bimetal temperature is low, the air by-pass port opens. As the engine starts and electric current flows through the heater, the bimetal begins to turn the shutter to close the by-pass port. The air passage remains closed until the engine stops and the bimetal temperature drops."

Here is the diagram:

 

Note the IACV-AAC valve is under the intake plenum, back by the fire wall. you have to remove the intake plenum to get to it.

 

you know, i been trying to get my idle issues worked out as well, that needle valve your talking about that can be adjusted to get the base idle? well i screwed mine all the way out and took it out to have a look at it, it is square on the end with a recessed area like a cup, im thinking something is supposed to be in there but there is nothing in there, nor in the hole i took it out of, can see all the way to inside throttle chamber, do you know if that is a two piece deal or a good picture of one? i ll try to post a picture of mine tomarrow.

[Alkorahil]

you know, i been trying to get my idle issues worked out as well, that needle valve your talking about that can be adjusted to get the base idle? well i screwed mine all the way out and took it out to have a look at it, it is square on the end with a recessed area like a cup, im thinking something is supposed to be in there but there is nothing in there, nor in the hole i took it out of, can see all the way to inside throttle chamber, do you know if that is a two piece deal or a good picture of one? i ll try to post a picture of mine tomarrow.

 

ummm.....that doesnt sound good to me IIRC that was connected to the trim valve.....

 

however the IAVC is not mounted on the throttle body....

 

Ill look at the one on the self tomorrow, but I think the screw is attached...

[Paffphinder1989]

Hot Damn! I will print this out and read it tonight, and see if I can find out more about it.

 

I will make another post as soon as I know what is going on

 

With the rings around the exhaust and sooty plugs, I gather I am running rich as well...

 

I think this may be just a bunch of little problems that all hit at once, but I am still troubleshooting and will get back asap!

 

Thanks!

[Red87Path]

ummm.....that doesnt sound good to me IIRC that was connected to the trim valve.....

 

however the IAVC is not mounted on the throttle body....

 

Ill look at the one on the self tomorrow, but I think the screw is attached...

it is on my 87, theres the iacv, and the ficd, in between the 2 is an adjusting screw for setting the base idle, according to alldata, but it is supposed to be a needle valve, but it doesnt look right, im going to take this thing apart tonight and clean it real good inside and out. it is caked in crapola.

[Paffphinder1989]

Finally got it back to the cities, hauled it on a flatbed trailer, so I wouldn't have to disconnect anything.

 

It is being looked at by a very good and very reasonable mechanic.

 

So far, I know my water pump is out, the shroud is what made it so hard to find my leak. The bad news is that it will cost $500 just for the water pump. Nissan dealer wanted $490 just for labor.

 

The guy has no idea what is causing the erratic idle problems, as of course, the problem does not occur around any other person in the world!? I have mentioned the IAVC and EGR valves, but he says they are hard to check.

 

He has compression tested it and said it is fine, and I know I do not have a cracked block or blown head gasket.

 

I will get back asap to everyone as soon as I find out more.

 

Thanks!

Edited August 18, 2008 by Paffphinder1989

[Paffphinder1989]

SO SORRY!

 

for the huge delay, but it is fixed!

 

Here is what I had done.

 

Water Pump replacement= $500

Induction/ intake cleaning= $100

+ Labor

 

Total = $700

 

My pathfinder is up and running again, but I did not have any sensors or valves or anything major replaced!?

 

Anyways just wanted to bring closure to the problem.

 

Once again thank you all you have all been very helpful!

:dance:

[Precise1]

Thank you for the update, it really helps when someone else has similar issues!! Just an intake cleaning? Man, that must have been junked up BAD!!

 

I'm glad you have it sorted out!!

 

B

[crazyhayseed]

$100 to clean your intake? You mean the just manifold? That DOESN'T include labor?

 

Holy Isht dude! I'm obviously in the wrong racket. I'd've done it for a six pack.

A can of carb cleaner and a bottle brush would have cost less than $5. A couple cans of Easy Off and some sun would've made the plenum shine.

 

I don't think this mechanic was quite as "very reasonable" as you think. He's probably got a parts washer.