Base Idle - how to set?

[Serious One]

I am still trying to conquer my rough idle problems, I think I've screwed something up trying to set the base idle, but I'm sure I did it incorrectly.

Does someone have a shop manual they can give me the proper procedure to set the base idle? I need to start from scratch and re-set this one.

BTW, this is on an EFI 4.2l.

Thanks.

[lwg]

I'm going off memory here as my manual is at a friends house right now.

1st - Remove the hose off of the Idler Control assy (Can't remember exact name). This is the rather short (6-8") hose that has a right angle in it.

2nd - completely block off the intake hole for the aforementioned hose. This is the hole left on the intake manifold after removing the hose. Make sure this is completely blocked off, i.e. no air can get in.

3rd - remove the vacuum advance hose off of the intake manifold.

4th - Connect your tachometer to the coil. I can't remember the exact connection but this is how your going to read the engine RPM.

5th - start engine and read RPM. I think it is supposed to be around 545 RPM? It is listed on the placard to the left of the hood latch.

6th - Adjust to obtain proper engine RPM. The adjustment screw (hex) is on the top of the manifold. I think turning it right increases base RPM.

Note, On my truck it would barely, I mean barely run with the base idle set to factory specs. I have done this on both a 3.9 and 4.2L and the procedure is the same.

When finished you might as well adjust the timing since your already in there.

Finally: Reward yourself with some good beer. I think the dealer gets a least 1 hour for this procedure.

Disclaimer: I am writing all of this off of memory. So if I missed a step blame my many years in college and the drinking associated with it.

[Serious One]

Sounds good to me.

No one else has chimed in to say you are wrong, so you must be right, right?

Thanks!

[scrover]

I have a flow chart from a TSB. Don't know if it will post big enough. If not I'll email it to you.

[scrover]

Ha, got a magnifying glass? Here it comes.

SC

[Serious One]

Got it, thanks!



EDIT: Several of the flow charts end in the following:

Check for: "What changes base idle" See page 1.

Can you scan and send page 1 too? It'd help maybe.

[scrover]

This is the rest of the TSB. I think page 1 is the first half of the text:

Base Idle Speed - Revised Checking/Setting Procedure

Bulletin: P93/19-001

Section: Product

Date: 6/17/93

Model: Range Rover/Defender

Applicable to: USA/CND

Subject:
REVISED BASE IDLE CHECKING/SETTING PROCEDURE

BACKGROUND

Over the last several years, changes in the MFI's Idle Air Control System (IACS) and software have reduced the number of false check engine light (Malfunction indicator Lamp) illuminations.

The purpose of this Service Bulletin is to update you on changes to the base idle checking and setting procedure which is now possible due to the improved IACS. Please review the contents of the bulletin carefully and make sure that all Land Rover Technicians are aware of the changes.

WHAT CHANGES BASE IDLE?

Base idle settings are influenced by anything which changes the amount of air entering the engine at idle. These include:

^ plenum bypass bore and throttle plate carboning

^ throttle cable/cruise control actuator adjustment

^ throttle plate stop adjustment

^ mis-adjusted base idle bypass screw

^ vacuum leaks

^ PCV system orifice and filter condition

^ engine internal wear (less volumetric efficiency)

^ ignition timing variations

^ altitude

^ defective IACV/faulty wiring connections to ECM

^ condition of ECM ground on left rear cylinder head

In the past, relatively small changes in the base idle speed could cause an on board diagnostic (OBD) fault code 48. It was necessary to set base idle to a very tight tolerance to reduce false MIL illumination caused by day to day changes in operating conditions.
With the introductions of the 2665 PROM in November, 1991 the system diagnostic strategy was changed to ignore small base idle changes which formerly could have caused a false light occurrence. All PROM's since 2665 have been made with this same idle control program.

WHEN SHOULD BASE IDLE BE SET?

(flowchart appears here)

The flowchart outlines the correct setting procedure for base idle based upon the symptoms.

Base idle should not be set on a periodic basis. It is not a maintenance item. It is only necessary to check and/or set the base idle whenever:

1. The MIL is illuminated and a code 48 is recorded on the OBD unit.

2. The customer complains of an idle stalling problem and no other reason can be found for the problem.


BASE IDLE SHOULD NOT BE ADJUSTED TO ADDRESS ROUGH IDLE COMPLAINTS. BASE IDLE ADJUSTMENTS HAVE NO EFFECT ON HOT IDLE QUALITY.

REVISED BASE IDLE SETTING PROCEDURES

Use Procedure A or B (see flowchart) which fits the symptoms of the vehicle on which you are working.

WARRANTY INFORMATION

Submit warranty claims as follows:

Procedure A:
Service Type: WW
Repair Code: 2R5A
Labor Operation: 999995 .5 hrs

Procedure B:

Service Type: WW
Repair Code: 2R5A
Labor Operation: 999996 .2 hrs

NOTES :

Procedure A:
Warranty claims will only be accepted with a customer complaint of MIL illumination and a verified OBD Code 48.

Procedure B:
Warranty claims should not be made for this procedure in conjunction with routine maintenance.

Procedure A or B may only be claimed once per repair.

[Serious One]

Sweet. This answers a few questions for sure.

Thanks man!

[lwg]

Damn that's thorough!

[pendy]

I am finally back from the restroom now. Thanks Mike. Whats her name anyway?

Remember Seafoam, it cures everything. At least that is what I remember you saying.

I have been meaning to build a tool for my shop that is helpful with these type problems. Snappy wants 1600 clams for his version so I want to try to make one first. A smoke machine to find vacuum leaks. I need an ammo box, glow plug, 12V source, air fittings and pressure reducer, vacuum line, and a little oil.

Smoke machines find the leaks carb cleaner can not.

JP

[Serious One]

Her name is Katrina. She was a model I used for a quarter in school. I was photographing nudes, and I used her probably a dozen times or so.

Paid her, got model releases, everything above board. I actually surprized and impressed my photography instructor who had challenged me to shoot some nudes. She didn't think I would.

It was actually more difficult than I thought it would be. Lining up the model and making everything legit was the first hurdle. The shooting, posing, lighting, and getting over my nerves were also some interesting challenges.

Anyway, this is a little chit-chatty for a base idle discussion (even if this is my thread).

[lwg]

Originally posted by pendy
I am finally back from the restroom now. Thanks Mike. Whats her name anyway?

Remember Seafoam, it cures everything. At least that is what I remember you saying.

I have been meaning to build a tool for my shop that is helpful with these type problems. Snappy wants 1600 clams for his version so I want to try to make one first. A smoke machine to find vacuum leaks. I need an ammo box, glow plug, 12V source, air fittings and pressure reducer, vacuum line, and a little oil.

Smoke machines find the leaks carb cleaner can not.

JP

Pendy sometimes I wonder what planet your from!

Ever been abducted by aliens?

[scrover]

Originally posted by Serious One
Her name is Katrina. She was a model I used for a quarter in school.

Awesome. You can't get anything for a quarter these days

SC

[SeaRover]

It was actually more difficult than I thought it would be.

all those compound curves. i could stare at the full size version of this all day. this is a good photograph.

surely it varies from model to model - but as a newbie, how did you first approach the task of establishing the trust level with your subject? did she kind of guide you along or was she shy? What kinds of things did you do evironmentally or in conversation to establish that? I'm intrigued with the pscyhology at work in these kinds of scenarios, and the irony - professional intimacy. woops?! look at me ramble on and forget this is PBB . . . i'm not gay . . .i'm a "metrosexual"

[Serious One]

Originally posted by SeaRover
...i could stare at the full size version of this all day. this is a good photograph.

Well, gee...thanks.

HERE'S THE LINK TO THE FULL SIZE PHOTO - 35% (kind of)

I take no responsibility for lost work time or hairy palms.

[pendy]

Originally posted by Serious One
Her name is Katrina. She was a model I used for a quarter in school. I used her probably a dozen times or so.

Paid her, everything above board. I actually surprized and impressed my instructor who had challenged me to some nudes.

It was actually more difficult than I thought it would be.

Anyway, this is a little chit-chatty for a base idle discussion (even if this is my thread).

Fixed it for you

LWG that would be uranus. Not mine, yours.

JP

[BAe146]

BTW:What is sympton of bad airflow meter(3.9 hotwire)?
Rgds:Jukka
RR92 Efi
PS:I have idlespeed approx.450rpm?Tried to rised w/o result????

[lwg]

450 RPM!! For Real? My truck barely runs with the RPM at 545. Not sure if your getting bad readings or what but that sounds a little crazy to me. If you don't remove the vacuum hose, the Idler Air hose and plug the hole from them both then you'll never get your base idle set properly.