John Pring & Dana Haydel on the Jag-Lovers website have written a document on testing the XJ40's Air Flow Meter. I tried to read it, but I was having trouble - someone has really bodged the html.

See what I mean by clicking here:

11.9 Air Flow Meter

It's important to be able to test before replacing one since I just read where the cost of a rebuilt one is $465.95 each, with a charge of $200 for a rebuildable core.

Some symptoms of a bad one are:

1. poor running conditions
2. possibly responsible for a NO START condition and
3. potential generation of a fault code (DTC 12)

I know some html programming, so I downloaded and edited (and deleted some parts and rewrote some others) the source code, and added a picture. I've, of course, retained the original authors and website source but added my name as an editor and revisor. I printed it out as a pdf and uploaded it here.

It is now infinitely more usable than the original.

I needed this document and can think of two fellows here who need to read this and test theirs. I thought I would share the rework with all who's interested.

We can now all TEST the MAF, hopefully to fix it by cleaning the connectors or repairing the wiring without having to replace it. Or if it really needs replacing, you'll know it for certain.

PS feel free to inform me of any errors you find in it. I can easily make corrections.

 

For example, here is a cut-out from the electrical guide for a 1988 XJ6 VDP. Note the pinout numbers are different and wires need to be traced back to the ECU and elsewhere (for powers and grounds and output) to determine which wire is which. At least the color codes for the wires are given.


I inspected another diagram for a 1990+, and there were only 5 wires. I somewhat expected this since there is NO manual idle trim adjustment on these models.

 

The sixth wire on the Air Mass Meters from 1988 to 1990 was simply a ground connected to the housing of the meter. For 1991 and later they decided it wasn't needed. The attached page is the only place I know of that actually depicts that expressly. The page actually applies to the 4.0L AJ6, but the circuits are the same as the 3.6L. It also shows the GR wire as the Idle Trim circuit, and that it was there for '93-'94, but was unused.

Cheers,

 

Thanks for the addition, Steve.

~~~~~~~~~~~~~~~~~~~~

Here are two pages consisting of an Engine Management Schematic and ECU tests for an XJ6 and VDP 1988 MY. Some of you may recall and recognize this as I posted it earlier on rcarpenter's thread, 88 Vanden Plas still won't start

I've included it here because it not only includes the Air Mass Meter (AMM) on the schematic (from which the above .jpg was taken) but also includes some test procedures (KEY ON, KEY OFF) for it on the first page.

It identifies the 6 AMM pins, 3 of which are GROUNDS -

1. 2 of which (AMM connector pins LI19-1 and LI19-2, BO wires) send their combined ground signals to ECU pin, LI2-3, BO, and
2. the third, LI33, is a Power Ground, B wire, connected to LIG32 which is an eyelet located on the Inlet Manifold/#2 Cylinder Firing Stud.

Just click on the following link to view/download.

Engine_Management-XJ6&VDP_1988MY.pdf

NOTE: Wiring Color Codes

• N Brown ▇
• B Black ▇
• W White ▇
• K Pink ▇
• G Green ▇
• R Red ▇
• Y Yellow ▇
• O Orange ▇
• S Slate (or Gray) ▇
• L Light
• U Blue ▇
• P Purple ▇

When a wire has two or more color code letters, the first letter indicates the main color and the subsequent letter(s) indicate the tracer color(s).

 

@Trick Freestones

Hi,
I have a 1990 4.0 with the MAF that has an adjustment screw.
The resistance between pin 1 & 6 is set to 650 ohms.

how much does she listen to?
what is the right attitude?

 

Hi Stojan,

Welcome to the Jaguar Forums! It's great to have you with us.

Note that the thread to which you have replied has had no activity since 2011.

Please visit the New Member Area - Intro a MUST and post an introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don