92 XJ40 Finally up and running, but rough.Replaced bad head gasket, EGR sensor tube plugged, and CCV lines gunked up. Got "fuel fail 14" after starting, then died.
Bled off some fuel/air at fuel rail, started right up but idles rough, dies after 1-2 minutes.
Now getting "fuel fail 33". Haynes says 33 is open or short circuit in injector circuit; can this be caused by stuck injector??
Almost there....

 

Shelby:
I threw a FF14 code just today on a lengthy trip. Should be a faulty coolant temperature sensor. I'm going to run tests on that later, but plan on taking another trip tomorrow. I might be wrong (probably am!) but I cannot imagine a FF14 would cause your stalling. Poor running perhaps. Not sure about the 33...

Scott

 

S,

What caused the bad head gasket, may I ask?

Did your engine overheat afterwards?

Are you burning oil?

You probably did the following but just to be sure:

1. Did you inspect the valve seats while you had the head off?
2. Did you measure compression now? Is it within spec?
3. Is valve timing correct?
4. Did you replace spark plugs?

To answer your question:

If there is an open or short in the fuel injector circuit, each of the injectors connects to two KB (pink and black) colored wires and two KU (pink and blue) colored wires. All 4 of these wires connect to the ECU. See attachment.

Disconnect your ECU connectors and both battery leads, Now you can test your fuel injector harness for shorts and grounds with a multimeter set up as an ohm meter.

You may want to pull the fuel injector connectors and check each injector resistance and see if it's within spec. See my thread, ... on Fuel Injector testing

You may additionally want to check if they are shorted or grounded.

 

Thanks to Midwest jag and Trick Freestones for their replies. I am replacing the two prong Coolant Temp sensor as well as the single wire temp sensor today, we will see if that eliminates that "14" code. Since my last post, I am also getting FF 11,16,17. Will use tests to try and isolate further. (Air temperature and TPS tests).
Noticed that previous owner had placed petroleum jelly or ?? INSIDE all electrical connectors, I am cleaning out as best I can. Have read several posts concerning possible problems doing that due to low voltage and milli-amps going through connectors.
Other notes: Head gasket looked like leakage at #5 cylinder (only low reading on compression test) Valve seals replaced while head was off, guide clearances were within specs, all valves and seats looked good, Bottom of head had stamp ".004" which I assume means head has been off and shaved slightly in the past.
Valve timing set correctly, plugs are new. Checked all plugs to see if oily or flooded and noticed all six were sooty as if fuel too rich or not enough spark. New coil, and amplifier seems to be within range. I will probably replace cap and rotor although only slightly worn. Oxy sensor replaced prior to me purchasing, using 3 butt connectors, will replace with one with pigtail attached, found too many bad connections in past with them.
148,000 miles; head and cylinders were clean except for exhaust ports very carboned up. Front cats were sooty but not melted, cleaned up good with no blockage.

 

Shelby:
Sheesh.. That's a lot of codes! You've been doing good work on this car. Keep it up! I think it is probably dielectric grease in the electrical connections, any surplus of which should be wiped off. Sounds like an over exuberant PO. The TPS and a few of those other parts can be tested (rather than just replacing - it gets expensive!) to see if they are good or what. Be very wary of moving the TPS from it's perch, though. It requires a precise placement in order to function. They can, over time, get all gunked up with oil and do benefit from cleaning. This is what sometimes sends our cars into "limp mode." Haynes doesn't detail that, but there is plenty in the archives both here and on other sites about guys who have had to do this. I don't wonder if some of those codes are connected. I.e., if you get the TPS running right, the others might follow suite. Trick will probably have a logical process for you to follow more helpful than my meanderings. Best of luck!
Scott

 

After starting car after head gasket replacement, had many codes. Replaced both coolant temp sending units and....no start. pulled fuel rail, cleaned, inspected injectors; used sons old model railroad transformer to test injectors (clicked on and off ok) and...no start.
Rechecked supply voltage on every sensor I could reach, resistance all within specs.
Rechecked compression, recharged battery overnight just to make sure at top of charge, and......no start. Nada, not even a hiccup. By now my 19 yo college student (this is his first car) is beginning to wonder about the old man and his mechanical abilities. He bought the car not running after the owner described classic blown head gasket symptoms (but assured us never overheated), and I told him we could fix without too much money if we were lucky. Had installed new coil when we bought car, doubled checked anyway; within specs. Checked resistance of every plug wire, stuck plug in one wire and turned over and.... no spark. stuck plug in end of coil wire and...great spark!! Cap looked fine, no cracks or visible problems, very little burning of contact points, rotor looked almost new.
Either spark is coming at wrong time or something was wrong with cap and rotor that was not visible . Getting late in the day, but decided we would purchase new cap and rotor anyway for later when we figured out what was going on. While installing we noticed the end of the new rotor looked considerably longer than old one. Looked like PO had filled down end to "clean up". Pulled one plug out and stuck in end of plug wire just to see if we got spark, and car started immediately even with one plug out and no compression in one cylinder!! Back in business, will post more tomorrow. Thanks for the encouragement from all.

 

.

 

By the by... The code 14 that I mentioned earlier in this thread was remedied simply by clearing the code. Fluke, I guess. It was damp that day...
Scott

 

Latest instalment. (92 XJ40 148000 miles). Replaced cap and rotor, car starts immediatly and after a couple seconds idles pretty steady at just under 1000 rpms. Getting sparks between center discharge boot of coil and terminal points (sometimes + sometimes -).Very slight misfire when this occurs.
Purchased brand new coil to dist wire with new connectors and boots attached; same problem. Have maybe 10 minutes idle time on new coil. Swapped for old coil, same thing.
Spark is going THROUGH insulating boots, (metal connectors fully inserted). No cracks on either coil tower. Running rough on acceleration, shorting seems worse. Ground at firewall tight, grounding wires from loom attached tightly at front intake manifold stud.
I'm stumped. Unless we're getting random "extra" signals from ECU, when rotor is between contact points, what can cause sparking while car is idling??
How can sparks be going THROUGH insulating boots??
Solved #14 code by replacing coolant sensor, now getting #37 (egr sensor circuit open or grounded.) Had Throttle potentiometer codes earlier, but are not now showing after disconnecting battery and clearing codes. Any ideas???

 

Hi Shelby676,

Well, you're almost there. Congrats.

This is not good news. You run the risk of frying your tach. The HV feedback could also fry your amplifier and go on into your ECU.

1. Did you replace the spark plug wires, too? Or did you at least check the resistance of each to measure if they are < 25000 ohms?

2. Read in your Hayne's (Sec 5.4) on how to measure the primary and seconday resistances of your coil. I'd do the new and old one.3. Find your receipt for the coil. You may have bought a BRAND NEW bad coil. I did a couple of years ago.

The above I would consider the "usual suspects".

Next on my list would be the harness and a couple of odd components I see on a wiring schematic.

Get back to us, please, whether joy or none.

 

Thanks Trick. Ordered another new Bosch coil, all resistance values identical to last coil purchased; but not in line with Haynes values(New coils both 1.4 ohms primary, 9,500 ohms secondary). Used some "liquid" insulating coating over tops of wire connections, seems to have fixed arcing. All wires less than 15,000 ohms. There is black wire with white dash at harness that was connected to coil base (ground) when we bought car, can't tell from Haynes diagram if that is correct connection point or needs to go to negative side of coil (better fit for wire length). Idling smooth, rough on acceleration but smooth at higher rpms (2000-3000) once there. Still getting gremlin codes, now FF12 showing (MA Sensor) No vacuum at EGR valve at 1500+ rpms, assuming bad EGR temp sensor or EGR solenoid. Still checking wire connections. Thanks again for input.

 

You need to download the AJ6 4.0L Engine Management Guide Publication S91.
I uploaded it some time ago.
It is in the 'sticky' section for all to download.
This is the OEM guide for your car.
I got this as a paper booklet when I was at the dealer and had it converted to .pdf
You will find all the systems covered.

bob gauff

 

Shelby676,

Here's an excerpt from a factory wiring diagram for an XJ6 VDP 1991-92 MY. It shows the wire colors and connections to and from the ignition coil.

Color codes can be deciphered in another thread, Jaɡ‧u‧ər Electrical Wiring Color Codes or read on.

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

Here's the excerpt:



NOTES:

1. diamonds, numbered 2 and 3, are ignition switched power leads
2. LIG32 is a ground
3. wires colored B and WR connect to the ECU from the amplifier
4. there is a 6.8 KΩ resistor in series with the tachometer from the -tive terminal of the coil and
5. there appears to be a CAPACITOR in parallel with the +tive terminal of the coil and ground!

I hope this helps you.

 

S,

This is my "decoding" of the pertinent wires you are "tracing".

• WB is white with black tracer
• WK is white with pink tracer
• U is blue
• RY is red with yellow tracer
• B is black and
• WR is white with red tracer

 

New member not sure how to post a question
1991 VDP code 44
How do you find what the various codes mean?

 

Dennis check the aj6 engineering or the jaglovers site. Code 44 is usually the o2 sensor.
Shelby676 have you checked the cps yet?