XJ Mods VSB 14

[alexbrown64]

Thanks for the input guys..

My truck weighs a ton. When i got it engineered, i had to take it to a weigh bridge station to get the GVM. Can't remember the figure, but i have a steel roof rack, solid steel rear wheel carrier, front winch, rear draws, 33" tyres with heavy Nitto mud terrains...
I am now at 4.56 on the diffs.

I have a yellow box electronic speedo adjuster. I still have not re calibrated it. It converts the speed signal out of the transmission before sending it forward to the speedo. Not sure yet if Jeep uses the speed info for anything engine related. It might be throwing out my shift points. .Not sure yet. I will adjust it asap.

Correct! I have the 777 injectors, so i upgraded the fuel pressure regulator.
O2 sensor at idle in closed loop is going from 0.35v - 0.70v. There is an "Exhaust" reading on my reader that goes between "Center" "Lean" and "Rich". That is what the O2 sensor is supposed to do.

I haven't checked it all while driving. The OBD1 reader is cumbersome, and plugs into the engine bay. I would have to rig it up through the window.

I will also do a plug chop.

So based on advice, i will reset my yellow box to get the speedo calibrated correctly. Might even check the throttle cable to make sure its opening all the way.

It has a lot of power down low, just gutless at high speed. It could be that its in the wrong gear for the speed, or it may be a problem with the Open Loop condition.. which, as Rainman pointed out, the Jeeps go into at WOT and use the Map sensor. My Map sensor was 1.6v at idle. I have a new, good quality spare i can swap out.

Ive heard of people swapping out the Map and it has helped.
I have lots of options to plug on with..
Will report back with news..

Cheers,

[rainman]

maybe get a speedo gear?
http://gojeep.willyshotrod.com/HowtoSpeedoGears.htm


The obd1 is only 4 wires, so i daizy chaind a plug to the dash so i can plug it in in the cab like a obd2 set up.


whats a plug chop?


Map
Ig on engine off 4-5volts
Warm idle 1.5 to 2.1 volts

[alexbrown64]

Thanks Rainman,

I will check the voltage on the Map sensor tomorrow, and also swap it out, and recheck the new one.
I used to race 2T motorcycles. A plug chop is when you go at WOT and then chop the throttle and pull the plug to get a reading. You get an accurate reading of what the engine is doing. I am loving the vacuum gauge too. Can really see whats going on with the engine when idling, accelerating and decelerating.

I dove into my FSM and found out a little about the VSS.. Vehicle Speed Sensor. Its attached to the plastic gear you can change out when you put different size tyres on etc.

"The vehicle speed sensor (Fig. 16) is located in the
extension housing of the transmission (2 wheel drive)
or on the transfer case extension housing (4 wheel
drive). The sensor input is used by the powertrain
control module (PCM) to determine vehicle speed and
distance traveled.
The speed sensor generates 8 pulses per sensor
revolution. These signals, in conjunction with a
closed throttle signal from the throttle position sensor, indicate a closed throttle deceleration to the
PCM. When the vehicle is stopped at idle, a closed
throttle signal is received by the PCM (but a speed
sensor signal is not received).
Under deceleration conditions, the PCM adjusts the
idle air control (IAC) motor to maintain a desired
MAP value. Under idle conditions, the PCM adjusts
the IAC motor to maintain a desired engine speed."

Anyway, i don't think it affects shift points or performance.

I downloaded some doc's from the Yellowbox website. Ive spliced the unit in between the VSS and the cable that goes up to the PCM. It alters the signal. So you can have any gear you want in there, but just adjust the Yellowbox and it alters the signal to get an exact speedo calibration. This signal then goes up to the PCM. I have the control module in my center console.

I will adjust it tomorrow and then use my phone GPS to check calibration, and adjust as necessary..

This old girl has a gadget for every occasion. It even has remote control adjustable shocks that i never use....

Pic below of the yellowbox unit and the Rancho shock remote control unit...



Cheers,

[alexbrown64]

Just a quick update.

So, i calculated the changes i needed to make on the Yellow Box to alter and correct the reading on my speedo. I made the adjustments in the driveway, set my mobile phone GPS speedo app on, and went for a test spin. I had to make some minor adjustments on the fly, but it is now dead accurate and spot on. Easy job!

Next, i adjusted the TV cable. Its the cable that works with your accelerator cable to adjust the kickdown points on the transmission. I adjusted this as per Bleepin Jeeps video and what a difference! I took a before and after pic of the adjustment shaft and there is a good 5/10mm difference in shaft adjustment.

I have combined the pics to show how adjustment is done, and the result.
My result was great. The shift points seem to have changed and now, at 90 kph, with just a gentle push down on the gas pedal, she drops back a gear and i have acceleration again. She quite comfortably sat on 100kph, which was my goal. Hardly any drive line noise or vibration. At 100kph, the revs sat on 2250 which is right in the powerband. She would kick down at 100kph and accelerate up to about 120/130kph. That seems about max speed, but i would never drive her that fast. Our freeways are 100kph so i am happy there.



This is a simple 5 minute maintenance item that can really change the feel and performance of your XJ.

I also checked the throttle body and gas pedal to make sure it all looked clean and the flap was opening all the way. All good there.

While on my drive, i tried to set the cruise control on. No luck. Its not working anymore. Its vacuum operated and i believe i have a small leak somewhere, as my aircon flaps (which are vacuum operated), also swap between the windshield and front vents sometimes while driving.

I have suspected a few vacuum leaks on the old hoses for a while.. so i will check that all out.

Overall, a good session. The car has some power back, and she is running smooth. I will look at the sensors now, more from an economy point of view.

Cheers,

[alexbrown64]

OK, buckle up, this is going to be a "riddle me this" moment....

So, after all the successful test driving and feeling much happier about my Jeep, a few other problems cropped up. They have been niggling in the back ground for a while, but reared up again.

Ive had a vacuum problem for a while. As i accelerate, vacuum drops, which is normal, but it was affecting my vents when i had the aircon on. If you loose vacuum, the default setting is windscreen vent. So my Jeep was bouncing around between the windscreen and front vents.

Also, today, i tried my cruise control, which was completely dead. This runs on vacuum too.. so it was time to break out the FSM and vacuum gauge.



After printing out some data on the vacuum system, i attacked the Jeep with the gauge. I connected it to the rear vac point on the inlet manifold, which is what the cruise control and aircon system uses. I could not even get suction. There was no vacuum that could be maintained at all. A serious leak. It wasn't the lines going to the football vacuum storage unit under the front bumper. It was the line that went straight through the firewall into the dash.

Without wanting to rip things apart... i devised a plan to use my Argon bottle to pump some argon into the system to listen for leaks. Straight away it pointed to a leak at the console hvac controls.



So then it was a matter of pulling the front facia, stereo and heater controls. I did some vacuum tests on the system and could hear gas escaping from the unit. I unplugged the vacuum hoses. They are on a connector and contain 6 vacuum hoses all colour coded to specific vents. I used my vac gauge to test each line. All held vacuum except one. It was the defrost control unit which has a green vac line.



So that was what i was looking for..... the FSM says to pull the centre consol out, remove the lower dash and you can access a lot of the vac controllers. I thought i would just stick my head up under the footwell and see if i could spot a problem.. And there is was..... A flap controller with a missing hose. Some how the hose had been pulled off. I reached around and found the green vac hose and reconnected it. Tested the system and all good again.

I started the car and all the flaps, controls and hvac unit worked great. I tested the the entire hose system and it all held vacuum.

That was that problem sorted. As i was playing around with all the vacuum hoses i noticed a T and a line that was tucked up under my accessory fuse box. It was disconnected and after inspection, i followed the line to the speed control servo. This is next to the brake servo and has a vac line going in, and a cable coming out that goes to the throttle body. This system works the cruise control.




There was problem number two.

I sorted out all the vacuum lines and got everything plumbed up properly. What a fuckeroo..

But.. now i believe i have everything sorted. Should have cruise control back now and i also have good vacuum back to the hvac controls. With the flap controller vac hose disconnected, i was loosing a constant stream of vacuum. With it fixed, i should have a lot of vacuum to maintain systems.

That was a full day of riddles and experiments, but worked out well in the end.

Cheers,

[alexbrown64]

A quick drive report from all the work i did yesterday.

Spent the day adding stereo noise filters and tidying up the jeep, which included getting all the heater controls, stereo and dash back together. Also did a bit of a clean and lube.

Anyway took her out on the road and found a nice long stretch. Put the blower on full and planted the pedal. She is kicking down nicely now and i have a nice bit of power everywhere. The blower did not drop at all and i had icy air blowing at full power the whole time i was thrashing the Jeep. I got up to 90 kph and turned the vacuum actuated cruise control on. Worked perfect.

Going along at 90 kph, tacho was on 2000 rpm. Vacuum was in the orange on my MotorMinder vacuum gauge (its been in the red up until now), cruise control was on, aircon blower worked perfectly (no loss of air, due to low vacuum and hvac doors defaulting to defrost). Jeep could still kick down nicely and accelerate. I had a few squeaks that are all gone now due to spraying everything up with WD40.

Came home and ticked some boxes. Overall, Jeep running much better and every time i work on her now, i am finding improvement.

The steering still sucks though as she is pulling way to hard to the left. However, the new gearing/bearings install has all but eliminated drive line noise and vibes. She feels and sounds like a truck, but she is running well.
Not even a hint of getting hot EVER now. Never seen the needle go 1 or 2mm over half way.

Jeep booked in for steering again next week... depending on the Covid19 situation, i hope to get that one sorted as well.

Almost at the finish line.....

Cheers,

[awg]

your fuel consumption may go down too, depends where that air was getting in from the vacuum leak, but the PCM may have compensated for a lean situation by injecting more gas

Do you know what your XJ weighs now ?