XJ Mods VSB 14

[alexbrown64]

Originally Posted by awg

I will follow your progress with much interest, as I am a qualified electronics technician by trade, although its 30yrs since I did that work.

Please photograph and document your investigations

A schematic diagram would be most helpful ?

also need one of those magnifying holders (and a few other tools)

Have a good soldering kit though !

Will do Tony. I got the magnifier from Jaycar.. Handy bit of kit.
My local shop didn't have all the parts i needed, so i am going to another one on Friday. Still need some Capacitors, tactile switches and some doohickeys..
I bought a small 12v battery and some alligator clips for $20, so will hook up a power supply and i can do some testing in the house once i have fitted the parts. If i ever get it running, and my fix works, i will post up all the details.

Cheers,

[Jonny Jeep]

The TPS voltage is normal from what I've read. They don't go to 5V at WOT, FSMs state 4.49V at WOT. As a percentage of supply voltage you are at 15% at idle and 76% at WOT. 4.49V would be 90% but I've never seen anybody posting those sort of values. Low-mid teens and mid seventies are correct from all the mentions I've seen. My scangaugeII shows my TPS values as 14 and 74.

[alexbrown64]

Originally Posted by Jonny Jeep

The TPS voltage is normal from what I've read. They don't go to 5V at WOT, FSMs state 4.49V at WOT. As a percentage of supply voltage you are at 15% at idle and 76% at WOT. 4.49V would be 90% but I've never seen anybody posting those sort of values. Low-mid teens and mid seventies are correct from all the mentions I've seen. My scangaugeII shows my TPS values as 14 and 74.

Well done Johnny, i need feed back like that. Sounds like my TPS is working OK, and within range.
When i get some time, and am still going to change out one sensor at a time. When i change one sensor out for a new one, i will take more readings and compare. I think its worth it just to check out and clean each sensor anyway.

Cheers,

[alexbrown64]

I wanted to check the health of my fuel injection system. I have upgraded my injectors from single pintle to multi pintle rebuilt units. I also upgraded the fuel pressure regulator (FPR) to a higher pressure unit. I got a lot of original info from this thread... http://www.ausjeepoffroad.com/forum/...ad.php?t=92236

Here is the procedure to check the system pressure while the Jeep is running....



My values will be different, as i have the upgraded system. Mine should look like the update Jeeps. Values should be about 41 PSI at idle with the vac hose on and 49 PSI with the vac hose off. With the vac hose off, its the equivalent of running the car at WOT as at WOT, vacuum is almost zero.

So, i needed a gauge to test my pressures. Ebay has a bunch of them, and i chose one that had a heap of adaptors and only cost $30 delivered.



Very easy to do the test. Locate the fuel rail and there is a valve. Screw in the adaptor, start the Jeep and then read the pressure. First pressure with vac hose on the FPR and second with the hose disconnected to replicate WOT (Wide Open Throttle).

My results came back surprisingly good. Pressure was spot on 41 PSI at idle with vac hose on.



Pressure at idle with vac hose off, to represent WOT was around 49 PSI, which is what the FSM for post 1995 Jeeps recommend.



So far, the Jeep seems to be passing all its checks with flying colours. It just seems that at wide throttle, there is no power, and it is also using a bunch of juice. Besides that, around town, she runs perfectly. Starts, idles, runs great up to about 90 kph. Any faster and she falls flat on her face.

Cheers,

[awg]

what RPM are you doing at 90kmph..also what weight is your vehicle..and diff ratio

with 30" tyres, 3.55, mine does ~2000rpm at 90.
The only additional weight is rock sliders, my wheels & tyres are lighter than stock

It will accelerate very strongly up to at least 130kmph, I am bit scared to go faster in it, but the RPM would be between 3000 to closer to 4000

when dirt roading I often put it in 2nd, and it hauls arse uphills between 3-4K

fuel use is 17L/100km

[rainman]

what injectors did you end up going with?

is MAP sensor is checkng out ok.?


what voltage is yr oxy sensor putting out :
1) at wide open throtel.
2) at 90km/ph+


at 80% throttel it goes into open loop using just the map sensor and the preprogramed tables.


why did u up the fuel pressure?......ah........777 injectors?


i have 44psi on the rail with the vac disconnected. and 65% add fule, but at wide open throttel its AFR of 12.5. if i wind up the fuel pressure its stupid rich at WOT.

bosch 703 injectors.

[awg]

Originally Posted by rainman

i have 44psi on the rail with the vac disconnected. and 65% add fule, but at wide open throttel its AFR of 12.5. if i wind up the fuel pressure its stupid rich at WOT.

bosch 703 injectors.

a good old fashioned sticky beak at the spark plugs color may give a clue if its running rich, especially if a WOT run is undertaken and the plug examined immediately