I do the same thing, once the idle drops it's time to go.Similar type question I've always had is this:
When you start a vehicle, should you wait till the oil has had some time to get dispersed? Or just take off? I usually use my RPM's as a gauge to when to put it in gear to go. When you start they're like 1200-1300 and then they settle to around 800-900. That's when I go. I just reasoned that since starting the vehicle is the hardest thing on the engine then I should give some time for oil to get throughout. May not matter though???
While common this is not a "normal" condition.View attachment 19467 i noticed when I'm sitting at a light with my jeep running my pressure gauge goes down to this level, then when I go it goes back up. Is hat normal??
Yes, newer TJ oil pressure gauges were reprogrammed to remove the normal ups & downs of oil pressure. So long as the actual oil pressure is within normal limits, the gauge is programmed to stay at its mid-scale position.My OP gauge stays fairly consistent from idle to full throttle. All that tells me is the gauge and sensor are not very sensitive. Fluctuation from idle to under load should be expected.
Yes, newer TJ oil pressure gauges were reprogrammed to remove the normal ups & downs of oil pressure. So long as the actual oil pressure is within normal limits, the gauge is programmed to stay at its mid-scale position.
This was done because too many new Jeep owners buying the new TJs were complaining about the oil pressure going up & down & the dealers couldn't convince them it was normal. They were the ones buying their first vehicle with a real oil pressure gauge & they were ignorant of how they are supposed to work. The factory was forced by all the dealer complaints to program the normal ups & downs out of the gauge and present a steady mid-scale reading so long as it was actually ok.
My '97 oil pressure gauge worked as it should, it showed the true oil pressure. I'm guessing the reprogramming happened around 2001-2002 or so.
I have a 2003 Sahara 4.0. It has 44K miles and just started doing this. I checked it with a mechanical pressure gauge and the needle didnt fluctuate at all other than what is expected with changing of the idle/RPM. So, I put on a new Sending unit and NOTHING changed. Well, actually after that, I started getting the check engine light on, so I scanned it and only code I got was a P0118, which is coolant temperature sensor voltage too high....(the only dash lights I got with the dropping oil pressure initially was the red 'check gauges' light/beeping when it bottomed out.
So, I changed the Coolant temperature sensor and Voila.....NOTHING!
Now I have a rough idle and some 'missing', especially when its cold, check engine light, and a Dancing Oil pressure gauge. (There are absolutely no changes in the sound of the engine either with the oil pressure dropping. I thought about installing a new oil pump, but dont think mine is faulty)
Please help.....And I am certain this TJ has been babied its entire life and with such low mileage, I seriously doubt that the mechanicals are worn out!