Im new to the jeep community. Im not much of a off road kind of guy. Just always loved the rugged-ness of a jeep plus it usefull to tow my car to the track. Little bit og background. When i bought my 88 yj i went to do a oil change but 3 times they gave me the wrong oil filter. So i had them give me one for a 4.0L and it worked. So that lead me to beleive i have a 4.0L swap? Now i was thinking of going tbi or mpfi. I already got the research and or what parts i need to do a tbi. But after finding out that i might have a 4.0L motor should i just go with a 4.0L mpfi intake manifold? Whats needed to go this route. I spent so much time researching the tbi setup so this time i just figured i put the question out to the universe for the mpfi setup. O yes im not looking in going the mopar route.
The amount of work needed to go to the TBI is more then going to the 4.0L if you have a donor system to get the parts from. The 4.2 and the 4.0L are essentially the same motor so it doesnt matter which way you go as far as the block is concerned just the amount of work and money. The 4.0L should be easier.
Ok so here is where my problem begins. Im not sure if i got a 4.0 or 4.2. I have a carb system on there now. But when i get the parts for a oil change at the auto parts store for a 4.2 they always give the wrong oil filter. But when i get the filter for a 4.0 it works fine. But i thought ALL 4.0 come fuel injected. And like i said mine is carburated. be uase if i have a 4.0 block i should have a 4.0 head. Than all iwould need to get is the 4.0 mpfi intake manifold with all the parts on it and a harness with the ecu right from a donor car or look up those parts at a junkyard?
It really doesn't matter to change the fuel system. The block is the same. If you want you can search the forum and find the thread that tells you how to run the numbers on the block to identify the year and type of engine it came from. A carb system will fit on a 4.0 & a fuel injected system will fit on the 4.2.
No, The intake will bolt up to the head. The MPFI head does give you more power though. You swap the intake and all the sensors. Swap the flywheel and you need to either mount up a housing setup for the crank sensor or get a hesco crank sensor. Swap the MPFI wiring and rewire the system for a 5 to fire. Swap the gas tank and the fuel lines. That is it.
Originally Posted by rustywrangler I just found this little tid bit while googling:
Build Date Code
The engine Build Date Code is located on the machined surface on the right side of the cylinder block between the No. 2 and No. 3 cylinders.
The digits of the code identify:
1. 1st digit - the year (e.g., 4 = 1994)
2. 2nd and 3rd digits - the month (01-12)
3. 4th and 5th digits - the engine type/fuel system/compression ratio (MX = a 4.0L 8.7:1 compression ratio engine with multi-point fuel
4. 6th and 7th digits - the day of the month of engine build (01-31).
Example: Code "401MX12" identifies a 4.0L engine with a multi-point fuel injection system, 8.7:1 compression ratio, built on January 12, 1994.
So I think you have a 4.0 bottom end, I just don't get the year thing yet. If my math is right, I think your lower end is from a '99. That would explain the lower miles too,.
Your oil filter is also in a weird location. it should point down or towards the frame, not up. Curious, they many have added a 4.2 connection durring the swap