Written / Photographs by: Tony Carricaburu

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MPI INTRODUCTION:

As any Jeeper who owns an older Jeep with the 258ci engine running the stock carter carburetor realizes how poorly these engines usually run. I know this from personal experience, I own a 1990 Jeep Wrangler which was the last year available with the 258ci powerplant. My Jeep has approx. 100,000 miles on it currently and has never ran worse. The problem started the day I got it. The continous unsuspected stalling, occasional vapor locking and just plain poor running. I researched several options such as the Howell TBI fuel injection conversion (est. price $1100.00), I also came across the Turbo City's TBI (throttle Body Injection) conversion (again $1,100.00 - $1,400.00). I also came across the Mopar MPI (Multi Port Fuel Injection) conversion. This is an actual mopar designed product that is also California Smog legal unlike some other applications. I searched and searched for a descent price but everyone seemed to want anywhere from $1995.00 to $2295.00 for the kit not including the Vibration Dampner (required). The dampner usually runs another $185.00 ontop of the already expensive price. I finally came across an unbelievable deal at Koller Dodge. They advertise in several offroad related magazines for a extremely low $1650.00 price on there complete mopar kits. Thats approx. $350.00 - 500.00 less than the competitors. I went ahead and gave them a call and ordered one. For my application I needed an automatic transmission version. (specify your preference when ordering)
Below I will be discussing my personal experiences I obtained while installing my MPI kit.

REMOVAL OF THE OLD INTAKE & CARB:

Before starting the removal process I first removed the battery cables, I also pulled the plug on the Radiator and began draining the coolant. From here I started by removing the air filter and assembly (including the million miles of vacuum hoses). You can set these items a side for re-sale or trash them. For me I was so happy to get rid of them I just trashed all the old parts. Anyways after removing the air cleaner I went ahead and removed all the necessary vaccum and fuel lines connected to the intake manifold and Carter Carburetor. Instructions specify what hoses not cut or remove but fore the most part everything you see attached to the Intake or Carb. is going to the trash. I then removed the throttle cable and added this item to the junk pile. The kit supply's you with the necessary throttle cable required to run the system properly. The only other part your going to have to remove before taking the Intake and carb off is the power steering pump. The rear mounting bracket for the power steering pump comes factory attached to the 4.2L (OEM) Intake manifold. I was now ready to remove the Intake manifold and Carb. together. I opted to take the carb off first and then the Intake manifold but figured it would be easier to just pull it all out at once. Below are some pictures of the Intake and Carburetor off.

INSTALLATION PART 1:

This is important! The Mopar instructions clearly suggest not installing this kit on a older tired engine. They dont specify why but im sure its because it might put to much strain on the engine. For best results id suggest bring your Jeep to a local dealship and sking them if your engine is able to withsatnd this type of conversion. As shown in last months article about the 4.0L Head Conversion, My engine appeared to be very clean, appeared new and ready for the MPI kit. Below are some pictures from the previous article (4.0L Head conversion) that shows the engines condition.

(click on image for large view)

   

INSTALLATION PART 2:

After removing the old Intake Manifold, I was ready to start installing the new MPI kit. The MPI instructions suggest that you start by removing all the emission controls from the engine. Including the three solenoids located on the valve cover. After removing those items I went ahead and removed the Pulse Air valves and hardware. Again these are all items you will no longer need. I then went ahead and removed the mechanical fuel pump located on the passenger side of the 4.2L block (behind the alternator) This pump was replaced with a cover and mount for the Ignition coil supplied in the kit. See pictures below for detailed pictures.

(click on image for large view)

       

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