4.0l to 258 swap
- Thread starter savin
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firemanharry
New member
To each his own.......but why would you want to do this?
Because I have replaced 2 computers and about $400 in sensors within the last year and I am tired of beeing broke down. Now it is fried again and this time the shop said the wiring harness is shot and will have to be replaced. If I am going to go to all of that trouble, I figured I would convert it to something I can work on myself and save the very expensive cost to have the shop work on it.
firemanharry
New member
If you are having problems with the FI system I'd suggest updating to a 90's version, I hear they are much better and more dependable. Check all the posts on folks having trouble with carbs and pollution controls and you'll see that a step back is not the solution. 8)
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Ok
First, there's the issue of it being illegal. You'll most likely have to replace the engine with one from the same model year or newer. I don't believe the cherokees came with carburated engines in '89. So depending on where you live, it might not pass inspection.
Second, If you were frying the computer and sensors, it sounds to me like you've got some MAJOR wiring problems. Such as a ground fault, abnormally high system voltages, or a dead short of 12 volts into the ground circuit. If your computer fried, then simply replacing it with a new one solves nothing, you must instead find the electrical problem and fix it before ruining more new components.
Third, Carburated engines still rely on electricity, so if you have electrical problems now, they're likely to cause future problems anyways.
I'd look towards either rewiring the vehicle and using the current setup, or finding a 4.0L Engine with the OBD-II compatible computer system (1995 or newer). :mrgreen:
-Nick :!:
Ok
First, there's the issue of it being illegal. You'll most likely have to replace the engine with one from the same model year or newer. I don't believe the cherokees came with carburated engines in '89. So depending on where you live, it might not pass inspection.
Second, If you were frying the computer and sensors, it sounds to me like you've got some MAJOR wiring problems. Such as a ground fault, abnormally high system voltages, or a dead short of 12 volts into the ground circuit. If your computer fried, then simply replacing it with a new one solves nothing, you must instead find the electrical problem and fix it before ruining more new components.
Third, Carburated engines still rely on electricity, so if you have electrical problems now, they're likely to cause future problems anyways.
I'd look towards either rewiring the vehicle and using the current setup, or finding a 4.0L Engine with the OBD-II compatible computer system (1995 or newer). :mrgreen:
-Nick :!:
Where I live, anthing older than 1990 does not need to be inspected to get registerd so that won't be a problem, and the motor I am going to use is out of a wrangler that was newer than my cherokee and never gave me a problem. So if was legal in the wrangler, I don't see why it would't be legal in my cherokee. As to go to the newer fuel injection, chrysler completly changed the system including the dash guages, sensors, head and manifolds. I already have the rebuilt 258 and all the wring harnes from it. (I wrecked the wrangler before I could put it in). The cost of changing everthing over to somthing else would be more than I paid for the jeep (I have already paid a shop more in repair bills than I paid for the bumb thing) :? . The wrangler had a stick and this is an auto and there is a seperate computer that controls the transmission. There is a throttle positon sensor that is used for the electronic transmission control and I need some help figuring out how to incorprate it into the carb design.
OBD-II is a style of automotive computer systems.
Prior to the 1995 model year, most cars with engine computer systems were based on a loose standard called On Board Diagnostics I (OBD-I). This was supposed to set certain minimum standards for what the computer systems were made up of and how they did things such as storing trouble codes. However, the OBD-I systems were very loosely based on any form of compatibility, and many of them used proprietary trouble codes, code scanners, etc.
So On Board Diagnostics II (OBD-II) was developed. The OBD-II systems are ALL compatible with each other in many ways. They all use a 16 pin data port with common pin designations, common codes and common scanners regardless of the make of the vehicle. Also, all OBD-II systems mandate certain sensors and monitor the vehicle much more precisely and strictly than the OBD-I systems. In OBD-II systems you'll usually find one of the three standard protocols: Ford (SAE J1850 PWM), GM (SAE J1850 VPW) or Chrysler/(Jeep)/Imports (ISO 9141). BTW, OBD-II systems also have non-violate memory that you cannot erase by removing power to the system - as could be done in the OBD-I systems.
Hope that helps :mrgreen:
-Nick :!:
Prior to the 1995 model year, most cars with engine computer systems were based on a loose standard called On Board Diagnostics I (OBD-I). This was supposed to set certain minimum standards for what the computer systems were made up of and how they did things such as storing trouble codes. However, the OBD-I systems were very loosely based on any form of compatibility, and many of them used proprietary trouble codes, code scanners, etc.
So On Board Diagnostics II (OBD-II) was developed. The OBD-II systems are ALL compatible with each other in many ways. They all use a 16 pin data port with common pin designations, common codes and common scanners regardless of the make of the vehicle. Also, all OBD-II systems mandate certain sensors and monitor the vehicle much more precisely and strictly than the OBD-I systems. In OBD-II systems you'll usually find one of the three standard protocols: Ford (SAE J1850 PWM), GM (SAE J1850 VPW) or Chrysler/(Jeep)/Imports (ISO 9141). BTW, OBD-II systems also have non-violate memory that you cannot erase by removing power to the system - as could be done in the OBD-I systems.
Hope that helps :mrgreen:
-Nick :!:
OBDI is a pain in the a$$ hehe OBDII is so much better everything is standardized from what each senisor is called to what each trouble codes is, its so much easier than working with a carb engine also, if its set up rite then you wont ever have a problem in fuel injection, i was goin gto take a step back to carb with my TJ but i decided not to. its easier for short term becouse its less wireing but in the long run it will be more of a head ache. i decided to instead of putting a carb 350 into my TJ im going to put a FI 98 or newer OBDII dodge 360. long term resultsof the FI 360 out weighed the long term results of the carbed 350, but if your set on using a carb, best of luck to you, and happy jeepin
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