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Ranger Compter Question

Junior

Well-Known Member
I have a 1987 Ranger Prerunner Wannabe that runs terrible in the low RPM range and would like some advice. I have recently had the motor overhauled including the installation of new heads and a mild cam. Other mods are limited to removal of the air box and replacement with a K&N.. The motor runs terrible in the low RPM range, constantly loading up and farting but the top end is strong and responsive. The idle is also inconsistant, uneven and sometimes it will even die. I suspect the that the stock computer is causing the problems due to the upgrades.......or maybe that the injectors are not performing up to snuff........Any suggestions? Thanks for any help! (The motor is a 2.9ltr V6!)



Junior
EJR Racing #244
 

rdc

- users no longer part of the rdc family -
Yes sounds like a vacum leak. If you don't find any leaks you might try calling Joe at Brothers Performance in Corona. He works with modified fords and possibly can help you out or at least tell you who can.

Tony
 

tkr

Well-Known Member
If you don't find any vacuum leaks, its probably the MAP sensor. Its a common problem on those. Another possibility is your cam. If it has enough overlap to decrease the vacuum at idle, the MAP sensor is going to think it under load and tell the computer to add more fuel.
Good luck.

Matt Nelson
Team Kwik Racing
 

mgobaja

Well-Known Member
The idle air sol problem can be checked fairly easily. if you unplug the solenoid the engine should die.The part is just beyond the butterfly on the intake manifold and is black in color with a two wire connector on it. It can easily cause the problems you are describing.
 

dezertchick

Well-Known Member
Junior-
Norm says the entire problem has nothing to do with Vaccume leaks or anything like that. Your problem is the fact you put a proformance type cam regardless of how mild it may be, onto a motor that has a speed density fuel injection system. Unlike the mass air system used on late model 5.0 Mustangs, a speed density system, provides it's injector timing and fuel distribution based on "max" ie programs, which are stored in the computer. By altering the engines overall air flow Characteristics with a cam shaft that causes air flow through the motor, outside the range the computer's abality to recognize (via the sensors) the computer then takes its "best guess" which is the wrong one. and provides the incorrect air/fuel ratio at any given RPM level.

In your case, it would seem that the upper RPM air fuel mapping stored in the computer is close to correct while the low RPM ratios are far off.

Then again I could be wrong ;-)

Norm Lenhart (typed by dezchick)
 

tkr

Well-Known Member
I assume when you say "constantly loading up", that it is running rich. Have you verified this? ie looking at the spark plugs?

Matt Nelson
Team Kwik Racing
 

Junior

Well-Known Member
All of your responses are GREATLY appreciated. I am currently checking into each one and will let you guys know how it turns out. I am going to obtain a check for and solve any vaccuum leak problems, obtain a vaccuum gauge and find out the amount of vaccuum at idle and compare it to stock values........I have access to a stock Ranger with same but stock motor. I will also check out the plugs since I plan on replacing them. I will also check out the solenoid deal and the map sensor.

Thanks again for the tremendous response both in this thread and from many people who have sent me private messages on the subject.

Have a great weekend dezert people.


Junior
EJR Racing #244
 

DougM

Well-Known Member
Vaccum leaks can be found easier by spraying carb cleaner around the hoses/fitting and your idle should go up if theres a leak. It wont actually find which hose is leaking but will get you in the correct area.

Norm is correct on the cam, a stock motors is programmed by the computer and little changes affect drivabilty greatly, not to mention wont allow you to pass smog (which may or may not be an issue?)

good luck
 

Jimmy8

Well-Known Member
I had the same year ranger with the same motor. It did have a very inconsistent idle, but never died on me. I used to put a bottle of injector flush in the tank about once every 2 weeks, so they would not get clogged, and I found out that that motor runs best with 50w vavoline oil. I had no problems with it. I think your problem comes from the cam. There is no easy way to get horsepower out of the truck, unless you change motors to a 302. I had a k&n, flowmaster, and 4.10 gears, and it was still gutless. The motor is just not meant for power or modifications. If you are looking for power look for a different motor because you will spend so much trying to get power out the motor that you could have already put a 302 in it.
 

Junior

Well-Known Member
I never intended to change the cam out. When I had the motor overhauled I was informed of the cam swap after the fact. It was a custom grind I am told. I am going to request the specs on the cam so I can compare them to the stock unit. I am not looking for HP, I just want it to run good with the power it has.

If I find that the cam is the problem, can I modify the computer somehow to make it work? Install a chip or something easier than swapping the cam out?





Junior
EJR Racing #244
 

Jimmy8

Well-Known Member
Dont mess with the computer. My best friend is a ford technician and he daily takes the aftermarket chips out of computers and replaces them back with the stock ones. Messing with the computer does nothing but make the truck run worse and have more problems. The only way to have the computer reworked is through Visteon, but I dont think they do anything with computers off of that old of a Ranger, and they will not do anything for a truck unless it is for a racing aplication.
 

Junior

Well-Known Member
UPDATE!!!!!!!!! The problem has been SOLVED! It turns out that there was a problem with the EGR vlave on the upper drivers side of the plenium just behind where the throttle body is located. After a process of elimination Poolman pulled off the vaccuum line leading to this valve and plugged the line with his finger. The motor was immediately cured! It idled great, had low end throttle response and will even chirp the tires from a dead stop! Since emissions is not an issue here we just plugged off the line and problem solved! Thanks a ton to all that responded to my pleas for help. I received over 40 e-mails with excellent advice. This forum is the bomb. Special thanks to the Poolman for finding and fixing the problem. Now its time to begin my education in traveling through the desert at speed! If I sound stoked it is because I am!

Junior
EJR Racing #244
 
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