Please help, 2.9 has a miss

[competitiveaudioman]

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I have a 1988 ford ranger 2.9 5 speed. It has a very noticable miss causing a cam like idle. It ran the way it was just fine but now is loosing some power and I dont trust to drive. The engine is sound, just replaced with a newer low milage one, the previous engine did the same thing so I thought the engine was bad. This new engine came complete so Im ruleing out the injectors, main sensors, ect due to the fact it ran the same before. I just put new plugs, wires, tryed new coil, has new fuel pump and filter. Its getting 35psi to the fuel rail. The plugs are black and were shortly after they were replaced. it puffs a dark black smoke after letting off the throttle, my guess is that its geting way to much fuel. The firing order is correct. I do not have a check engine light on. My guess is the ecu is not reading the knock sensor or ecu is bad. Can someone lead me in a direction to figure out my problem?

 

[martin]

Pull the vacuum hose off the fpr and see if it has fuel in it. Check the pcv system is not blocked.

 

[competitiveaudioman]

Pull the vacuum hose off the fpr and see if it has fuel in it. Check the pcv system is not blocked.

I did not see any fuel or smell any in the fpr. How do I check the pcv system?

 

[competitiveaudioman]

Just ran a new ground, one 4 ga to my block and one 4ga to my frame. Did not help a thing. Im stumped

 

[jhammel85]

Hmmm..

Did you check for codes? It does indeed sound too rich.....How's the timing? You know to check it with the spout out right? Are all of the sensors connected and is the wiring OK? Any vacuum leaks?

 

[Psychopete]

You mentioned you had a check engine light turn on, good place to start is to see what it's complaining about, and also are you sure you have a knock sensor?

Could be bad input from a sensor, and if it's a real recent build, double check your vacuum lines. I accidentally left the vacuum line from the vapor canister disconnected from the bottom of the throttle body and had a similar issue. Also make sure everything is plugged in. Might be worth while to check TPS w/ an analog meter. Check out the MAP vacuum line too.

 

[robertc1024]

If it's running rich, it might be your engine coolant temperature sensor too.

 

[kimcrwbr1]

Run the KOER test and ten seconds after the last code push the pedal to the floor quickly and it will give you one digit codes the computer turns the injectors off one at a time and measures the drop in rpm for each. It is called the cylinder balance test and you need to do it three times. Write the numbers down for each test cycle and the common numbers indicate a problem 1 is less severe and three common numbers is severe and can be the cylinder or clyinders to look at.