89 bII running rich?

[cbneff]

My 89 with the 2.9 is running rich exhaust smells of fuel pretty bad and smokes a little bit on the initial take off. Ive changed the map, and the fpr. Even after doing so it still runs rich. The timing is good I have it at 10*. The bronco runs good it'll pull 70 down the highway but that's about all she's got. So any other ideas what this might be? Don't know if this is related but it idles around 800-850 don't and on the first cold start of the day it'll sputter and die in about 3 seconds but as soon as I crank it over again its fine. Any ideas would be greatly appreciated.

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[cbneff]

Nobody?

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[ab_slack]

What happens if you unplug the O2 sensor? O2 sensor is used for trimming mix I believe, if it thinks there is more O2 than really is, it can dump more fuel, or signal can be so bad it is running open loop.

Unplugging the sensor will put it open loop. If the O2 sensor isn't giving good signal it could improve it. If it makes no difference at all, that could suggest it is already running in open loop.

Try getting codes out of it see if that suggests anything.

 

[jhammel85]

The timing should be on or around 13 degrees. I Dont this is enough to make it rich but it might make a difference.

Other than that, it might be a leaky injector or something...as already suggested, I'd check for codes first and the timing too.

 

[cbneff]

Well I unplugged the o2 sensor drove it around didnt notice any change actually kicked a light when I warmed up so I don't know.. ill pull the injectors next thanks

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[ab_slack]

Leaky injectors can be ruled out by putting a pressure gauge on the fuel rail. After running and rail pressure is up to normal running level, if you turn ignition off it should hold pressure. If it does, the injectors are probably not leaking much at all. If it drops fairly quick, a leaky injector is one possibility, but there are others.

There are some other sensors that can make it run rich as well. I don't know all the ins and outs.

 

[vwa1]

A bad or unhooked coolant temp sensor can cause these issues. If unhooked, broken, bad wire, etc they default to -40f. Basically the computer will be telling the fuel injection to go full rich because it thinks it's so cold. Wouldn't hurt to read the ECT sensor data with a scan tool if you have access to one.

 

[cbneff]

Hmm my coolant temp does seem weird I just changed the thermostat thinking that was the issue but while driving the temp gauge doesn't go past the N on normal on the gauge. I don't have access to a meter but where is this sensor at I've only had it for maybe a week now not to familiar with this yet. And no matter what it stayed at the n on normal even when climbing the mountain to the next town up which is about a 7 thousand foot elevation increase.

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[ab_slack]

I thought the ECU used a different coolant temperature sensor than the dash gauge. So even if the gauge reads correctly the engine control unit (ECU) can see faulty data and mess things up.

Even it is the same sensor, there also can be a broken signal line between the sensor and the ECU in which case the control sees bum data despite seeing temp on the gauge.

I been going thru checking sensors and was thinking earlier today to check the temp signal to the ECU. I posted my question here.

http://www.therangerstation.com/forums/showthread.php?t=151049

 

[jhammel85]

Yeah, they're two separate sensors on the 2.9. The eec sensor is next to the Thermostat housing. Fun to remove that one it looks like...The previous owner on mine went a little crazy replacing it with pliers...ugh, previous owners.......

 

[cbneff]

Alright found the one under the throttle body Can already tell its not gonna be fun. Wheres this other sensor.

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[ab_slack]

If you pull the air intake hose off the throttle body and get the connector unplugged it is possible to get ohm meter probes on it and check the resistance. Do cold and heat up and check hot. If the resistances are in range you don't have to mess with it.

The dash gauge sensor won't affect operation. I know I have replaced the other one but that was back in the 90s sometime so I don't remember.

 

[cbneff]

Welp it wasnt that sensor. 47k cold and 2.5k warm so next is the fuel pressure test to see if my injectors are weeping stuck wide haha. I still feel like my dash reading is off though for coolant while driving sometimes itll get real warm on the gauge then cool off really quickly

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