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SOHC Nobody forgot about you guys. 1st and 2nd gen will be included in here

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  #1  
Old - October 12th, 2013, 06:52 PM
candjstealth91 candjstealth91 is offline
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Unhappy 91 sohc running very rich!

My 91 SOHC stealth is running very rich (smoke pouring out of the tail pipe). The engine light is on, the codes I pulled are intake air temp sensor, throttle position sensor, coolant temp sensor and barometric sensor faults.

The history on the car is that it was in storage for about 6 years, my wife and I inherited the car when her father passed away and we really wanted to get it back on the road for sentimental purposes.

Brought it out, put new fuel in it, new battery and fired it up. After a bit of smoke it ran beautifully, even passed the emissions test.

It would always take a long time to start up from cold. I replaced the plugs, cap, rotor, and wires. Ran some injector clean through it. Still would take along time to start when cold.

Now when it finally starts it is running very rich, it runs and idles fairly well but pukes out smoke.

I found online that the ecm's in these things are garbage so I pulled it and found the typical capacitor leakage. I had it repaired hoping this was causing all the faults. Just tried it and its still doing the same thing.

I've also replaced the coolant temp sensor.

I'm running out of ideas, any thoughts would be greatly appreciated!
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  #2  
Old - October 12th, 2013, 09:54 PM
checkered vr4's Avatar
checkered vr4 checkered vr4 is offline
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Location: Bartonville IL
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Re: 91 sohc running very rich!

Are you sure the smoke is from Fuel not bad valve guide seals? Slow to start after a car is been sitting for a while sometimes ends up being the fuel pump dying. Try turning the ignition on for a few seconds a few times before cranking to see if it starts right away. That should give the fuel pump time to bring the line pressure up if that is the problem.
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Old - October 13th, 2013, 10:37 AM
candjstealth91 candjstealth91 is offline
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Re: 91 sohc running very rich!

Thank you for your response! Ive tired turning the key on and waiting a few seconds, doesn't change, still takes a lot of time for it to fire. I thought about the vale seals as well, but it does smell more like fuel.

I keep thinking that its more to do with the faults that are stored. Those sensors all appear to be on the same harness and I'm wondering if there is a correlation between the faults.

I feel that these faults are whats causing the problem. Ive also read that a faulty O2 sensor can cause the car to run rich like this, but I would have expected to see an O2 sensor fault.
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Old - October 13th, 2013, 10:32 PM
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checkered vr4 checkered vr4 is offline
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Re: 91 sohc running very rich!

I'm not familiar with the sohc engines but maybe your fuel pressure regulator is bad. The O2 sensors are what the car uses to adjust its fuel map to be in tune. Throttle position sensor could be bad - telling the ecu you have the gas peddle down. It may be worth the cost of the dealer diagnostic charge to let you know more
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Old - October 14th, 2013, 07:50 AM
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95gto 95gto is offline
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Re: 91 sohc running very rich!

I would check into the tps and your baro sensor. The ecu uses pre-set fuel values during startup and initial idle so a bad O2 would not come into play until the car has warmed up.
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