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Discussion Starter · #1 ·
i've been trying to go through the car recently to get it ready for spring and as it sat through the winter, everytime i would go to start it and let it warm up every week, it would refuse to stay running longer than 5-10 seconds. To solve this, I could just throw the scanner on it and erase all the adaptive memory and everything would be fine. That no longer works and realisticly, that isn't really the way I would like the car to operate. Just swapped out coolant temp. sensor, TPS, and IAC. Upon the first start up, everything functioned better than it ever has. Car runs and drives fine. Then it sat overnight with temps in low 40's. This morning, same old song & dance. No start again. I really don't know where to look other than possibly o2 sensor. Car is a 91 Spirit RT, all stock style electronics. I believe the o2 is about 2 years old, intake air temp sensor is new, and of course the others listed above. Any ideas?
 

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O2 is not going to create a no start, especially when cold and the vehicle is in open loop.
If the vehicle runs fine after warm up then I do not think base idle,carboned throttle plate is your problem but since you have a scanner go to minimum idle test and check.
Also after sitting overnight humidity and dew are present, check for wires/coil arcing to ground or corroded grounds or connectors that would be affected by moisture.
Get the car running and warmed up and use a spray bottle to mist the ignition and connectors in an attempt to duplicate the condition.
Back in the 80's we had a Chevy Celebrity that the customer stated would not start on damp mornings, if they waited until 11:00 AM it would start. He wanted it fixed so I told him I would start the car every morning, if it started we did nothing until the next morning, took 2 weeks and finally it would not start, cranked the engine and looked under the hood and the coil was arcing to the block, took just the right amount of moisture to make that an easier path to ground.
 

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Discussion Starter · #3 ·
It can be attempted to start during the day on a dry day, just the temperature was what I thought was affecting it. But it is another place to look, so will give it a whirl tommorow. Now, erasing the adaptive fuel won't do the trick. I have to pull the battery cables off for about an hour to fire it.
 

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Use your scanner to your advantage, before attempting to start, with the key on/engine off take a good look at your sensor readings to see if something is out of range that may help narrow down the problem circuit. Look at baro, baro to map (should be the same key on/ engine off) tps(connect a voltmeter between the signal and signal return and slowly sweep to see if voltage change is smooth and consistant,the refresh rate of the scanner is too slow to get accurate readings) coolant, air charge(air and coolant should be the same on a cold engine that has sat overnight) when cranking does the controller see a crank signal(check hep connections for looseness, corrossion)What are the AIS steps reading before starting and after starting.
What is fuel pressure, do you have good strong spark?
 

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Had the same problem, turned out to be the MAP sensor. No codes ever came up. One way to check it is when the car won't stay on, disconnet the MAP sensor. If it stays running, then plug it back in. If it wont stay running for more than 5 seconds, you know the problem.
 

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Discussion Starter · #6 ·
just found out it was the map sensor. Wish i would have checked the site this morning, would have saved me about 3 hours today. Ended up writing down all the sensor's values under different conditions for the past couple days, getting different map readings all over the place. Thanks for the help guys, it is much appreciated.
 
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