Hopefully this is an easy question for somebody to answer. I have a '99 Intrigue with the 3.5 engine and about 123K miles. The problem I am having is that on cold start after the car has been sitting (usually over night) the car does not want to accelerate very well at all for the first 1-2 minutes after start up. The best way to describe the symptom is that the engine stumbles a lot like cars of years ago did when the engine was warming up and the manual choke was not in the right spot. By the time the car has gone 1/2 mile, then it is fine. I also get a SES somewhat randomly that flags codes 100 and 300 (do not remember the prefix off hand), indicating Mass air flow sensor problem and multiple cylinder misfires. I suspect the two symptoms (SES and start up problem) but am unsure of the exact cause.


Any Ideas?

 

it's not an easy question...need to work hard to understand...


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max@digitalhardcore.us

 

If the MAF sensor is malfunctioning, then that would cause a stumble in the engine because the PCM wouldn't be getting the proper air readings to adjust the fuel to. I'd recommend disconnecting the battery, removing the MAF and cleaning it with some spray electrical parts cleaner. Leave the battery unplugged for 30 minutes to give it time to reset the PCM. While the MAF is off, look in the throttle body and see if it needs to be cleaned out. Also check the PCV. Oh, if your air filter is old, change that out as well. After the above listed items have been checked/cleaned, reinstall everything, connect the battery and start it up and see what it does. Let us know.

-ImpalaMan

 

Thanks for your feed back, ImpalaMan. I tried your above. While I was looking around, saw how black the back side of the throttle plate was so I pulled the throttle body. Got everything cleaned up and put back together and it actually ran worse for the first couple of minutes then went back to running like it had previously.


I ended up reading the repair manual more and looking at more information on line and finally figured out that the computer uses the MAF and MAP as a cross check. At that point I figured the car would probably run without the MAF connected at all. The car not only ran better without the MAF at cold, all performance was like it had a 4 cyl. and now had a 6 cyl. I then reconnected the MAF and pulled the MAP connection. The car went back to running like it did with everything connected and it stalled a couple of times in the 10 minute test. During both of these tests the SES was on, so neither was going to be a permanent solution. The final thing I did was verify that I had good signal (voltage) on the wires going to the MAF. The ground pin ohmed out to less than 0.5 ohm so there was no problem there and the other two pins read 5 and 12 volts with no waver as I moved the wires around. I picked up a rebuilt MAF from "XXX auto parts" store and dropped it in. The car now runs GREAT!!!


One caution I would make to anybody reading this thread. The first place I went to for a rebuilt MAF had a less than optimal replacement part. I looked at the "honeycombing" on the intake side of the sensor and it looked like somebody had smashed all the openings shut and then poked something through from the back side to open them back up. I think the guy was dumbfounded when I said I would not take it and walked back out the door with my original. The second place had a unit that looked like the original (i.e. not damaged). I had thought about a mail order replacement to save $20, but after seeing what one place was passing off for a replacement, I am glad I spent the extra $20 to be able to see the part before handing over the money.