444gd

Hello,

I am in need of a bit of diagnosing with an idle issue.

1991 300 I6 w/ 121,000

The truck runs GREAT other than starting when the motor is cold. When I turn it over for the first time, the motor with crank through, but not start. Turn it over for a second time, then it will start but act like its missing very bad or running on a few cylinders. And at this time, it will not respond to me pressing on the throttle. It will eventually die after a few seconds. Then when I turn it over for the 3rd time, it cranks and idles perfect. The truck runs absolutely flawlessly other than the idling issue. After doing some research, I replaced the IAC, but the problem still exists. I checked the TPS with the voltmeter and its perfect. Timing doesnt seem to be an issue because its only when the motor is cold, and runs perfect when it actually gets running.

At this point, I dont know where to turn next. Any help would be greatly appreciated!

Chris_1

iTrader: (1)

Check fuel pressure.

444gd

I am reading code 128, (MAP sensor). I cannot find any vacuum leaks. Potentially a bad sensor?

Thanks

Chris_1

iTrader: (1)

Computer says MAP sensor. That might not be the issue, and something else is causing it ti give a false reading, but there's areal good chance that the sensor is the issue.
Fixing that problem might improve your gas mileage too. Worth the investment to give a new sensor a try.