Hi-Speed Miss under load on Park Avenues - Both Ultra and Non-supercharged
Both cars have under 40K miles - 'just changed the fuel, air and oil filters on the non-supercharged car as a precaution. Both have exactly the same issue. At normal temperature, either pulling even a slight hill or with light to moderate accelaration on level ground, they miss badly. Power drops off instantly and miss continues until RPM picks up to 2000+, but pulling power is still abnormally low. I got an engine warning light one time (code was miss on #2 cyl) for the Ultra, but the light extinguished on its own.
I also had a 1998 Ultra with 160K miles that did essentially the same thing. Can you point me to the probable issue or help me with troubleshooting? It only happens while moving under load - most often with engine RPM at 1500 or below. I cannot duplicate when I'm under the hood. Thanks
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Re: Hi-Speed Miss under load on Park Avenues - Both Ultra...
I think he crank sensor is defective, or installed wrong. The cam sensor controls fuel injector timing and
can cause sputtering and hesitation. The timing must be correct for the
injector to fire when the intake valve is opening. Check for any
scratch marks on the cam sensor. In addition, check the cam interrupter
magnet and be sure it in place and not damaged.
The ECM sends a 5-volt reference signal to the
CTS sensor. As temperature changes in the coolant, the electrical
resistance of the CTS sensor also changes. The best way to test this
sensor is with a scanner. When the engine is cold, engine coolant
temperature should measure near the same as the ambient temp. Another
way to test the CTS sensor is to measure voltage from the time the
engine is started, until it warms up. Record the voltage changes as the
engine warms up to operating temp. i.e. 120, 140, 160 & 180. You
should see close to the full range of voltage (5.0-1.0V) during this
test. If it does not change from what you first measured cold, replace
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It is not necessary to change the oil in the supercharger. The only maintenance required is to CHECK the oil level every 30.000 miles. GM says that it is normal for some of the oil to get lost during normal use by seepage therough the front seal area. It requires 5W-30 synthetic oil.
I guess if you really want to CHANGE the oil, it would require removal of the supercharger and remove the oil fill plug and turn the supercharger upside-down to make the oil drain out.
Normally the first thing that would cause a miss like that (under load in a tall gear) is a secondary ignition miss, usually caused by a plug wire, or possibly a distributor cap or rotor-have these been replaced in the last 30,000 miles? If not, I would do them first. If it still happens, you might then change the fuel filter, clean the throttle body and Mass Air Flow sensor, and replace the air filter-that's a complete tuneup, it should last you another 50,000 plus miles as long as you change the oil religiously and don't overheat it.
It depends on if you have the supercharged engine. Your manual will tell you for sure. If you have the non supercharged 3.8, it's just 5 quarts with a filter change, 4.6 without a filter change. A little side tip. Don't wait for your DIC to tell you when to change oil. It's not as reliable as GM wants us to believe. Don't go more than 5000 miles on traditional oil. It's cheap enough stuff that you should really shoot for 3000 mile oil changes.
If you have already done a tune-up changed the wires, plugs the only other thing i can think of would be the fuel pump. If you have a check engine light on along with the other lights your local advance auto parts would check this at no charge. That may give you a clear view of what is wrong. Hope this helps.
Mercury had a recall on 3.0 duratech motors in 2000 and 2001. If you get a fuel smell at startup then you might have a bad lower intake gasket, it could cause a miss if seal is cracked. Article No. 01-4-3 you can get it on AllData.
Also, check the PC rubber L piece that runs from the PVC valve to under the throttle control - it could be busted.
Make sure ignition wires are not cracked. If you haven't tuned it up in over 30-40K consider doing that.