94 cam sensor check engine light

[wsimmons3]

I have a 94 Bonneville with an "L" code 3800 engine. The check engine light comes on regularly. It often comes on within a few seconds of starting the car. Other times it comes on after it runs for a while. It may be off for two weeks at a time, but is on more than it is off. The code is cam sensor failure. I have replaced the cam and crank sensor. Changed the plugs and wires. When the light is on the engine misses periodically. 99% of the time it is barely noticeable only when you take your foot off of the gas. Other times, I will be driving at 70 mph. After 30 minutes or so, it looses all power. It misses and acts as if it is being starved of air. If you press the petal down until it downshifts, it will start to act normal and accelerate. It loose power again once you let off of the gas. This will go away after a couple minutes. It has 156,000 miles. The exhaust is original, but does not seem to be bad. It passes the states exhaust gas certification with very good results. I do not see a difference in the gas mileage. Once in a while I notice a pressure build up in the gas tank. It will vent for a few seconds when the cap is removed. This happens mostly after driving for an hour with a low gas tank. Any ideas. This thing has been driving me crazy for the last year.

Thanks

[maxwedge]

Welcome to AF, if you continue to get a cam sensor code attack that first, the magnet may have fallen off the cam gear, common, some of your symptoms match that issue, not the tank pressure though. Look thru the cam sensor hole with a mirror to see if the magnet is still there.

[Jrs3800]

Also make sure none of the wires are pinched of chaffed in the loom if the loom is still there.. Cam Interrupter failure is not as common on the newer 93-95 L27's as the older LN3( 88-91 ) and L27( 90-92 )... But it is possible, and its easy enough to inspect for..

You should have the car checked for codes, the PCM in this car is OBD1 but uses the Pxxxx Codes... This may lead you in a better direction as there may be more than one code stored.. And keep in mind that not all Scan Tools will display the Manufacturer Specific Data.... In some cases where there is a code like P0361.... In the case of this car its actually a P1361.... So in a few instances I have seen the codes get mixed up..

Also if this is the Magnet causing the problem the car will drop off in performance... That magnet is used for the Cylinder #1 TDC reference... This both allows the timing to be more precise and allows for the SFI( Sequential Fuel Injection ) to function at its optimum range and performance...