Random missfire

[ted_culver@yahoo.com]

Hello,got a few ??'s I have a 1991 Pontiac Bonneville,with 71k original miles,and vehicle was garage kept,bought about 2 months ago,since then many problems have accured,hesitation when under light load,stalling at stop lights and signs and when putting in reverse and if i go from idle to WOT it will just die out,i went and checked under the hood to find when when i give it gas it wants to die before it goes, basically if i give it little pedal it goes fine if i give it alot it sounds like its bogging down before it picks up RPM,so i threw my genesis obd1.1 scanner on it and it came back with,TPS,And cam sensor,ive replaced both,the tps is adjustable and ive adjusted to manufactured specs, and the cam sensor,since the replacement and the reset on the ecm,the vehicle still runs the same and im still getting the cam sensor code #41....I need help.....

here is a list of things ive already replaced
Plugs/wires/alternator/TPS,cam sensor,and cleaned maf,my scanner shows live readings so i see how many G/S the Maf is reading ive checked all other sensors and they all seem to be fine.......but i still get a lag from idle to wot and a miss fire you can clearly here at about 2500 rpm,every 10-15 revolution ite will miss fire ive actually gotten it to back fire and stall the engine whilst trying to find this problem with the random missfiring..........

[Merrillspontiac]

Have you checked to make sure the cam magnet is still in place?

[ted_culver@yahoo.com]

Where the the cam sensor is sitting,just left of the water pump,after taking old one out i looked in the whole where the C/s was i see the cam in side the whole, egg shaped,but i did not see a magnet on the end of the cam\so i assumed it was to be that way and the reading came from the sensor,but no i did not see a magnet and one did not come out with the old one either,but if there is a mag that could very well be my problem,any chance you might have a pic of what this magnet looks like.....ohh and where in the forum should i be posting my ??'s i noticed it was moved......

[J Wikoff]

You did crank the engine over two rotations while looking through the cam sensor hole, right? It's just a little round magnet in a plastic carrier that snaps into a hole in the cam gear.

This is the right forum.

[ted_culver@yahoo.com]

Ill get a pic of the cam and post it,there was not slot,snapring or magnet,on the cam lobe,just the end of the cam,now mind you i did not pull the cam out just the sensor,and looks in the hole for any damage,.And yes i also turned over the motor sevral time to see f it was there and it is not,like i said ill post a pic of the whole without the sensor in,rotation or not i should still see the mag,right?

[RPACODY]

"hesitation when under light load,stalling at stop lights and signs" does it run ok cold after setting overnight but long crank time warm?


might check the FPR

[oddie121]

I kinda had something like this, but i'm assuming you mean its only this way in gear (ie forward or reverse). Mine bogged down a little when going from forward to reverse or a hard stop. After i changed the transmission fluid and used seafoam transmission before and after the change its been working like almost new.
Just my 2c

[J Wikoff]

The cam sensor magnet will come in and out of view through the sensor hole as you turn the engine over. Everytime the cam makes a complete revolution, the magnet passes the sensor, and the PCM knows where the cam is at that moment. In general, it is referenced for fuel injector timing. So if there is no magnet (or no signal at all from the cam sensor), the PCM defaults the injector timing to some "retarded" value and you'll experience some hesitation, lugging, and lower gas mileage.

[ted_culver@yahoo.com]

yes light pedal i get heitiation and shaking in gear out of gear its fine,still getting cam sensor on Diag machine,somtimes will stall going in to reverse,somtimes it stalls at at red light,other times i given gas from stop and it just dies,but restarts and goes fine,i checked the FPR,no leak and proper restiance occording to engine temp,but i looked everywhere in that hole and i dont see a mag,lol,also still missfires every couple revolutions,if i full throttle just when its about to missfire,ittl backfire and stall out,i think all my prob is coming from this cam sensor i tried to take pics but it was to dark for my phone to get the pic to even see,how can i tell if the sensor has gone default on me??

[J Wikoff]

If you have code 41, it's gone default. If there's no magnet nub on the cam gear, you have to replace the magnet if you want the issue to go away. Which either means you have to take the front cover and cam gear off (since the magnet brilliantly snaps in from the back of the gear), or JB weld one into the hole in the cam gear. I think it was Padgett that made a how-to on it. Search padgett and magnet together and you'll probably find it.

EDIT: Here it is.

viewtopic.php?f=20&t=28603&p=302384&hil ... et#p302384