code 42

[figgnzb219]

my 2.8 seems to throw a code 42 after it sits overnight, especially if the moisture was high overnight, it doesn't run any worse than normal though, and usually after it warms up a little and it restarts, its gone. It don't matter much but I want it to go away. It doesn't happen every time but kinda frequently, a couple times a week.

Also sometimes at idle or low rpm accelerating, i get a miss or hesitation, or it kinda seems like the engine shuts off for a half or quarter of a second at idle, but this is intermittent and not bad, but just annoying. The engine doesn't run as smooth as the 3.1 lumina I drive, of course it has less than half the miles on it but the acceration of the engine is much smoother. Almost seems like the timing is retarded, but its controlled electronically of course. Do you guys think maybe it's the ignition module or something like that. I checked the plugs they are fine, fairly new. The car does have high miles 226,XXX, I have done things like clean the throttle body carbon buildup, IAC valve, air filter, oil change. Some seafoam treatment, could use another one though.

[Money pit Beretta]

When I have had a problem with the ICM it kills a coil. Now have you checked at night to see if a spark is jumping from a coil?
All and all I'm thinking that the crank sensor is bad or cracked. The crank sensor is a magnet and can get weak after time. It is in the back near the firewall, only one bolt and somewhat hard to get to. Just remember where the crank is and you will see the sensor about midway on the block. There is a tab just like all sensors that needs to be pulled up to get the pig tail off.

How old is the fuel filter?

[figgnzb219]

Ya I'll check out these things possibly, I'm not getting any CAS codes but i can test it with a voltmeter for ohms and such, could still be bad. and the fuel filter, I don't know its the one that was on the car, that is another good place to start. I forgot to change it a few times.

[Money pit Beretta]

Yeah that filter is one of the problems then. Not sure if you will get a code for something that is more or less going out. Kind of like an O2, yeah it has no code, but it still can be going bad and not helping. I hear that they last about 40k and people have the stock one still at 100k. The only time you get a code is when it has failed.

[figgnzb219]

Well, I just tried to change my fuel filter, and I ran into a problem. The fitting was pretty rusty and I couldn't get it loose without risking breaking the fuel lines from the sending unit. It is so rusty just a little tweek of it the right way and it will snap, costing me 200$ or more. I'm gonna eventually do it but I'm tight on money right now. It just sucks, but next is the CAS, its only 16$ and I should be able to get it out no prob.

[Money pit Beretta]

Don't forget to oil the O-ring on the crank sensor.

[figgnzb219]

well, I changed the crank sensor, now I have another problem, my tach don't work, I hook up the scanner and it shows rpm, and the engine starts but this problem happened right after i changed it. I dunno what it is, I didn't check the fuses yet, for the cluster or whatever, but has anyone encountered this before, I took the negative battery terminal off, it cleared my old code 42 that was stored for a while. So maybe it had to relearn the input or something, but I don't know. I like the tach because I use it to gauge fuel consumption, not only that but for something to be non functional on my car drives me crazy. It still runs the same way too, although I hooked the volt meter up and running it it wasn't running to spec.

[figgnzb219]

Update after letting it idle for about five minutes straight without touching the pedal at all, it started working. Also it seems to shift and accelerate smoother and no hesitation like before, I think all is good now.

[Cliff8928]

well, I changed the crank sensor, now I have another problem, my tach don't work, I hook up the scanner and it shows rpm, and the engine starts but this problem happened right after i changed it. I dunno what it is, I didn't check the fuses yet, for the cluster or whatever, but has anyone encountered this before, I took the negative battery terminal off, it cleared my old code 42 that was stored for a while. So maybe it had to relearn the input or something, but I don't know. I like the tach because I use it to gauge fuel consumption, not only that but for something to be non functional on my car drives me crazy. It still runs the same way too, although I hooked the volt meter up and running it it wasn't running to spec.

Do you have digital or analog gauges?

[figgnzb219]

analog it works now though, but still weird.

[Money pit Beretta]

Glad to hear that it's fixed.

[Cliff8928]

analog it works now though, but still weird.

I was just wondering because the analog gets the tach feed directly from the ignition module. while the digital get the tach info via serial data from the ecm.

[SuzukiGhostRider]

Cliff is 100% correct and I would keep an eye on that ICM. It's sounding a tad on the iffy side...

[3X00-Modified]

I wouldn't point at the ICM, I would double check the largest plug on the ICM and make sure that the wire in Pin C is seated ok, and that there isn't an issue with that wire itself, since that goes directly to the dash for the tach feed. If the ecm is seeing RPM fine then thats where I would look first.

[figgnzb219]

Well, My codes 42 is back again, I just got three GM service manuals so I'm gonna try to diagnose the next problem down the line, the crank sensor was out of spec though. Also my tach quit working momentarily so I have to check the tach wire on the ICM. I'm pretty sure my fuel filter is getting worse, or I think I may have gotten some watery gas. The gas station near me closed their unleaded pumps for a week or two and was testing for water content.

I seen a sending unit is only 45$, I was suprised. I need one to change my fuel filter because the line is so rusty that if I were to even slightly twist the line, it would break right off.