motor shaking, smells like rotten eggs, no start., code 13

[88bonnsse]

1987 olds delta 88
yesterday I started my delta 88 to run to auto part store only 10 mins away. as soon as I started it, motor had a pretty bad shake.

let it idle for a few but shake did not go away, drove to auto part store and drove back home. car seemed a lil sluggish but still ran.

let car sit over night, then today my wife went to go to work and she let the car warm up and started to drive, made it about half mile from the house and the car started shaking really bad, then the check engine light came on so she pulled over to call me. I told her to try to start the car and it would not start. it would crank but not start at all. so I scanned the computer and got code 13.

( code 13 - Oxygen sensor voltage stays between 0.35 and 0.55 volts for 30 seconds when the TPS signal was above 0.55 volts. The engine had been running for at least 40 seconds with an engine temperature above 110° F. )

so while I got to my wife where she was stranded, I tried to start the car while stepping on the gas, it would sound like it wanted to start but it would not stay running at all.

so I then un plugged the M.A.F ( don't ask me why ). and with m.a.f unplugged I started the car while stepping on the gas and it turned over and stood running. so while it was running I plugged the M.A.F back in and took foot off the gas and it still stayed running.

so I had my wife drive it home. while she was driving home it started shaking again, and smelling like rotten eggs when she got to the has and was parking..


can anybody please help me with this. I need to try to figure this out today and fix it so my wife can safely return back to work..

my Bonneville that I just changed the transmission on runs great but has a bad axel I need to replace before she can drive it.

HELP PLEASE.. THANK YOU.

[88bonnsse]

also when I put my hand under the tail pipe of the exhaust it smells bad like gas.

[MattStrike]

First thought - bad MAS. Junkyard pick one if you can, they aren't cheap new. Is this an LG3? If so, try to find one off an '86 that doesn't neck down, but that's just a preference.

[88bonnsse]

you mean m.a.f right ? you said mas lol

[J Wikoff]

It could be an injector stuck open, or the fpr failed dramatically, but the maf seems more likely.

[MattStrike]

MAF sensor = MAS = mass air flow sensor; the older CSMs referred to them as a MAF sensor. Most '88+ refer to them as MAS.

IDK why I know that.

[RJolly87]

My first guess was ignition issue, but you should be able to tell if that's the case even with the MAF unplugged.

[88bonnsse]

maf would make sence being as how it did start after I unplugged maf. but why would maf or ignition problem cause a code 13 ?

[RJolly87]

Because the exhaust isn't hot enough for the o2 sensor to give a reading. Pig rich means colder combustion temps. Colder combustion temps means the o2 is pegged rich, and doesn't cycle in a manner the computer thinks it should, thus the code.

[MattStrike]

The MAF is the primary input used to determine the AFR. In this case, the O2 sensor is signifying that it's running lean (less than 0.5v).

The ecm is thinking it should be running 'rich' based on the MAF and TPS readings, so it faults the O2 sensor.

Normally, at about 50% throttle, the AFR should peg 'rich' on the O2 sensor (.8v). I don't know if this is a limitation in the software/OS or just something that wasn't considered as a failure mode. But it's not uncommon for the computer to not be able to recognize a MAF translation or failure unless it's an open circuit.

[88bonnsse]

My first guess was ignition issue, but you should be able to tell if that's the case even with the MAF unplugged.

how would I tell if its an ignition issue or a bad mass air flow sensor ?

[MattStrike]

If the problem goes away, even though it will run like crap, with the MAF unplugged then the problem was the MAF. If the issue persists after unplugging the sensor then it's not a problem with the sensor.