Car acting crazy, throwing codes P1642 and P1642 - NJFBOA - Home of New Jersey's Camaros and Firebirds

vipergtx500 · 01-01-2009, 09:21 PM

My car is acting very strang, the tachometer periodically works, most of the time it doesnt. My car has alot of trouble starting and usually doesnt. And when it does start, it will stall after a few minutes, but usually it will misfire a few times and then turn off. The SES light is on and its throwing codes P1641 and P1642. I brought it to my mechanic and he checked all the relays and grounds, and replaced the ignition module and crank position sensor and nothing changed. I am running out of options and my mechanic thinks I need the get my PCM reflashed. Anyone heard anything like this before?

LTb1ow · 01-01-2009, 10:22 PM

Opti!

ar0ck · 01-01-2009, 11:20 PM

If you have a friend that you can trade Mass Air Sensors with I would try that first.

SRGN · 01-02-2009, 01:47 AM

Those codes correlate to primary and secondary cooling fan control circuits. Quite possible that the codes are just a symptom of the actual problem. Don't just assume that you need a code for something to be bad, monitor data on your scan tool and verify there is no in range failure.

vipergtx500 · 01-02-2009, 04:02 AM

the opti was replaced by the previous owner right before i bought the car so i ruled that out immediately. I will look into finding a Mass Airflow Sensor to swap in so i can (hopefully) fix it, or rule that out as well. I am trying to find another computer to swap in and see if its a bad pcm. SRGN would any scantool work or do i have to have one that does more than just read codes?

Pampered-Z · 01-02-2009, 09:40 AM

Sounds like two unrelated problems. The codes for the fans should not result in the car missing or stalling.

Do you happen to have a manual fan switch installed? They can cause the ECM to throw codes? If not, check the fuse (25 amp) and them check the relays. You can first try swapping the relay for the fog lamps with a fan relay, see if both/either work. If not you should probably break out the volt meter and check the current and resistance going to the relays.

Since the tach doesn't always work and it stalls I'd start at the ICM and work back. make sure you have good contact with the coil/ICM/Head/grounds. The tach is driven off ICM, it's the wire with the 1"x1" box that is taped to the harness. Make sure that wiring harness is connected properly, no loose wires or corrosion. Also make sure you have a good ground. There should be a ground strap from the frame as well as 2-3 other wires that connected to the bolt that attaches the ICM to the head.

sweetbmxrider · 01-02-2009, 11:48 AM

Quote:

Originally Posted by Pampered-Z

Also make sure you have a good ground. There should be a ground strap from the frame as well as 2-3 other wires that connected to the bolt that attaches the ICM to the head.

this is what i would check first. just because someone else did it, doesn't mean it was done correctly or with new parts.

going on a limb here, if the cooling fans actually aren't working and the car happened to overheat.......well we lt1 owners know what that does

vipergtx500 · 01-02-2009, 02:04 PM

the ICM was replaced by my mechanic, i just swapped in a different Mass Air Sensor and it didn't change anything. The codes thrown for the fan relays don't explain the stalling/misfiring and the tach issues, so im still leaning toward something with the pcm or like you said Pampered_Z something with a ground. Its snowing right now so i can't really take a look at it. Im gonna scan the codes to make sure they didn't change up on me. Also, I have a pcm from a 95 A4, so i know it wont work right, but does anyone think by swapping it in for a min i can tell if its my pcm?

UPDATE: Rescanned the PCM and got code P0336 - crank position sensor (but he replaced that?) and P0372 - Timing Reference High Resolution Signal 'A' Too Few Pulses (WTF)?
P1641 and P1642 are coming up as well like i mentioned

LTb1ow · 01-02-2009, 02:59 PM

Opti!

sweetbmxrider · 01-02-2009, 06:38 PM

sounds opti-ish to me. if the car overheated and soaked the opti because the fans didn't come on, well there is your cause and effect!

vipergtx500 · 01-03-2009, 02:10 AM

Did some more research and found this . Reason to believe that it unfortunately is indeed the opti (sorry shownomercy for not believing you). The previous owner had his friend replace that and the water pump at this friends shop, they must of either got it wet or the water pump might of leaked or something. Does anyone know where to find one for reasonably cheap. Ill probably put it in myself so I KNOW its sealed properly this time.

sweetbmxrider · 01-03-2009, 08:40 AM

ahhhhh thepartslady i think it is on ebay......

stick with ac delco (what she sells) i would personally stay away from aftermarket like msd.....there are great how to's on opti replacement. have fun!

vipergtx500 · 01-03-2009, 01:17 PM

seems like she's not selling anymore she doesn't have any items for sale, and i've seen a few how-to's but if u know a good one and you could post the link thatd be much appreciated

sweetbmxrider · 01-03-2009, 02:41 PM

i can't find the good ones but this is the run down if you will....

http://www.njfboa.org/forums/showpos...51&postcount=7

SRGN · 01-03-2009, 11:25 PM

Quote:

Originally Posted by vipergtx500

seems like she's not selling anymore she doesn't have any items for sale, and i've seen a few how-to's but if u know a good one and you could post the link thatd be much appreciated

http://cgi.ebay.com/95-96-97-OPTISPA...QQcmdZViewItem

It's thepartsladi with an "i", not a "y".

vipergtx500 · 01-04-2009, 03:18 PM

before i take on such a task, i was wondering if it could be the coil? They didn't replace that and i want to exhaust all options before i take on an opti swap.

miketa95 · 01-04-2009, 03:48 PM

completely random.. but are you the kid who test drove my car like a month or two ago?

LTb1ow · 01-04-2009, 03:54 PM

Quote:

Originally Posted by vipergtx500

before i take on such a task, i was wondering if it could be the coil? They didn't replace that and i want to exhaust all options before i take on an opti swap.

If the coil was going out, it usually causes the engine to break up at higher RPMs.

vipergtx500 · 01-04-2009, 06:22 PM

i just replaced the coil, i tried starting the car but it sputtered and then a little smoke came out of the intake, i tried again, it started but died immeadiately, so i tried again and gave it a little gas when it did start, and white smoke came out of the intake, this time i had the K&N off so it came out of the MAF, i don't think i blew anything, the car was barely started when the white smoke came out the first time, and it never did this before, could it be the fuel built up in the cylinders from trying to start it and it ignited all at once? i need some kinda of answer, im going to drain the oil tomorrow and check for coolant in the oil to make sure i didn't blow a head gasket, but i seriously doubt it, it wasnt on enough to blow anything but why did this happen only after i installed the new coil?

vipergtx500 · 01-04-2009, 07:13 PM

Quote:

Originally Posted by miketa95

completely random.. but are you the kid who test drove my car like a month or two ago?

yea that was me, i was gonna buy yours but someone made an offer i couldn't refuse, to fix this its costing me close to what i wouldve spent. can't win em all i guess

miketa95 · 01-05-2009, 01:35 AM

Sorry to hear your having problems, but I got to thank you. You were the only person interested, and since you never called back the truck I wanted got sold, and now I'm keeping my TA AND getting a truck in the spring. I think I would've missed my car way too much.

If it helps, when my opti went out about two years ago my car did what yours did, It would start up then slowly choke a few times and die. My car didn't even throw codes too when it happened until about two weeks into it happening. It also knocked out my starter (the first of three times I got a starter for that car.) Be careful about having your mechanic doing random things though, mine put about a grand worth of parts into my car before the SES light came on and they finally figured out it was the opti.

vipergtx500 · 01-05-2009, 01:51 AM

glad to hear your keeping it tho, i still wanna know what exhaust is on that, it was the nicest sounding fbody ive heard. Im probably gonna do the opti on tuesday, im going to see if the screws backed out, if they didn't, then im gonna go and spend the 260 on a new opti at napa or somewhere. The white smoke scared me tho, hoping its nothing, ill know when i drain the oil tomm.

Pampered-Z · 01-05-2009, 09:00 AM

If the car is throwing that many codes, specially the high res, then the opti is probably bad, or you might get lucky and its just possible the opti wiring harness?

sweetbmxrider · 01-05-2009, 04:09 PM

Quote:

Originally Posted by miketa95

Sorry to hear your having problems, but I got to thank you. You were the only person interested, and since you never called back the truck I wanted got sold, and now I'm keeping my TA AND getting a truck in the spring. I think I would've missed my car way too much.

If it helps, when my opti went out about two years ago my car did what yours did, It would start up then slowly choke a few times and die. My car didn't even throw codes too when it happened until about two weeks into it happening. It also knocked out my starter (the first of three times I got a starter for that car.) Be careful about having your mechanic doing random things though, mine put about a grand worth of parts into my car before the SES light came on and they finally figured out it was the opti.

can you take pics of the exhaust? i'm sure we can figure it out. stock manifolds? cat? give us a little challenge!

miketa95 · 01-05-2009, 04:38 PM

I cant take any pics right now bc i don't own a camera, it has stock manifolds and cat, its just a catback system with 3 inch tips, and a small muffler off to the right side. I think it might be a mac system but I cant be sure bc I had it on a lift and it has no labels on it. Sounds good though, so whatever.