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

vipergtx500

01-01-2009, 08:21 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, 09:22 PM

Opti!

ar0ck

01-01-2009, 10:20 PM

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

SRGN

01-02-2009, 12:47 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, 03:02 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, 08:40 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, 10:48 AM

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 8-)

vipergtx500

01-02-2009, 01:04 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, 01:59 PM

Opti!

sweetbmxrider

01-02-2009, 05:38 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, 01:10 AM

Did some more research and found this (http://www.f-body.com/forum/showthread.php?t=15811). 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, 07:40 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, 12:17 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, 01:41 PM

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

http://www.njfboa.org/forums/showpost.php?p=123251&postcount=7

SRGN

01-03-2009, 10:25 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

http://cgi.ebay.com/95-96-97-OPTISPARK-DISTRIBUTOR-CORVETTE-CAMARO-FIREBIRD_W0QQitemZ350148734690QQihZ022QQcategoryZ3 3690QQrdZ1QQcmdZViewItem

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

vipergtx500

01-04-2009, 02:18 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, 02:48 PM

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

LTb1ow

01-04-2009, 02:54 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.

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

vipergtx500

01-04-2009, 05:22 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, 06:13 PM

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, 12:35 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, 12:51 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, 08:00 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, 03:09 PM

miketa95

01-05-2009, 03:38 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.

sweetbmxrider

01-05-2009, 05:20 PM

in the I-pipe or after the over-axle pipe?

miketa95

01-05-2009, 05:50 PM

h.o im going to just go take phone pictures

sweetbmxrider

01-05-2009, 05:54 PM

:clap: its probably some rando muffler :lol: i like the effort though

miketa95

01-05-2009, 05:54 PM

its after. and the pipes are black i noticed too, but not the muffler. muffler is about one foot wide, its small.

p.s. i love not even realizing it was night time. I'll get the tomarrow. possibly even with the gf's camera

sweetbmxrider

01-05-2009, 05:56 PM

saweet!

vipergtx500

01-06-2009, 01:47 AM

im currently mid- opti job, i was gonna start tomorrow but me and my friend decided to get at jump at midnight. drained the coolant, removed the fans, intake and intake elbow, serpentine belt, and disconnected all the hoses to the water pump. The important stuff comes in the morning, ill keep everyone posted on how it turns out

sweetbmxrider

01-06-2009, 04:23 PM

aw thats the easy stuff. i bet your hands weren't even dirty :lol:

you got new waterpump gaskets right? be a good time to replace the pump and/or thermostat if you are unsure of them.

vipergtx500

01-06-2009, 08:29 PM

yea i got new gaskets, it was pretty easy just annoying sometimes. I ended up opening the opti and the bolts werent backed out but when i looked at the wiring harness going from the main harness to the opti it was RTV'd into the opti. So i pulled it out and the clip was broken off, guessing by the previous owner when he replaced it. But the main problem was at the connection, some of the metal was exposed because it chipped off. Im thinking this was the reason why it was doing what it was. The dealer wanted $228 for this 12in wiring harness lol. I got one in decent shape from the junkyard for $15. Waiting for the RTV to dry overnight, then im gonna try and fire it up

LTb1ow

01-06-2009, 08:32 PM

You made sure to get the opti in the right spot?

vipergtx500

01-07-2009, 01:45 AM

i never actually took the opti off, just the cap to see if the screws backed out. It would have been easier to deal with if i took the whole opti out but i didn't wanna go through the hastle of making sure i put it back in right.

vipergtx500

01-07-2009, 03:01 PM

That didn't fix the problem, the car doesn't even start. It cranks but never turns over, where before it did. The opti looked fine, there was no moisture and the screws didn't back out. I changed the wiring harness from the opti to the main wiring harness. Im going to check the cable from the coil to the opti. Any1 have any more ideas. besides the obvious, being the whole optispark is bad. another thing i noticed, when i turn the key to on normally the car goes "ding ding ding", but my car goes " di di di di di di di di ding ding ding" and the interior lights flicker a bit. This is related to whats going on because it only started happening when this problem occured. short somewhere? bad ground? im all out of ideas except the opti, but the opti has nothing to do with any of that.

LTb1ow

01-07-2009, 03:50 PM

Dead battery.

sweetbmxrider

01-07-2009, 04:26 PM

ya battery or loose connection. check that first

vipergtx500

01-07-2009, 06:23 PM

it cranks fine, im gonna try and jump it to see if there is too weak a charge left but i dont think thats the case. Where should i check for a loose connection besides the actual leads on the battery?

sweetbmxrider

01-07-2009, 09:39 PM

did you remove any grounds on the engine? like the one behind the coil? did you properly wire the opti harness? do you know how to check for spark? make sure you are getting spark and fuel if you have a fuel pressure gauge.

vipergtx500

01-08-2009, 12:19 AM

i made sure the grounds on the on the coil bolt was tight, im pretty sure i know what im doing to check for spark but if some1 could enlighten me so im positive that would be great. if that all checks out ill get a fuel pressure gauge to check for that

sweetbmxrider

01-08-2009, 07:00 AM

with the opti together and harness connected, plug in the coil wire and number one ignition wire. hold the plug end of the wire next to your manifold with insulated pliers, have someone crank. if you see spark jumping across, you have spark. if not, check that the coil is producing spark in a similar fashion. check fuses too and double and triple check your wire routing. very easy to cross them, esp how they duck in and around and under a bit.

vipergtx500

01-09-2009, 10:42 AM

I connected the coil wire to the coil and held it next to metal, and there was no spark. Should i try leaving it connected to the opti only, and see if there's spark between it and the block? I also jumped it and the battery was fine so i ruled that out. And what were you talking about with the wire routing? from the opti to the pcm? or coil? or just in general?

LTb1ow

01-09-2009, 11:05 AM

He means spark plug wire originates from Opti being cyl. # 5 and ends up going to cyl. # 3.

LTb1ow

01-09-2009, 11:07 AM

http://shbox.com/1/95_ign_system_schematic.jpg

I still think its the optical part of the Opti.
http://shbox.com/1/4th_gen_tech2.html#opti_test

vipergtx500

01-09-2009, 11:12 AM

k thanx, ill check out the plug wires, and then ill get a mulitmeter and check all the connections.

sweetbmxrider

01-09-2009, 02:32 PM

yeah if the wires were crossed it would at least make a little thunder.

so did the coil produce spark?

well if the opti was bad it wouldn't have a reference signal for the coil to produce spark right? yeah its gotta be the optical sensors.

LTb1ow

01-09-2009, 02:33 PM

vipergtx500

01-10-2009, 12:21 PM

im trying to use this multimeter to test for spark but im not exactly sure wehre to have the leads. The diagram has CADB on the ICM, and then there's DCBA coming from the opti. Do i make contact with the pins in the ICM? or the leads in the wire connecting to the ICM? BTW battery is fine, still makes a repeated clicking sound and the lights flicker when i open the door.

ant

01-11-2009, 11:31 AM

Kemper service opens @ 730 tomorow.

you have all day today, you're not working. make sure you do all these tests of connections.

sweetbmxrider

01-11-2009, 12:32 PM

stick the multimeter on the battery and tell us what it reads.

vipergtx500

01-11-2009, 03:28 PM

11.53 V from the battery,The wiring to the ICM is little different on the 96-97 models, so the colors don't match up right, but i figured it out. aroud 12V from pink wire (to ignition) on the harness going into the coil, and about 12V from the outer wires (to coil, i think) on the harness going into the ICM. I cranked it and check the other lead, It was jumping alot, but it was from 0 to 1.4, not 1-4 like shbox said it should be. And there is definitely a bad ground or short somewhere, the clicking/flickering has gotten worse. I couldn't even turn the key it just kept doing it and eventually it stopped, the seatbelt light a few other lights flash along with the lights as it clicks away. For this reason i think im gonna take it to the dealer, if it were just the opti (i prob need this too), it would def not being doing all that nonsense.

sweetbmxrider

01-11-2009, 03:38 PM

yeah without seeing this in person, its tough to diagnose. especially over the internet. i would just retrace and recheck everything you did. if there wasn't a problem with the interior lights and such before, it should be something you did.