diagnostic trouble code 16

[95 GA/TA]

I just got my scanmaster to day and installed it.I have made a copy of freds manual and am learning so after i read through the manual i start the car up and look through all the functions.I am getting a dtc 16.The ses light has not came on,over the past few weeks ive noticed the car taking a 4-6 seconds to start at times and other times it would start fine.I am new to all this, i understand that code 16 is low resolution pulse from the distributor.Do i need to change the opti?,im not sure but from the looks of it it could be original??I made one quick pass with the car,i noticed my retard was kinda high,it would peak at about 10 degrees at wot,i believe it was occuring during shifts,i was wondering if the two problems could be related.The car runs perfect,cant hear any knocks or problems so i just thought i might mention.I have a trip coming next weekend,im just trying to figure out what to do.I dont wanna get stranded.If anyone could give me some advice id appreciate it.Also how do you erase stored codes on scanmaster?

[Injuneer]

It is not unusual to see DTC 16 as a "stored" code. ScanMaster does not differentiate between "stored" and "active" codes. If DTC 16 was an active code, the engine would not be running, because the PCM shuts down the fuel system when it can't find the low resolution pulse from the Opti.

I am just guessing that it sets when the PCM can't immediately find the low res pulse when you try and start it. That might also explain the slight delay in starting.

Clear the code by pulling the "PCM BAT" fuse for 30 seconds. Watch on the ScanMaster to see if it returns. I don't think DTC 16 necessarily turns on the SES light. After you see how long it takes to return, or if you can see that it sets when you have a delayed start, it will point you toward the fix. There can be problems with corrosion on the wiring harness connectors. You could check the one on the Opti, and also the one on the passenger side of the inake manifold.

[95TransAm]

I see you are at 136k...you're pretty lucky if you're opti made it that far if it's stock.

If it is stock, I probably would replace it just because. I can say though that my opti started to go out on me last winter. I drove it minimally as possible, and didn't really beat on it, and it managed fine up until late july. I remember getting on it a bit, and it stuttered and backfired on me at upper RPM's.

I just recently replaced it, as well as some other things, and noticed a night and day difference. It's not the easiest job ever, but certainly not the hardest. Also, driving your car with a brand new distributor in it makes it a lot more fun

If you do decide to change it, feel free to post some questions if you want...I'm sure many of us here would be willing to help you out

[95TransAm]

There can be problems with corrosion on the wiring harness connectors. You could check the one on the Opti, and also the one on the passenger side of the inake manifold.

Very good advice...didn't even think of it.

Fred's da man...always listen to this guy

[95 GA/TA]

Thanks guys, ill check it out this evening, i reset the code last night,i am gonna drive it some and see how fast it comes back on.Does anyone know where there might be a how to on replacig the opti?Is there any opti spark better than a GM one?Ive seen some aftermarket ones but didnt know.I know its usually hard to beat oem parts.Thanks for all the help

[95TransAm]

Thanks guys, ill check it out this evening, i reset the code last night,i am gonna drive it some and see how fast it comes back on.Does anyone know where there might be a how to on replacig the opti?Is there any opti spark better than a GM one?Ive seen some aftermarket ones but didnt know.I know its usually hard to beat oem parts.Thanks for all the help

A genuine GM opti is the best for replacement. As for a how to, I just did it this past weekend and the whole process is very fresh in my mind.

1) Jack up your car and drain the coolant using the drain valve seen here.
2)Start disconnecting your hoses, sensors, etc...
3)Take off your intake elbow, MAF, and I took of my CAI also just because I wanted to recharge my filter. It's also a good idea to get some electrical cleaner and clean up that MAF while you are at it.
4)Remove fans. Disconnect connector that goes in to each, 4 bolts per fan, located at the corners.
5)Take off your water pump. To do this...
~Make sure all hoses going to water pump are off. 4 in all I believe, 2 big ones on top, 2 smaller ones underneath.
~6 bolts, 3 on each side. 4 main longer bolts (1 in each corner), a smaller bolt on the passenger side, and a nut on the driver's side. To get the small bolt on the passenger...you will have to take out the 2 bolts that hold the power steering pump in to get better access. The power steering pump bolts are roughly located at about 7 o'clock and 12:30/1:00 in regards with the pulley. On driver's side, you will have to take off your ICM, Coil, And AIR Pump. Just bolts that hold these in. When you look, you'll find them...pretty easy. Remember the grounds that are there too (when facing the car, there's 3 grounds behind the upper right nut.)
~When your ICM & Coil are off, it's a good idea to clean that terminal on your coil that hooks up to your opti with that spark plug like wire. It's also a good idea to replace this wire.
~After you get all that off and cleared out on the driver's side, the water pump is ready to come off. Just remember how everything went on that side, and keep your bolts separated. I remember some things were held in with a nut, and some with a bolt. You'll see it as you go, it's pretty easy.
~Start to remove the water pump. Pull it back. You'll probably have to slightly wiggle it from side to side, but it will come off.
~After you take it off, you'll notice there is a splined sleeve that connects your water pump to a splined shaft that your water pump hooks up to. Sometimes the sleeve comes off with the pump, sometimes, it stays on the shaft. If you decide to replace your water pump (like I did) when doing this just for the heck of it and to get it out of the way, make sure that sleeve is on the new pump.
6) Take off the 3 bolts that are on your crank pulley, as well as the center bolt. You might need a puller, and you might not at this point. Some people said they didn't need it, I did. Some people have said that you can just remove the bolts, and lightly tap the dampener with a hammer to get extra access for your bottom distributor bolt. If you do decide to do this, do not hit that pulley hard...you do not want to damage it one bit. This didn't work for me, and I opted to take it off. Depending on what type of puller you use, you will either need to keep that center bolt out, or screw it back in a couple threads. A conventional puller will require all the bolts to be removed. I found it easier, when using a 3 jaw puller seen here to leave in that center bolt. That pulley in the picture, by the way, is the exact one I am talking about right now.
7)Disconnect spark plug wires. If you choose to keep the stock wires (if they are stock), you will notice on each wire there is a number...that is the number cylinder for each wire. If you get a haynes, chiltons, or even look online, you will find how to hook up the wires. I honestly cannot remember, but this is very important.
8) Take off distributor bolts. There are 3, 2 on the top, one on the bottom passenger's side.
9) Take off opti. Just wiggle it out.
10)Scrape off all that gasket material left on by your water pump. You will need new water pump gaskets.
11) It's a good idea to replace the distributor seal. It's the seal that is right behind the opti on your block. An easy way to do this is to use a large pry bar (the larger, the easier), stick in on the seal on the bottom (not the housing around it...make sure it is on the seal), and just whack it on top. The seal should pop out. To put the new one in, a seal installer makes things easier. I didn't have one, so I found a metal cap that was the size of the seal. I fit the seal, fit the cap over it, and hit it with a hammer. You do this so the seal goes in evenly. You want to do this until the seal is flush with the block.
12) It's also a good idea to replace the 2 washers on the water pump shaft (one on the block, one on the water pump.) If you buy a new water pump (GM is the best choice also), then it comes with a new washer on the water pump. As for the splined shaft on the block, just use a razor, cut it, and pull it off and replace.
13) It's also a good idea to replace your water pump seal at this point. It's located behind that shaft.
14)It's also a good idea to replace your front main seal. If you choose not to though, you will not have to go through all of this to get to it at a later time.
15)I see you have a '95, then your opti will have a dowel pin that it fits in to. You will see this pin on the engine from where you just took your opti off. This only fits in to one place, the recessed portion on your new opti that is different from the other two.
16)If you are replacing plugs/wires...do this now. If not, go to next step.
17)Put on opti. You first need to line it up to get it on that dowel pin. My siggestion (with adequate lighting), is to kneel down on your radiator support, and look down. You need to line it up perfectly...it will slide on. The first time it goes on though isn't good enough. You will still notice a space in between your opti and your engine. (You can see the opti seal and all). You need to gently wiggle it on (up, down, side to side...whatever), until it is flush on the block. DO NOT USE THE DISTRIBUTOR BOLTS BY TIGHTENING THEM DOWN TO FORCE IT ON FOR YOU! It will go on, just play around with it a bit.
18)Reverse the whole process....

If I remember anything else, I'll post it.

This is a good site for component location views and many other things.

Good Luck!

[95TransAm]

A couple extra things...

You will have to take off your serpentine belt. To do this, while you're under the car, put a socket w/wratchet, wrench, whatever on your belt tensioner. You belt tensioner is the smallest pulley (the one in between your a/c and your crank) and just act like you are tightening the bolt. The pulley will move upwards, and the belt will come off.

Also, if you do take off your crank pulley, when you are putting it back on, make sure those bolts are in there nice and tight. When you finally get everything up and running, take a look at your crank pulley from above as your car is running. Make sure it is not wobbling at all. If it is, turn off your car and tighten it dowm better.

[95TransAm]

I just remembered also...

On your new opti, next to each port that you hook up your wires to, there is a number. That is the number for what cylinder the spark plug wire should be hooked up to. Like I said, if you have stock wires, the number for what cylinder that wire belongs to is printed right there on the wire. Just match the number of the wire to the number on your new opti when you're putting it back together.

[Jeff_in_Atl]

I would highly suggest silicone dielectric grease on the OPTI connector to prevent corrosion.

[95TransAm]

I would highly suggest silicone dielectric grease on the OPTI connector to prevent corrosion.

Ahhh...I knew there was something I also left out.

Good call

[95 GA/TA]

Thanks guys, i thought about it and decided to go ahead and replace the opti.Im pretty sure its original so im on borowed time.It will be here monday,ill let ya know how it goes, i hope to get started on it monday evening.Thanks for all the help and instruction.

[Injuneer]

Do you realize why the picture in your signature doesn't show up? You've got an extra "[/img]" at the beginning of the address. Or is that intentional for some reason?

[95 GA/TA]

Thanks Fred,i had tried to post a pic the other day with no luck.I had forgotten about it till you mentioned it.I didnt have any luck the other night but i think i got it now.Also thanks for all the info on the scanmaster,i am still reading ,learning and hopefully i can make some passes tomorrow since i kinda understand what each thing means that it reads.This site is great,im glad to be a member here.

[95 GA/TA]

I just got the new opti in and everything seems to be working perfect!!I am very surprised at how well that job went.Luckily i have a friend with a lift that helped me.We replaced the opti and lt4 knock module in about three and a half hours.Im not sure if working around the supercharger helped or hurt us but it felt soo good when that thing started right up after all that work.So far it starts great and no problems,i still am getting as much as 10 degree retard at shifts and high rpm gear changes.At cruise and normal driving it stays around 0- 3 degrees.I spoke with a tuner today and he says he can help me so im excited to get that done.I feel fortunate to have had no problems so far with the car since me and my buddy have done all the modifications to it.I would like to thank everyone that helped,especially 95 trans am, i had bought a chiltons manual just in case but your directions were spot on!!!Ive said it before, ill say it again, im proud to be a part of this site and thanks to all!!

[95TransAm]

I just got the new opti in and everything seems to be working perfect!!I am very surprised at how well that job went.Luckily i have a friend with a lift that helped me.We replaced the opti and lt4 knock module in about three and a half hours.Im not sure if working around the supercharger helped or hurt us but it felt soo good when that thing started right up after all that work.So far it starts great and no problems,i still am getting as much as 10 degree retard at shifts and high rpm gear changes.At cruise and normal driving it stays around 0- 3 degrees.I spoke with a tuner today and he says he can help me so im excited to get that done.I feel fortunate to have had no problems so far with the car since me and my buddy have done all the modifications to it.I would like to thank everyone that helped,especially 95 trans am, i had bought a chiltons manual just in case but your directions were spot on!!!Ive said it before, ill say it again, im proud to be a part of this site and thanks to all!!

Glad to hear that everything went well and that we all could help ya out
It's the greatest feeling when you start that puppy up with no problems for the first time...especially after you've just put all that work in to it. Doing a job yourself successfully always makes you feel especially good.

You can't beat these boards. I couldn't tell ya how many times these guys have saved me from heachaches...as well as helping keep the wallet a lil fatter.

Enjoy her!