1995 SC Riviera - P1670 Code - Issues

Hello all!

I (and the Buick dealership that I took my car to) am having a difficult time finding a solution to my P1670 Quad Driver Fault issue...

The scenario is this: I went to start my car about a month ago, and when it started, the idle was terrible rough. Rough enough to make my serpentine belt almost jump off of the alternator pulley. The exhaust smell was super rich, and when I pressed on the accelerator, the engine bogged down instead of revving up.

After about a half-hour of sitting with the rough idle, it worked itself out enough for me to drive it to the local Buick dealership. I got them to scan it and they came up with a Cam Shaft sensor fault and suggested I replace it.

I replaced both that and the Crank Shaft sensor, but to no avail.

I took (by trailer) my Rivi back to the dealership and had them check it again. I get a Quad Driver P1670 code and they suggest I replace my PCM. I did that three years ago, I tell them, and they say it is probably the solution but can't guarantee it.

I go to the salvage yard and pull one out of a '95 LeSabre for $42 instead of the $1000 the dealership wanted, install it, but no luck. I don't know if it needs re-calibrated for my Riviera or not.

So now I have a car that doesn't perform any different AND my PRNDL shows every gear selected and flashes at me.

Anybody have any suggestions?

Thanks,
Justin

I dont know how it would affect the car differently but Im almost positive the PCM would need to be replaced with another 95 S/C PCM. I think there would definitely be issues. I also have PRNDL issues and have seen a code from it at times but I think it is because there is a bit of play in the shift lever. It causes no problems with drivability for me. Hopefully someone else knows for sure!

When you swapped PCMs did you keep your original PROM? (I think that's what it's called)

Quad Driver tends to be a PCM issue, but it's possible that it's something else. My '95 knowledge is a little rusty so I'm taking a stab that quad driver may be from the ICM?

The symptoms you describe has me thinking dirty/bad MAF sensor. Any chance you have a reusable (oiled) air filter? i.e. K&N etc

th3fr4nchi5e - The PCM serial number/part number is the same: #16183247. So I don't think compatibility is an issue... Maybe programming or calibrating is though.

deekster_caddy - I took only the PCM from the LeSabre. I didn't change anything else. I'm not familiar with the PROM. I replaced the ICM this summer because mine tested faulty on all of the tests O'Reilly's performs. No aftermarket air intake. Maybe the MAF needs to be replaced, but I change my air filter every other oil change if that makes a difference.

I have heard my coil packs could be the issue as well, I just need to "test" them, if that's possible.

Thanks for the input thus far!

Inside your original PCM is a PROM chip programmed specifically for your car. When you replace the PCM you need to retain your original PROM and swap it into your replacement PCM.

** If that's the kind of PCM you have. I think that it is, but need someone more familiar with the 95s to back me up.**

Deekster is spot on as usual. You have to take the two screws off that hold a metal cover down and remove the PROM from your original PCM. It's a very simple swap but be careful not to bend any of the pins. Who did the PCM swap three years ago?

Regarding the coil packs, the factory coils are almost bulletproof.

pbrktrt - A dealership replaced it with an ACDelco Refurb.

I'll give the PROM swap a shot tonight when I'm off work.

Thanks again all! Hopefully I can keep her running... I'm not ready to give up on her yet.

PROM swap solved the flashing PRNDL, but didn't resolve the incredibly horrible idle.

While running, besides the shuddering almost off the motor mounts, I have multiple softer "backfire" sounds emitted from the exhaust. MAF sensor perhaps as deekster_caddy suggested.

I need to get it scanned again with the Tech 1 I have access to, to see what codes are showing up, and maybe clear them out if nothing else.

Justin, see if you can get a fuel sample from your car in a clear glass container. Just a suspicion at this point, but if you see any separation, as in water on bottom/fuel on top, you see where I'm going.

Have you replaced plugs and wires? The SC 3800 is particularly sensitive to bad and/or cheap wires. AC Delco is the preferred replacement set...

aodsnyp wrote:

PROM swap solved the flashing PRNDL, but didn't resolve the incredibly horrible idle.

While running, besides the shuddering almost off the motor mounts, I have multiple softer "backfire" sounds emitted from the exhaust. MAF sensor perhaps as deekster_caddy suggested.

I need to get it scanned again with the Tech 1 I have access to, to see what codes are showing up, and maybe clear them out if nothing else.

Worn motor mounts can also contribute to this problem, do you know how to check?

pbrktrt - I can try to get some of my fuel, it was a fresh tank when this started happening.

deekster_caddy - Plugs and wires were replaced about three years ago when I did the PCM. I'm pretty sure the dealership was grasping at straws to find the solution to my problem back then.
They had it for over a month!

albertj - I haven't checked the mounts. When the idle gets "stable", everything seems to be fine.

Sometimes, after letting it sit (i.e. overnight), it will start up and idle just fine. I can drive it for a mile or two, and then BAM, she'll bog down and barely run.

That's kind of what I wanted to hear. It's possible you pumped a bunch of water in with the fuel. If the stations tank had just been filled or heavy rains recently, water does get into the underground tanks. It's a long shot, but I'm trying to help remotely, which is tough for all of us. You'll get it figured out, the car is worth it.

I appreciate all the helpful input!

Is there any one way that's eaier than another to retrieve some fuel from my tank?

Do you think that would cause the Cam and Quad Driver codes to appear?

I would suggest the connection between nylon and steel line behind the brake booster. Have a helper turn the key on to pump fuel until you have a decent sample. Do this with a cold engine only.

aodsnyp wrote:

pbrktrt - I can try to get some of my fuel, it was a fresh tank when this started happening.

deekster_caddy - Plugs and wires were replaced about three years ago when I did the PCM. I'm pretty sure the dealership was grasping at straws to find the solution to my problem back then.
They had it for over a month!

albertj - I haven't checked the mounts. When the idle gets "stable", everything seems to be fine.

Sometimes, after letting it sit (i.e. overnight), it will start up and idle just fine. I can drive it for a mile or two, and then BAM, she'll bog down and barely run.

When the idle goes stable, the engine does not vibrate to challenge the motor mounts.

You need a pcm calibrated to yer Riv. Someone with a Tech II might help.

You check coils by ohmmeter. Look for specs on this site in a coils thread. You are checking resistance along the windings and for shorts across them. If you need replacement coils, junkyard OE coils will likely be fine but should be checked when bought. Many of us have over 200 k miles on original coils.

It is not uncommon for the riv to burn our aftermarket ignition wires and even the OE wires only last so long. I would put in only OE or Magnecor or Taylor wires although there are others that should work. See http://www.magnecor.com for info about wires.

Hi all! It's been a while since I've last posted an update.

It turns out that my ICM was bad (I had just replaced it at the end of April). The "new" dealership I took it to, located the problem and got back to me within two hours! They also pulled the old one, gave it to me to exchange, and installed the warrantied one for a shop parts fee of only $6! With the diagnostic charge, I walked out of there for under $100.

Unfortunately, I had to take it back in today since it left me stranded at the local grocery store...

There has been an underlying starting/firing issue for the last year or better. I would drive it (over 20 minutes), let it set (for 10 minutes or more), come back to start it up and it will just crank over, and over, and over. I thought it might be the fuel pump, among other things, but I have never known a fuel pump to not just fail instead of slowly dying. The dealerships prognosis is that the fuel pump is going out.

Now I'm not sure what to replace it with. O'Reilly's has two for the same price; Airtex and Precision ($244); or do I go to a salvage yard and pull one there ($33)? I know I'm not paying the $700+ the dealership wants to install one...

Does anybody have any recommendations?

Thanks again!
Justin

If you haven't changed the crank sensor yet, it could very well be the problem. The fuel pressure is easy enough to check with a borrowed or rented test kit.

Crank and cam sensors were both replaced. The dealership checked the pressure and said it wasn't getting enough consistantly. I might just go pull a used one and give that a whirl before spending $250 on an aftermarket unit.

It's worth a shot Justin, but finding the correct pump for our cars will be tough used..I would highly recommend going with a Delphi or AC- Delco for a replacement and a new fuel filter at the same time. The only good part about this is, we have an access panel in the trunk to change the pump.

Have you tested for fuel pressure during the no-start?

Consider getting a Bosch or Carter fuel pump if you can find them, OR the AC Delco fuel pump repair kit (under $100 from ACDelco parts stores but hard to find). IIRC Summit Racing has them (or a pump kit that will work).