95 riv high idle, no speedo, intermittent no start DTC 1640,1650,1670

Hey guys,
Im a little stumped and wondering if you guys could help. I have a 95 S/C, riv 130k miles. The car has started to give me grief. It started intermittent and became more constant. The car idles at 2k in park and idles high in gear (1500-1700 rpm. Also the speedometer (and odometer as well) dont work.Then it wont start at times as well, but eventually does. The Tech 2 gave me DTC 1640,1650,1670. Quad driver failures. Went through the trouble trees and replaced the BCS with PN# ac delco 214-474. Seemed fine on the first start but acted up after a few.Im at that point where I am suspecting the ECU , or is this the wrong BCS, seems to work fine. Is there something I overlooked or am not seeing? Any input is appreciated. I dont have the voltmeter #s with me on what i had while checking the circuit but any help or advice would be great. Thanks

Did you check the wiring at the big firewall connection for wires fatigued under the insulation?

Did you check the grounds?
.

All the grounds underhood and in the back seat compartment seem to be fine. As far as the bulkhead,no I did not yet. I will look into that as well. I would think that if they were, my resistance readings would be high but not always. I'll look into the bulkhead and get back to you. Thanks again.
As far as the vehicles background, I bought the car 3 years ago from the original owner who maintained it very well. The car had 60k on it when I purchased it. And has been well maintained since.
Thanks

All wiring seems to be fine. Checked grounds under the hood. Getting 12+ v to ground on both the grounds at the coil pack bracket and on the rh side wheel well. Qdm reads high on the tech 2 for all of the qdms.

A bit of an update.
As of now, fuel pressure is verified at 40psi, 38psi cranking.there is spark present when cranking using a noid light and spark plug jumper. Injector pulse width is present at 14m/s cranking. Now the vehicle will not start at all. There is intermittent starts when rapping in the ecu occasionally . Waiting to go to work to get the ecu schematics and verify ecu ground. Still looking for valuable input and any advice. Thanks guys.

Thinking out loud... I apologize for the stream of consciousness...

when was the last time the service records show the crank sensor was replaced? when they fail they don't usually set any code themselves because they have to work for the PCM to get thru the start sequence (look at the sequence, you'll see)

Since You Have A Tech II I think maybe the best thing to do is get good junkyard PCM, flash it to your VIN, i think you also have to do a CASE learn but I am not sure... and see if the car starts and the codes go away. (or flash the last GM update to your current VIN - it was some years ago so you may have to do some digging).

Get the PN off the current PCM (you know, it's up in there behind the glove compartment) and get one with that PN from a yard. Install it according to the replacement guidance in the FSM, you know the drill.

wait a minute...

still thinking out loud I wonder if somebody tried to jumpstart your car or if you tried to jumpstart something else with it. That can cause problems. I also wonder if your battery is marginal, what is the battery voltage? If it is low, NONE of the sensors will read 100% right and all kinds of crap goes wrong. If you are below 450 CCAs you ought to replace the battery anyway even if it does not fix your immediate problem. If you don't have a Group 79 battery in there, that's a problem too - I forgot about that one. Continuing thinking out loud --- an OE Delco battery that tests good, out of a junkyard, will work fine - the OE batteries in these things run a decade or so new no issues. Almost any OE-quality junkyard battery you get should have some years in it yet if it tests good (450 CCA or better) when pulled. Donor cars would be Auroras and some Cadillacs of same vintage as your Riv (+/- 3 years or so), again it's a Group 79. Do Not Substitute Something Else (except maybe an optima red-top if you make a base for it)

Again thinking out loud bottom line for me - thing I'd do right now is check the battery, its connections, and maybe the thermistor (in the positive cable) too (if it is bad it will eventually kill the battery). Once that is all made good then I would swap out the PCM for a good one flashed to your VIN. The Riv's PCM was right outta the GM parts bin but you have to flash it to make it work.

I gotta run please post update.

Albertj

Hey Albert. Thanks for the input. Battery and alternator are less then a year old. It's an exact group 79 style, cca replacement for the delco that was in there originally. Voltage is 14.5 and 12.5-13 ish cranking. Tech 2 reads rpm when cranking. All connections are clean an tight as there were coated with die electric grease when I serviced it. Very weird issue. The only problem I have with a yard ecu is that at the u pick em by me, it's about $30. And then $10 for a warranty to bring it back if it's bad. Plus a core charge. Autozone says $116. For a new one without a EPROM it takes two days as its special order. I don't mind buying it if that's what this problem is leaning towards as it seems that way. Thanks though for the advice. Still looking to hear more.
Thanks
Johnny

JD94SS wrote:

Hey Albert. Thanks for the input. Battery and alternator are less then a year old. It's an exact group 79 style, cca replacement for the delco that was in there originally. Voltage is 14.5 and 12.5-13 ish cranking. Tech 2 reads rpm when cranking. All connections are clean an tight as there were coated with die electric grease when I serviced it. Very weird issue. The only problem I have with a yard ecu is that at the u pick em by me, it's about $30. And then $10 for a warranty to bring it back if it's bad. Plus a core charge. Autozone says $116. For a new one without a EPROM it takes two days as its special order. I don't mind buying it if that's what this problem is leaning towards as it seems that way. Thanks though for the advice. Still looking to hear more.
Thanks
Johnny

I don't have much more. You eliminated the battery thing, and you did not answer if the car had been used to jump start something else. A little detail - on the Riv if you use the car to jumpstart something else as often as not you will get a voltage spike that will mess up the PCM. If you have to jump something with a Riv you have to connect the Riv to it, start the Riv and let the Riv alternator charge the battery on the other car. 10-15 minutes is usually enough to build up some charge on the other battery - then you disconnect the Riv and try to start the other car. If there is not some serious underlying electrical problem on the other car - that is, it would not start because the lights were left on all day or something but it's all good otherwise - that will work. The spike comes when the other car starts, sometimes you get voltage spike transients through the jump in field current on its alternator or crap like that. Likewise if you have to jumpstart the Riv the best way is to swap in a charged battery, next best is with the Riv OFF you charge the battery from the power point under the hood by attaching the other car's battery in parallel and running it a while. Point is you must disconnect Riv before jumpstarting other car or else there is a likelihood (not a guarantee) that you'll mess up the Riv's electronics. And you must have the Riv off when jumpstarting it and let the batt charge up - don't start it with the other car connected. Sometimes the PCM gets zapped and dies later from normal thermal cycling -- whatever led to the battery being replaced less that a year ago, if the old batt was drained too far or jumped a couple times that could have set the stage for it dying later.

As for the junkyard PCM $40 for a warranted one is not bad actually. Since you have a Tech II if you went ahead and did that (got it and flashed it yourself) you'd have an answer already. I still kinda wonder if you'd get anything simply flashing the one that is in place. The problem is - and I forgot this - you have to flash an update, the GM system won't let you reflash the same program back onto a PCM. You probably already know how and what not - for others reading this the following article should help with the flash thing:

http://www.aa1car.com/library/2004/us10430.htm

Thinking out loud again - if that Riv did not see much dealer maintenance chances are the calibration in your Tech II for it is an update. No kiddin sherlock you might want to flash in the update and do a CASE learn.

Albertj

Hey Albert,
Thanks again for the reply. As far as to why I changed it. The original battery was getting weak, and I had a hard time starting it once. At that point I changed the battery, alternator and starter all at once as a preventative maintenance. Also the starter solenoid was starting to go too. Thanks for the jump tip though. I jumped a vehicle once a few years ago at a parking lot before I changed all the above. The tech 2 is up to date and just had a 2012 update done on it. I will look at the link you sent once I'm done with this reply. Currently at work though so my hands are tied at the time. No $40 isn't a bad deal at all. I agree with you. The problem is that majority of the rivs I see in the yard( which isn't much really to begin with) there 96 and up and or n/a if there ore obd 2. I think I've seen 4-5 in the past few years in about 1/2 dozen yards.

The 95 PCM doesn't need to be flashed, you use your original PROM. I think you may be having a combination of low fuel pressure and a bad crank sensor. let us know how it turns out, it is well worth repairing.

Hi pbrktrt,
Yes 95 has an EPROM. Fuel pressure is fine. Checked static, prime and cranking. Never dropped below 38-40 psi. Scanner sees a crank reference while cranking as rpm is live and consistent.
I too thought of the crank or cam sensor. But there are no cam sensor errors while cranking. I think the most I saw was 1-2. And that was before the (now) no start condition.

Thanks for the reply and info as well

JD94SS wrote:

Hey Albert,
Thanks again for the reply. As far as to why I changed it. The original battery was getting weak, and I had a hard time starting it once. At that point I changed the battery, alternator and starter all at once as a preventative maintenance. Also the starter solenoid was starting to go too. Thanks for the jump tip though. I jumped a vehicle once a few years ago at a parking lot before I changed all the above. The tech 2 is up to date and just had a 2012 update done on it. I will look at the link you sent once I'm done with this reply. Currently at work though so my hands are tied at the time. No $40 isn't a bad deal at all. I agree with you. The problem is that majority of the rivs I see in the yard( which isn't much really to begin with) there 96 and up and or n/a if there ore obd 2. I think I've seen 4-5 in the past few years in about 1/2 dozen yards.

Yeah, that jumping thing happened to me once and the PCM later had issues. As for a PCM the thing to do is look in the RockAuto.Com catalog for one - if you click on the part number for the replacement PCM you'll get a list of all the other cars it appears in. Point is since you can reflash you *don't* have to get one out of a Riv. They show the following for the 1995 SC Riv:

BUICK LESABRE (1994 - 1995)
BUICK PARK AVENUE (1994 - 1995)
BUICK RIVIERA 1995
CHEVROLET LUMINA APV (1994 - 1995)
OLDSMOBILE 88 (1994 - 1995)
OLDSMOBILE 98 (1994 - 1995)
OLDSMOBILE SILHOUETTE (1994 - 1995)
PONTIAC BONNEVILLE (1994 - 1995)
PONTIAC TRANS SPORT 1995

...so basically a PCM from many of the GM BOP cars with OBD-I will work. I mean it's not every stinking car but there's more than one on the list and SC or not does not matter its the same P/N. You have a Tech Ii which is a BIG advantage. The ECU has a similar (longer) list of "same part" cars.

You changed the alternator and starter as PM? Hmm... not sure I'd a done that but I am not you.

Oh by the way about that PCM. Another way to finesse that is get one off eBay. There are a couple vendors that specialize in pulling and reflashing the things.

Thanks for the info Albert. Once the battery went, and the starter solenoid starting giving me issue; I changed all 3 as a whole. I get pretty tied up working 7 days and am always driving somewhere. Whether it be business or pleasure. I like to take care of things once mileage gets up there as I figure it will take care if me.
As far as an update. Well came home from work and I had to move the car to drive another vehicle tommorow. Car started after a wrap on the ecu and idled fine. No ce light. Still dtcs 1640,1650, and 1670 exist. I'll post a follow up as I might have time to look into it tommorow after and or Sunday am.
Thanks again.
John

JD94SS wrote:

Thanks for the info Albert. Once the battery went, and the starter solenoid starting giving me issue; I changed all 3 as a whole. I get pretty tied up working 7 days and am always driving somewhere. Whether it be business or pleasure. I like to take care of things once mileage gets up there as I figure it will take care if me.
As far as an update. Well came home from work and I had to move the car to drive another vehicle tommorow. Car started after a wrap on the ecu and idled fine. No ce light. Still dtcs 1640,1650, and 1670 exist. I'll post a follow up as I might have time to look into it tommorow after and or Sunday am.
Thanks again.
John

You have to clear the DTCs with the tech II (or other scan tool), or they take a VERY long time to go away by themselves.

If you has to rap on the ECU to get a start, you are in for a replacement ECU or some bench time with a soldering iron. In the meantime wiggle the wires to the ECU connector at the terminal crimps to see if one broke inside the insulation. Sometimes a wire maker gets a run of brittle copper and their wires will fracture with age. So as long as you are in there maybe you should check...

I know what you mean about driving somewhere daily. My riv has over 250K and is still in service as a daily driver. I do some work, dealer does some, and I also use a couple independent mechanics for some things - one for transmission work - the guy is a Mechanical Wizard, works on racing stock cars; another for heavy maintenance when I am time crunched (overhauled my SC/replace valve cover gaskets etc).

Fortunately the Riv is not a disaster to work on but it does have its quirks. Many of the headaches have to do with engineering and marketing tradeoffs. For instance, the OE front struts, in normal driving, are way too soft for my taste. Put in a set of struts that are firmer and it does not feel all that much like a Riv. The H-cradle mounts don't really last all that long but since they are under compression you don't suffer much until you have to drop the cradle to work on the transmission and the mounts crumble or rip. Turns out GM makes several firmnesses and compositions (rubber or urethane) for the mounts. Put in the firmer mounts and it changes the drive even more. There's more but what you might want to do is look at the LINK and see the high mileage repair reports.

I have to run, let us know what you experience after you clear those old codes and drive a while.

Albertj

Thanks again Albert. Just got back from a 16 hr day. I'm going to take the ecu to work and filet it open for s&g's. I cleared dtcs and attempted a drive cycle but they come right back as soon as they clear. I plan on doing some work to it tommorow along with wrapping up my GN. I'll get back with some info.
Thanks,
Johnny

JD94SS wrote:

Thanks again Albert. Just got back from a 16 hr day. I'm going to take the ecu to work and filet it open for s&g's. I cleared dtcs and attempted a drive cycle but they come right back as soon as they clear. I plan on doing some work to it tommorow along with wrapping up my GN. I'll get back with some info.
Thanks,
Johnny

Got it. With the DTCs coming back (but the vehicle running) my guess is swap in a known good unit, clear codes, drive.

When you open the ECU look for a brown (burned) spot on the phenolic and/or open connections on solder pads. I would hazard to guess that Delco used resistors or diodes that met spec for power handling but just barely - that was the problem in my HVAC head. I suspect they figured people would not be driving more than 2-3 hours at a time without a stop - on road trips I and spouse tend to switch driving and keep rolling so the car will run 5-7 hours at a stretch.

Anyway - I get small quantities of higher spec electronic components from http://www.digikey.com and you can too. Radio Shack sells decent stuff but they did not sell the small ceramic power resistors I needed to repair the HVAC head properly. Digikey did, the cut sheet claimed they were great for RF applications or some such.

We will see what tomorrow brings...

Albertj

Hey guys,
Well the ecu was bad. I don't have time tonight to get into the final on what I did. I will post some more info on the troubleshooting later. Drove the car to advance. Bought a new ecu. Swapped the EPROM. Drove to work. No case learn or anything required. Car drives like it did when I bought it at 60k miles.
Thanks again to those that gave their input.