New member g941

A big thank you to all who make this forum what it is today. I'm in SW Florida and new owner to a 1998 Riviera supercharged L67. It ran the great first couple weeks until I put Walmart 93 gas in it.That's when things went down hill. It started sputtering during acceleration only after I was driving for around an hour. If I were to give it too much pedal it would actually stall. When cold it ran great.
A little history on the car. I'm the third owner and the previous owner put in a new fuel pump, fuel filter, alternator, AC compressor and master cylinder. Since then I have changed all the fluids an filters, put on new front struts assemblies, power log on front bank, and am in the process of installing new plugs and wires. Oh I also replaced the coil packs.
Thanks again,
Greg

Welcome!

Are there any members in the Sarasota county area?

Welcome Greg.

Enjoy your-'98

g941 wrote:

A big thank you to all who make this forum what it is today. I'm in SW Florida and new owner to a 1998 Riviera supercharged L67. It ran the great first couple weeks until I put Walmart 93 gas in it.That's when things went down hill. It started sputtering during acceleration only after I was driving for around an hour. If I were to give it too much pedal it would actually stall. When cold it ran great.
A little history on the car. I'm the third owner and the previous owner put in a new fuel pump, fuel filter, alternator, AC compressor and master cylinder. Since then I have changed all the fluids an filters, put on new front struts assemblies, power log on front bank, and am in the process of installing new plugs and wires. Oh I also replaced the coil packs.
Thanks again,
Greg

...time to quit firing the Parts Cannon and do some troubleshooting. The gas is probably co-incidental, you do have fuel filter, they generally trap water and debris.

If your Riv is supercharged and you put standard replacement coils in, that alone will cause headaches on hard acceleration. On this generation of GM car the standard and supercharged coils could be interchanged... physically... the SC coils work fine on normally aspirated cars but the standard coils don't work so well on the supercharged cars, and what are sold as new coils for this application are almost all the standard coils not the SC coils, although they will be LISTED for the SC application.

You can go to a junkyard (in person or on line) and get a set of used coils for supercharged engines (this is a low risk item, those coils are mad durable, if you're worried buy 5 or 6, ohm them out and use the matching set). SC coils are not really sold new any more.

Also see this thread:

https://rivperformance.editboard.com/t11575-misfire-rough-idle-and-lacks-power-spark-okay

Check if you installed that power log correctly. A manifold leak will suck air, causing the oxie sensors to read wrong, causing the misfire. This especially shows up after the car warms up, a crack or opening at a gasket would widen with heat.

If you are putting in wires, put in OE or high-spec (Taylor, NAPA, Magnecor USA) wires. Because - if you *do* have the high-energy ignition coils they will eventually burn through standard wires, typically the terminal connections will ablate metal or the conductors will break at the crimp; although the spark will usually jump the ablation the phenomenon will burn out your coil, causing a misfire. (NOTE: I used Magnecor wires for more than a decade but quit because they reneged on their warranty. The company has since changed ownership. )

Another thing that could happen, if the PO put in a standard fuel pump, they fit fine but generally have inadequate flow to handle hard acceleration with the SC motors and will cause a misfire.

Time for old school troubleshooting. Do you have a copy of the service manual set? (if not, get one they are usually for sale on eBay).

Best

Albert

Thanks for pointing me in the right direction. Will be wrenching on the Riviera when it cools down this evening.

g941 wrote:

Thanks for pointing me in the right direction. Will be wrenching on the Riviera when it cools down this evening.

What did you find out?

Well I removed the fuel rail checked out the injectors and fuel pressure regulator. The regulator was a mess and full of crap, same with injectors. It appears that a few injectors were stuck open.
Got a hold of a buddy of mine that had a very clean rail who only ran "corn". We rebuilt injectors and reinstalled the clean rail. Still didn't feel right but was much better and drove it home.
After 30 miles went to "floor it" and stalled in center lane on interstate but was able to coast to the shoulder. It started without hesitation and drove fine back to the house. It now is sitting in the garage and I'm taking a break. Will tackle it another day.
Greg

I'm ready to delete the 150,000 mile engine coolant reservoir. It's a waste of space and is in the way. Any thoughts? Same with washer fluid reservoir.

Have mentioned deleting the coolant reservoir an the windshield washer reservoir. They're in the way if you try to do any work, specially removing the rail. And will open up engine bay and get rid of unnecessary bulk. Less crap in the engine bay should run cooler.

g941 wrote:

I'm ready to delete the 150,000 mile engine coolant reservoir. It's a waste of space and is in the way. Any thoughts? Same with washer fluid reservoir.

Keep the reservoirs. My coolant bought me time to diagnose a small leak that turned out to be a cracked radiator end that only leaked when fully warm, and the washer reservoir holds a lot because the car uses a lot of fluid to wash that huge windshield.

It is in the way of... what?

If you're looking for horsepower:

1) port the front exhaust manifold. You need a new exh manifold gasket and a dremel moto tool with ball and cone grinder bits, and a sharpie. If you need further details just ask.

2) promise yourself you will ALWAYS run premium fuel, and then get a smaller supercharger pulley (the 3.6" off a Series I with blower is just peachy for this) and install that. You will need the ZZP supercharger pulley puller, a regular puller Will NOT work.

Don't bother modifying the airbox, it is already plenty big.

Beyond those 2 changes you generally need to hack the PCM to make them really work.... And you really don't need the reservoir spaces for anything else.

Albertj

Hey Albert,
We will be installing a ported and polished SC this evening. With smaller pulley. As for the exhaust manifolds I already put on power blocks from zzp, we'll have to do the crossover pipe at a later time.
As for the reservoirs I just wanted to clean up space for air to travel through the engine bay. I still have the issue with this heating up after about an hour and a half of driving that it will want to stall. we'll be checking on the tune later this evening after the new supercharger is on with the smaller pulley. Will keep you updated.

g941 wrote:

Hey Albert,
We will be installing a ported and polished SC this evening. With smaller pulley. As for the exhaust manifolds I already put on power blocks from zzp, we'll have to do the crossover pipe at a later time.
As for the reservoirs I just wanted to clean up space for air to travel through the engine bay. I still have the issue with this heating up after about an hour and a half of driving that it will want to stall. we'll be checking on the tune later this evening after the new supercharger is on with the smaller pulley. Will keep you updated.

Your issue with heating might simply be the radiator cap, upgrade to a 16-lb unit if you have not already, and make sure not too many of your fins are bent, that the electric fan is in fact coming on when it is supposed to, and that the end tanks in radiator have no cracks or leaks **at all**. For daily driver use be sure to run the AC in "auto" position - car's designed assuming the thing is running and with the windows closed there is no real fuel mileage penalty.

Second what albert suggested; I was chasing an overheating issue on a car for months, did thermostat, checked headgasket, etc etc etc. It was a radiator cap. lol

We have the "new" P&P supercharger from a 96 installed along with the smaller pulley. Still need to install larger idler pulley to make up for the new belt length. The 96 SC has an extra hole that needs to be plugged also. Hopefully we'll have it running soon to give it a spicy tune. Will do the radiator cap tomorrow.