high rev hunting - need help

Hi. I'm new to the site and really find it helpful. I have a 96 Riv S/C and have an issue that I'm trying to solve. When I floor the engine in neutral, the engine rpm decreases and increases as if it were hunting. Up - down - up - down- etc. at about one second intervals. I'm thinking either the fuel filter might be partially clogged or the pump pressure might be low. I'm not 100% certain that it's a fuel problem so I thought I would ask you experts. Could it be electronic? It seems to operate OK at idle and mid RPM. Is there something I should be looking for?

PS: I have another 97 Riv that I'm parting out if anyone needs parts. 3.8 is still strong with about 181,000 miles. Smashed on RF corner. Hood is still OK and mucho other parts. Air bags deployed so windshield got it.

Thanks,
Randall in St. Albert, Alberta

well if you floor the gas in neutral the rev limiter will kick in. thus giving you wild fluctuations in rpms.
maybe explain your problem in a little more detail

Rev limiter? My other Riv (the 97) didn't do this. I didn't know this was normal. Maybe the rev limiter was disabled on my 97. On the 97, you could hear the SC kick in when reved up. The 96 just hunts. Is there a way I can disable the rev limiter? Or is this asking for trouble?

Still learnig more and more each day about this beautiful ride.

Randall

The Rev limiter is set at 4,000 RPM in Neutral IIRC. You cab disable this with a tuner but there really is not reason to. You're asking for trouble if you want to raise the revs and then drop the trans from neutral to drive (assuming thats what you wanted to do). Plus revving the engine without load isn't really that great for it either.

All years should have a rev limiter that engages around 4k RPM in neutral, around 6k RPM under load. Revving it WOT in neutral is extremely bad for any engine, so the limiter is a good thing.

If your '97 didn't do this, it could be someone modified the PCM, but I highly doubt it, as Riviera PCM mods are not that common. But it is possible to disable with a computer and the right software.

Do you remember exactly what RPM it was cutting out?

I can't remember the RPM it limits at. I'll check in the next few days. I haven't road tested it yet since I picked it up so that's my next step. You guys have been a huge help.

Thanks,
Randall

No, it's all right. Please don't check - it's really not a good thing for the engine.

What I mean is road test the car on the road. No more reving at idle. We'll see what the performance is on the hiway.

Someone could have replaced the crank sensor or PCM and now the engine needs a CASE learn procedure done.
It will do as you describe if needing the CASE learn procedure.
Look under the Search function here for it, if you don't know what it is.