This might be the wrong place to ask, but, since it is the same car as a Bonneville really, thought I'd give it a shot.. '99 Olds eighty-eight, not supercharged, 37K miles, flawlessly maintained, flawless runner, great mileage, no codes. When warm, she sometimes hesitates or lacks power under very light acceleration, like in stop and go city traffic. Nail it, and it runs great. Idles perfect. Cruises perfect. I pulled the plugs, they are all the same and look perfect. Now I know that this can be caused by a million things, just hoping someone can say "Had the same thing.. check the bla bla bla!" Any input would be appreciated. Thanks, Mike.

Typically plugs and/or wires. 90% of the time. How old are yours? Moving to "other H bodies" for you.

Plugs and wires are definitely a good start.

I'd also change the fuel filter too. For $8 it'* good insurance anyway.

On a similar note... I had the same issue with my 99 Bonneville. I'm at 124K now, but it was going on for the past 25K or so. It ended up being weak fuel pressure at the rail. I was only getting ~ 38 lbs. Two weeks ago I ended up changing the pump and it'* running better than ever now. I'm now getting a consistent 48 lbs. of pressure. Check your fuel pressure too.

Plugs are brand new, when I pulled them to see how they looked, I replaced them, just in case. The wires were new just before I bought the car 5K ago, but I swear the hesitation got a little worse with the new plugs, so I was thinking maybe I had a funny wire, and messing with the plugs made it worse. Also, it has the feel of being lean, so to the point of low fuel pressure, my thoughts were not necessarily to the pump, but maybe the regulator was sticking, and not increasing pressure when engine vacuum drops, unless it dropped a lot, like when you nail the gas.
Still love my Bonneville, the restoration is going great, but I also love my Olds... I'm probably a little older than most of you, and I like the cushiness.... Plus, I don't think they are as popular, my last two daily drivers have been the Olds, and it seems that both times I have gotten comparably equiped cars for about 10% less than the Bonnevilles.
Over the weekend, I'll pull my plug wires and put and check their resistance, then I'll measure fuel pressure at various vacuums...
This leads to a question.. the '93 had an electrical pigtail near the battery that when hooked to the battery, would make the fuel pump run with the car off. This was excellent for testing fuel pressure, since then you could put your trusty vacuum pump on the regulator and see how the regulator was performing. Is there a similar pigtail on this 99?? Thanks. Mike

I'm not familiar with the pigtail you described. How I tested my pressure was just to turn the key "on", but not start the car. That gave me the at rest pressure. Then, I started the car to get the running pressure. I'd watch the fuel pressure fluctuate (it shouldn't much) when I'd slightly rev it at the throttle body.

Did you get a recall for your fuel pressure regulator? All the 99 L36s got a recall. You might want get that replaced as they were faulty. It could be something as simple as the free fix the dealer is offering! You said you just bought it...I'd call the dealer and see if the fix has ever been performed.

Yes, I have to agree with you on the comfortability factor on the Oldsmobiles. The 94 Royale I have rides like air! It'* no performer in the turns or anything, but it'* an awesome highway cruiser. It just floats. The taller gear ratio is nice because I save a little in the gas department too.

Where are you from? We might have someone local that could help you out.

You should have that pigtail right by your battery on your '94, on mine, it is a red wire with a green connector, female spade connector. This is VERY helpfull when pulling your tank, you can run the fuel as low as you dare, then remove the RETURN line from your fuel rail, thus giving you a 5/16" steel pipe to connect a rubber hose to, put that hose in container, connect the pigtail to the battery, apply vacuum to the regulator so it allows maximum flow, then sit back have a beer and wait for the pump to change pitch, signifying that you are sucking air... TANK EMPTY!! I don't know about you, but I HATE pulling a tank down with even 1 gallon of gas in it. Of course you can't do that if the pump failed. :)
Again, I don't know of a pigtail on the newer ones, sure would be nice if there was one!!

I live in Northeast Ohio, about 30 miles due east of Cleveland.

I'll look for that on the 94 today. That would be handy.

I just replaced the tank on my 99 and it had about 2 gallons left in the tank. It wasn't bad, though because I used a transmission jack. That was a life saver and key to making it easy!

Too bad I didn't know about your issue sooner. I just returned from the Cleveland area on Tuesday. I was free all night Monday. We have a plant in Oberlin, OH that I was visiting. I could have easily come by and helped out....

Ha! Figures! My family was out of town this week, spending time with grandma, so I have been pretty free this week too!! You could have checked out my Bonneville project too.. Well, what are ya gonna do, win some, lose some.
I check these few things on the Olds, see what happens...
thanks for everything
Mike

That pigtail should be on all 92-99 Bvilles and similar cars. If you jump it to 12V (the conveniently close battery), your fuel pump should come on. If you read resistance through it, you read the winding resistance of the fuel pump.

If you read resistance through it and turn the key on, it should open the circuit (infinite resistance) as an indication that the fuel pump relay is working and has changed state.

Didn't the 99 have a recall on the bleed down of the FPR causing intake explosions? Pull the vacuum line off your FPR. If there'* gasoline in it, change the FPR or call the dealer to check on the recall. Have your VIN handy.

Did a little messing around tonight, the fuel pressure, per the GM manual, is right on the money. I looked up "hesitation, sag, stumble" in the manual and checked some of the basic things, all seems okay. By the way, I can't find that fuel pump pigtail near the battery, not that I need it now, but I can't find it.
Now here'* a potentially dumb question... The car was idling, and I removed the oil fill cap to reinstall the plastic cover, and I noticed that the crankcase seems to be at a tremendous negative pressure. When I removed the cap, it made the swoosh sucking noise, then the idle went to hell. With all these cars I've owned, I guess I've never removed the oil cap with the engine running - but is this normal? Also, when I shut the car off, you can hear the suction going away in the engine for a second or two after the engine stops. I know I have never heard this with my other cars.. Is this normal??I understand that this may be part of the crancase vent system, but it seems excessive. It idles great when the cap is on, but maybe it has "learned" and adjusted for a problem? Please reply. Mike