My 99R has been periodically losing power over the last few weeks. Every once in a while when getting on it, it just doesn't have all the power I'm used to. The rest of the time (about 95%), it is strong as ever. When experiencing this loss, it is not surging, missing or anything else dramatic, just doesn't seem to wind up as well. Kind of feels like there's no supercharger...or like a 4bbl carb car where only 2 barrels are opening...or like my old SHO when the intake runner activator broke and the long runners wouldn't open.

The first few times, I thought it wasn't warming up properly (thermostat?) but yesterday, it happened after a 40 mile drive yet a few minutes later, was fine.

My first thought was fuel filter(s) but I should think that would be more consistant and/or wouldn't clear up so easily and completely.

Another thought is 02 sensors. The car has 120k and gas mileage has slipped a bit over recent years so perhaps a faulty sensor could intermittantely be fouling the mix?

Can anyone else suggest what I can look into? No codes are thrown...


Thanks,
George

 

Brutal? Anyone? Ideas??

 

I just changed BOTH of my fuel pumps. Tomorrow, I will button it up and get to drive it. I'm HOPING it will perform better than I'm used to, since the Secondary Pump failed I'm sure before I bought it. The Primary Pump just failed in my Daughter's driveway. A little loss of power past few days before failing, so Maybe related?

Also, NO Codes on a Standard Reader.

 

I would do a compression/leak down test just to rule out a possible Nikasil issue. Depending on fuel quality in your area and oil change intervals you might be experiencing the early symptoms of liner wear (unless the motor has been replaced with a steel lined motor).

 

I have no definitive proof that my fuel pumps caused any power loss, but I will say, after replacing BOTH failed fuel pumps, my car is breathing new life. It is MUCH more powerful than it's been since I bought it. My guess is that I have not been getting full fuel pressure during throttle to floor acceleration ever since I've had it. It made a considerable difference.

I'm not saying this is your problem and I'm sure there are hundreds of things that can cause this, but it's one other thing to check.

PS: $224 for BOTH fuel pumps. 50-100 knuckle bumps, a couple hundred swear words (and I don't swear), 6 hours, a broken fuel line, dinner for my son-in-law/helper. But it was REALLY worth it.