Engine going flat between 3-5k rpm

[johne4]

Greetings

I have a 2000 Boxster with 54,000 miles, last week the engine started running flat between 3-5k rpm, the car accelerates great till 3k rpm, then goes flat, feels like fuel starvation, but when it hits 5k to redline it accelerates normally again.

Since it was close to the 60,000 mile service I went ahead in changed the plugs and air filter. That did not fix the hesitation.

I have not ruled out the possibility of some bad fuel, still got a 1/2 tank to go through before I can rule that out.

Just trowing this out to see if anyone had a similar problem and what the fix was since there are so many possible culprits from a clog fuel filter (on order) to pluged cats.

The check engine light does not come on.

Thanks in advance, any information/help anyone can provide will be greatly appreciated.

John

[BuffaloBoxster]

I had similar behavior when my MAF went bad, but my check engine light did come on.

[MNBoxster]

@ BuffaloBoxster

Good Call! I bet you're correct...

Happy Motoring!... Jim'99

[just_me]

That probably would nto throw a code, being hydro-mechanical........

Not much help beyond that I'm afraid, except to suggest you keep it about 5k :-()

[johne4]

Thanks everyone for the response, it appears that it was a tank full of bad/contaminated gas............I added a bottle of "Gumout" injector cleaner and ran the tank down, fill'r up with Sonoco 93 octane (at my normal gas station, the last tank I was on the road and filled up at a 7-11)........runs like new... :dance: I will keep my fingers cross and monitor.........

I do have a follow up question/issue I would like to here comments on; K&N air filter...........I have been using one since the first service, I do clean it and recharge it every 5k miles, never had an issue..............but i've been reading alot of tech articles against using them, specifically K&N don't filter the particles small enough and it damages the MAF......I would almost bet that the people having problems just install them and forget about them.......the box does say 100,000 mile filter...lol

Thought/comments

Thanks Again

John

[MNBoxster]

Originally Posted by johne4

Thanks everyone for the response, it appears that it was a tank full of bad/contaminated gas............I added a bottle of "Gumout" injector cleaner and ran the tank down, fill'r up with Sonoco 93 octane (at my normal gas station, the last tank I was on the road and filled up at a 7-11)........runs like new... :dance: I will keep my fingers cross and monitor.........

I do have a follow up question/issue I would like to here comments on; K&N air filter...........I have been using one since the first service, I do clean it and recharge it every 5k miles, never had an issue..............but i've been reading alot of tech articles against using them, specifically K&N don't filter the particles small enough and it damages the MAF......I would almost bet that the people having problems just install them and forget about them.......the box does say 100,000 mile filter...lol

Thought/comments

Thanks Again

John

Hi,

I'm glad you seem to have corrected the issue, but I wonder if the Gumout is just a temporary fix? Gumout can have an octane boosting effect and your DME may just be running a different MAP as a result.

Now that I know you're running the K&N, I suspect a little more strongly that you may have a masked MAF issue. I'm not a Fan of K&N's on any Car, but especially the Boxster. On other Cars, I believe that many of the reported gains are simple Placebo Effect or only show in Dyno results at the Top of the Power Band (often sacrificing some Mid-range performance), but generally, they do no harm. Not so on the Boxster, running one here has shown, somewhat conclusively, that they have a detrimental effect.

My suggestion is to keep an eye on it and ditch the K&N at the 1st sign of the symptoms returning and either clean (not always successful) or replace the MAF. Probably not what you wanted to hear. But, hope this helps...

Happy Motoring!... Jim'99