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Old 11-02-2004, 12:12 PM   #1
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Chuggin' and Shudderin'

Okay, so I replaced the Mass Air Flow Sensor about a month ago, brought it into the Porsche shop, they ran the remaining codes, fixed an O2 pump, and the car was running beautifully. Porsche said all's well, and I embarked on a 1,200 mile road trip in two days to bring me down into the glorious ::ahem:: hills of MIssissippi.

However, when the car is just starting to "warm up," it shudders and almost stalls when I give it gas, EXACTLY like how the car was when I got the Check Engine Light and had to replace the MAF sensor. Though there's plenty of oil, and just had an oil change, sometimes the little "oil" light blinks for a split second as the car is about to stall. It sounds like its gulping air, and there's no response in RPMs from the engine, even when I push the throttle all the way in. Then, suddenly, it lunges forward, and everything is fine. It almost sounds like there are small "pops" every once in a while, a disturbing sound like the engine might be hinting at a detonation.

It does this for about the first couple of miles, then it runs fine, though there seems to be more "click-click-click-click" noise than normal when in first gear.

So has my brand-new MAF Sensor already become soiled on the long drive here? Is it something else? Should I be worried about Vacuum seals?

Remember, there's no Check Engine Light going on, so I'm a tad confused. Nearest Porsche dealership is in Birmingham Alabama, about 100 miles away.

Thanks!!!

-Kevin



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Old 11-02-2004, 06:56 PM   #2
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How many miles on your motor.

I am now getting on my soap box:troll:

In the old day's mechanics did not put new engines in for oil leaks, remove parts and put new one's in until it was fixed.

Whenever I hear stories about my MAF and my O2 pump [secondary air pump], and oil separators and so forth. The so called mechanics are just R&R guy's putting new parts in until the light goes out and trying to fix it.

It's only money right...........

No one diagnosed your problem they just replaced stuff until it was better [temporary.]

Off the box now:

Don't worry about your oil light it is only blinking when your oil pressure drops when it idles to low.

Are you running 0-30 Mobil 1 [baby oil.]

If mileage gains and you run thinner oil you will hear the Tic Tic Tic.

In the old day's we liked a little tic tic tic because it meant the valves were a little loose and better loose then tight.

I would say you have an air leak, maybe from the components they put in failed or something new which was disturbed in the R&R process.

Monkeying around in the engine compartment can cause air leaks on an aged motor or for unlucky driver.

Scott

Last edited by mrmickeymouse; 11-02-2004 at 07:00 PM.
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Old 11-03-2004, 07:44 AM   #3
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Hmmm....after the MAF was replaced, it ran fine...and then Porsche said one of my O2 pumps wasn't working, but that it was simply unplugged. They got in there and "plugged it back in" and thel ight went out, and the engine was fine.

But this morning, on my way here to the base computer cluster, the engine sounded worse than ever, and I'm all freaked out. How do I go about getting this problem identified? I wish there were a porsche mechanic around here close by.

grrr
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Old 11-03-2004, 07:45 AM   #4
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PS- There are 58,000 miles on the motor...
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Old 11-04-2004, 02:38 PM   #5
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You will need to do a little detective work on your own, it is likely an air leak.

How does a secondary air injection suddenly get unplugged.

Beware of that R&R guy.

Can you do some work on your own. Sorry not trying to be wise guy some people can and some people can't.

Scott
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Old 11-05-2004, 08:20 AM   #6
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I can, though I'm just learning about this engine. I spent years working on Hondas. I was actually the one that installed the MAF sensor...and don't worry, I figured out which one it was (old style 2000 sensor). I'll need to find some online walkthroughs to figure out how to do certain things, but I think I could start to sort things out.

I just got a lexis nexis report, and the car has had probably over $10,000 in maintenance and warranty work done over the past 3 years.

WTF. I don't understand...something big must be wrong with the car that nobody has 100% fixed.

PS- I got a GREAT backfire today, sounded like a cannon going off in the parking lot.

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Old 11-05-2004, 11:07 AM   #7
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It has to be a timing problem, or a an air leak of some sort.

Have you checked your CEL for operation. no way the bulbs burned out - right.

Scott
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Old 11-06-2004, 12:16 PM   #8
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YEa, the bulb works...it had been burned out a few months ago, but its all in working order right now. Which is odd, because I'd think with all this bad stuff going on in the engine...one would assume the CEL would be coming on.
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Old 11-06-2004, 12:26 PM   #9
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You are running lean with all the backfiring, or your timing is off - nope.

Can you take it back and let them figure it out on there nickle.

~if not~

Check for an air leak with Carb cleaner, spray around after doing a visual check with the engine running. Be careful it's flammable.

If you hit a an air leak the engine will rev a little higher. Manipulation of the the hoses can worsen the problem.

Scott
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Old 11-06-2004, 12:39 PM   #10
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I'll give it a shot and see what's up. The nearest dealership is 100 miles away, and I'm not sure if there are any porsche-qualified people here in the backwoods of mississippi...

Thanks for your help, though

kevin
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Old 11-06-2004, 12:49 PM   #11
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My problem is that I am not there to help you [1200 miles].

It is very hard to diagnose a engine without being there, when someone can, without a doubt diagnose over the internet it will make life a lot easier.

Tic... Tic... Tic... I am still waiting.

Scott
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Old 11-09-2004, 10:29 AM   #12
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I haven't had the chance to check for leaks (extremely busy this week), but I think its most likely a vacuum seal issue.

The reason I think this lies in the fact that once the engine is fully warmed up, there are no problems at all. The engine runs fine. Its only when the engine is cold that it runs so poorly, leading me to assume that once the engine pieces and vacuum tubes have heated up, the pieces expand and seal any leaks that there might be.

Sounds logical? Now, how much should I be expecting my dear Porsche mechanic to want to charge for testing/verification/solution of this problem?

Ugh.

-Kevin
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Old 11-09-2004, 02:17 PM   #13
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No, I think your problem is the IACV, it resides next to your TB or the secondary air injection.

Since you just had that fixed it seems it is leaking [air] into of one of the hoses or valves.

The OBDII [3] manual gets pretty indepth in order to check this out.

IACV is pretty easy to repair [dirt is the problem], I am going to PDF my OBDII manual. I have found this area most asked by the forum members.


Scott
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Old 11-10-2004, 07:21 AM   #14
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Okay, that makes sense...I'm still trying to figure out this engine here. That OBDII manual sounds mighty useful...thanks.

Kevin
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Old 11-12-2004, 11:08 AM   #15
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Any luck yet? I've found the part online in case it needs to be replaced, but I'd like some more information about what's going on first, so that I don't fix something that isn't broken.

On a side note, bamaboxster just posted alerting us that Ted Williams Porsche has screwed him over so badly that he sold his car!!! And alas, that is the closest dealership to me, thus convincing me that I really do need to try to solve this on my own (with everyone's help, of course).

I was going to call them today and just talk to their service department and see what they have to say about it...but I am a little hesitant now.

BTW, Scott, thanks for helping me out thus far...

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