[Cloud9...68]

My '92 has developed a hesitation problem which is getting worse. It happens most noticeably under two conditions: 1) When I'm "lugging" the engine (running at too high of a gear for the speed the car is going). When I try accelerating under this condition, the engine hesitates pretty badly. Once the revs climb a bit, it smoothes out, and accelerates normally. It's done this for some time, but I didn't pay too much attention to it because I rarely drove it under these conditions, and I assumed this was somewhat normal behavior for the engine. But it's getting to the point where pulling away from rest has become a tricky operation; if I don't give it just the right amount of gas, it bucks and hesitates. 2) Under wide open throttle, particularly starting at around 4K rpm. If the engine is doing around 3000 rpm in any gear, and I floor it, it pulls strongly until 4000 rpm, then starts running pretty rough and hesitating, and the power curve seems to plateau, meaning that the rpm continue to climb, but the power goes flat., and probably even drops off.



The car has a Racer-X chip. I put some fuel system cleaner in the tank recently, and have driven about 75 miles with it, but it didn't help. I haven't added cleaner directly to the throttle body yet, but I plan to do so tomorrow, though I doubt it will help. I also installed a new DME relay, but that didn't help either. The car pulls very strongly at any rpm at part throttle, and runs very well in general at intermediate rpm's.



The problem feels more like fuel delivery than spark related, but that's just speculation. I'm hoping the wealth of 968 knowledge out there will point me to some places to start looking. Thanks in advance.

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[Greimann]

My first thought is bad gas, or less than premium gas. Then my thoughts turn toward a misfire under load and could very well be ignition realted. I would start with the basics first. New plugs, rotor and cap. If those are in and the condition persists, then move toward fuel items, or sensor related items.

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[rustech]

Some ideas:

Would bad gas not trigger the knock sensors and throw the Check Engine light?

Can you check for DME Fault codes and see if it says anything?

Could it be variocam related since you say it kicks in around 4000 rpm?

Tough one to troubleshoot.

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[flash]

check to make sure you ahve the late DME - the racer x chip is not to be used in the early one

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[Cloud9...68]

I'm very particular about filling up at the same Exxon station every time (with 93 octane, of course), and the problem has been there in a mild form for several months, which pretty much rules out a bad tank of gas.



Flash, when you ask whether I have the late DME, do you mean the actual DME, or the DME relay? The car (which I bought from Chris Aarons) came with the Racer-X chip, and originally had the early 994. relay, which I just upgraded to the new 993. one.



Rustech, I just replaced the Variocan tensioner pads and chain, so I assume the Variocam is healthy. Since the Variocam does it's work between 1500 and 5500 rpm, over which range I have both good and bad engine performance, I'm going to say the Variocam (thank goodness) is probably not the culprit here.



I'll continue working on the basics; I was hoping my particular symptoms were something common to these cars, and as such could short-circuit some time-consuming troubleshooting. I'll call the previous owner and ask him if he replaced the plugs (he did the wires, and I thought he told me he did the plugs as well, but I'll have to confirm), cap, rotor, etc. If this doesn't take care of it, I'll take it to a mechanic to check the fault codes. Thanks; If anybody can think of anything else, let me know.

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[rustech]

Rustech, I just replaced the Variocan tensioner pads and chain, so I assume the Variocam is healthy. Since the Variocam does it's work between 1500 and 5500 rpm, over which range I have both good and bad engine performance, I'm going to say the Variocam (thank goodness) is probably not the culprit here

It hasn't happened since you replaced the items above has it?

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[Cloud9...68]

[quote name='rustech' date='Apr 10 2005, 04:23 PM']It hasn't happened since you replaced the items above has it?

[right][post="3109"]<{POST_SNAPBACK}>[/post][/right][/quote]



I replaced the variocan pads and chain last August, and the problem started maybe two months ago on a very intermittent basis, and got to the point where it's noticeable in routine (if you can can periodic blasts at WOT throttle routine <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> driving a week or so ago, so it seems like there's no connection to the Variocam components.

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[flash]

i was talking about the actual DME, but since this was chris's car, i'm ruling that out as a problem - his car ran well with the chip - also, i thought that because you mentioned the chip, that it was a recent change that now presented a problem



i'd look at the distributor area first, and then the fuel

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