y2kse

iTrader: (1)

The following correspondence appeared on Page 142 of the January 2001 edition of Road & Track. Although the article refers to a 2000 Mercury Cougar V6 manual and not a 2000 Nissan Maxima V6 manual, both the Cougar and the Maxima appear to share the fuel-cut condition in common:

"Question: I have a 2000 Mercury Cougar V-6 with a manual transmission. When the accelerator is released while shifting, the engine speed will drop only gradually. To obtain smooth upshifts it is necessary to keep the clutch disengaged for about 1.5 seconds to allow the engine speed to drop to the transaxle speed."

"I have spoken with the factory and was told the engine-management computer keeps the throttle open during shifts for emissions-control purposes. The dealer told me my engine is operating within the acceptable range. Needless to say, this detracts from the joys of manual shifting. A 1999 Cougar I drove did not exhibit this trait. Similarly, there is very little engine braking when decelerating with the accelerator released, so the brakes must work harder. Is there a solution? Or is this a common problem with modern cars?"

"Answer: The short answer is yes, this is common in modern cars. When the throttle is suddenly closed, a momentary burst of high hydrocarbon production ensues as a bit of rich mixture is trapped in the cylinders. By effectively not allowing abrupt throttle movement, this condition is avoided."

"Unfortunately, to an enthusiast driver it results in a maddening loss of precision accompanied by the many undesirable side effects you mention. The only cure would be to rewrite the computer code in the engine-management computer."

"Aftermarket chip manufacturers seem to think this condition is caused by an automatic transmission computer code being used in a manual transmission application. In any case, they had not done the research and development to locate whatever code is causing the "hung throttle," as they hardly had any call to do so."

[The remainder of the article is specific to the Cougar.]

The article does not explain the underlying mechanics driving the fuel-cut condition, but it's clear that independent mechanical engineers, Nissan Zone Reps, and others are correct in pointing out a logic issue as the true source of the problem.


[Edited by y2kse on 12-12-2000 at 02:44 PM]

TimW

iTrader: (6)

oh come on... those Road & Track people need to learn how to drive

thats new about the auto tranny code tho.. that makes sense... may not be true, but makes sense

y2kse

iTrader: (1)

More important, my Zone Rep suggested it as a possibility when he drove my car. The test drive took place before the article was released.

Perhaps we're on to something here.

[Edited by y2kse on 12-12-2000 at 08:35 PM]

wdave

This has been a problem for many years. The smog explanation is correct - sudden throttle closing releases a burst of unburned hydrocarbons. In the old days you ccould get flames or a bang out of your tailpipe by getting the pipes hot and flooring and releasing thre gas pedal. In the ancient early seventies carburetted cars had dashpots on the linkage - they slowed the return of the linkage to the idle position. Now the smog rules are tougher and the job is computer controlled, but lazy rpm drop between shifts has been around for about 30 years, it's just getting worse.

Dave

My 4DSC

I beleive that I stated over a month ago in one of the bazillion threads on this subject that I drove a manual 1995 Ford Contour SE (2.5L DURATEC V6)- which shares the exact same engine as the new Mercury Cougar...the Contour I drove had the same problem (rpm's hanging up between shifts) that you guys are complaining about with your Maxima's...except its 1000 TIMES WORSE with the 2.5L DURATEC engine found in these Fords-Mercs! Drive one of those cars and you'll stop complaining.

PS: This problem has been around in the Fords for 6 years now and obviously nothing has been done about it. I'm guessing we're going to have the same outcome with Nissan.

y2kse

iTrader: (1)

but for sure nothing will be done about it if nobody complains and brings it to Nissan's attention. Consider it a waste of time if you like. But it's my time to waste.

tomz17

What you really need is a bunch of bright programmers, some mechanics, physicists, chemists, tons of geeky goodies, and much money... [MINUS THE ENVIRONMENTALISTS] Then maybe you could bribe some of them to reprogram your Maxima to shift like a porshce...!!


You gotta consider that the core demographic of Maxima purchasers are not performance freaks... So Nissan is unlikely to rectify the situation on our account!!!

y2kse

iTrader: (1)

that's why I've enlisted the aid of Chris Wardlaw and Brent Romans. Chris is the Editor-in-Chief of Edmunds.com and Brent Romans is a Contributing Editor for Super Street Magazine. They have agreed to test a AE 5-speed within a matter of weeks for the precise purpose of investigating the fuel-cut condition. And I think you'd agree that the pen is mightier than the sword.

tomz17

Agreed... The ***** mightier (sorry, SNL celebrity jeopardy)


I was thinking more along the lines of getting Steven Hawkings to figure it out, but I'll settle for Chris and Brent.. :-)

Shingles

Although I don't know the exact nature of what's going on with the 5th gen(I though the problem was a sudden cut in fuel causing bucking in low speed situations)... but anyways, if the problem is as the cougar... there is potentially one fix to the problem... lighter flywheel. I suspect that a lighter flywheel will cause the rpms to drop faster(depeneding on how much lighter). The ECU will continue to do it's thing, not letting the throttle close all the way, but the rpm's should drop faster and thus making the drivibility part a little better.

I know that this should be somethign that Nissan should address, but if they won't, this could potentially be something that could easy the pain.

-shing