My throttle stuck open in traffic (!) What should I inspect?

[Epod]

I've got a 97 Q45 with 120K. I've had it for about 15 months. I had a gasket replaced when I first got the car, but haven't needed to go under the plenum since then.

I was driving home from work and had just come off an Interstate on-ramp into heavy traffic. I realized that I couldn't slow the car. For about 2 seconds I thought "Crap, the brakes have failed, even though the brake pedal feels fine and the brake idiot light is not on", so I shifted the transmission into neutral. As soon as I did that the RPMs shot up to the 7000s, at which point I knew the engine was getting too much fuel.

I downshifted to L-1, which dropped the RPMs to something sane. I was able to fight my way over a few lanes into the far right hand lane in the space of about half a mile. (I had joined the Interstate on a ramp that merged into the left hand lane) I shifted to neutral, turned off the engine and drifted onto the paved shoulder. (I was surpised at how different the steering was without the power assist - I had never done that in a car as heavy as the Q before.)

I shifted into park and left the engine off for a moment while I collected myself. I thought it might have been a sensor or computer problem, so I restarted the engine (I don't recall if I was in Park or Neutral). The RPMs went right into the 7000 range, so I shut it right off. The gas pedal felt perfectly normal to my foot. I worked the pedal a bit with my foot and tried starting it again; it went right back to the 7000s, so I turned it right off. I lifted the hood and looked around, but I'm not one of the Q owners who has memorized the FSM.

I got back in the car and made sure that there was nothing foreign interfering with the gas pedal. The factory floor mat was where it belongs. I vigorously shook the pedal in all axes with my hand (but I didn't go crazy). After that I started the car and the RPMs were normal. I merged back into traffic and gingerly drove home, keeping lots of room between me and the car in front of me, (much to the delight of other drivers, as you can imagine), keeping my eye on the tach to be sure that it fell when I released the gas pedal.

I got home safely, and I looked thoroughly at the gas pedal and the associated parts on the floor on the drivers' side of the firewall. So far I didn't see anything obviously wrong.

I'll look at the gas pedal and linkage with a flashlight, and assuming that I still don't see anything, I plan to limp the car to my mechanic early Monday. I wanted to poll the board's collective wisdom and see if anyone had a comment like "Be sure that you or your mechanic look at X", or "The two common causes of that symptom are Y and Z, and the way to distinguish them is _____"

Oh, to anticipate a question, I'll mention that the engine spent a cummulative total of fewer than 10 seconds in the 7000 RPM range, and the engine has the proper amount of recently changed, decent oil in it, so I'm assuming that I didn't do anything to the engine itself.

The tach did NOT peg or go off scale. I believe that it just touched the begining of the red zone; I assume that the computer declined to let the engine run faster than that.

I'll mention, too, that my mechanic is an independant shop that has specialized in Nissans for about 25 years. They don't get a lot of Q45s, but they get a few, and I trust them more than the local Infiniti stealership. He's only about 1.5 miles from my place, so I'm comfortable crawling there very early Monday.

Thanks in advance for your advice.

.

[Infinitiguy19]

I've got a 97 Q45 with 120K. I've had it for about 15 months. I had a gasket replaced when I first got the car, but haven't needed to go under the plenum since then.

In those 15 months have you done anything to the throttle?

What was the gasket that was replaced?

Did you wiggle the throttle on the throttle body to see if it was stuck?

And shifting at 7000 RPM's while the throttle is open isn't good for the transmission Check that an the oil just in case.

I think that if it runs you may have proved Maxnix point of what these cars can handle if you had it up at the 7000 Range for 10 Min.

Hope you didn't bet much xerexabante on the bet for holding the engine at high RPM's will damage it. But we have yet to see.

[Epod]

1) I've done nothing to the throttle in the time I've owned the car.

2) I believe it was the passenger side head gasket to fix an oil leak, 15 months and 20k miles ago.

3) Good thought on the transmission fluid - I'll check it

4) the total time at 7000 RPM was less then 10 seconds, not 10 minutes, so I'm optimistic.

5) No, I didn't wiggle the throttle on the throttle body. I only looked at stuff forward of the firewall; I didn't touch.

.

[maxnix]

1) I've done nothing to the throttle in the time I've owned the car.

2) I believe it was the passenger side head gasket to fix an oil leak, 15 months and 20k miles ago.

3) Good thought on the transmission fluid - I'll check it

4) the total time at 7000 RPM was less then 10 seconds, not 10 minutes, so I'm optimistic.

5) No, I didn't wiggle the throttle on the throttle body. I only looked at stuff forward of the firewall; I didn't touch.

1.) You had to if you replaced the head gasket. If you just replaced a VC gasket you don't have to. Is there slack in the cables? Do they operate properly?

2.) But why just one VC gasket? Why not TB, EGR, and IAC cleaning?

3.) Search on auxiliary ATF transmission cooler.

4.) 7K won't hurt the short stroke VH41DE.

Joe and his crew at IoS is our friend, and he can be yours also.

Call them.

http://www.infinitipartsusa.com

Define "decent oil", and presumably, filter, please.

[xerexabante]

Oh, to anticipate a question, I'll mention that the engine spent a cummulative total of fewer than 10 seconds in the 7000 RPM range.

I don't think he ran it for 10 mins. More like 10 seconds. Don't be scared about this, thus Manix will atest to this that it is ok. I have yet to set a schedule with him to schedule him to run his motor at 6700rpm for 4 mins.

[Infinitiguy19]

Yea sorry I miss read. (long day for me)

Can't believe your really serious about this. I thought you were kidding, Wonder what you guys are going to bet.
Modified by ppastos at 12:45 AM 10/4/2008

[Epod]

- I didn't do the gasket myself; my mechanic did the work. I recall that the invoice included some plenum related stuff, so I assume he had to remove the plenum. He's an efficient guy and has been around Nissan engines long enough to know the expedient way to do any common task.

I haven't taken a good look at everything connected to the accelerator yet. Partly I was out of useful light here, and partly I was hoping this board might have one or more specific suggestions based on experience.

- I only did (er, "had done") only the one gasket because it was the only one leaking. I confess that I am not the sort of Q owner and board member who believes that he has been entrusted as the curator of a precious, rare work of modern art. I recognize that the Q is a *very* nice car, and I do basic maintenance like fluid changes and so forth, and I'm good about fixing anything that's broken or hinting that it's unhappy. I want to keep it in good running order, but at the end of the day it's still a 10 year old car, and I don't aspire for it to be showroom new.

- "Decent oil" I couldn't tell you what brand my mechanic stocks. I also can't tell you the exact alloy my dentist used in my last filling. I do a fair bit of homework to find competant professionals, and I generally trust their judgment after that. I've trusted this guy for 15 years ever since he correctly diagnosed an 87 Stanza that had stumped several other places including the dealership.

[Q451990]

I must say this is the first time that I have EVER heard of a throttle sticking open on any Nissan or Infiniti! Some G's and newer drive-by-wire models have had problems sticking closed due to a servo failure, but that's as close as I have heard.

My guess would be a defective throttle cable, pedal assembly, or very dirty throttle body. If it were my car and I couldn't find a definitive answer to what caused it - I think I would make an exception to my usual aversion to throwing parts at a car and replace at least the pedal assembly, throttle cable, etc. with OEM new parts. The potential for damage and injury if this happens again in a different situation would warrant that in my mind.

Good luck and please let us know what your tech. finds!

Heath

[maxnix]

Big difference between an 87 Stanza and a VH41DE. A whole different level or two.

I think your interest level in your car's maintenance is inversely proportional to the failure level.

[Epod]

And the early reports attribute it to...

...a squirrel.

Apparently a squirrel (or rat, or something) had dragged more than a few acorns and some random crap up onto the engine, with an eye towards making a nest. Some portion of that apparently interfered with the free travel of part of the system. ( the throttle drum, I'm guessing, but I'll ask ).

I can believe that, because my neighborhood is infested with far too many squirrels that have ceased to have any aversion to humans. They'll let you get within 5 or 6 feet of them, and they rummage through trash like ...rats in fur coats. My county has had several wild animals test positive for rabies this year, so it skeeves me out when critters that should flee me don't.

The odd thing is that my car is a daily driver - I've heard of this happening to cars that are parked for long stretches (and I've even had it happen recently to another car in my family 30 miles away that was parked for a month while the owner was in the hospital), but not to something parked short term. My car is driven at least 6 days a week, and usually 7.

I guess the good news is that they didn't find half a squirrel wrapped around a pulley.

.

[96Qowner]

Glad you're still alive, man. I know that deer are responsible for killing 200 American drivers every year, but I've never run across the squirrel-related death rate.

Whew.

[Q451990]

Wow... glad to get a definitive answer at least! Maybe you should get some Monroe shocks and support the little critters. http://www.monroesavethesquirr...deo_m

Your only hope is that a more educated squirrel population will yield critters that can pick better hiding places. Or maybe a garage...

Heath

[maxnix]

I wouldn't think of rodents getting under the engine cover. Must be slim ones.

[Epod]

Just to show the squirrels that there's no hard feelings, I'm tempted to leave them a saucer of delicious, refreshing anti-freeze. Mmmmm, anti-freeze - yum!

(And I realize that's an irresponsible thing to do, so I'll resist the temptation)

[Infinitiguy19]

You might attract dogs around the neighborhood too if you did that because they like the sweet smell.

Not my idea, just saw it in another thread.

[northt]

Seen plenty of squirrels driving in my area but first time hearing of one under the hood. Wrote service for Acura for a while... Ever seen a mouse go through a heater fan? Not pretty...

[maxnix]

Ever seen a mouse go through a heater fan? Not pretty...

Did the squirrel cage fan slice him pretty thin?