Differential diagnosis -- high rpm at idle(2750);

[ponzy]

Still code 51, high rpm at idle (park & neutral = 2750); drive = 1150

it happened last night when i used the q for the whole day, wot at times in the highway (reaching 3500 rpm max prior to change gear at 2nd) after 2nd, it never reached more than 2500 rpm prior to gearing up. And in stoplights, rpm base at 1150, i have to push hard on the brakes, otherwise car drives as if im pressing gas. And it drives the car >20 mph even when not pressing the gas pedal. i have to press hard on brakes when changing gear and it jerk wild (enough that car lurches when changing gear)

im gonna bring her to a shop later this week, i just want your opinion about what could be wrong that would lead to this kind of symptoms. sounds timing? Or a real bad vac leak?

history: underplenum 4 months ago, fuel pump replaced, a couple wks ago i ohmed the injectors from the connectors- all good.

thanks in advance guys, do you have recommendations aside from vanmeter in new jersey( too far fr my place)

viva nico,ponzy

[Q451990]

Please update your profile with the year and options on your Q45. If we're talking about a G50, I would suspect that the throttle cables are adjusted incorrectly. There should be some slack in the cables when the throttle body is closed and the engine is hot... e.g. the fast ilde cam is not holding it open.

Heath

[ponzy]

Thanks heath, its 1994 q45 with TCS. I did the underplenum r/r myself 4 mo ago at 103.5k mi. Right now its 104,835 mi

[maxnix]

im gonna bring her to a shop later this week

thanks in advance guys, do you have recommendations aside from vanmeter in new jersey( too far fr my place)

How far one will drive to get competent service for their car is a measure of how serioius they are about their car.

He's in NJ, how far could that be? Less than 2 hrs., I bet.

[ponzy]

Brian, i move out in jersey, and currently in queens NY. Almost 3 hrs drive going there close to pa/nj boundary. and besides i wanna go and visit the car fr time to time whle its being rehabilitated. Maybe some of our folks here know some shop that handles/experience with G50's. Or someone that do side job as q45 tech that is willing to take care of my car please let me know and email me with your "talent fee" at [email protected] (who is close to jersey city-5-borough-new york) preferably not a parts changer type mechanic.

thanks nico,

[Q451990]

Thanks heath, its 1994 q45 with TCS. I did the underplenum r/r myself 4 mo ago at 103.5k mi. Right now its 104,835 mi

Did the high idle start then, or just recently?

Heath

[ponzy]

Heath, before its a rough fluctuating idle from 750-450(3 mo ago), then after using 2 cans of bg44k it resolves a little fluctuating from 650-350(just above the 1st line on rpm needle)(a mon ago) then now, its not fluctuating but idle rpm starts from 1750 - cold - then gradually increases and bases as high as 2750 -warmed up.

thanks for any input.

[elwesso]

The high idle could be caused by a stuck throttle cable. My Q did that a few times and I lubed it real good and it fixed it.

The fluctuating idle sounds a lot like a vacuum leak, and the stuck throttle could make it smooth out at 2750 RPM very easy.

[ponzy]

thanks wes. i'll try that tomorrow. im still contacting jamesmost, hopefully he'll chime in soon.

[ScottJackson]

check the cruise control cable too!

[ponzy]

Is that the one attached to the 'actuator' ? I've never got to the car yet today and i got no grease, i figured i'll use the petroleum jelly or better use motor oil as an alternative.

is it still safe to run the car? Is driving the car acting up like that wont harm the engine or transmission?

thanks to all replies.

update: i did lube the cables with motor which helped the high rpm. It toned down to 1500, but fluctuate to 1750. Sounds a real bad vac leak. Cant chase it, i guess im gonna go with james mechanic @ NJB auto.
Modified by ponzy at 8:54 PM 6/12/2007

[ponzy]

Update: i brought her to long island NJB auto yesterday. Have a word from bruce (master tech) and told me it could be a pinched intake manifold rubber gasket.

it wouldnt start the car at all right, just like what happened to ross(celingolmo)(where is he now? ).

[ceningolmo]

it wouldnt start the car at all right, just like what happened to ross(celingolmo)(where is he now? ).

I'm still around... just lurking for the time being. I'm afraid real life is keeping me busy at the moment.

I need to post up some pics of my Q with the FX45 wheels on it soon... I'll see what I can do.

[ponzy]

nice to hear from you again, ross.

[ScottJackson]

yes, it certainly can hurt to drive it like that. I got my '95 BMW because the previous owner kept driving it after the cruise control motor (little electric motor in a box) wouldn't allow the throttle to go back to the closed position. So the brakes were held against a motor that was pulling against it and it quickly burnt up the transmission. Not a cheap or easy fix once the trans is fried.

[ponzy]

Update:

need to replace coil pack #3 (!?@¤???). They said it wont fire on #3 cylinder.good thing i bought all packs from the wise guy Jazz.

[ponzy]

Update::

master tech reported the whole left bank isnt firing, need to change the ignitor chips, luckily, jamesmost dear, donate his spare. Thanks a lot on him.

[96Qowner]

I think that's one of the VERY few times a coilpack has gone bad on a G50. Let's hope the master tech actually knows what he's doing.

[ponzy]

That's what i thought too. Work has been started already. Any suggestions? Pls do reply. Thanks a lot

[goody90q45]

You may very well have a bad igniter chip (power transistor) and coil pack but I'm not sure of either these would cause the extremely high idle you've been having.

Has the mechanic loosened or removed the plenum to make his observations about the vac hoses and intake gaskets or just inspected with a mirror?

[ponzy]

Honestly, I dnt know. They told me they have removed the plenum?. First, They told me its probably pinched gasket and ashton(one of the mechanics) said there's no piched gasket. They "sound" they fixed the high idle problem. Their concern now is the misfire and MIL is on. i hope they'l nail it with the power transistor. I've suggested to master tech that could it be a failing O2 sensor? He told me its only for fuel milleage. Thanks a lot for the replies.

[silkysmoothyjud]

Failed coil pack? o2 sensor? Gimme a freakin break!!! What a rip off!! Ignitor? The car would even run! That mechanic just racked up about 2000$ in repairs for whats probably a cruise control or throttle cable problem. Take your car somewhere else!! That is making me sick!!!!!!!!!!

[maxnix]

Brian, i move out in jersey, and currently in queens NY. Almost 3 hrs drive going there close to pa/nj boundary.

Never thought twice about driving from Seattle to Portland for major service from a competent Infiniti Senior Mechanic since I could bring my own parts, not pay sales tax, and got a reduced labor rate. Essentially gas and lodging were free compared to Seattle dealer.