Vibration at Idle

[SanCarlosQ45]

Basically my question is is a vibration at idle a normal thing? I know it sounds silly but I cant convince my dad that the car should not be vibrating like this at idle in gear

It only does this when it is in gear, not in park, under load.

My car is a 1994 base Q45, nothing special. I have recently replaced the fuel pump, fuel filter, and air filter. I have also checked/cleaned the IAC valve and is set at about 3 turns out. Also cleaned the EGR valve and sensor. MAF sensor is clean and connection is good.

[Hogg]

Mine started after I swapped in a fuel rail and injectors off a parts motor

[oldmako]

Not normal.

There are many things which if old/ dirty/ worn/ could affect the idle, from fuel quality and delivery, to air intake to ignition, to wiring.

I'm no Q expert, so I'll defer to those who are smarter and more experienced with the marque.

[Q45denver]

Throw some BG44K in the tank and if that doesn't clear it up ohm test the injectors. Odds are one is slightly off.

[SanCarlosQ45]

Next fill up we will. Didnt have a funnel to do it the last fill up.

Will be getting a consult cable soon. Hopefully the software has the powerbalence test built in. I think the version is 1.5.

My digital multimeter doesnt seem to work because on every part I have tried I cant get resistance readings, on the IAC and the Injectors

My question is would you notice a fuel injector was bad during driving and acceleration? I am only having problems at Idle. No check engine light. I also just replaced the spark plugs which seemed to help in all areas of performance. The old spark plugs looked decent, were not black and the transfer of the platinum was looking normal (I dont know what you call that, trasfer from the tip?)

[Haitian_King]

Next fill up we will. Didnt have a funnel to do it the last fill up.

Will be getting a consult cable soon. Hopefully the software has the powerbalence test built in. I think the version is 1.5.

My digital multimeter doesnt seem to work because on every part I have tried I cant get resistance readings, on the IAC and the Injectors

My question is would you notice a fuel injector was bad during driving and acceleration? I am only having problems at Idle. No check engine light. I also just replaced the spark plugs which seemed to help in all areas of performance. The old spark plugs looked decent, were not black and the transfer of the platinum was looking normal (I dont know what you call that, trasfer from the tip?)

The rough idle is how it starts. Next, you'll be accelerating (Either through a curve or going to pass someone on the highway) and you'll feel a serious miss that goes away as soon as you let up. That was how my #8 injector behaved when it went.

[goody90q45]

Basically my question is is a vibration at idle a normal thing? I know it sounds silly but I cant convince my dad that the car should not be vibrating like this at idle in gear It only does this when it is in gear, not in park, under load.

If everything is working properly your Q should be purring like a kitten at idle and you should have a hard time telling if the engine is even running.

It sounds like you've got a marginal injector or two. If you can afford a consult cable you can certainly afford to go to Radio Shack today, buy a $15 volt meter, and test your injectors and knock sensors. It's just a guessing game until you know the resistance readings.



On a positive note, you're on the right track getting a consult cable and scan program. With it you'll be able to narrow it down to the cylinder using the power balance test. It doesn't cost more than about an hour's labor charge (CA rates) at a shop so it pays for itself the first time you use it.

Tell Dad to get his own Q. He'll be wanting yours once you get the miss fixed. I bought my Q for my son who was moving away to college and he didn't want it. He said it looked like an old man's Buick. He knows now he made a mistake. Post up those resistance readings when you get them. Good luck.

Mine started after I swapped in a fuel rail and injectors off a parts motor

I'm having the exact problem as you with my 90Q right now. The PO was having idle and acceleration problems so he got a fuel rail with injectors from a salvage yard and bolted it in. He didn't know how long the carcass had been there (2 weeks or 7 years?) and had the same problems. It turns out that in addition to one dead injector two others are hopelessly plugged, even after a BG injector flush at a local shop.

[maxnix]

It turns out that in addition to one dead injector two others are hopelessly plugged, even after a BG injector flush at a local shop.

Well, at lest now you know.

No mention of mileage nor previous intake maintenance. Dirty TB, Plenum could contribute to idle instability.

[oldmako]

Hey Goody,

Can you tell me if one can ohm the pins on FY33 exactly the same as a G50?

Thanks.

[SanCarlosQ45]

All injectors tested out in spec, around 12.8-13 ohms. This doesnt mean they could be dirty but I dont think that this is the problem.

IAC, TB, EGR have all been cleaned. I dont know where to go.

[maxnix]

Plenum cleaned? BG raiil flush?

http://www.bgfindashop.com

[Haitian_King]

All injectors tested out in spec, around 12.8-13 ohms. This doesnt mean they could be dirty but I dont think that this is the problem.

IAC, TB, EGR have all been cleaned. I dont know where to go.

MAF connector?

If it's not the MAF itself, it could be the connector pins. Wiggle the connector while the car is idling. If the idle changes during a wiggle, it could be the connector.

[Kiven422]

Its not normal in any car.

Try fuel injector cleaner.

I used the GUMOUT brand fuel injector cleaner forgot which one exactly but it was the one thats NOT for carbourated engines. First bottle w/half tank gas completely fixed the issue (stalled on me once leavin the gas station but no biggy). I used a 2nd bottle to get it absolutely still. Used in Sept 07 and its been good ever since.

[Q45tech]

What is rpm at idle in park and drive with coolant hot................inside tach is not accurate enough to answer this question?

[atlq45]

Misfiring at idle can be a symptom of a vacuum leak. Engine vacuum is highest at idle since the throttle plate is almost closed. Check for leaks around the intake manifold spider.

[atlq45]

Check for leaks by spraying carb or brake parts cleaner around the manifold while idling. Idle will momentarily change.