Shaking at 40 MPH

[Infinitiguy19]

N/A

[SteveTheTech]

Sounds more like a miss.

Since it's happening off idle I would suspect fuel supply first. Have you checked fuel pressure?

[Infinitiguy19]

well I do have an extra good Fuel Pump Control Unit AKA FPCU I will try that and see if theres a differnce.

But would a bad throttle body (I Mean the screw that adusts it) cause this or a bad throttle position sensor?

[qship96]

Ever thought how much easier life would be if you had a 4-5 year old Honda and you could spend your youth chasing young girls and spending the allowance on beer and pizza?

[maxnix]

well I do have an extra good Fuel Pump Control Unit AKA FPCU I will try that and see if theres a differnce.

But would a bad throttle body (I Mean the screw that adusts it) cause this or a bad throttle position sensor?

A bad pump will trash any good FPCU.

Do not adjust the TB!

[Infinitiguy19]

Thanks I know about both of the things your talking about so now I have to take on the TB removal which was annoying when the engine was out of the 1994 Q45 so now it will be impossible while the engine is still on the car.

But thanks for the post and help unlike someone cough Qship96 cough

[jmorasch]

I had some of the same issues with my Q awile back...got a good fuel pump from goody after I checked the fcu.put that pump in and gave up,took it in to service and it was the gas.two bottles of ISO HEET and injector cleaner solved my problem....my shutters started out the same way yours did at first.at IDLE was the worst with those HEMI like shakes.

[SteveTheTech]

A bad pump will trash any good FPCU.

Do not adjust the TB!

I got scared for a second there, that the Q guys here were routinely adjusting the screw. I am sure Q45Tech would have had something to say about that. I think i may have adjusted one once in the many years of working on these cars. A bad fuel pressure regulator may cause this too, a clogged fuel filter,a fuel filter that was installed backwards may also cause a restriction. But it still sounds like it might be a trans issue, hard to tell without driving it.

This is still only a rough guess it may be many other things. Any more information you can provide would be helpful,

recent service history?

when did it first start happening, did something change right before it started?

do weather conditions effect the symptom?cold,warm, worse in the rain?

does driving time effect the problem? do you feel it more when cold in comparison to warm?

[Infinitiguy19]

Well it all started one day as I got up in the morning and started the car and it just started shaking really bad like a bad cylinder (coil pack, sparkplug, injector).

But then I thought it could be the alternator because I replace a bad battery and thought I could have waited to long but nope the alternator was good but the guy I took it to (my dads friend who he knew for 10 years) adjusted the idle despite the fact that I wrned my dad not to let him touch it and but he said if that doesnt fix it he can put it back to where it was (or so my dad said) so now I have a new TB but need to put it in.

And this happens more when its cold I would say but I let iit warm up for 1 min

I have run Bg44k and Redline S1 but I have started using Redline more

Cleaned MAF and bent pins down and I pull the connector and ther is no stalling so there is a good connection

Checked all 8 injectors all came back good

Will check knock sensors tommorow and clean the connectors for injectors and knock sensors.

fuel pump was replaced in 2005 from the recipt and I have been using 93 octane ever since ownership

Motor mounts were replaced aroun this time: zerothread?id=116045

Differntal fluid was changed 1 week ago

Fuel filter was changed recintaly I will change it againg because its cheap.

I have a boat load of recipts from preivious owner so feel free to ask any specific questions but I have too much to list.

[SteveTheTech]

It's good to see that you care about the car, its uncommon for guys your age(I'm not busting one you) .

How did you check the injectors?

Do you have access to a fuel pressure gauge?

You might want to check compression and spark plus condition.

Is your CEL on while this happens?

[Infinitiguy19]

Thanks

I checked them with the help of this tutorial: http://q45.org/ohminjectors.html

Not the inline one no, A mechanic I know can make it for a one time use for $25.

Don't know how to check compression/The spark plugs were replaced 60,000 Miles ago but I will check the passanger bank and see if ther good.

No.

[SteveTheTech]

Check the plugs and see what type they are and check the gap (1.2mm?)(someone is going to bash me if I am wrong ) I cannot find the number in the book so that's a guess. It does say under the hood.

[Infinitiguy19]

Ok just pluged in the used FPCU and it works great havnt done a fuel pressure test though to confirm.

Cleaned the MAF again and it seems the problem has dissapeard.

I will still check the plugs when I go to my mechanic newxt week.

[SteveTheTech]

Sounds good there are so many things that can cause this that's most likely the way to go.

Keep us posted. Good Luck.

[Infinitiguy19]

Yup problem solved 100%

I will get an OEM air filter because this one is kind of dirty

all thats wrong now is that the idle is too high due to the TB screw being touche now I will see if I can fix or install the other one Hope I can fix it though.

[SteveTheTech]

Congrats

[maxnix]

check the gap (1.2mm?)(someone is going to bash me if I am wrong ) I cannot find the number in the book so that's a guess.

The 11 at the end of the NGK specification specifies the gap at 1.1mm.

Civilians gapping plugs is a no no as few have the professional tool to keep the elctrodes parallel.

[SteveTheTech]

Fahking Sh*t 0.1mm off Good looking out.

I know I trust them out of the box, I don't know if he was using the NGKs. All I do is apply a dab of anti sieze and have yet to have an issue. Except with those damn pulse plugs.

Some people are religous about verifiying gap correctness, if it is done with a feeler gauge and gently inserted into the gap. I get what your saying.

[Infinitiguy19]

Ok I guess not all is well, I still get that shake wheather in park or nuetral when I rev the engine warm or cold from idle to about 1000-2000 RPMs

[SteveTheTech]

Sounds like a fuel or ignition problem.

It's probably always there they tend to be less evident with a V8 at higher RPMs. A power balance test should give you an indicator of what to check next.You gotta get the plugs checked. See whats in there and what they look like.

[Infinitiguy19]

Yea That consult cable should be here monday but thats not soon enough I want it now now now butI have to wait to run a power balance test.

At least for $44 bucks I can do it my self anytime I want without going to the stealership.

But hope its a spark plug and not an injector.

[SteveTheTech]

If it does turn out to be a plug you should go ahead and replace all of them with NGKs.

I'm wondering what the results will be as well, make sure you let us know what you have.

[Infinitiguy19]

Ok just got the servie history from 1994 and what scares me is that the lady had this car in the water in deep water and had the #7 connecting rod go on her it was replaced with a ll the rings and gaskets as weel as RTV.

But went to kelly infiniti and sweet talked the senior Infiniti tech so he ran a free power balance test and it showed that the #6 and #8 injectors are not dead but not great "they are a little low"

I got my consult cable and did a power balance test and I got strange reading from OBD scan tech.

But I did what goody said and shut off all the cylinders 1 by 1 and the car shook badly for each on that was shut off so it means they all work but just the 2 are "slow".

Would redline or a BG flush fix this problem?

I have run redline every 3000 miles

Sparkplugs are also due to be replaced so I need to get on that ASAP.

I know I should have got the service history before buying but the guy was a NICO user and I got a carfax report and did an inspection before buying so who would have thought she would run the car though high water.

But whats done is done and I own the car now and I am not giving it up.

[maxnix]

Have you ohmed the injectors?

[Infinitiguy19]

Of course all came within spec and I checked the knock sensors aswell.

[Infinitiguy19]

Okay got a digital Multimeter couldnt get an exact reading with the analofg one and I got 13.5 from each injectors for all 8

And I cleaned the thottle body and Now its just over all alot more smother.

The Injectors that came up somewhat bad in the dealer power balance test must have been clogged.

I also did a full thottle 1st gear run I went to 7000 RPMS but there was nothing stopping the car there wasnt a rev limmiter it felt like it wanted to shut off though but I was expecting there to be a rev limmiter just like hondas when you rev them they bounce off the red line but not in this case.

O and I did a 0-60 time with minor tire spin I got 8 seconds which is where its supposed to be i think its off by .5 seconds actually but I just need to clean some things and get better tires.

[goody90q45]

Sounds like you're making good progress with your Q. You'll see improvement with every component and connector you clean. Now it's time to tackle cleaning the IAC and EGR valves (get gaskets first).

[Infinitiguy19]

Thanks The dealer can't get them either of them so I went to advanced auto and got the EGR gasket . I got some gasket paper made of rubber so I will just cut one out and make the AAC I also have RTV which do you recomend?

[goody90q45]

IAC gasket is the same material as the TB gasket so you want to use paper and not any rubber material. Don't use RTV in a tube for this application.

[Infinitiguy19]

What about cork gaskets paper?Some one put RTV on the TB elbow not the main one.