q45 bucking/jerking DESPERATE!

[QE86]

Pretty much same problem here Jesda, my Q is fine if I just give low throttle....However, if I try to floor it and the car will buck approx. every 1k rpm all the way up to redline. The revving is fine when in Netural but bucking when put in gears.....I have cleaned Throttle body and MAF sensor 2 weeks ago so what's my problem??

[Jesda]

I gave my old fried fuel pump relay to a friend to solder two bypass wires to see if we could get it working again. Just for the heck of it, I'll see if it resolves my bucking problem. My old fuel pump relay/module has no noticeable burn marks on it from overheating, however.

I'll update in a couple days.

-Jesda

[reliant]

I had identical bucking and intermitint running exactly as you described. It was the MAF just buy one new from joe and install yourself.Why waste so much time and hassle. This is not a problem of cleaning anything just replace MAF.

[Jesda]

Thank you sir for the straight-up answer! I know exactly where to get a perfectly good used one.

[SurfinGator]

Well, the ground wire to the pump from the FPC wiring harness stopped working last night. Shudder Studder ...

It seems there are two or three separate problems being defined in this thread by various posters, so I will define mine in the hopes it may help another poster at some time. I am heading to the dealer, they have one good mechanic there and I let them know the car will stay there until he can look at it.

The history:

My car had no problems except the fuel pump was buzzing. I replaced it with a OEM new one, fuel filter at the same time. Three weeks later, the car would randomly sputter and want to die. At mid pump output, the pump is three stages, a one second pause would occur in the car. When I stopped, low pump output time, it would stall. Putting the car in neutral and revving the engine would stop it from stalling. Then it would go away. I could drive it for miles and no problem.

Grounding the fuel pump resolved it. After ISO-Heet in the tank, cleaning the MAF, and re-soldering the connections, it appeared to work. Next day, at it again. I replaced the FPC with a salvaged unit, worked for a few days and then at it again.

I can run the car 70-80 mph on cruise control and it works fine on the highway for 400 miles. When I slow to go through a town, you might make it without it sputtering, but even if it did it usually sputters when you first re-engage the cruise to 70-80 again. Zoom Zoom, then sput sput for two seconds ... then clean ... for another hundred miles before you have to slow down.

I have really been trying to save up some cash for a multi-stage paint job, the bumper's paint is flaking and I have a ding on the hood. But this car is starting to eat $$$. And I haven't had to do the chain guides yet ...

seems I need to get a third car before I worry about paint ....

[logisoft]

Since the weather has turned cooler, I've been driving my Q and have had very little bucking. It just died once at a light and I restarted it and no bucking occurred. It has balked once or twice while cruising but it never resorted to the 5 minute bucking and jerking that was the norm before. I kinda thought that heat build-up in the engine after it had sat for awhile after running and then restarting was the way to reproduce the problem. With the cooler weather, maybe whatever is getting too hot is not. We're due for some warmer weather so I get a chance to see if outside temperature is a factor.

My battery is loose, no hold-down. I've been meaning to get a replacement hold-down. The battery slides a little sideways but doesn't travel too much. Think that could have anything to do with it?

Thanks

Dan

[Jesda]

Surfingator, do you have a photo of that? Did you run a separate wire from the fuel pump to the chassis? I should get some alligator cables.

[SurfinGator]

I'm an engineer ... I got clips. It is viable the connection was not making, I didn't care. I just connected back to the FPC and she ran the three miles home.

Inifinity gave me a new G35 to ride while they play ... they still haven't found what is going on. I told the mechanic already, don't throw parts at my car trying to fix it... and me pay for it.

Sweet pic by the way, you are the man! You have helped me more than a few times ....

will holler back tommorrow ... hopefully they will have it done then.

[Jesda]

Thanks for the props!

The fuel pump relay mod was inspired by "Tangalora", whose amazingly well documented posts made it possible. My friend did all the work; I plugged it in today and so far it works perfectly! I'm leaving it in for a week to see if the bucking comes back.

Here's close-ups in case anyone wants to do the same:http://www.spilky.com/bo/stf/fuelpump/

[QE86]

Ok just come back from Infiniti Dealer with the diagnosis.....The MAF Sensor as well as both of the knock sensors failed. They try to charge me $2k for fixing all the 3 sensors

Just wanna ask how much will it be purchasing those sensor (new and/or used)?? And how hard will be the installation of the knock sensors??

I only know how to replace the MAF but not the knocks.......sorry for these newbie Qs...

[elwesso]

The knock sensors can be seen how to replace in my plenum guide, http://www.q45.org/plenum . Also there you can buy Knock sensors, for about $100 each, shipped.....

[DAEDALUS]

At dealership prices, the parts are upwards of $1000 probably, so I'd say roughly 50/50 parts and labor on the bill. You could probably save $1200 off the quote, plus sales tax if you do it yourself. Don't buy used knock sensors. Verify you need new knock sensors by getting the codes yourself. Do them first. If the problem persists you can then troubleshoot the MAF and possibly replace it.

[QE86]

At dealership prices, the parts are upwards of $1000 probably, so I'd say roughly 50/50 parts and labor on the bill. You could probably save $1200 off the quote, plus sales tax if you do it yourself. Don't buy used knock sensors. Verify you need new knock sensors by getting the codes yourself. Do them first. If the problem persists you can then troubleshoot the MAF and possibly replace it.

So how can I get the codes to verify I need knock sensors?? Thanks for the quick replys

[Q45tech]

Consult display or ecu flashing code light sequence!Measure their resistance ~~550,000 ohms [+-50,000] VOM ground to engine block other lead to center lead of shielded cable. The KS gets grounded thru its mounting bolt.

Dealers usually don't pad [tell you something shows bad when it is not] serious parts......enough is usually bad so that this is never necessary.

[logisoft]

Well, the Q just bucks after it has been thoroughly heated up. I threw up my hands and will take the thing in to Infiniti today for a new MAF. I'll know within a day or two if that was the problem. Sure hope so. Wonderful car but so annoying when she bucks.

[QE86]

Yeah I feel you Logisoft...makes u so frustrated when you try to step on the gas and it bucks

I will try to change the MAF first and see what happens....let me know your result!!

[Jesda]

Just thought I'd update everyone since some folks have their eyes on this thread for solutions, and because its linked at Q45.org.

As a recap I have done the following:SeafoamNew plugsNew TCUNew negative cable and groundNew negative terminalNew batteryAlternator diagnosed OKAdded bypass wires to FPCUClean TBClean MAFClean MAF connectorClean CAS connectorClean TPS connector

And recently I found this thread: http://nicoclub.com/zerothread?id=33796"Forecast" (Daniel) thoroughly explained the likely causes of various idle and drive problems in an extremely handy list. Keep that one in your bookmarks.

Based on the information there, I removed and cleaned the IAC -- the manual refers to it as an AAC, took me a while to figure that out. I did not remove the rod and spring but I did spray them generously with carb cleaner.

I also loosened the plastic screw, which I guess allows more air to flow at idle and while cruising.Obviously, this is NOT a proper fix, and once I get a new MAF (which will be quite some time for now, since getting a transmission flush done is a higher priority) I'll have to readjust the IAC screw again. At least I can get around town now without bucking like a wild bull.

So "Reliant" in the above post is right; my problem is a bad MAF. I found one for $35 ($50 shipped) from a junkyard 91 Q which I'll be ordering as soon as I can afford it.

I could have replaced the MAF from the beginning, but throughout all this I've learned a -tremendous- amount about my car and took care of some things that could have developed problems anyway.

-Jesda

[logisoft]

Well, I got the new MAF last Thursday and not a sign of bucking since. I think I can pronounce this problem fixed. Infiniti charged me $600 for the deal. OUCH! But the car does run like BUTTA!

Thanks to all who tried to help.

Dan

[Jesda]

Holy crap! You could have saved big bucks by ordering it from Joe ($366 before shipping) and putting it in yourself (takes 5 minutes).

I hope my used MAF does the trick. Cant beat 35 bucks. (Decided to just order it)
Modified by Jesda at 1:16 PM 10/19/2004

[QE86]

Hey Jesda did you get your MAF from local junkyards or online? I am searching for used also but dont want to buy from ebay since I heard they are no good...

Let me know please, she has been sitting in the garage for 2 weeks already

[Jesda]

http://www.car-part.com/ -- I got the last 90-94 MAF for $35, but theres more for $50 and up.

-Jesda

[QE86]

http://www.car-part.com/ -- I got the last 90-94 MAF for $35, but theres more for $50 and up.

-Jesda

So 90-96 MAFs are the same right?? Just want to make sure....Thanks BTW Jesda!!!

[Jesda]

Only 90-94 are the same. 95 and 96 use a different connector.

[Jeff Williams]

I got a rail flush, for about $115, at the dealership.

[Jesda]

They sent me a 96 MAF instead of a 91. The connectors of course did not match. I'll take photos of the two when I get back from school.

I got curious and put my 92 connector on the 96 MAF. But while doing this I made a mistake -- I didnt realize the connector pins were soldered to the MAF -- "Hmmm, this darn connector wont come off... *crack* oh ****!"

Performing some magic with a flathead screwdriver, I got the pins on the connector to push against the MAF. Reinstalled everything, and the bucking is all gone and idle is improved.

Whee!

Next item is Jeff's suggested rail flush.

[QE86]

Good to hear that Jesda!!! So you put the 96 MAF on your Q???

Show me some pics on how you damage the connector if you can!!

[Jesda]

Yep! I'm running a 96 Q45 MAF on my 92. Although its not the proper solution, its good enough for me.

I tugged on the connnector, and it broke off. Notice that only three of the pins have solder on them. The fourth one was connected to nothing! I took a flathead screwdriver and pulled them out so they would push on the pins sticking out in the image below...

...and by golly it worked.

This is the other side of the connector, which of course doesnt work with the 90-94 wiring harness. The white goo in there is just dielectric grease I put on the pins.

Drives smoothly, purrs like a kitten.

-Jesda

[Microsoft94Q45T]

Holy crap! You could have saved big bucks by ordering it from Joe ($366 before shipping)

I know this is an old post, but EverythingInfiniti now lists the MAF @ $488 (for a 94 Q45) - am I looking at the wrong thing or did the price jump that much?

[Jesda]

It should be the price in bold on the right.

[Microsoft94Q45T]

Wow... it's been a long day