Need Help ASAP...CAR Jerking/bucking badly

[NightRiderQ45]

here is my issue. i filled up with a full tank of gas on monday and drove around and SEL light came on. end up being o2 sensor rear bank left. well i put in chevron techron cleaner and drove to work tues and light went off on it own during commute. on my way home from work tuesday, the car started bucking badly on the interstate. not small misses, but bucking. it would buck worse when ac is on and while pulling hill. crazy thing is that my SEL is not on at all during this time. these problems only come up once the engine is warm. yesterday was worse. i started my car and it had trouble running (smoking and all)...it even cut off when i came to a stop sign! i took today and tomorrow off so I can try to fix this asap! i thought that the fuel filter was clogged so I replaced it tuesday and it's still running rough. a lot of black gunk came out when we took the line off the fuel filter.

what do you all think it is?? i really need constructive feedback at this point because i'm headed to the mechanic now and I will read your comments while I'm at the shop. Maintenance done: changed fuel pump in 08 after it died on me on the interstate so HAD to go with NAPA fuel pump since I had no choice at time. cleaned tb in 08 and i never cleaned the plenum but i don't think that will have anything to do with this anyway. haven't changed spark plugs since mid 05. could it be spark plugs, could it be injectors, could it be fuel pump going out, or could it be bad gas that has all of this going on. my mileage was horrible so i finally ran it all out and i refilled with chevron and added isoheet to see if that would help my situation.

I don't think it is the maf (those were issues with g50) right? i read the issues with ignition coils but these are not small misses, this is heavy car surges/jerking/bucking with a sound like something is knocking hard in the back of car. plus ignition coils issues with the fgy33 made the check engine light come on.

Please help! I'm going to have the mechanic check the maf, the injectors, check fuel pressure which should be around 45psi. 02 sensors won't make your car run horrible or could bad fuel cause the spark plugs to fire badly? if so, would I atleast get a service engine light??????

*****sorry for everything in small letters, I'm in a rush to get this fixed...especially when I have a wedding to be in on Saturday****

[qship96]

My guess is MAF or coils- have codes read and report back.

[NightRiderQ45]

dang....21 views and only 1 reply!? Well this site has gone to sh*t quickly after the merge!! qship...I stated above that my check engine light is not on at all. If I knew the codes, I would've had this issue fixed by now! After reading multiple coils issues with y33's, I don't think that is the problem especially since no check engine light is on. Same goes for the MAF. This issue still isn't fixed but after we "T" the fuel pressure gauge to the fuel regulator, the car ran butter smooth. We unhooked the gauge and put the fuel line back on and it ran rough. After hooking the gauge back up, it ran smooth again, even under load with ac. This time when we unhooked the guague and the car ran smooth. We took it for a test run under load, even pulled some hills and it never bucked, missed, or dropped in rpm's at light. I'm happy at this point. After this, I ruled out injectors, coils, and MAF but if that was the issue, 1) I would have a miss which would turn CEL on 2)My car would still run rough at all times. After leaving gym after it sat for 2hrs, ran into the same issue rough running issues, but it got better the longer I drove teh car which is weird.

I was told that the bad gas might have had a lot of water and it prolly will get better after the new gas run through system. I was also told that the fuel regulator probably got some water in it and destroyed it. Told I probably need to fix that. I think that I will buy that regulator and if that still don't work, I'll bite the bullet and go to the dealer. If it is MAF, I wonder if I can just clean it and see what happens but I've read bad threads when some people do that.

[NightRiderQ45]

Also fyi...I forgot to add this

FSM states that for fuel pressure check, the fuel gauge should read around 34psi at idle. Mine was 40psi. It also stated that after ignition off to ON, it should be around 43pis...mine read 47-48 psi. Since both of my readings are higher than the FSM, is this a bad thing or is it something that is causing it to read higher.

[SteveTheTech]

I would look at the fuel pressure regulator and cam position sensor first.

Vacuum hose degradation is very common in the back of the motor and often the IACv will compensate for a slightly lean mixture but adjusting its opening cycle. If it gets too far to the lean side you might get an O2 code.

Go get you a can of brake clean and a flash light and go rubber hose hunting.

[Q45tech]

When and how did you test the accuracy of your fuel pressure gauge?

[NightRiderQ45]

Test accuracy of gauge itself? How can I do that? I'm quite sure the gauge is accurate since it looked brand new once opened in the shop. Could you at least let me know if I'm going in the right direction? I've ordered the fuel pressure regulator and I purchased the laser platinum oem PFRG-11 plugs yesterday for $10 a pop! I was going to purchase the laser iridium for same price since I was told that is an upgrade, but stayed with engine spec'd platinum plugs. I will change out plugs (old plugs have 131k on it) and regulator today so I'm looking fwd to see how my car runs afterwards. Should at least accerate better since plugs should be shot at this point. Odd thing is that on my commute to work today, I HAD NO ISSUES at all

[NightRiderQ45]

Well went to try to install the BWD fuel pressure regulator and my car wouldn't start at all with the aftermarket part. Also pushed fuel pressure up to 73psi and it never released. Took new part off and put factory regulator back on and car started up fine again. 38-40psi while idle. We didn't have time to do plugs yesterday. Since people brought up MAF, I went and purchased MAF cleaner and cleaned the MAF. Car ran better after cleaning, even had quicker acceleration so I'm happy until this morning. Car ran good then started bucking while doing 75mph.

This is frustrating! The car has NO check engine light, tried to pull codes, but no code! The only code it spit out was 02 sensor Bank 1 Sen 2 when problems first started but light turned off by itself. It said high voltage.

Questions I have:
1. Will 02 sensor cause surging/bucking? Car is running VERY RICH. Gas mileage is horrible right now.
2. Cleaned MAF. Will bad MAF throw on engine light?
3. Will bad plugs throw on engine light for misfire?
4. Will bad coils throw on engine light? From reading threads here, I think the answer is yes. I don't think its coils since car runs great at times then turns horrible.

thanks!

[SteveTheTech]

I'm going to start with what you were saying about what happened after you replaced the FPR. Now according to the book Fuel Pressure should be ~43 with the FPR vacuum lead disconnected. If you have 30psi more than that seems like a huge waving red flag.

From there I would start by checking the switching mode of the FPCM. This is not detectable and will require you to perform the circuit tests listed in the book.

As for your list of potential codes... all of those items will cause a normallity code if there is an open or short in the circuit but very few logic based codes. In 98 OBDII was still fresh so the P0xx codes were all standardized but there is nothing existed for this type of issue.

As far as MAF dtcs go.
There are some logic based codes that have been used throughout the hot wire style MAFs lifespan but in order to trip a dtc the readings are going to have to way outside the realm of normalcy, like to the point where the car will not run. Watching what we call Calculated Load value is the absolute most acurate way to verify ideal sensor operation...however that is only accessed via the Consult.

O2 sensors could cause an issue...however they are more a reactionary device, if one side is leaning hard that would be more logical. However if both sides are lean well then I'm guessing it will be something related to both banks.

Good Luck,

[NightRiderQ45]

Thanks. There was a issue with the new new regulator, but I took it off and put the old one back on and my car was able to start. It even fell in specs of what the fsm stated. After reading multiple old threads, I'm thinking that its either my MAF or coil. I read that some coil failures won't come with a code and some are lucky to get the code which states with cylinder is missing. I don't want to replace all 8 so I plan on putting my car through both gears and pull a steep hill to try to force my check engine light to come one.

I also read to see if the MAF is going bad with the circuit board, tap the plug/circuit board with a screwdriver, knife and if car stumbles, dies, or change idle, the circuit board is the culprit.

[DrivingMyQ45IntoTheGround]

sounds like your car and mine are part of a greater conspiracy..

[goody90q45]

......Will bad coils throw on engine light? From reading threads here, I think the answer is yes. I don't think its coils since car runs great at times then turns horrible.......

I drive a G50 but from what I've read in other posts your symptoms sure sound like a dead/dying coil(s). There's been at least a handful of owners that have waited many weeks/months for the CEL to come on and when it finally did it was a bad coil. The O2 sensor Bank 1 code may have helped a little in pinpointing it. You could try switching all the coils from left side to right side of the engine and see if the problem follows to Bank 2. Or you can bite the bullet and install 8 new coils and be done with it. Good luck.

[SteveTheTech]

Always sage advise in the world of classic Qs. I doubt its an ignition miss partially due to the increased fuel pressure. After quickly skimming the thread again I never saw a mention of what the O2 sensor DTC was. It could have been a simple heater code, which is not related to any engine operation. Internet strategizing has its limitations sometimes as do all aspects of the repair process.

[NightRiderQ45]

Thanks for the replies all. Steve, the DTC code for the O2 sensor was P0138 (high/max voltage) but it went away by itself after driving THEN all of my issues started. As far as the fuel pressue, I've read that increase of fuel pressure (73psi car OFF switch in ON position) is due to bad fuel regulator. That makes sense because the new one installed (BWD not oem) would not allow my car to start period. I took the new one back off and installed old oem regulator, car started and fuel pressure was 38-40psi while idle. FSM states that it should be atleast 34psi while idle. Spoke with an Infiniti tech yesterday and he stated that FSM states 34psi at idle but they like to have psi around 38-40 at idle. That made me back away from fuel pressure regulator issue.

I spoke with someone yesterday about the MAF and they stated that if you unplugg the MAF while car is running, if it continue to run, MAF issue for sure. I did this and the car shut off so they stated that it isn't a MAF problem. I cleaned the MAF sensor with MAF cleaner on Monday but forgot to clean the pins and plug. Yesterday I used CRC QD contact cleaner on both the plug and pins of MAF and Temperature sensor. Dust was in the pin area so that lets me know that area isn't sealed like it should. I finished by putting dielectric grease on the pins and snapped everything back together. Drove car yesterday and today to work and no stumble. I will see the true test when I drive back once its hot outside.

I plan on testing out each coil today while car is running. I read that if you pull coil while car is running and performance doesn't change, that is the bad coil. Pulling good coil from spark plug should cause rough idle. But you are right goody, I might have to buy all 8 coils and be done with it. I saw a good price on eBay for Hitachi brand coils. $550 free shipping. I don't want to buy used coils.

[NightRiderQ45]

car ran fine yesterday until I filled back up with gas and the problems came back this morning. i'm tired of dealing with this car so I'm going to just start throwing parts at it. It has 226k and it hasn't been a problem child until now. I'm going to put spark plugs in it on Saturday. If that doesn't cure the problem, then I'm going to throw a rebuilt/new aftermarket MAF next. Don't want to deal with used where it already has a lot of mileage on it. If that still doesn't work, then I'll do the coils. don't think it's coils since my car ran perfect while it was low on gas. maybe me cleaning the contacts just helped the maf out for a while, then the true problems came back. was able to get code P0110 even though check engine light wasn't on yesterday. this is the idle air temperature sensor that's connected to the air duct. highy doubt that this will cause my issues. i think it's just the maf! if I don't go with oem, I will reset the ecm so that it can relearn the new maf.

[bullittandy]

I don't know for sure but could the full gas tank be a problem? Seems like a pattern but I don't know why that would be a problem.

I am also a fan of throwing parts at a car when stumped. Do change the plugs and really consider replacing the coils, I know its expensive but they're gonna need it anyhow.

I would also replace the O2 sensors, wear item and you got a code on one, again throwing money at it but I would suggest this even without a code.

Don't do a new MAF, get a used one off ebay, cheaper, ($75) and easily sold again if not needed.

[DrivingMyQ45IntoTheGround]

question: are you purchasing your gas from the same place all the time..


check to see if the SEL turns off on a empty tank.. and only use 91octane

check TPS
check MAF
check your alternator, a bad alternator with throw alot of random codes out. let alone other issues..

but if your light turns off on a empty tank than stop using that stations gas, cuz your issues sounds like water in the fuel to me. throw some octane booster in there and see what happens.. and smell your tail pipe a bit to see how rich you are running..

[NightRiderQ45]

Thanks for replies. I'm actually at shop now at it isn't the coils. We just checked all resistance between coils while they are off during plug change and they all fell in specs (1.3-1.5V). If 0ohms, then the coil would be bad. We also checked all coil harness connectors they all checked out good too (12V to ground). I'm glad that its not the coils so that save me money. I think its the maf and ur right Andy, I'm going with ta used one. Saw one online that came off a 99 maxima and they stay it has 87k on it. My passenger side VC is leaking so I'm going to fix that too. I pray that its just a bad sparkplug that is causing the problem. Will check back later.

[NightRiderQ45]

******UPDATE*******
I think I may have found the issue with my car. New spark plugs didn't fix anything. Car ran well then died on me. According to specs of fsm, it isn't the coils or MAF; both specd out good after I did test with volt meter today. I have to change both valve covers since oil is dripping on a plug on passenger and driver side. One thing that made me think it wasn't coils or MAF is because some days my car will run with no issues then some days I will have intermittent problems. I went back to the drawing board and thought it was probably a fuel issue so I checked the FPCM and Fuel pump dropping resistor.

Specs from FSM on FPCM and FP dropping resistor:
FPCM voltage should be ~4.4V @ idle plug connected
Dropping resistor resistance should be ~0.8 ohms @77 deg. plug disconnected

Specs from reading after testing today on FPCM and FP dropping resistor:
FPCM voltage was ~2.2-2.4V @ idle connected
Dropping resistor resistance was 0.1 ohms during first reading and 2nd reading after idle FPCM test was 0.9-1.1 ohms.

I'm a electrical engineer so I think that the dropping resistor needs to be replaced. It's obvisous that the dropping resistor is not within fsm specs. My logic is that the resistor isn't working correctly so it sends a bad voltage/reading to the FPCM which in turn sends bad voltage to my fuel pump which cause bucking. I think that the dropping resistor is imtermittent so that why I'm able to drive without any problems at times (it's within specs so it send correct value to FPCM to fuel pump) so my car drives with no issues. When the dropping resistor gets out of specs, I have the issue with bucking.

Does my logic makes sense. By the numbers above, the FPCM and dropping resistor were not within specs, but I think that the bad resistor is causing bad readings at dropping resistor. Or am I backwards and FPCM is causing bad readings at dropping resistor? Someone with knowledge please chime in. I see that Q45tech who has the most knowledge with our Q's read this eariler but hasn't offer to help at all which is ok...I'll get this car going. Right now I plan on replacing the dropping resistor.

[SteveTheTech]

Sounds like you might have nailed it.

I am not an electrical engineer but I play one on TV. It makes allot of sense that a faulty dropping resistor would have a drastic ripple effect. People often overlook these simple circuit elements due to a lack of knowledge of basic electrical theory. The dropping resister would be the easiest and cheapest (most likely) as to the best of my knowledge the fpcm is more than $400 new.

[NightRiderQ45]

thanks for the reply Steve. Well the problem is getting worst so I'm about to start pulling the plug on parts before this has me stranded. I ran across a very old post here were Qtech said that intermittent problems with the FPCM usually happens after the pump have been replaced within 2yrs. Well my pump was replaced in 11-08 so that sounds about right. Plus the FPCM did spit out an unspec voltage. Thought it was just the dropping resistor, but that old post stated that the resistor was added in 97 for safety concerns (car wouldn't completely fail due to fpcm). Tried to find one used online, but went to IOS and saw part for $188. #20 and dropping resistor is #21. Is this the correct part? http://www.infinitipartsusa.com/partloc ... atalogid=0
I'm guessing a new one would be better than a old one but hate to spend the coin and the problem doesnt correct.

[Q45tech]

I would bet against the dropping resistor as it is SOLELY a fail safe in case of FPCU failure.

[NightRiderQ45]

Thanks Tech! I read a old post from 2003 where you really broke down the fpcm and the dropping resistor. After reading that the fpcm starts to fail after the pump being replaced withing 2yrs(intermittent issues) I went ahead and called IOS today and ordered a brand new fpcm for $201 with shipping. It's only two screws holding it in place, so I should be able to replace quickly. i also picked up a used MAF on ebay (state 75k on MAF) so that should be here by Thursday latest. Once I receive that I will clean MAF and connector pins with MAF cleaner and use dielectric grease afterwards. Hopefully the fpcm didn't cause problems with fuel pump thats running now. Out of these two, one of these should fix my problem after extensive research and reading! My head hurts...

[NightRiderQ45]

My problem is fixed! I just wanted to update this thread for future Y33 owners who will probably go through this! I read a lot of old threads where people were selfish and didn't even update their thread with the solution. I put in a used MAF with 75k on it yesterday and my car didn't jerk/stumble at all. Drove it to work today (45mi commute) no jerk! The sad thing is that my $200 fpcm will be in Sat. and it seems like I don't need it now. Well I will still install the new fpcm with my 1.5yr old fuel pump and keep old module for spare.

What I've learned with this issue:
1. CEL doesn't have to be on for MAF to be bad
2. Don't automatically assume it's your coils. Ohm each coil and make sure they are in fsm specs. If not change THAT bad coil. Again, I didn't get any CEL for bad coil.
3. FPCM could've been the problem too. After studying the fsm, MAF is one of the sensors that sends values to fpcm. If MAF is bad, it sends bad values to fpcm.
4. ONLY use CRC MAF cleaner for MAF not CRC electrical contact cleaner. The electrical contact cleaner contains petroleum distillates that leaves film on sensor where as MAF cleaner doesn't. People do use the electrical contact cleaner with no problems, but why take the chance when they have the correct product on market!? I used MAF cleaner on MAF and elec. contact cleaner on pins and plugs. While you are at it, clean IAT sensor inside air duct with MAF cleaner. Button everything back up with dielectric grease for better connection.

So in layman's terms, FGY33 serious car jerking/buck and stalls/loss of power it's most likely MAF! If fuel pressure isn't adequate, could be fuel pump going bad along with fpcm.

If you are getting the slight stumble, miss at idle, it is most like your coil(s). Hopefully this will help someone in the future because I did a lot of testing and reading!

[ZMARKUS]

When I had these issues it was coils. I dealt with it for a while because it was a long time till it tripped a CEL. So you can have coil issues and not get a CEL. When it finally tripped a misfire code on a particulardid I replaced thecoil and it improved a great deal. Not completely though because all coils were in need of being replaced because of age. When I replaced all coils, problem solved and has been since.

[NightRiderQ45]

Exactly. It would be either coils or MAF with our cars. It the car is jerking violently, car cutting off while applying brakes, jerking once warm and pulling hills, it's most like the MAF. If you are getting the slight stumble(s), then it's the coils. When you had coil problems, did you car ever actually jerk badly and cut off at lights or while applying brakes?

[SteveTheTech]

Congrats,

Did you use contact cleaner on the MAF before realizing that?

I like how you make a point to say it might be _____ .

Although many symptoms may seem like they are the same as another thread here or elsewhere, that may not be the case. This thread is a great example, the fuel pressure seemed to be the problem. At the age these cars are at anythings possible.

That's part of the "fun" of owning an old Infiniti, it gets pricey fast.

[ZMARKUS]

Exactly. It would be either coils or MAF with our cars. It the car is jerking violently, car cutting off while applying brakes, jerking once warm and pulling hills, it's most like the MAF. If you are getting the slight stumble(s), then it's the coils. When you had coil problems, did you car ever actually jerk badly and cut off at lights or while applying brakes?

It never stalled but shimmed intermittently at idle. It would buck from stand still take off and would buck more noticeably if taking off fast from stand still. This became worse with A/C on. To remedy the problem I tried ISO-HEET in gas tank, fuel injection cleaning, induction cleaning, throttle body cleaning and none of these things worked. Replacing the coils did it for me.

[ZMARKUS]

Exactly. It would be either coils or MAF with our cars. It the car is jerking violently, car cutting off while applying brakes, jerking once warm and pulling hills, it's most like the MAF. If you are getting the slight stumble(s), then it's the coils. When you had coil problems, did you car ever actually jerk badly and cut off at lights or while applying brakes?

It never stalled but shimmed intermittently at idle. It would buck from stand still take off and would buck more noticeably if taking off fast from stand still. This became worse with A/C on. To remedy the problem I tried ISO-HEET in gas tank, fuel injection cleaning, induction cleaning, throttle body cleaning and none of these things worked. Replacing the coils did it for me.

Oh I almost forgot. Like I said this went on for man months before it tripped a CEL. I even took it to the Infiniti dealership and felt it was the coil but couldn't say which one. Reason is the diagnostic computer show all coils were within range of working properly, making it impossible for them to say which I should replace. They recommended replacing them all or waiting till it tripped a CEL that would expose which cylinder was bad.

[andersonfan]

I have an '02 Q45 (I know it's a different engine) and had some of the same issues; it turned out to be the camshaft position sensor was going bad. I don;t know if you have one of those on your Q but that was the culprit in my case (that time).