Something I noticed when cleaning out my TB today (also did the Seafoam thru brake vacuum hose for the first time, though only used 5 ounces versus the entire can). Definitely smoked a lot, hopefully it’ll cure my blue smoke too…seems to.

Anyhow, the issue with my throttle lagging on acceleration and even highway driving has returned!! Idk why the f***. I literally haven’t had this problem all year long, but between my engine idling for almost two hours when I locked the keys in, and then replacing the battery after it died: seems the issue has come back. Trying to walk back thru what I did before to fix it: replaced one TPS sensor, but guess there’s also a TPS switch as well. I wonder if that may be causing it, but still no codes pointing to it!

For whatever reason, I don’t recall the first throttle plate being wide open, but the 2nd one is closed. No high idle or anything, 650 in N.

Also changed my EGR valve, first time probably ever since it still said Nissan. Was a like gummed up but not blocked.

Have you checked the camshaft position sensor? It does the same thing a distributor does as far as engine timing is concerned. Also, check and ensure the power transistor and starter are good also.

cbird805 wrote: ↑

Mon Aug 07, 2023 6:35 pm

Have you checked the camshaft position sensor? It does the same thing a distributor does as far as engine timing is concerned. Also, check and ensure the power transistor and starter are good also.

I did mess with it awhile ago, it was leaking and had to replace the o ring. Starter good, cranks right up.

It's a optical sensor that reads what degree the camshaft is reference to the crank. The reason I brin it up is that it has to be timed like a distributor does. With a timing light, it should be adjusted to 30 degrees plus/minus 2 degrees. If it needs adjusting, then idle has to be adjusted as well IAW FSM section EC. But if the car was running fine before, and you noticed a performance deficiency, then it probably isn't the issue. It's a mechanical throttle, that has a secondary tied to the cruise control actuator. Maybe that's the problem? How does your cruise control work? or your WOT is stuck?

cbird805 wrote: ↑

Mon Aug 07, 2023 9:23 pm

It's a optical sensor that reads what degree the camshaft is reference to the crank. The reason I brin it up is that it has to be timed like a distributor does. With a timing light, it should be adjusted to 30 degrees plus/minus 2 degrees. If it needs adjusting, then idle has to be adjusted as well IAW FSM section EC. But if the car was running fine before, and you noticed a performance deficiency, then it probably isn't the issue. It's a mechanical throttle, that has a secondary tied to the cruise control actuator. Maybe that's the problem? How does your cruise control work? or your WOT is stuck?

Well I looked at the FSM , it does show the first butterfly valve is open normally. Though I wonder why it’s not closed like the other one is. Doesn’t give much explanation I can understand.

Cruise control works as it should also…

Problem that happens: pull off from a stop (and this is very intermittent not every time), engine lags. I can try to give it gas, but it’ll just bog down more, won’t go above 1,000/1,500 rpm for a few seconds, and then surge up to 2,000, then pop back down. Almost as if there’s water in the gas tank. But I put the Heet stuff in already, and several times when it has happened. It does seem to fix it, but not all the time.

On the highway the other day, I can feel it bogging down while driving. Just accelerating from 50 to 70 mp, it has to “revv” up like it’s a loaded Corolla lol. Maintains speed but just feels heavy. Get off highway, stop for gas: turn car back on, temperature gauge moves to 3/4 a way to H…Almost to the first hot line. meaning the bogginess is putting so much load that it’s causing the engine to also run hot.

Had this conversation here before, some said catalytic converter. I could run another exhaust cleaner I suppose, but I’m not getting cat codes except rear 02 sensors.

The issue will also magically disappear if I turn car off sometimes. Then it acts normal, before doing it again at some point in the drive. But this is frustrating because I haven’t had this problem in MONTHS! Even did some long distance trips.

I’m just exhausted trying to put parts into the issue. This is the only performance issue I have. I’m not losing (much) coolant either, so can’t imagine it’s a head gasket. It almost seems like an electrical issue…I started to change the battery cables. But it’s not having problems with starting or electrical usage so figured probably not

Do you have a scanner to look at live data? You might want to see that your MAF reading is in spec, and see what the o2s are reading when the engine is bogging down.
Do you know that the engine is actually running hot when the gauge moves to H? Could be an electrical problem. Might want to check your grounds.

fontana dan wrote: ↑

Tue Aug 08, 2023 10:06 am

Do you have a scanner to look at live data? You might want to see that your MAF reading is in spec, and see what the o2s are reading when the engine is bogging down.
Do you know that the engine is actually running hot when the gauge moves to H? Could be an electrical problem. Might want to check your grounds.

Yeah, I have a small plug in scanner that I can look at on my phone. Maybe I can try it, take some screen shots and post here…

So here’s a few images: basically showing the temp gauge going up under load on the highway with the A/C on. And then the codes (I already changed intake air sensor before, must have been some point when I unplugged it.

And then a screenshot of the maf versus one o2 cat sensor. And then versus the 2 o2 sensors.

I’m just so pissed off. I’m about to maybe run another bottle of cataclean or similar in the meantime until I can get it to a real diagnostic… if it seems to be exhaust related. I know I did the Seafoam/gumout thing on 2 vehicles: The oil burning Q smoked way more than my other vehicle that doesn’t smoke but had a problem with gummed up EGR valve.

You have a lot of codes. Figure out whats going on with your knock sensors, IAT, and downstream O2 sensors.

fontana dan wrote: ↑

Sat Aug 12, 2023 5:50 am

You have a lot of codes. Figure out whats going on with your knock sensors, IAT, and downstream O2 sensors.

I already tried the downstream o2 sensor replacement. Was a waste of money because it didn’t even fix the CEL. Previous owners cut the wires and used an aftermarket. Went and had them replaced and re-wired, $180 later and still didn’t work. Even replaced the fuse, which I found to be open. I probably should have tried that first.

I think the knock sensor comes on as a result of the bogging issue. If I clear all the codes, usually it’s just the o2 sensors that will come on.

I watched a video yesterday of guy with a G35 changing out the TPS sensor. Same symptoms (pressing peddle and it intermittently not having power and just getting worse over time) and some people not getting codes. I think I changed out the wrong one. I’m going to take one last ditch effort to change the “main” one and see if that’ll fix.

Is your first throttle plate for traction control? If so, I think it would only close when the TCS is actively trying to cut power.

Stop throwing parts at it and diagnose the problems. You've got a handful of codes stored which gives you the places you need to start diagnosing - follow the diagnostic procedures in the FSM for each code, because codes don't tell you what parts to replace, they just tell you where to start looking for the problem.

Ryantzer wrote: ↑

Mon Aug 14, 2023 3:48 pm

Stop throwing parts at it and diagnose the problems. You've got a handful of codes stored which gives you the places you need to start diagnosing - follow the diagnostic procedures in the FSM for each code, because codes don't tell you what parts to replace, they just tell you where to start looking for the problem.

Well, for the most part I’m mainly just checking my bases. Air filter and egr were likely due anyway.

However Part of the issue with the FSM: half the time I can’t get it to open the menu. It gets to q45, then doesn’t do anything when I click on it.

The intake air sensor one is new…I wonder if it’s related to it. That would certainly be an after market part gone bad since I replaced it couple years ago already.

Have you worked on the cooling system? Download the manuals. Here are some snapshots from Engine Controls manual.

98_Q45 wrote: ↑

Mon Aug 14, 2023 5:31 pm

However Part of the issue with the FSM: half the time I can’t get it to open the menu. It gets to q45, then doesn’t do anything when I click on it.

I've got a PDF of the FSM on my laptop, it opens every time.

Thanks for posting that. I use a chrome book so not sure that has anything to do with it. I can usually open it, lately haven’t. Idk why.

I have worked on the cooling system, oddly enough I’m not losing coolant during the hot running. Which is good, probably rules out head gasket.

Based on the manual, it’s saying the air intake sensor doesn’t control engine function which maybe mean: it wouldn’t cure the issue if I replaced it?

And come to think of it, I don’t think I did replace it before. I replaced it on 2 other vehicles, but I think I just cleaned this one, and also repaired the wiring and harness, as it was torn at one point.

It’s so disappointing having this go on and not knowing why. Not to mention my clearcoat on the roof is all peeling off by the week. I just don’t want to “give up” on it, but I’m like dayum: should I see if I can get $1,500-$2,000 for it? Problem is, I need a 2nd vehicle and at that price, that’s only a down payment on more payments for something different. Seen a FX35, 2008, going for $8,000. But I don’t even have that lol

Main thing is, how did this issue come back? I did like two road trips and hadn’t had the problem all year. I think the last thing I fixed that seemed to solve it, was the ignition coils. But I’m not going to do that again since it’s not misfiring.

only thing that has changed was: letting the engine idle for over an hour and a half (which burns oil) and then replacing a failed battery (econo power salvage yard rebuild from interstate). But everything electrical works fine. I’m really fearing the catalytic converter, one or the other is gone to toast. I have a bottle of cat cleaner that I’ve used before with some success, but gas is so high I can’t afford to fill it up lately and do the whole cycle.

Will try one last effort to replace intake air sensor and perhaps clean the maf (which was replaced earlier on during this issue) and see. Next stop is the shop lol.

Instead of replacing the intake air sensor, test it first to see if it's good. You're still just wanting to throw parts at it hoping something fixes it.

Ryantzer wrote: ↑

Wed Aug 16, 2023 8:26 am

Instead of replacing the intake air sensor, test it first to see if it's good. You're still just wanting to throw parts at it hoping something fixes it.

Well, I did take a look at the sensor and…just noticed one of the wires is separated from the harness. So that’s why that’s giving the code. Can’t believe I missed that. I replaced that before, salvaged…But guess it’s time to go with a new one. Perhaps that’s been the issue the whole time, but I don’t know until I get a harness for it.

I know part throwing is frowned upon but…I’ve fixed a lot of mystery issues and overlooked maintenance items by part throwing lol. At one point had no idea my whole purge valve system was clogged with charcoal lol. But I understand how it can be a waste of money and time.

However: at one point, I had all codes clear except the catalytic oxygen sensor codes. And I even took it to a shop to have it re-wired and installed. Like what the f***?? I’m hoping maybe the IAT wiring was just giving intermittent issues all this time, and goes away with a new harness

And considering the issue of acceleration bogging occurs mainly when reaching operating temperature: I’m hoping this intake sensor will be what’s wrong. I just can’t think of anything else…unless the catalytic converter only clogs when it’s hot idk…definitely last resort on that, it’s a $600 part

Good idea to check and replace that harness. The service manual indicates that an IAT fault can cause drivability issues, so I think that is a good place to start.
Do you have the original cats on the car?

fontana dan wrote: ↑

Thu Aug 17, 2023 10:34 am

Good idea to check and replace that harness. The service manual indicates that an IAT fault can cause drivability issues, so I think that is a good place to start.
Do you have the original cats on the car?

As far as I know yes. But I’ve only had it since 2018 so not sure what could have happened prior to then. I just know whoever tried to replace the cat oxygen sensors (and why idk) messed them up with aftermarket crap and bad wiring job. I replaced both with Bosch and had a shop re-wire it, yet I was still getting the same CEL. Replaced burnt fuse, same thing too. But I wasn’t too pressed to keep chasing it down because it’s been that way long before I started having this issue.

At this point, waiting on the connector. 2 part stores advertised it but couldn’t have it ordered. So had to rockauto it. Debating if I want to return the sensor but, considering I already brought it…f*** it. $65 extra so far, diagnostic wouldn’t be any cheaper.

Last ditch effort, if not…guess I’m paying $169.99 for Infiniti or $89 at local shop, to figure it out

Also not sure if this matters, but I did the seafoam “trick” and had smoke immediately coming out as I was pouring in the liquid, and more as I was driving. exhaust does burn oil, but it’s not like I can’t drive it anywhere without adding. most times, I can drive highway 1,000 miles and only need to add 1/4 quart. Basically about 1 to 2 quarts per 5 to 7.5k oil change intervals. And that’s on old oil. With new oil, I barely need to add anything. I use oil additives regularly.

Update: replaced the connector, as well as replaced the intake sensor. Put it all together but…It seemed to have fixed it until after a few miles, it started having the same issue bogging down again. Still intermittent and comes and goes. So far these are the only codes that trigger after being reset:

Knock sensors could cause the issue you’re having. If the ECU thinks there’s detonation due to false info from a bad knock sensor it will retard timing.

Ryantzer wrote: ↑

Sun Aug 27, 2023 9:06 am

Knock sensors could cause the issue you’re having. If the ECU thinks there’s detonation due to false info from a bad knock sensor it will retard timing.

Hmm, thanks. It’s just I had knock sensor code on maxima for years. Finally changed it (damn near impossible to) but didn’t notice much in way of performance differences. But I will say…something else shows up when I reset the code and let the issue trigger. The code for high voltage and slow response seems to pop up moreso.

I did buy one knock sensor already, but I never installed it because the work involved. And also the issue went away for awhile, before returning.

Knock sensor code only triggers when the acceleration issue pops up. It’ll feel like it’s struggling to accelerate and will seem to “backfire” or pop if I give it too much gas. It’ll slowly get up to speed as much as it needs to, but I can feel something like I’m towing 10, 000 pounds, and giving it too much gas will hardly do anything.

If I’m pulling off from a stop, something in the engine or exhaust sounds like pop. If on highway, it’ll require revving to like 3,500-4,000 just to go 10 mph faster. The issue will intermittently go away, and shift as usual: but lately all of a sudden it’s been more frequent.

Ran a bottle of catalytic cleaner yesterday which seemed to have also helped, but has still cropped up again today. Haven’t completed the tank though.

As an update: unfortunately the intake sensor fix didn’t fix the issue. It’s still losing power on hills and acceleration, getting crap fuel mileage, and running hot. I even gunned it today with O/D off and flooring it as far as it’ll go: but it wouldn’t even go above 85 mph.

I honestly don’t know what the f*** it is anymore. Will have to take it in to get diagnoses because it’s just beyond me. And at this point it’s doing it often enough to hopefully be monitored versus just intermittent. I’m in between cat clog, or timing/knock sensor issue. I just can’t invest anymore time or parts into trying to figure it out without a definite cause.

So annoying…probably have to wait 2 weeks or so just to get it in to a shop. Exactly why I keep more than 1 vehicle.