HELP! weird bog/boost problem! help asap at track now! naked chicks inside!

[300Plus]

Glad to here its not rings or headgasket. I threw in new plugs and added a better ground to the the coil pack rack, and still had the same problem. I noticed after a little data logging run with the problem that I had a little plateau on the MAF voltage, pegging at 4.0 for a split sec, and I'm pretty sure I'm not running 320hp yet to max the stocker MAF out. I'm running the stock MAF as blow through and using the stock skyline gtst fuel pump. but when the bogging occurs for me, my AEM wideband hits 10.0 and flashes so I'm not running out of fuel I'm getting too much.

I read that a 95 maxima MAF is the same as the series II maf, so I'm going to look for one this week/weekend, hopefully that will fix my problem.

This weekend I will also check my Neutral safety switch, it hit me lastnight that maybe a wire came lose and now the computer thinks its in neutral, and cuts spark....

Any other thoughts ?

[240z4u]

300+

Yes you can use that MAF. I have one on my S2 motor. Works fine.

I too am maxing out my MAF at some points. Its not totally consistent. I think its a turbulence problem under boost. I am also blowing through mine.

I know I am not making enough HP to max out my MAF but still do sometimes. Then of course, it runs super rich and like poo.

Keep us updated, because I am wondering if this is a symptom of my maf location. I am assuming you pretty much have your car tuned, I have heard its pretty normal to run richer with the blow through setup.

Evan

[300Plus]

300+

Yes you can use that MAF. I have one on my S2 motor. Works fine.

I too am maxing out my MAF at some points. Its not totally consistent. I think its a turbulence problem under boost. I am also blowing through mine.

I know I am not making enough HP to max out my MAF but still do sometimes. Then of course, it runs super rich and like poo.

Keep us updated, because I am wondering if this is a symptom of my maf location. I am assuming you pretty much have your car tuned, I have heard its pretty normal to run richer with the blow through setup.

Evan

Awesome, thanks for the confirm!

But see i ran fine for 6-800 kilometers with the same exact setup, then I turned up the boost a little (from 7 to 12psi) and then this problem started. the cars runs fine outta boost but when boost hits I get nothing but fuel... its basically like I have no motor after 3800rpm no matter what, every single time.

[300Plus]

240z4u - Was the 95 Maxima a 4 cylinder or 6 cylinder?

[Yellow4g63]

I had my cas go out about a year ago, this feels NOTHING like that...I don't think I'm gonna be able to source one before sunday....

My friends went out in his RB25 before and the car ran fine. It just didn't make any power up top. Something to check out if you have any other RB friends.

[Sil240]

95 Max is a 6 cyl, the 4 cyl Max's were like in 85 i dont even know

[Carl H]

when maf voltage hits 4.1v for more than 3 sec the ecu will hit the boost limter and will dump mad fuel...that being said a maf that has taken a **** will also cause it do dump fuel.

[300Plus]

when maf voltage hits 4.1v for more than 3 sec the ecu will hit the boost limter and will dump mad fuel...that being said a maf that has taken a **** will also cause it do dump fuel.

Awesome to hear from a trusted source. I can tell by looking at the data logging graph that I am having the issue as the MAF is maxed for a sec or two. so the maf might not be bad. But I was under the impression the MAF would be good for 320hp as blow through or the stock setup.... I doubt I'm pushing 320hp at 12psi (stock turbo).

If I can find a cheap 95 maxima MAF I might extend the wires and run it behind the filter, if that works I'll try it as a blow through , to see if the problem returns. If I have to swap to the stock setup for good I guess I'll have to go recirculated...

[Carl H]

blowthru or drawthru you'll still see the same ammount of air, only way around this is to either rechip (stupid expensive) or get a pfc.

[300Plus]

blowthru or drawthru you'll still see the same ammount of air, only way around this is to either rechip (stupid expensive) or get a pfc.

well thats true. This is what makes me think the MAF is damaged because I shouldn't be pushing 320hp at 3900 rpms... (I wish)

Am I right win I say the stocker should max at 320hp?

I mean I've heard of so many people running a stock setup and turning the boost up to 12psi... I'm wondering why I'm maxing out. I'm running the HUGE custom intake mani (nateco), Q45 TB, FMIC, 3inch coldside, 2.5inch , hot, Nismo FPR, r33 gtst fuel pump, stock ECU, stock turbo...

Thanks for the Help guys!

P.S... Carl, Nate was wondering if you had a chance to send that stock intake mani? get me on AIM (waahiven)

[S12_hybrid]

It doesnt sound ignition related, as it would normally just bog under power with bad plugs, or coils.. It really sounds like a leak (I know you've tested the pre-manifold stuff).

But try this: Grab a butane torch, and with the car running poke it in and around the intake manifold runners (near the gasket) and the IAC valve, and anywhere there would be a potention crack. And if the idle rises, you've found your leak. note: DO NOT LIGHT THE TORCH!

-Dan

[300Plus]

It doesnt sound ignition related, as it would normally just bog under power with bad plugs, or coils.. It really sounds like a leak (I know you've tested the pre-manifold stuff).

But try this: Grab a butane torch, and with the car running poke it in and around the intake manifold runners (near the gasket) and the IAC valve, and anywhere there would be a potention crack. And if the idle rises, you've found your leak. note: DO NOT LIGHT THE TORCH!

-Dan

Yea I don't think its ignition either... something is telling me its some senor making the ECU dump fuel. I hope to have a big update this week , going to try a new maf and a few other tricks.

I've heard to the butane/propane trick before and figured I might have to go as far as that but we will see. thanks guys!

[Sil240]

It doesnt sound ignition related, as it would normally just bog under power with bad plugs, or coils.. It really sounds like a leak (I know you've tested the pre-manifold stuff).

But try this: Grab a butane torch, and with the car running poke it in and around the intake manifold runners (near the gasket) and the IAC valve, and anywhere there would be a potention crack. And if the idle rises, you've found your leak. note: DO NOT LIGHT THE TORCH!

-Dan

Yeah, thats a good trickI've done it with a cigarette, just blow the smoke where you think it is and see if it gets sucked up.

[T_love]

I suddenly have the same problem, except mine bogs when idling, driving like Miss Daisy and gunning it. Every once in a while, mostly at highway speed, it drives normal but then goes back to cutting off. this just started a few days ago and i thought(still think) it might be weather related since temps dropped this past week.

Is there anything that might be affected that much by weather?

This morning it was bogging and popping so violently i almost got stuck on an onramp. Needless to say its kinda getting embarassing not to mention dangerous.

P.S. car has been on the road for about 2 years now without much of any problems.

[300Plus]

I'm pretty sure I have some how damaged my MAF to the point where it reads but maxes out sooner then it should. Check the ground wire to your maf.

Still working on picking up the new MAF for mine to see if that was the problem

[Darius]

cdorhout blew a silicone coupler off when the temps dropped around here and he described the car as a buckin' bronco. He couldn't get it much above 2000 rpms, but he also has a pfc with a blow thru maf. Might want to check your intercooler piping, etc.

[Sky80]

I'm pretty sure I have some how damaged my MAF to the point where it reads but maxes out sooner then it should. Check the ground wire to your maf.

Still working on picking up the new MAF for mine to see if that was the problem

Hey let me know if this works out or not, i am having the exact same problem with mine right now and we both have the same mods except mine is a 20 (q45 TB/ 3"cold/ 2.5" hot/ RBTally intake manifold/ stock turbo/ RB20) i am running 12 psi as well and it acts like it is some how sensor related, i have a friend that has a 20 locally but his has a z32 maf so i cant switch mafs with his, but we have switched just about everything else and still it does the same thing...

[T_love]

so, i took out the MAF and cleaned it, took out the O2 sensor and cleaned that too, cleaned some of the intake piping, loosened up and re-tightened most of the IC piping. I was going to change the Air Filter too, its filthy, but i bought the wrong size so i will be doing that tonight.

Keeping my fingers crossed but it seems like something in that whole process fixed the problem. Car drove great all the way to work without a single hiccup. It is a tiny bit warmer today but i would like to believe that its not the reason why its running well.

My O2 sensor had thick black layer on it. I assume that means i'm running super rich?

[Joe]

its normal for o2 sensors to have carbon deposits on them. its a harsh environment for a sensor to be in.

[rcrdps]

The bucking and bogging on mine was a MAF. I changed it to a Z32 and it has worked fine.

I have also had a high end very slight bogging. That was it kicking into the knock sensing map. I have the knock sensing map setup with very low timing and very rich so that I will know when it kicks in. Aside from the feel of the car, I can also watch the wideband. If it goes to 10:1 or lower, that's my knock map.

When my MAF went bad, it did the eact opposite as ya'll are describing. It would drop a volt( Maybe it was going to zero. I was watching a gauge, not a log). That usually lasted a couple of seconds. Then it would go on about it's merry way. But often, it did the same thing several seconds later. I still won races,...just not by as much.

Gene

[300Plus]

Hey let me know if this works out or not, i am having the exact same problem with mine right now and we both have the same mods except mine is a 20 (q45 TB/ 3"cold/ 2.5" hot/ RBTally intake manifold/ stock turbo/ RB20) i am running 12 psi as well and it acts like it is some how sensor related, i have a friend that has a 20 locally but his has a z32 maf so i cant switch mafs with his, but we have switched just about everything else and still it does the same thing...

Hey man.

I'm 98% sure my problem was, I had one tiny strand of wire still attach to the MAF ground the others apparently broke when I drop the clutch at 6k rpm on drag radials... the scary thing is I'm using solid metal mounts.... so what moved?

But anyways I found the mostly broken ground wire and in the process of re-soldering I did something stupid (long story) and killed my MAF so I'm going to grab a new one and make sure the ground is good to go then I'll let everyone know for sure. But my advice... CHECK YOUR GROUNDS, especially the maf grounds.

[Chaos the Xile]

I had a similar problem, awhile abck, what happened was the #1 & 5 Spark Plugs fouled out, I think I read that you checked them, also check your fuel injectors to see it they are working properly

[Joe]

Update: last Saturday was an event i have been organizing and planning with a couple friends since September. my car ran PHENOMENALLY all day. absolutely no issues. so whatever the problem was, hasnt resurfaced. i murdered 10 tires and covered my car, myself and my passengers in tire dust. it was a great day.

[Sil240]

Hey,Have you checked all of your wires.Sometimes Squirells or whatever start chewing on your wires.I had a customer come in twice for chewed up windshield water hoses, because of that.

Or have you checked your Knock sensors. (if you did, I didn't read the whole thing 2 lazy)

[300Plus]

***UPDATE*** but not good

Threw a new MAF on, re soldered and wired the maf wire extension....

Checked ground wire for continuity to the chassis and was no resistence....

cranked her up sounded strong....same problem

I'll be driving at like 20 mph (speed has nothing to do with it) and I'll hit the gas and as soon as boost hits the wideband pegs at 10.0 and the car bogs horribly.

After checking with my nissan consult software I see that my MAF is still pegging at like 4.6 volts when the problem starts....

why would I be maxing it out guys??

My next post will be pics of the graph showing the voltage and the data log file if you guys have software to veiw it please help fellas gettin tired of it ya know?

[300Plus]

You can see the sensor being measure on the left and its voltage at the point were I have the red arrow. If other sensor are needed to be compared (as in RPM & AAC valve) just let me know and I'll do that and post the pic.





Hell here is even a pic of the data replay again notice the Air Flow

[rcrdps]

Your slopes are all nice and smooth. No spikes like a faulty sensor. Looks like it could be more of a boost leak.

Where is your BOV? Is it operating as a blow off, or as a bypass?

Then again, maybe you really are maxing your MAF. You nearly doubled your boost, and with that high flow manifold,......

Gene

[T_love]

I celebrated prematurely. My car just became undrivable today. Whatever my problem is, it seems to get really bad when its cold outside. Temps went down today and suddenly its dying all the time, whether i'm on the gas or its idling, its all the same.

I think i might go get some coils and get the timing checked too.

[300Plus]

Your slopes are all nice and smooth. No spikes like a faulty sensor. Looks like it could be more of a boost leak.

Where is your BOV? Is it operating as a blow off, or as a bypass?

Then again, maybe you really are maxing your MAF. You nearly doubled your boost, and with that high flow manifold,......

Gene

Well I went throw the obvious boost leak areas and felt around every coupler but it hit me lastnight that the hose I have running under the intake mani that goes to the IACV may have a leak...

Since I'm running a Blow throw MAF on the cold side (B.O.V on the hotside) I figured the only boost leak that would cause such a problem would be obvious but for some reason I hadn't thought of this one hose, so I'll update you guys after I get a chance to check it out. If it is the hose I will most likely have to yank off the intake mani to get to it

[T_love]

interesting article here: http://www.nissanexa.com/mods/n13/cleancoils/index.html . I have been leaning toward the coils and ignitor but don't have the funds to change all of them so i might try the cleaning and see what that does