Candidate for a new MAF?

Post by **Microsoft94Q45T** » Mon Aug 29, 2005 4:32 pm

Since purchasing the car at the end of July I have done the following:

Coolant flushDiff oil changeOil flush, oil/filter changeTransmission fluid flushBrake fluid flush/serviceNew NGK plugsNew fuel pump (old one was a bit noisy at startup)BG Induction serviceNew OEM Air FilterCouple treatments of BG44k in addition to the BG induction cleanMAF & Maf Connector clean (they were spotless but cleaned anyway)New drive beltsInifiniti Consult including power balance test injectors range from 57-89rpm (this was done before all the work above)Power steering rack was replaced recently by previous owner

These items were done at different times over the last couple weeks since I have owned the car. I think that the new fuel pump and NGK plugs/induction service have done the most out of everything to reduce the hesitation and increase throttle repsonse. However... when I WOT it on an onramp or accelerate driving around the city there is more of a hesitation than I would think... especially when temps outside are hot (80+). When I am on the highway and up to cruising speed ~70mph, accelerating for passing/lane changing is pretty zippy.

Idle sits right at or just below the 750rpm when stopped in Drive. Putting it in Park idle sits at ~1000rpm. I also notice that if I put it in Neutral (when stopped in traffic) the brake pedal sinks just a bit and RPMS go up to 800 or so. Does this indicate anything in particular? Brakes work great and pads, rotors are within specs.

The car throws no codes, and makes no undue sounds that I can tell. No vibrations through the steering wheel - a pleasure to drive - I guess I just want to make sure I am getting maximum the throttle response I should be getting.

I will probably order a new MAF, even though the old one looked clean, w/120k it could be nearing the end of it's life.

About the only thing I have not done (proactively) is TCS fluid exchange and a fuel rail flush (I assume this is different than the BG Induction service?).

Any other suggestions?

Post by **maxnix** » Mon Aug 29, 2005 5:07 pm

IAC valve adjustment. Usually it is turned too far out to compensate for a less than pristine intake path.

Maybe check timing. Doubt it is MAF, but do check connection. Then check voltage vs. rpm.

Post by **greg_atlanta** » Tue Aug 30, 2005 1:52 pm

I just replaced an MAF which went bad on my '92 Q at 215K miles. Car was stalling at idle, and fuel cutoff at highway speeds (not fun). After replacing it the general sluggishness in hot weather did not change. I don't think you're a candidate for a new MAF, probably won't have any impact.

Post by **FarFetched** » Tue Aug 30, 2005 3:44 pm

I say KS ...No offer to help there sorry missed the opportunity

Post by **Jeff Williams** » Wed Aug 31, 2005 11:33 am

It does sound like retarded timing, more than a MAF issue.

First, check the initial timing and adjust it.

Knock sensors are difficult and expensive to replace at the dealership. T3 charged nearly $900 for Lola's sensors and harness.

Post by **Microsoft94Q45T** » Wed Aug 31, 2005 3:59 pm

Thanks, I am new to these so I am learning as I go along...

I am putting together a little consult pc so I can take a look at the diagnostic info and data without having to take it to a dealer. That [edit + this forum ] and the FSM should help me make sense of where the issue is.
Modified by Microsoft94Q45T at 8:53 AM 9/1/2005

Post by **maxnix** » Thu Sep 01, 2005 2:55 am

Microsoft94Q45T wrote:I am putting together a little consult pc so I can take a look at the diagnostic info and data without having to take it to a dealer.

Now there is a future article!

Post by **elwesso** » Thu Sep 01, 2005 5:57 am

let us know how that goes!!!

Post by **Microsoft94Q45T** » Wed Sep 07, 2005 12:22 pm

Well the temp outside has gotten cooler and the responsiveness of my Q has gotten noticeably better...

While I am waiting for the necessary parts for my consult pc, does this change in behavior make it more or less likely that failing KS are to blame?

BTW I have checked the MAF connector and it seems fine... there is no variation in engine idle when I try moving/flexing it.

Post by **FarFetched** » Wed Sep 07, 2005 5:53 pm

What gas statations(locations/brands) are you using?It does sound like KS. Wait until i rains for a day or two and see if it gets worse. Than it is for sure KS!P.S When you had it on Consult last time, were there any DTC's at all?

Post by **elwesso** » Thu Sep 08, 2005 6:00 am

Just got to autozone to have them check the codes, for free... that way youll know if the KS are bad

Post by **Microsoft94Q45T** » Thu Sep 08, 2005 6:01 am

No DTC's when the Infiniti dealership checked it... and no CEL at all since I have owned it.

From what I have read the ECU won't throw a code until the KS are totally toast though...

Post by **elwesso** » Thu Sep 08, 2005 6:03 am

Microsoft94Q45T wrote:No DTC's when the Infiniti dealership checked it... and no CEL at all since I have owned it.

From what I have read the ECU won't throw a code until the KS are totally toast though...

yeah but if they are retarding the timing they should throw a code... OBDII is different than OBDI

Post by **Microsoft94Q45T** » Thu Sep 08, 2005 7:12 am

So... are you saying that if I am not getting a code (on my 94 OBDI) then my KS are a-ok?

If so that is good news

Post by **elwesso** » Thu Sep 08, 2005 7:31 am

Wow I was extremely confused, i thought we were talking Y33, we were talking G50... Sorry for the misinterpritation....

IMHO, if the computer says theyre good, then they are good... They can give false readings but you woudl assume as they get worse they would at least once give a reading bad enough to throw a code.... A specific code is erased if it is not thrown for 50 startups...

Also, I think that when the KS go bad, as they are getting worse, it would show up as a small loss in power, say .2-.4 seconds (with some days being better than most, assuming temp/humidity is constant) off your 50-80 time (saying it would be roughly 5.5-5.7 vs 5.3) and when they go bad you can expect it to drop to the lower 6 second range in the 50-80 times.....

Doing a 50-80 time would really help show your HP and how healthy your car is.. Floor the car at 40 MPH, start timing at 50, and then stop at 80... Do maybe 4-5 runs and we can average them together

Post by **CoastyAV8R** » Thu Sep 08, 2005 8:38 am

Myself and Micro Q are in the same boat as we have a very similar problem. I personally think I have a heat sensitive MAF. The car runs great cold but once its warm and the MAF gets heat soaked, it hesitates and basically doesn't like to accelerate until the RPM's get up above 2500 rpm.

Here is the troubleshooting I did to help isolate the MAF. I got the car warm and verified it was running poorly. I then packed a bag of ice around the MAF and let it sit for 10 minutes. Then I drove the car and was running much better and after 5 minutes of driving with the ice bag still in place, it was running great. After seeing that, it was enough for me to roll the dice and get a new MAF.

Post by **Microsoft94Q45T** » Thu Sep 08, 2005 9:13 am

Very interested in your results - I can say, now that it is <70 ambient temp around here, the car drives a *LOT* better. Before I would put the hammer down and there would be a delay in acceleration, right now, there is none .

This improvement is regardless of how long the engine has been running and seems equally responsive cold or hot. I have also noticed MPG getting a little better as well (was ~15-16, now 17-18) in mixed city/highway agressive driving.

There is one other variable (other than amb temp)... I am running Auto-rx in the oil right now, so some improvement could be attributed to that, but I am pretty sure it is the reduction in temp that it helping.

Can't wait until I can get some diagnostic numbers myself... should put the issue to rest (or find new ones )
Modified by Microsoft94Q45T at 12:35 PM 9/8/2005

YouTube · Post by **Jesda** » Thu Sep 08, 2005 9:25 am

What are the odds you know my friend who works on the XBox escalation team?

Post by **Microsoft94Q45T** » Thu Sep 08, 2005 9:36 am

I know some folks on the Xbox Live team...

Post by **Microsoft94Q45T** » Thu Sep 08, 2005 9:37 am

Now we just need an ice maker in the engine compartment ...

Post by **CoastyAV8R** » Thu Sep 08, 2005 4:55 pm

We still have temps well into the 90's unfortunately so I don't know how it would run in cooler weather. I could probably get a darn ice machine for how much the MAF cost, I even bought it from Joe. I'll let ya know how the new one turns out...

Post by **Microsoft94Q45T** » Fri Sep 09, 2005 5:57 am

Can you explain what you mean about the rain? It was cool this morning, but rainy and I still had the improved performance I noted earlier...

Post by **CoastyAV8R** » Mon Sep 12, 2005 2:40 pm

Well I rolled the dice and came up snake eyes. It didn't fix it so I'm on to my next troubleshooting step, whatever that is...

IAC and TPS are where I"m looking next.

Post by **Microsoft94Q45T** » Mon Sep 12, 2005 3:02 pm

Just got my consult cable and software so I should have some interesting news on my end, perhaps it will help you with yours...

BTW I had a couple days there of much improved behavior, but the last couple have slipped a bit in the performance dept.

Post by **maxnix** » Mon Sep 12, 2005 6:02 pm

Does your service history indicate the KS and harness have ever been replaced?

Post by **Microsoft94Q45T** » Mon Sep 12, 2005 7:03 pm

Nope, but no indications of overheat either... Of course from what I have read here 120k seems like as good a time as any to have them replaced.

Post by **maxnix** » Mon Sep 12, 2005 8:57 pm

Yep, that's it. You could check the harness first, but by the time you get to it to replace it, might as well do the KS and hoses also and be good for your next 120K.

Post by **Microsoft94Q45T** » Tue Sep 13, 2005 6:43 pm

Well, got the consult pc setup and I see I have a Code 34 Detonation Knock Sensor

Too late tonight, tomorrow I will double check the harness and connectors (assuming they are within easy reach?). I will be digging into the FSM...

Post by **CoastyAV8R** » Wed Sep 14, 2005 11:59 am

Yuck, sorry to hear that. Did you try to run a diagnostic on the car first to get the codes out? The reason I ask is because that is what I'm going to look at next.

Post by **Microsoft94Q45T** » Wed Sep 14, 2005 3:52 pm

Not sure what you mean... when I ran the consult self diagnostic, it came back with the Code 34. I have not tried erasing it and seeing if it will come back though (will try that tonight).

The consult also confirmed my idle is a bit high, but I am not going to mess with that until the knock sensor stuff is worked out.

Candidate for a new MAF?

Candidate for a new MAF?

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (greg_atlanta)

Re: Candidate for a new MAF? (FarFetched)

Re: Candidate for a new MAF? (Jeff Williams)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (maxnix)

Re: Candidate for a new MAF? (maxnix)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (FarFetched)

Re: Candidate for a new MAF? (FarFetched)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (elwesso)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (elwesso)

Re: Candidate for a new MAF? (CoastyAV8R)

Re: (Jesda)

Re: Candidate for a new MAF? (CoastyAV8R)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (FarFetched)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (CoastyAV8R)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (maxnix)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (maxnix)

Re: Candidate for a new MAF? (Microsoft94Q45T)

Re: Candidate for a new MAF? (CoastyAV8R)

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