Ugghhh!!! Is this a Knocksensor sympton 95 Q45

[rsiwicki]

Well on my way up to the 1/4 mile track tonight I was on the turnpike where traffic had thinned out and I was able to get some nice WOT and almost WOT on the way up there. Well come to find out...my car has a one time miss under 99% throttle as soon as it gets above 4,000 rpm. The miss goes something like this....say you are at about 70mph and then accelerate, not at WOT, but the next notch down from that where you can feel the pedal sort of stop before hitting WOT causing the car to downshift, anyway cruising at about 70mph and then pushing the pedal all the way down to that notch before WOT and the cars rpms jump up to about 3,500 or so and climb at a good steady rate under a good load.....well when the car hits about 4,200 rpms all of a sudden the rpms just jump right back down to 4,000 and begin accelerating again all the way from there until the redline with no more jumps or anything like that. You can also hear the engine change as well for that second where the rpms drop by 200rpms then it just starts climbing again. This also does it when I accelerate from 80mph where I am going from cruising to almost WOT the rpms go to about 4,500 and then accelerate fine until about 5000rpms and then all of sudden, wham!!!, there it is again this funny decrease in acceleration for 200rpms and then everything is fine again until redline. Under WOT I don't see or feel this at all and my idling and normal driving rpms are perfectly smooth. The cruising rpms also appear smooth as well. This only happens when the rpms are above 4,000 rpms and only happens one time until redline with the throttle pressed right to the notch before WOT happens and the car downshifts.

Any help is much appreciated as I am trying to get this car running in top shape, but have not had the best of luck lately with dealer mechanics and the like.

BTW...the car is a 95 Q45 with 137K and was just at the dealer for numerous things including O2 sensors. The knock sensors were replaced at 117k buy the dealer and I specifically remember them saying that they replaced all of them so I don't know why they would be acting up again as the feeling in jump in rpms is close to what I was feeling the last time when the knocksensors went bad, but not exactly.

Q45tech...I think it is very safe to say that we will get to meet each other face to face in May or the beginning of June as I would really like you to look over my car after I get all these mods done to make sure everything is operating correctly and to have a piece of mind that somebody would not forget to hookup and air hose after doing a throttle body cleaning.

:help :help :help :help :help :help :help :help :help

[rsiwicki]

okay...I had the dealer mechanic that worked on my car go for a spin with me this morning to show him the problem. After I replicated the problem he tells me that he does not know what it is but that maybe it is normal for this car with 137K on it.....Again this is the same damn mechanic that replaced my steering rack and was givign me crap about how the adjustment is not included in the price. I tell him where he can stick that comment and ask him what car on earth would it be normal for all of sudden to have the rpms drop by about 250rpms and then start increasing again all of this while under hard acceleration. He says...that he does not work on these car much and that he would get the head mechanic to go for a ride wit me. Then he tells me are you sure that it was not doing it before...I am 99.9% positive that this was not happening before and then he tells me that this is going to cost more money to find out what wrong with it....No $hit Sherlock!!! I told him that I just did not get done spending over $3,000 on parts and labor to not have my car running running like crap and I speicifically told this mechanic while he was working on my car that I want it running it tip top condition...nothing left untouched and to check it all over. This whole experience is really the pits to say the least. Well the head guy was busy under a car for a while and I needed to get my day going and could not wait around any longer and I was going to lose my cool with them all which never gets you anywhere. I will be taking the car back to them next week Thursday when they have a loaner available for me to have them look into the problem in more detail. Also the mechanic told me that when he replaced the O2 sensors that he had to reset the idle, timing, and air to fuel mixture and that he bumped up the idle above specs a tad. I asked him why....he says because it helps smooth out the vibrations in the engine and the customers prefer it that way. Okay my next question is was there any vibrations in my engine before hand. His reply is No, but I thought that you would like the timing and idle bumped up. Another fine example of incompentance.

I can't believe this crap and after having them service my car always...such as 120 service, knock sensors, driveshaft....etc they give me this crap.

Sorry I had to get this off my chest. If anybody has an idea of what this could be please comment becuase I don't think that they have the clue as to whats wrong.

[DAEDALUS]

Can you check to see if there are any codes stored on the ECU? If it's your knock sensors the codes will show up.

Ask the tech how he reset the timing and air/fuel mixture. Is he into reprogramming ECUs? Customers do prefer a smoother engine, but bumping the idle is a cheap shortcut.

[rsiwicki]

thanks for your response DAEDALUS....I guess I need to buy a code reader thing. Where can I buy one and what brand, make do I need. This would probably save me a lot of aggravation with the dealer.

I will ask him about how he adjusted the timing and air fuel mixtures...I am a novice car loving nut and read up on cars so my knowledge on this stuff is somewhat limited...but I was thinking the same thing about increasing idle speed was a cheap trick.

Just another question about ECU....When I get my JWT ECU, will the dealer be able to reset the new programing??? I asked JWT this and they said no...that only they could reset the programing of the ECU as they put a code lock on it. Is this true that once I get my JWT ECU that the dealer nor anybody else will be able to reset it. If so this is great...otherwise I am going to have to worry about the dealer wipping out my $600 JWT ECU program.

[rsiwicki]

Does anybody have T3's number. If things don't work out next week Thursday...then I am going to get the car one way or another up to Denise very quickly to have all these issues fixed. I really need to address all these issue with the amount of mods and $$ that I am sinking into this car. Otherwise all of this work is no good when the car drops by 250 rpms for no apparent reason...it is a very smooth and controlled drop, but damn it sure the heck is not right.

Thanks...Rob

[rsiwicki]

Well I talked with Doug at T3 today...he said that it was almost definetly the knocksensors as this is the only thing that can do this to the engine as I described the problems. It go worse today on the way in to work doing 100 on WOT it started to hesitate and wobble the rpm needle which it was not doing last night and I remember this sympton very well from the last time my knocksensors went to the $hitter. I am seriously thinking about getting my car up to Atlanta within the next 2 or 3 weeks after I get the new transmission and differential. I have a god child to see and I grew up about 5 hours from Atlanta in Florida so I can say Hi to my folks as well.

:help Does anybody know where I can get an ECU code ready and what brand/make/model I need so that I don't have to pay the dealer another $100 to tell me that it is the knocksensors. :help

Doug said he has seen knocksensors fail for no reason at all within the first 20,000 miles and I have about 23,000 on my sensors....that really sucks, but at least I will get to meet the guys at T3 and Dennis.

[DAEDALUS]

You can check for codes yourself with a few tools.

http://www.nissaninfiniticlub....41287

[rsiwicki]

Thanks for the thread...I am reading it right now. I will try to test it this weekend.

[rsiwicki]

well I did the ECU code check thanks to you all for your support and Wes's directions and a telephone conversation...it was realatively easy. Unfortunately I got a 55 code which sucks as I was hoping for something more definitive. I tried several times...but no good even took the car up on the freeway and as soon as the problem started I pulled over and shut it down and then tried to read the codes...still got 55. I know from my past experience that one dealer never got a knocksensor code on my car and therefore could never figure out what went wrong with it. The other dealers service write guy diagnosed the problem over the phone and when I brought it in within 3 hours the called to tell me it was knocksensors....I have no idea if the other dealer ever actually got a code or it was an educated guess by process of elimination.

I checked my O2 sensors and they work perfectly....10 blinks within 10 seconds...at least those are working right. I have an appointment with the dealer next week Thursday and if it is knocksensors...then to Atlanta the car goes for the pilgrimage to the mecha T3.

[rsiwicki]

I also tried cleaning the MAF...and no luck at all still the same problem.

[rsiwicki]

does anybody know why my car would idle lower after doing the ECU code checks??? Before it use to idle at 700 & 800 (load vs. noload)....now it idles at 600rpm :-) and I really like it there. The engine was really smooth as I popped the hood to see if I could tell a difference...there was no noticeable rough idles....as the mechanic said that he bumped up the idle to make the engine run smooth and I asked him...why was it running rough...reply.."no, just that many customers prefer it higher". lame excuse for adjusting something that does not need to be adjusted.

[Q451990]

Did you notice if the test screw on the ECU was set in between the "test" and "normal" positions? If so, that would explain it - not sure why, but the idle increases when you move that screw toward the test setting. It actually acts as a new baseline for the car when it's in drive - unlike the IAC adjustment that still tries to return to the ECU programed idle when you have the car in drive, a/c on, etc.

Heath

BTW - 750RPM seems to be the spec. for idle after several revisions by Infiniti.

[rsiwicki]

thanks for the info...I thought that the 750 rpm was spec also...but my car now idles perfectly smooth at 600 rpms. the testing screw was turnng all the way counter clockwise each time before I ran the car on some test runs to duplicate the problem...still no good. We will find out next week Thurday what is going on, at least I hope so, from the dealer.

[rsiwicki]

well I have been with the head mechanic at the dealer this morning versus the other regular mechanic and we have come to a preliminary conclusion after running the consult while driving & duplicating the problem as the car is not showing any codes. The initial thoughts are torque converter failing. We duplicated the problem several times...while cruising while he took the consult and kept running different tests....like a readout every other second of every parameter and what finally came back is it looks like the TC is screwing things up as something about it being at 94% right when rpms drop by 200 around 4000rpms while under acceleration. We also noticed through the readout that there is a very slight pinging sound and they are going to look into the timing and knocksensors to see how it is related. I had heard the pinging sound before...but ever so slight and only during a specific situation....we got one test in and it initially looked like somehow after a WOT run and then cruising that when you give it a little gas again....slightly that the timing is not correct. We went through all the checks....high octane, regular service (fuel filters, etc.) and then he says....might be an injector is dirty.....Hmmm now I start laughing and he realizes that he had told me about a week ago that I did not need a fuel rail flush and refused to do one. I just smiled and said whatever it is...again check it all over and I want it perfect....he is still a little hesitant on the exact cause of the pinging...but will look into it. In the end he gave me thumbs up and said that he has not seen a Q maintained this good in a very long time...Well the TC thing will be resolved late next week as I am getting a new transmission & TC anyway...talk about timing. Well it looks like my trip to T3 will be on hold for a little while as it does not initially appear to be knocksensors.

BTW...the head mechanic is very familar and a fan of the original Q and told me stories of chasing down 5.0's when he had his Q which made things easier and he said that he would make sure that he over sees any work done on my car....Now this is service