Yes, I'm new. Yes, I'm old. It's hard getting through to post something with all the rules and stuff so I'm trying. I live in a rural area, no one works on old cars here, even this crappy ford dealership. So either guide me to where I can post, or ban me at this point I've spent 2 hours reading threads and still can't find my problem. My 95 maxima was running fine, a few years ago I had the os replaced to the tune of 600.00 up the street (rip offs). My car is surging again. It goes from 1000 rpm to 3000 rpm back and forth, so I read on it and what stood out was the TPS so I bought one and tried to replace it today by myself. Back screw was stripped which made it a huge chore just getting it out. I put on the new one, made sure everything was connected correctly. My fingers hurt terribly. When I started it, it revved to 3000 rpm almost to 3500. I don't want to blow up my engine so I shut it off. I tried resetting the tps from some videos by turning the key to acc off and on 20 times, still it revs way high. I'm wondering if the old tps was fine and there is another issue. The tps I bought was aftermarket but fit perfectly, it does have the tension so I could move it back and forth to try to adjust the throttle but it didn't matter, still revved at 3000 and over. I shut it off. I'm scared of cracking my block, it's cold here in New Mexico and without warming up the motor I'm afraid of revving to high and causing more damage. Honestly, I'm old and this is hard for me, but I'm willing to do whatever it takes. This is my only car and I will go through whatever I have to to try to fix it. Please let me know where I can post this to get the most help. I'm sorry if this isn't the right place, but I honestly spent a lot of time looking to see where was the right place. Thank you for your help, or your ban if that's the case.

 

Looks, to me anyway, that you’ve asked your questions in the right place, so I’m not thinking a ban is in your future.

TPS install/replacement isn’t a super-simple process. After installation, there’s also typically some adjustment (based on voltage readings) needed to get it working optimally. But, I’m thinking that adjustment can happen later as I’m not sure an old malfunctioning TPS, or a new maladjusted unit will result in the RPM ranges and swings you’re experiencing.

That being said, you’ve got a code scanner, yes? If so, what DTCs, if any have been stored … let’s start there.

Also, these RPM surges … they occur when the engine cold or at operating temp.?

 

I actually do not have a obd1 analyzer, I've read on them.(I did purchase this adapter online to go into a obd1 to obd2, but then I read they are worthless) ugh. I'm not sure I could actually figure out the whole blinking light thing. I'm not a mechanic but I'm smart, but this seems over my head. I do have a roommate (male) he's pretty smart maybe I should try that, but I couldn't do it on my own. I am going by forums only at this point, or reading on problems with maximas (hence the tps). I also forgot to mention, last year I replaced the MAF also. I think my roommate does have a voltage meter so he might be able to check it for me. The code reader is so beyond me and the places here tell me they don't have that type so they won't work on it. So today he (my roommate) told me he'd try to help me. So you asked about the revving, well it starts immediately and it does it when it's warm also. So I let me son take it about 1 1.2 hours away the other day for his anniversary, when he got back he told me about this. Then I drove it and went a few places in town. It was surging when i started it, but not while I was driving (or I didn't feel it) but the minute I hit the brake, or put it in park it wanted to surge forward through braking, scared the bejeeziz outta me. So we are going to take off the one I just bought and try putting the old one on. The thing is there is not way to stop it from surging when i start it, even if i grab the throttle and try to manually turn it down it won't, it only goes higher.. so it starts now at almost 3000 rpm. I will post later after we try again, maybe I did something wrong. I'm gonna keep my fingers crossed. Thank you guys for not banning me I really did try to find a problem like this first. Later this afternoon I will post what happened. Sorry I keep editing this but I wanted to clarify, when my son borrowed my car he said it ran far all the way to pueblo 1 1/2 hours away, ran good on the way back till they had to make a stop a 1/2 hour away from our town, that's when he noticed it. So it was very warm at that point. Thought that might be relevent. Thanks so much for your reply.

 

I posted yesterday to another thread that is now gone! Throttle Body and IACV do more to control the idle than the TPS. Probably need a good cleaning..... HOPEFULLY. Vacuum leaks can also make things more complicated and confusing..... MAF too, but you said that has been replaced. The whole Intake section is like a watch.... Every part has to be well for it to perform normally. Finding which component(s) isn't, can be a challenge, especially when it's several.

If you are in there cleaning, also consider cleaning the EGR tube as that also has some effect in running properly. Remember, everything you take off and clean, needs NEW gaskets and hopefully torqued back on. Look at all vacuum hoses, Intake Boots, Valve Cover breather hoses, and so on, for leaks and cracks too. Like Tb said above, the TPS gets fine tuned after the rest is sorted out.

I'm not sure if places like AutoZone can read the 95 codes, but it's worth a try.

Hopefully, the others with 95s will chime in on a reasonable reader offering.

And sometimes your LOCATION plays into advice and choices, so please at least put your State. Help us HELP YOU!

 

Welcome to the forum ! I'm also oldish. I'm 68.

I'm not familiar with this form of surging.

Perhaps the throttle it's self is sticking.
Please open the throttle by hand from under the hood.
make sure that the throttle is not bring kept open by the screw on the rubber boot which attaches to the throttle body. I've experienced wide open throttle on the freeway due to that error. I loosened the screw on that clamp, then rotated the clamp out of the way. Tightened the screw again. Problem solved.

Also look for possible air leaks around the throttle.

Regarding reving at 3500 rpm. Don't be afraid.
The engine reines at 6500. And rpm below that is ok.
the engine runs at 3500 some every day.

please look on ebay or Amazon for an OBD 2 scanner.
They cost about 20 dollars. They communicate with your android or Apple phone wireless. Or your lap top.
I imagine that your check engine light is on.

let us know which codes you see after you whale the old 2 scanner.

 

Thank you for your reply, my roommate and I are out there now working on it. So the new tps revved the motor extremely high not surged but just started and revved. We took the new one out and put the nissan (older one) back in and went back to the surging between 1 and 2 1/2 rpms, so we left that one in. So we are back to square one, I wish I could video this so you could all see it but I know you know what surging is so probably unneccesary . The obd2 doesn't work on my car, I have to have the obd1 like I said in a previous post no one in this tiny town does that. I saw only a connector from obd1 to obd2 which I bought, but from what everyone says that was a no go it does not work so I bought it for nothing. I will show my roommate D.j. what you said to do and i know he'll try it..I swear this is something simple but simple nowadays is so complicated. I will repost after we try your suggestion. Thanks for posting all help is appreciated.

 

Looks like you just might have an OBDII connector on your 95 after all....Under the lower left corner of your Glove Box.

https://www.my4dsc.com/1995-1999-4th...e-information/

Good Luck!

 

Thank you again for any suggestions. My roommate wants me to type for him so he can tell you in his words. So here goes D.J.: So he says when we put the new TPS on you really have to turn the tps unit itself very far to get it to line up for the throttle (lever, the little rod inside to match with the spring on the tps) to catch, which leaves the throttle open quite a bit, which made it rev to 6000 rpm. The old tps and the new tps he says is clocked differently, one arm on the inside of the tps ones farther forward than the old one, so we are guessing this is not a good match for this part, even though it's supposed to be. So the new one leaves the throttle cable really loose, which isn't the same with the original nissan one. He thinks it's not the tps because the throttle position doesn't move, it just revs up and down. So what he's thinking is replacing the IAC valve. Although more expensive on one part of the iac valve i have where the pink module goes into it is chipped at the very end. Not big by any means but it does make one wonder. Anyone that can guide me or I should say us cuz he's now helping me with this is welcome to jump in. So far, 53.00 for the tps which is non returnable. Gonna keep adding this up till we can figure it out and then figure out how much it would've cost to tow this car to say colorado springs 2 1/2 hours away plus mechanic repairs. Who knows I might come out less. One can always hope. Thank you all

 

All 4th Generation Nissan Maximas are OBDII.

The difference in the ‘95 model year is limited the location of receptor/plugin.

See Keith’s (KP11520) reply above.

 

So the throttle is open quite a bit so that the TPS would fit.

That's why it runs at 3000 rpm. The throttle let's too much air in. So reverse what you did. The throttle should be fully closed at idle. The engine gets idle air through the Idle Air Control Valve. Or IACV.

You might just install the original TPS. and adjust it.
why was it removed in the first place

yes, the 1995 is OBD2. Like another member said.
so plug in the obd 2 scanner at the other location.
let us know about the codes.

Also. People commonly start their cold car and go directly on the freeway. Not the best thing for the engine, but it can tolerate that. So it can also tolerate your experiments.

 

Thank you for replying. So I went to the page and looked at the obd sensor it showed, then I went out to my car and took a picture. Looks exactly the same except there is no white obd coder under mine like that picture shows. Everything else looks the same except for the bottom of the fuse box, I don't have the white obd there? I can only go by what this Ford dealership told me and they said they didn't have a coder for this older model. I am going to post a picture of mine.

No white obd on the bottom?

 

So sorry the pic was big, I will try to make it smaller next time. Yikes.

 

Thank you for your response. So D.J. said when he puts the new one on that the throttle will not close all the way, not even close he said. Where the original one almost closed all the way but not quite. So I posted a pic of the obd coder well the one that isn't there, I did look around and couldn't find anything that looked like that particular obdII. Not sure now. I"m more than willing to buy the coder but I want to make sure I'm getting the right one...so I will await anyone's response to that pic I posted.. any ideas are helpful. Thanks again you guys for your time.

 

That white plug you picture there.....that's not the OBD receptacle.... that is the plug for a special Nissan code reader called "Nissan Consult". Whole different animal.

The plug you need is on the passenger side of the car... where the passengers left foot would hit if he leaned it toward the left.... there is a plastic cover hiding it. I think there is some sort of screw holding that cover on....if you get down there and look. Get that cover off and you will see a big wiring loom... that loom is attached to the ECM... the control module for the car. The OBD plug is to the left of that, and it's white, also. It is vertically oriented...

I've got a 95, too.

As far as your engine running away like that...can you manually grab the throttle shaft and twist it back counterclockwise as the engine is revving.... moving it towards idle?

I know it's impossible, but maybe the cruise control system is pulling the throttle open?

Personally, I don't think a code reader is going to tell you anything, anyway. There is limited information displayed from the diagnostics on these cars, and it's mostly just numbers showing values like engine rpm, oxygen sensor readings, water temp., air temp from the mass air flow, amount of air being consumed by engine... stuff like that. Nothing in there is going to shine light and expose the problem you're having.

 

For some reason, he's selectively ignoring good guidance. Multiple times.

Of course codes help us get closer to Probable causes for unstable RPMs. O2 sensors even have an effect when they report too lean when it's NOT.

But whatever!

One can rotate the Throttle Body all the way and disconnect the Cruise Control cable ONLY, to see it that contributes to the slack in gas pedal cable. But that isn't they problem this time.

Shark Tank.... I'm OUT!

 

So...... you said that before you attempted this latest fix
that the throttle was close to all the way shut, but not quite. Then after the last repair attempt the throttle was open still more.

Your surging happens mostly because your throttle is partly open. So air gets in to the engine.
the sensors are doing their job. The computer thinks that you have your foot on the gas. So it adds fuel to all that air.

Your issue is mostly MECHANICAL.
So first figure out how to close the throttle plate all the way.

Once the throttle is shut all the way install and adjust the tps. Reinstall the original one first. We know that one fits tge car. It will probably function as it should once it's adjusted. If it does not, install the new one Exactly The Same Way. The throttle plate should be able to shut. If it does not, you might have bought an incorrect sensor. Opening the throttle some so theTPS will fit Will Not Work.

You really do need the scanner. Both for thos issue as well as future ones. It costs about 20 dollars.
We are willing to help those who follow instructions.

the scanner port is on the passenger side in the 1995 cars. That confuses people. So find it there.
It's probably there because the Japanese have the steering wheel on that side.

 

Here’s a link to the ‘95 FSM (Factory Service Manual).

https://boredmder.com/FSMs/Nissan/Maxima/1995/

Also, here’s a photo showing the location of the ‘95’s OBDII scanner port … passenger side, under-dash portion of the center console … at your left knee/shin.

https://cimg0.ibsrv.net/gimg/maxima....637cc33525.jpg

 

Well, he's probably frustrated! I can relate.

The way I understand it, all the throttle position sensor does is send a voltage reading to the computer, so it can tell the injectors to inject more fuel. The sensor itself performs no mechanical function. If it was malfunctioning and was sending bad numbers to the computer... telling the computer that you had the throttle wide open...the computer would tell the injectors to give it more gas... but, without the throttle actually being opened wide... all that's going to happen is "flooding" the engine, not an increase in RPM. But if that was happening, the O2 sensors would nip that in the bud when they notice the rich condition.

I, too, think it's something mechanical .. something keeping the throttle plate open.

What can apply pressure to the throttle cable to open it? Idle air control valve?

 

Thank you for your response. I didn't think the white receptacle pictured was the obd, someone had posted a link to me to show the obdii but mine didn't look like the one pictured that's why I posted mine. To answer the question on the throttle stick, when the car is started and revving high I've tried grabbing that throttle stick and it only goes one direction and that's higher, I can't get it go lower not even to a slow idle. Just revving. I will check the cruise control unit? I swear I might end up buying an IAC valve, a new MAF again and whatever else I could try. I even am tempted to buy both the upstream and downstream oxygen sensor. At this point that would all be cheaper than having my car towed 3 1/2 hours to someone that might be able to figure it out in Denver. Very hard living in a town with no mechanics, so it's a guessing game for me now. I do have the Chilton's book for my car which is great if I have to exchange or replace parts, but also that's a guessing game. I will try anything that anyone suggests. Again, thank you for your suggestion

 

Thank you for your post. I will bet money that's where that obdii is. Will open that up today and take a look.Thank you again for your post

 

Thank you for your post. I'm thinking yes it might be it IACV. I can't see anything blocking that throttle arm when it is turned it goes high, when it drops to its normal position it is still high. It's like I can't get it to turn down only up. Someone had suggested the cruise control. This started happening after my son drove an 1 1/2 away and then back, when he was almost back it started this high surging. I wonder if he used the cruise control on that drive, i will have to ask him.. It's always weird to me how a car just out of the blue starts doing weird stuff. LOL. Thank you again for your suggestion.

 

Thank you for your post. I will try to figure out how to close the throttle plate. I'm not sure why I can't turn it the opposite way to get the idle lower. Just gets higher. I have taken the tps both the new one and original on and off 4 times now trying to find a sweet spot. The original does not seem to surge as high, just at 1-3000 rpm, but when i use that new oem one.. geeziz it jumps to 7000 rpm and that freaks me out a little. I will keep trying anything that anyone suggests.. I guess my next purchase is an obdII. Hopefully it's the digital one because that whole flashing light and counting them is way beyond my understanding. Again thanks so much for your suggestion.

 

Can you send photos of which screw you are turning.

I think that you and your friend are used to carburetor cars. Have either one of you worked on a fuel injection vehicle at least somewhat. Again, you need to find a way to Close The Throttle Plate ALL The Way.

I think that your friend opened it some so tgat the TPS would fit. That's why it idles so dang high

the scanner I'm talking about can be found on Amazon
search term : BAFX OBD 2 . The ones which cost 20 or so dollars would work well enough. They send information. To your cell phone. They display code numbers. In the phone screen. There are two types of scanners. Some work with Apple phones some with android phones. Get the one compatible with your phone.

 

You should try to find some information about throttle body adjustment, TPS installation, and how to set idle speed on you tube. Search ( year of your maxima) and what I just wrote. One at a time.

Please send photo of which screw you are using to try to adjust the idle. Also of the TPS. Fairly close up.

To adjust a plug on the IACV needs to be disconnected before you turn the idle speed screw. But first close the throttle all the way.

 

I recently replaced the TPS in my '95(well, my father in law's '95). I took pictures of the related section from my Haynes manual. I don't know if it will fix the surging problem or not, but maybe it'll help with adjusting the both the new and old unit.

 

Thank you Urb _______ !

your information might help him diagnose the problem.

 

Thank you for your reply.

 

Sorry I have not touched base but I am also building a huge fence around my property. Then snow storm. So before I ordered a part my roommate had put his hand over the metal tube on the iacv to the tps? The metal tube.. the idle would slow dramatically. Then he did that a few times and the motor sounded really bad, like it was missing. It stayed that way then. I'd hoped we didn't do something more serious. It was cold and the motor was still cold. Everytime I started it again it would rev again but omg, it would miss so bad it sounded like we blew the motor. I ordered a new iacv, we put that on today. It's not revving anymore (yay) but now it's doing that very rough idle with almost a clunking sound like a lifter tapping, but different. It's running so rough. He revved it really high and then it seemed fine for a few minutes, now it's back to running rough (like misfiring). At least it's not doing that high rev now, but now a new issue... This sounds like it's not running all all cylinders. Could him putting his hand over that tube on the iacv a few times have done something else? When he did put his hand over that tube (metal) on the iacv it would slow a lot, not rev or just die. I'm wondering if by doing that we did something else, could that possibly have made the motor jump time? So weird, but I feel I'm a little close without this high rev. Thanks for your help. I just know that before all this it was running good, but it did surge a little when started when cold. After D.J. put his hand over that tube on the old iacv it started misfiring.. I guess my question now (now that it is not revving with a new iacv) is what could we have caused by closing up that tube a few time and now making it misfire? Geez. One thing after another. Thanks for all your feedback.
So he would place his hand over that silver tube.. not sure where that goes sorry. But when doing that, that's when the motor starting running really rough (which wasn't a problem) till then. The problem initially was the high revving which is now solved.. but now like i said.. it's this... Thanks

 

I wanted you to take the IACV apart to clean it.
With carb cleaner. That would have saved you some money. So it runs differently now. That's good.
Surging stopped.

No, it didn't jump time. That would be impossible.

next step is to remove one of the wiring connectors and set the idle speed.

I've forgotten which connector that is.

Perhaps you can find info on You tube.

probably under heading. Adjust idle speed
1995-1999 maxima .

or perhaps another member might help you

 

@Itzlmntry , it sounds like you're making progress. Now you have moved on to a more mundane problem, with many solutions hiding within the Org's old threads. Happy hunting

I suggest when making significant-length posts on the forum you start using paragraphs and organizing your thoughts a little better. Communicating in cyberspace is not 100% stream of consciousness - it's a bit essay, as well. Paragraphs make it easier for people to go back and read through what you have written in previous posts. Faceborg encourages people to make posts in one big paragraph, because if they don't the algorithm penalizes them by hiding part of their post with the "read more" clickable. It's a bad habit that some people get into.