Auto Trans question(s)

91WBSE · 10-31-2004, 02:08 AM

In a previous thread I asked if the TPS had anything to do with my trans issues. I never got around to checking TPS. The trans lately has been shifting really slow and soft. Also when accelerating, when the trans torque converter goes to lock up at 45mph it locks then unlocks, lock and then unlocks, and will keep repeating this unless I let up a little on the gas and it locks. When cruising in 4th gear, I try speeding up it feels like a slipping clutch in a manual trans car, rpms rise but speed doesn't. The engine doesn't free-rev but there is some slippage.

Tonight I thought I'd try unplugging the transmission resistor plug thing on the strut tower. I drove it around and the trans of course shifts hard. Full throttle shifts are really firm and quick. Part throttle shifts are firm and quick. There is no slippage whatsoever in 4th gear like before and the torque converter locks up quick like it should at 45mph. Of course I didn't leave the resistor unplugged, but, wouldn't this mean my tranny probs seem more likely to be electrical rather than a dying trans?

*internetautomar* · 10-31-2004, 04:54 AM

sounds like it.
now test your darn TPS!

nismo3366 · 10-31-2004, 10:44 AM

How do u test the trottel postion sensor??? i think i might have a problem with it also??

**Greeny** · 10-31-2004, 11:06 AM

Try this link...http://www.autozone.com/servlet/UiBr...3d8004f8f2.jsp

nismo3366 · 10-31-2004, 01:50 PM

so does autozone proform the test if we go down there?

10-31-2004, 05:46 PM

Quote:

Originally Posted by 91WBSE

Tonight I thought I'd try unplugging the transmission resistor plug thing on the strut tower.

where exactly and what does this transmission resistor plug thing look like and go?

10-31-2004, 11:09 PM

Quote:

Originally Posted by blacks92seAuto

where exactly and what does this transmission resistor plug thing look like and go?

bump

*avmaldo* · 11-01-2004, 02:59 PM

its under the air box. its white and rectangular and its mounted on the wheel well. it has like 3 wires connecting to it, i think.

They are kind of hard to find if your looking to buy one. by the way does anyone have a good one i can buy off them?

lenterri · 11-04-2004, 05:03 PM

91wbse, When you find out the problem please post what is causing it. I have a 94 maxima with the same exact problem. Will a bad tps cause it?

mark77 · 10-02-2009, 05:20 PM

I also have this problem yet have failed to find any info about it. I have checked my TPS and it is fine.

Is there a way to test this resistor? Could it be the cause of our problems?

I find it unusual that this issue has not been resolved. Maybe it is only affecting a small number of people.

maxinout93 · 10-03-2009, 07:23 AM

Well before my tranny died 3 days ago, I was experiencing the same conditions in my 93 gxe. As long as the tranny was cold, not up to operating temp, it would shift smooth and nice. When it got at operating temp, for a long while, the first to second shift would be so so soft. The most annonying part would be that torque converter lock-up at 45mph. Right at 45 it would lock then unlock back and fourth, until I either let up off the gas or gave it some more gas to do 50mph instead of 45mph. I thought I was the only one to experience this. I have to buy another tranny, but I will install an external tranny cooler along with it.

mark77 · 10-13-2009, 04:02 AM

Yeah that's exactly what mine is doing! Do you think it may have had something to do with the tranny dying? Was it doing it for a long time? Now i'm really concerned because mine is doing this all the time.

maxinout93 · 10-13-2009, 11:53 PM

Quote:

Originally Posted by mark77

Yeah that's exactly what mine is doing! Do you think it may have had something to do with the tranny dying? Was it doing it for a long time? Now i'm really concerned because mine is doing this all the time.

I think It may have had something to do with the tranny dying. I noticed one day that it started to slip between 2nd and 3rd gear in power mode, then I also noticed one day while I was driving this weird sound like a straining sound comming from somewhere. I stopped the car, and put it in park, and revved the engine a little bit to reproduce the sound. It seemed to be coming from the transmission, Also I checked the condition of the fluid and it was darker than it normally was. I thought it was a bad switch, so I swapped out the transmission control switch in the car( the Power, comfort, and automatic switch) It seemed to stop the slippage a little, and the straining noise went away for a little while, and then came back. All was good until one day I went to Augusta GA, about a 70mile ride. I noticed that a few days before, there was this annoying miss going on at speeds below 60mph, it was like something was jerking back and fourth constantly. The same symptoms were going on when I was going to Augusta, the jerking and what not, an also it lacked power! It would downshift with the pedal pressed to the floor, but it would not be the power you would normally expect from a Maxima thats in good condition! Another thing on that same night I had to fight to keep the car at a steady speed of 70mph, it didnt want to stay at 70. I made it to Augusta, but on the way back, in the early morning hours of 4am, the tranny died almost unexpectedly and on a dark and rural stretch of I-20 between Aiken, and Batesburg exit. I was able to keep it at 60mph for the next 30miles in order to get it closer to home, and the first time I stopped I realize how serious the problem was. The tranny made a loud boom, or a pop sound and the fluid was burned and the smell of it was terrible. If I werre you I would keep a close eye on the fluid condition. Cause mine started to slip unexpectedly. I can tell you one thing though, it seems that trannys are pretty hard to find for this car(the GXE model and Early 89-91 models with the REFO2A tranny) The 92-94 SE trannys are much easier to locate.

mark77 · 10-14-2009, 03:19 AM

Thanks very much for that information. I'll keep a close eye on it. I changed a couple of litres of it not that long ago. Maybe it would be best for me to continue driving as is and be prepared to change the tranny when the time comes. Mine is a '93 model. I might start looking around over here in Australia to see how hard they are to find. Still curious as to why it occurs and whether it is a sign of wear or perhaps something not quite right which may contribute to damaging the tranny. It surprises me that people seem to have managed to sort out pretty much every issue with these cars over the years yet there is no info on this that i can find.

Thanks again

1992maximase30 · 10-14-2009, 09:17 PM

ohh...i don't like the sound of this.
i get the t/c lock and unlock...but thats with tthe trottle pressed down lightly. you press down a lil more it goes away.

also there's a delay 1st-2nd shift between 3500-4500rpms only.

mark77 · 10-18-2009, 01:45 AM

Hi again,
I think i has a breakthrough of some sort. I unplugged the hard switch and tried to drive it. The car would shudder really badly as it went up in the rev range. After about 100m i stopped and plugged it back in. The problem went away!! The car seemed to be behaving differently. Before when i would back off on the throttle, the revs would drop quite alot and you could feel the car breaking quite sharply. Now the revs hold up with the speed of the car and it coasts nicely. This leads me to beleive that the bouncing revs while coasting was in fact something to do with this switch, however i have no idea why it suddenly fixed itself.

I performed an idle relearn, and during the procedure the idle went up to about 2000rpm. I reduced the base idle to spec and the car seems to be running nicely except for 1 thing. Now there is a fluctuation in the idle. It wasn't happening before but now the idle just goes up and down every few seconds. Not heaps but noticibly.

Anyone have any ideas why this may be occurring or general comments on what may have happened with the switch?

Thanks

mark77 · 10-18-2009, 01:49 AM

Sorry a correction tot he above. I unplugged the oval connector thinking thta this was the hard switch, but usn't this actually the TPS? After checking the FSM i think this is what the oval connecter that sits horizontally on the side of the black box????

*CapedCadaver* · 10-18-2009, 09:47 AM

Quote:

Originally Posted by mark77

Sorry a correction tot he above. I unplugged the oval connector thinking thta this was the hard switch, but usn't this actually the TPS? After checking the FSM i think this is what the oval connecter that sits horizontally on the side of the black box????

i was thinking the connector that's molded as part of the tps was the variable circuit, and the connector with 4" of wire on it was the hard-switch. it could be the opposite tho.

i can't remember which one i unplugged on my car.

mark77 · 10-19-2009, 05:08 PM

I have a 1993 J30 with a VG30E and auto tranny

This information stems from a problem that I was having with bouncing revs when coasting at about 1500rpms that I previously thought may have been to do with the tranny and is a summary of the information above. I think there are quite a few people who have had this symptoms and I think this may help them if the same happens to their car as did to mine.

I inadvertently seemed to solve the problem by attempting to drive the car with the TPS (not CTPS) unplugged?! When trying to do this, the car wouldn’t run properly at all and after about 100m I plugged it back in. The car behaves completely differently now and the previous problem is gone.

But now I have other problems that I feel may relate to the TPS and I am reluctant to just go out and buy a new TPS with out being sure that it can’t be fixed by adjusting something. I have read countless threads where people have stated “I replaced the TPS but it didn’t fix the problem”, usually prompted by mechanics to do so.

Since trying to drive the car with TPS unplugged, I have performed 2 idle relearns and adjusted the timing slightly. Incidentally as part of the procedure for adjusting timing that I found, it stated to unplug the TPS and rev the engine a couple of times for 1 sec before adjusting. As I mentioned previously when the TPS is unplugged, I cannot rev the engine past a bit over 2000RPMs. Not sure if this is normal. The engine just bogs down and “chugs”. Also when measuring resistance on TPS, I only get 7.4 kOhms at WOT not 9 as sated in FSM. I confirmed that the CTPS has continuity at closed throttle and resistance when opening throttle slightly.

The main problems that have appeared now are:
a) the car misses when it’s first started in the morning for a few minutes
b) the idle seems to change i.e. sometime 1500rpms in N(causing it to “clink” into Drive), then next time it is started it may be 700rpms in N.
c) there is a cycling fluctuation to the idle speed. i.e. tacho needle constantly goes up and down at idle.

I have read that the IACV can cause some of the symptoms above but I haven’t touched it during all this.

Has anyone had similar problems that they managed to fix - with or without replacing the TPS??

Thanks for your help

LvR · 10-19-2009, 08:38 PM

Quote:

Originally Posted by mark77

I have a 1993 J30 with a VG30E and auto tranny

This information stems from a problem that I was having with bouncing revs when coasting at about 1500rpms that I previously thought may have been to do with the tranny and is a summary of the information above. I think there are quite a few people who have had this symptoms and I think this may help them if the same happens to their car as did to mine.

I inadvertently seemed to solve the problem by attempting to drive the car with the TPS (not CTPS) unplugged?! When trying to do this, the car wouldn’t run properly at all and after about 100m I plugged it back in. The car behaves completely differently now and the previous problem is gone.

But now I have other problems that I feel may relate to the TPS and I am reluctant to just go out and buy a new TPS with out being sure that it can’t be fixed by adjusting something. I have read countless threads where people have stated “I replaced the TPS but it didn’t fix the problem”, usually prompted by mechanics to do so.

Since trying to drive the car with TPS unplugged, I have performed 2 idle relearns and adjusted the timing slightly. Incidentally as part of the procedure for adjusting timing that I found, it stated to unplug the TPS and rev the engine a couple of times for 1 sec before adjusting. As I mentioned previously when the TPS is unplugged, I cannot rev the engine past a bit over 2000RPMs. Not sure if this is normal. The engine just bogs down and “chugs”. Also when measuring resistance on TPS, I only get 7.4 kOhms at WOT not 9 as sated in FSM. I confirmed that the CTPS has continuity at closed throttle and resistance when opening throttle slightly.

The main problems that have appeared now are:
a) the car misses when it’s first started in the morning for a few minutes
b) the idle seems to change i.e. sometime 1500rpms in N(causing it to “clink” into Drive), then next time it is started it may be 700rpms in N.
c) there is a cycling fluctuation to the idle speed. i.e. tacho needle constantly goes up and down at idle.

I have read that the IACV can cause some of the symptoms above but I haven’t touched it during all this.

Has anyone had similar problems that they managed to fix - with or without replacing the TPS??

Thanks for your help

My FSM on EC30 says nothing about unplugging TPS/revving before setting timing and EC31 also says nothing about the TPS before setting idling speed .................. so where did you get that method from?

IMO EC30/31 is correct and have been used many a time to set a VG properly.

The precise TPS outer track resistance is not critical at all imo (probably 40% variation from 9KOhm will still be fine as long as its constant) because that potentiometer in the TPS transmits a changing voltage signal not a resistance signal

mark77 · 10-19-2009, 10:39 PM

errm, I found the procedure on the net which stated it was for maxima's. I couldn't find the procedure in my FSM. Maybe i didn't look hard enough. So am i to think that the behaviour with unplugged TPS maybe normal. The real question is then, if the TPS smoothly increases resistance to 7.4 kOHm and CTPS is set properly can i rule out a problem with the TPS? Also in that case what might be causing the problems i'm having.

LvR · 10-19-2009, 11:04 PM

The TPS's influence could have been your "bad luck" only ............. and imo that is all it really is and should be ignored for now.

Your points a,b and c imo points to a IACV in vain trying to compensate for a vacuum leak somewhere - you may go through the motions of adjusting idling properly, but that poor thing cannot cater (and was not designed to) for hugely variable vacuum variances

mark77 · 10-20-2009, 09:31 PM

Quote:

Originally Posted by LvR

The TPS's influence could have been your "bad luck" only ............. and imo that is all it really is and should be ignored for now.

Your points a,b and c imo points to a IACV in vain trying to compensate for a vacuum leak somewhere - you may go through the motions of adjusting idling properly, but that poor thing cannot cater (and was not designed to) for hugely variable vacuum variances

Hey thanks,
You were pretty close to the mark. Last night i think i put myself back to where i started from. I cleaned the IACV not very long ago. I checked all around the engine bay and i think the idle problems where being caused by the air filter element not being seated properly and letting air through. Bizarre because i hadn't touched it. Has anyone else had this problem? Anyway the idle is alot better (stable and correct) after i performed relearn again.

Only thing is now the bouncing revs (coverter locking/unlocking) while coasting at 1500rpms is back! Arrhhgg. Any advice for me? Should i think TPS again even though it tested ok? or something else?

LvR · 10-20-2009, 10:57 PM

Quote:

Originally Posted by mark77

Hey thanks,
You were pretty close to the mark. Last night i think i put myself back to where i started from. I cleaned the IACV not very long ago. I checked all around the engine bay and i think the idle problems where being caused by the air filter element not being seated properly and letting air through. Bizarre because i hadn't touched it. Has anyone else had this problem? Anyway the idle is alot better (stable and correct) after i performed relearn again.

Only thing is now the bouncing revs (coverter locking/unlocking) while coasting at 1500rpms is back! Arrhhgg. Any advice for me? Should i think TPS again even though it tested ok? or something else?

Nope - sorry - I think your conclusions doesn't make sense at all.

1. You can remove the air-filter element completely and your idle should not be influenced ............. and that's by design - you can in fact remove everything in front of the AFM including the whole air-box assembly and it shouldn't/mustn't affect your idle.

2. The AT's converter cannot possibly be locking/unlocking at 1500 rpm - once again its by design.

If you are quite sure you have absolutely no air/vacuum leak on the intake then I don't know to be honest.

Is there enough ATF in the box?

Me? - I would start by stripping down the IACV again and confirming the smooth operation of the actual control valve as well as the temperature governing flap controlled by engine coolant temp that also forms part of the IACV assembly (if that governing flap is stuck in the open position then its possible the valid IACV's control action could be the cause of your miseries).

Check O2 and MAF (as well as MAF connector for corrosion).

What is the battery voltage when the car runs at 1500rpm .............. check all battery posts terminals and alternator terminals for corrosion.