90 Q45 - Erratic random downshifting after a bath?

[staats]

I posted these over on the Yahoo site but it's been several years since I was over there and it seems pretty dead so I thought I'd try over here.My 90 Q45, original owner, has 137K on it now. I did the chains etc.some time ago down at T3 and have been driving it very little since I did that 3years ago. The trans which starts in 2nd gear has been up-shifting ina little bit of a sluggish manner when it's cold out (below 45F) fora couple of years. It took into Level 10 here in NJ 3 years ago for atrans flush and it's been reasonable since then. My wife has beendriving it again for the last 2 months and she's the one that hasnoticed the problem. I have limited experience with this problem buthere's what I've observed. At highway speeds it seems to down shiftfor no apparent reason sometimes. The other day I was in slow trafficand it was stuck in 1st even though it starts out in 2nd and I hadthe selector in "D". When I moved the selector to "2" the problemdisappeared. It seemed to be going back and forth between 1st andsecond abruptly even thought the driving conditions didn't warrant it.

So OK what's up. A sensor problem or is it new transmission time?

Bob.

[staats]

I got a chance to drive this car for a couple of hours yesterdayunder local and highway conditions. Here's what I noticed.

Some times the rpms would jump up but not enough do indicate a gearchange. It was more like the torque converter was unlocking andlocking erratically at times.

Sometimes it would actually downshift at inappropriate times likewith a slight depression of the gas pedal under a light load.

Sometimes it would negelect to upshift leaving you in 3rd or 2nd. Ifyou let completely off of the gas it would eventually upshift.

Sometimes the upshifts were very slow.

Sometimes it was normal.

Bob

[staats]

An update from the field.

I now find out that my wife drove the car through "some" water during a huge downpour and that's when it started doing this. No, I don't know how deep.So .... Do you think it's related? I know, like duhhhhhh.Please bare with me.Is it just some harnesses that need checking and if so where?I see no evidence of water on the transmission dipstick.

Bob

[DominickJ30]

Your transmission vent sucked up water when your wife drove it through the puddle.

Every single paper clutch in the transmission is now junk. Time for an overhaul.

Check your fluid level and condition to confirm this.

[staats]

Perhaps, but it does seem electronic in nature and when it's not acting up it's just fine.

Do you know where the vent is located, i.e. how high?

[elwesso]

Sounds like a TPS sensor has failed, IMO..

if your interested, i can send you one of my extra ones, free of charge for you to try... Just try it out, and hten if it fixes it you can send it back and buy yourself one.....

[staats]

A generous offer indeed. Now where is this sensor and how do I change it?

My situation is that I no longer have a lift or garage to do my own work, sigh. That's why I'm trying to get a better idea of what it could be.

I have a local dealer that's been reasonably decent, not great. I always like to go in well prepared.

Perhaps the water thing is a coincidence but it does seem like at times it will just start going erratic, even at highway speeds, so that's why I thought it was possibly a connector or both!!!!Thank you

[elwesso]

A generous offer indeed. Now where is this sensor and how do I change it?

My situation is that I no longer have a lift or garage to do my own work, sigh. That's why I'm trying to get a better idea of what it could be.

I have a local dealer that's been reasonably decent, not great. I always like to go in well prepared.

Perhaps the water thing is a coincidence but it does seem like at times it will just start going erratic, even at highway speeds, so that's why I thought it was possibly a connector or both!!!!Thank you

Attached and below is a picture of the TPS.. Theres 2 screws that hold it onto the Throttle Body, you can only see the top one, the other one is directly below it on its respective side...

Its held in with a 6mm socket.. Just take out the 2 screws and it just pops out...

The only thing is when you install it you have to adjust it properly.. I assume you have a digital VOM.. If you dont konw what that is, you dont have one

the following post will focus on adjustment of the TPS..

[elwesso]

Ok so now onto adjustment of the TPS.. Attached is a picture of how to do this, via the FSM...

Basically all you do is once you install the new TPS, you adjust it based on this chart... With the accelerator fully released (IE the butterfly is completely closed), you probe the 2 listed things on the TPS connector (there are 2 connectors, one one for the Throttle switch and the throttle position sensor, the throttle switch connector is on the sensor body, the sensor switch is the one on the little wire connected to the sensor).......

Anywho, probe the 2 listed prongs on the TPS harness connector and adjust it so that your VOM reads approx. .7 ohms...... you put your VOM on the lowest OHM reading..... on mine for instance it is 200ohm.....

Let me know if theres anything i havent made clear.

[staats]

Ok I suppose I should have guessed what TPS stood for. I've been dealing with a data aquisition and logging system on my race car all season. Brain fart! So you think that's it? Well I'll hookup my digital VOM and follow the proceedure to see what's what.

A good place to start thanks.

Bob

[DominickJ30]

Care to check the fluid to confirm or deny whether there is water in there?

[staats]

So I'm guessing that if I don't get those readings or more probably if I see a sudden change in value as I move the throttle or wiggle the connector then I may have found "the" problem.

Bob S.

[DominickJ30]

With the key on you should have .5v at closed throttle and 4.5v at wide open throttle.

Now this is in no way an accurate check of the TPS. The proper way to do it is with an osciliscope. That way you get a waveform and can precisely check for a dead spot where the voltage dips to zero.

[staats]

An update from the field.

II see no evidence of water on the transmission dipstick.

Bob

Just in case you missed it.

[AZhitman]

Bob - Off topic, but does your screen name have anything to do with bikes?

Just an old BMX dad wondering...

[Jesda]

When I drove with my TPS disconnected, my Q exhibited similar behaviors. Try cleaning the connector and dabbing a little dielectric grease on it.

[JedCoop]

Nice experiment Jesda!!!I hadn't thought of that.

[staats]

Bob - Off topic, but does your screen name have anything to do with bikes?

Just an old BMX dad wondering...

No, there's no significance to it.

Bob

[jamesmost]

Your transmission vent sucked up water when your wife drove it through the puddle.

Every single paper clutch in the transmission is now junk. Time for an overhaul.

Check your fluid level and condition to confirm this.

Transmission vent??

[jamesmost]

Perhaps, but it does seem electronic in nature and when it's not acting up it's just fine.

Do you know where the vent is located, i.e. how high?

sounds more like the solenoid pack.

[jamesmost]

Statts where in NJ r u? if northern i have a friend w/a trans. shop in Elmont by Belmont racetrack(40-60 min drive)t and honest will give a free look. and let u know what is up

[staats]

Statts where in NJ r u? if northern i have a friend w/a trans. shop in Elmont by Belmont racetrack(40-60 min drive)t and honest will give a free look. and let u know what is up

Jamesmost,Yes I'm in Northern NJ but I cant find an Elmont NJ. I can find a Belmont Park NJ. Where is this shop????

Bob

[jamesmost]

Jamesmost,Yes I'm in Northern NJ but I cant find an Elmont NJ. I can find a Belmont Park NJ. Where is this shop????

Bob

elmont is on Long Island Queens Borderline Drom me an e-mail i will give u info he rebuilt a killer trans for me

[jamesmost]

\e-mail sent bty my mechanic is 20 minutes from him and has become a great Q mechanic because of me if u need him

[staats]

Ok so now onto adjustment of the TPS.. Attached is a picture of how to do this, via the FSM...

Basically all you do is once you install the new TPS, you adjust it based on this chart... With the accelerator fully released (IE the butterfly is completely closed), you probe the 2 listed things on the TPS connector (there are 2 connectors, one one for the Throttle switch and the throttle position sensor, the throttle switch connector is on the sensor body, the sensor switch is the one on the little wire connected to the sensor).......

Anywho, probe the 2 listed prongs on the TPS harness connector and adjust it so that your VOM reads approx. .7 ohms...... you put your VOM on the lowest OHM reading..... on mine for instance it is 200ohm.....

Let me know if theres anything i havent made clear.

I just got the harness off of both points on the TPS and yes there were tiny amounts of corrosion so I'm cleaning those up to see if that's my problem.

I measured as specified and got 4.51 closed and .63 WOT between B&C.

I got 4.62 and .76WOT between A&B

A&C is 5.06 as you would expect.

This seems reasonable to me.

Of course if something is causing a wild fluctuation when warm I may not see that with this simple test.

The other connector gives a 0 ohm reading at about the 1/2 throttle position and is open when the throttle is closed.

So now let me clean things up and try to drive it again.

Bob

[jamesmost]

put dielectric gel on all connectors- i just did to my car and it seems to be happier

[DominickJ30]

Transmission vent??

Are you asking what a trans vent is or are you implying that this trans doesnt have one?

[staats]

I cleaned everything and went for an extended drive on a beautiful day here in NJ and after 1.5 hours everything worked flawlessly. Manual shifting , throttle induced kickdown etc. No high speed driving though nothing over 60 mph.

Let see how it goes after a couple of days of commuter duty with my wife.

Next will be replacement of a leaky ABS pump. Oh joy.

[jamesmost]

Are you asking what a trans vent is or are you implying that this trans doesnt have one?

how is a trans vent going to take in H20 where is it ?? is it a pressure release valve??

[elwesso]

I agree,the transmission vent is on top of the transmission..... way up in the tunnel, it would be nearly impossible for water to get up there unless half the car was submerged... Unlikely and now proven that was not the cause.....