trans question

Bonestock · #1 02-02-2010, 07:08 PM

Am I the only one that the following happens to?

Low speeds (like 20mph school zone) traveling at a steady throttle position and in D. RPM is around 1900ish... all of a sudden the engine will rev to 3k+. I dont seem to accelerate, its more like the trans is slipping. If I let off it goes back to normal.

The car accelerates normally at WOT, from a standing start or passing. The above situation is the ONLY time I have noticed the "problem".

is this normal behavior for a SVX? I was going to see if it does the same thing tomorrow with the trans in 3rd.

Blacky · #2 02-02-2010, 07:13 PM

It's not normal. Your transmission is on it's way out sorry to say.

K_Dub · #3 02-02-2010, 07:19 PM

Is it slipping, or kicking down into a lower gear? If slipping is your symptom, then I hope somebody else jumps in. If it is indeed dropping down to a lower gear then you might want to check your TPS. Mine had similar symptoms, although at a different speed but similar RPM, when the car thought I was flooring it but I was barely pressing down on the gas pedal. Turns out there was a bad spot on my TPS; at WOT it was reading proper, but at low throttle it was way off. Test procedures are in the How-To documents.

I might be wrong here, but testing the TPS was easy and might be worth ruling out.

dcarrb · #4 02-03-2010, 05:31 AM

Quote:

Originally Posted by K_Dub

I might be wrong here, but testing the TPS was easy and might be worth ruling out.

Second that. My car was gear-hunting (I never sensed this was "slipping," tho'), only at constant throttle in a certain RPM range. A new TPS eliminated the problem. I've always felt this car was shunned because the previous owner and potential buyers feared the transmission was on the way out. In fact, in the trunk I found a Chilton's manual with page markers in the transmission section.

dcb

Bonestock · #5 02-03-2010, 01:42 PM

Well I tested it in 3rd this morning and sure enough it "hung" between gears. On my way home today I unplugged the resistor and it didn't hang at all. Shifted quite nicely, actually.

So, now what?

Conn SVX · #6 02-03-2010, 02:29 PM

I am not really sure if mine is doing the same thing. If I am driving at say 45 to 50 MPh on the high way and I depress the gas even slightly it seems to down shift and the RPM goes up about 500 RPMs and then settles back down . like there is no lock up in the converter .

K_Dub · #7 02-03-2010, 06:06 PM

Quote:

Originally Posted by Conn SVX

I am not really sure if mine is doing the same thing. If I am driving at say 45 to 50 MPh on the high way and I depress the gas even slightly it seems to down shift and the RPM goes up about 500 RPMs and then settles back down . like there is no lock up in the converter .

This sounds a bit more like the TPS to me. My car could never choose between 3&4 while cruising, but did fine when I leaned on it a bit more. 1-2 shifts were also really hard. I knocked off $2k when I bought mine because it felt like a blown trans. That little sensor got it running like new and I haven't had any trouble since.

I know I'm no expert, so I won't muddy up the thread any more, but I wonder how many SVXs were scrapped over misdiagnosing this problem.

oab_au · #8 02-03-2010, 10:17 PM

Quote:

Originally Posted by Bonestock

Well I tested it in 3rd this morning and sure enough it "hung" between gears. On my way home today I unplugged the resistor and it didn't hang at all. Shifted quite nicely, actually.

So, now what?

Well to me, it looks like the line pressure is low. Disconnecting the resistor, gives full throttle pressure. Low pressure can be caused by the screen in the pan, being restricted, or from a lot of wear.

.
You could get the line pressure checked, but if it is low, there is not much you can do, other than, get one of Svxfiles resistors that will allow a bit more line pressure,and drive it in 3rd below 40mph.

Harvey.

oab_au · #9 02-02-2010, 07:28 PM

Quote:

Originally Posted by Bonestock

Am I the only one that the following happens to?

Low speeds (like 20mph school zone) traveling at a steady throttle position and in D. RPM is around 1900ish... all of a sudden the engine will rev to 3k+. I dont seem to accelerate, its more like the trans is slipping. If I let off it goes back to normal.

The car accelerates normally at WOT, from a standing start or passing. The above situation is the ONLY time I have noticed the "problem".

is this normal behavior for a SVX? I was going to see if it does the same thing tomorrow with the trans in 3rd.

I would say it is the brake band slipping, to go back to 3rd.

Quote:

Low speeds (like 20mph school zone) traveling at a steady throttle position and in D. RPM is around 1900ish

It is because of the high gearing and the low pump speed that there is not enough pressure to hold the band on. If it does not do it in 3rd, that is the problem. Get one of Svxfiles resistors to raise the pressure, it may prolong the life of it, and don't drive it in 4th at low speeds use 3rd.

Harvey.

Bonestock · #10 02-02-2010, 07:53 PM

Quote:

Originally Posted by oab_au

I would say it is the brake band slipping, to go back to 3rd.

It is because of the high gearing and the low pump speed that there is not enough pressure to hold the band on. If it does not do it in 3rd, that is the problem. Get one of Svxfiles resistors to raise the pressure, it may prolong the life of it, and don't drive it in 4th at low speeds use 3rd.

Harvey.

That is EXACTLY the conclusion my friend and I came up with... a drop in pressure. Will run some tests tomorrow and report back.

trophy956 · #11 02-02-2010, 08:04 PM

hi id check the TPS also ,before i made mine a 5sp i would drive with the select monitor on my car because the trans would do funny things ,the tps voltage would change even though i was not depressing the throttle more ,it was better after the tps was replaced ,but the trans still died ,because the tcm is looking at tps for shifts ,its a cheap place to start,but you still could have bad trans
charlie

Trevor · #12 02-02-2010, 08:09 PM

Your problem indicates low line pressure. The fix should not be expensive and may only involve solenoid valve “A”, which can be replaced without removing the transmission.

In order to properly diagnose the fault, have the line pressure tested. Do not accept an excuse that this is not required and advice that the tranny is stuffed. Your money is the goal.

Do not mess with the resistor and proceed to use the car. The specific purpose of the resistor circuit, is to protect the “A” solenoid. if you require detailed information in thus regard, I will be pleased to oblige.

Yes, meantime drive in third gear. I always religiously do so round town, no matter what, for obvious reasons.

Bonestock · #13 02-02-2010, 08:27 PM

I have been reading your posts Trevor. Please by all means, educate me! As I stated in my first post on this forum, I am ASE Master Certified and I-Car Gold certified but I can and will shut up and listen to anyone that is willing to teach me about a vehicle I have no experience with.

The resistor, is it ok to unplug for testing to verify the shift firmness & speed will increase?

I am not a transmission specialist but I am sure my friend Rob has a line pressure guage.

Trevor · #14 02-02-2010, 10:10 PM

Quote:

Originally Posted by Bonestock

I have been reading your posts Trevor. Please by all means, educate me! As I stated in my first post on this forum, I am ASE Master Certified and I-Car Gold certified but I can and will shut up and listen to anyone that is willing to teach me about a vehicle I have no experience with.

The resistor, is it ok to unplug for testing to verify the shift firmness & speed will increase?

I am not a transmission specialist but I am sure my friend Rob has a line pressure guage.

I do not appreciate your somewhat sarcastic post.

I did not see your first post in this forum.

I was not aware of your credentials.

Your credentials are impressive.

My effort to assist was directed into cyberspace. You have my true name but I do not have yours.

I have never asked you to shut up.

I tried to help you.

It is obvious that it is ok to unplug the resistor for testing.

It is strange that this was not obvious to one so highly credited.

It is bad English to end a sentence with a preposition.

It is not my intention to be a smart arse, I deal only with fact.

bcpianoman · #15 02-02-2010, 10:30 PM

Hi Trevor:

I've admired your efforts to help others for a long time and I've learned a lot from you over the years. For that I thank you.

Now I'm about to stick my nose in your business and I hope you take no offense. I just read the Bonestock thread and I see that you took offense. For what it's worth, I don't know Bonestock at all. I interpreted his post a little different from you though. I thought he was genuine in this request for your help and was setting out his credentials so that you would have an idea of how simple/complex to make your response. That's how I read it anyway - . . . for what it's worth.

Interpreting the intent of posts is often difficult because you can't hear the tone.

Again - I hope I've caused no offense.