"Bogging" at low speeds

Mr. Cynical · #1 07-30-2004, 06:49 PM

Good day, everyone!

A while back, I posted that I was experiencing a problem with low-speed acceleration. Advice given was to check the tranny fluid and perhaps the fuel filter.

Well, the fuel filter's changed, and the transmission fluid is good too. I'm still bogging down at low speeds. I notice it most when I'm going around corners in my neighborhood, and in traffic.

(Today, I had my coolant flushed, not that it's related, but just thought I'd add that in there as well.)

Also, today I noticed that the "Performance Shift" wasn't lit up at a point where I turned it on. If I throw the car into either neutral or park, it comes on, but when I move it back into a drive gear (or rev the engine while it's in neutral or park) it goes back off.

Folks, this is my daily driver, and I'm on the road for work every day around Denver. Anyone got an idea? I'm definitely on a budget for the next couple weeks, and I'm afraid that if it craps out on me, I might lose my job!

Your Pal,

Mr. C.

bbuckli · #2 08-06-2004, 05:28 PM

Hey Mr. C,

Not to long ago I was experiencing some problems similar to yours. I tried to fix them my self but nothing came up, no service engine light, no nothing. I finally ended up taking it to a local shop and they found out that it was leaking antifreeze through the plannium gasket which is right by the throttle body. A week and 600$ later i got it back and it ran fine for 200 miles but im experiencing that same problem again but even worse this time. Grand Prix's are known for the problems with antifreeze locking up the cylinders. I know a few that have had the same problem with Gp's over 110,000 miles. thought maybe that might be helpfull, doesnt hurt any. Post a reply if you find the problem, i would like to know so i can get some ideas.

Thanks,
Buck

Mr. Cynical · #3 08-07-2004, 01:11 AM

Quote:

Originally Posted by bbuckli

Hey Mr. C,

Not to long ago I was experiencing some problems similar to yours. I tried to fix them my self but nothing came up, no service engine light, no nothing. I finally ended up taking it to a local shop and they found out that it was leaking antifreeze through the plannium gasket which is right by the throttle body. A week and 600$ later i got it back and it ran fine for 200 miles but im experiencing that same problem again but even worse this time. Grand Prix's are known for the problems with antifreeze locking up the cylinders. I know a few that have had the same problem with Gp's over 110,000 miles. thought maybe that might be helpfull, doesnt hurt any. Post a reply if you find the problem, i would like to know so i can get some ideas.

Thanks,
Buck

Well, it can't hurt to check it out! I'm planning on changing the plugs/wires, as well as perhaps the tranny filter. Let's hope it gets no worse!

GTP Jeff · #4 08-07-2004, 10:31 AM

For a low speed bog like that, the first thing I'd suspect is the throttle position sensor or a vacuum hose that's become detached..

Mr. Cynical · #5 08-07-2004, 11:10 AM

Quote:

Originally Posted by GTP Jeff

For a low speed bog like that, the first thing I'd suspect is the throttle position sensor or a vacuum hose that's become detached..

The vacuum hose sounds easy! I'll go look for that soon! I wouldn't know how to check the TPS, but I'm sure someone will

GTP Jeff · #6 08-07-2004, 03:26 PM

I can't tell you specificly how it's done on Grand Prix's.. But I can tell you how it was done on Mustangs..

Throttle Position Sensors are nothing more than a varible resistor, but they cause more than there fair share of drivability problems.. They are very sensative to getting wet.. So if you've washed your motor, it may have screwed your TPS up, if you didn't protect it.. Plus, they can wear out from just being mechanically opened and closed every time you step on the gas..

Your cars computer sends a voltage to the TPS (usally around 5 volts), and measures how much comes back.. That tells the computer how far the throttle is open.. Something like 1 volt means the throttle is closed, and 5 volts will mean it's wide open.. Part throttle is everything in between..

The testing procedure goes like this.. Using a digital voltmeter, pierce two wires coming from the TPS harness with safety pins.. You may have to switch wires or polarity to get the reading you want.. Usally one wire is ground, another is the supply voltage, and another is the return voltage..You want the return voltage and ground..

Once you meter is hooked up.. With the Key On Engine Off, you should have a specific throttle closed voltage (I don't know it for GP's).. But "most importantly", when you open the throttle by hand, the voltage reading should rise and fall in a linear manner..

If you can move the throttle a little and the meter doesn't go up.. And then when you move it a little more, the voltage shoots up.. You know the sensor is bad..

If the TPS has the correct closed throttle voltage, but just doesn't respond in a linear manner.. It will cause a stumble, but not give a fault code..

The rapid change in the TPS voltage is what causes the injectors to act like accelerator pumps in a carburetor.. When you blip the throttle, the computer tells the injectors to give a little blast of fuel, so you don't get a stumble..

Mr. Cynical · #7 08-09-2004, 11:22 PM

Well, just a couple weeks to go, and PAYDAY! The company owes me a chunk of change from last month, and I plan on sinking it into my car until it works right!

I'll be first changing Plugs, Wires, and TPS. From there, I'll report as to what I've noticed (whether there's improvement) and will go from there

And, to be smart about things, I'll test things out in between each item, so that maybe I can isolate where the deal is for some other schmo down the road with this stupid problem!

richtazz · #8 08-20-2004, 01:16 PM

your trans light acting crazy might indicate a bad tcc. This will cause the torque converter to lock when it shouldn't and make it boggy on acceleration, similar to a stick shift car in too hig a gear. you can temporarily unplug the tcc connector, which will not allow the tcc to lock and eliminate this as a cause. The connector is located on the drivers side of the engine compartment in the front, just under the air intake tube. It is a square plug with 4 wires

Mr. Cynical · #9 08-20-2004, 01:32 PM

Quote:

Originally Posted by richtazz

your trans light acting crazy might indicate a bad tcc. This will cause the torque converter to lock when it shouldn't and make it boggy on acceleration, similar to a stick shift car in too hig a gear. you can temporarily unplug the tcc connector, which will not allow the tcc to lock and eliminate this as a cause. The connector is located on the drivers side of the engine compartment in the front, just under the air intake tube. It is a square plug with 4 wires

THAT'S what I've been trying to describe; the feeling like it's in too high a gear. I will wait till it cools off, and go unplug it for the drive home and report back what happens. Thanks!

troy1 · #10 08-20-2004, 02:06 PM

If the torque converter is locking up at 20 - 25 mph thats way to soon, There is a little tiny filter on the VB plate under the side cove that spins and gets cut off under light trottle SOMETIMES it will not lockup the converter and if you get into it more it will. This really bogs down the motor because you engine can not rev up

troy1 · #11 08-20-2004, 02:09 PM

Quote:

Originally Posted by troy1

If the torque converter is locking up at 20 - 25 mph thats way to soon, There is a little tiny filter on the VB plate under the side cove that spins and gets cut off under light trottle SOMETIMES it will not lockup the converter and if you get into it more it will. This really bogs down the motor because you engine can not rev up

this is very common on the 4t60's and if the TC is coming on you will know it it comes on hard sometimes.

Mr. Cynical · #12 08-20-2004, 09:10 PM

I just got back from my local Checker Auto Parts, where I got them to give me a scan. The results?

No Codes.

The guy who was doing it thought it was odd, since in his words, "Your car will blow a code if the air filter is bad."

So, I guess I'll have to find some tools and remove the airbox to try the TCC plug trick. If that doesn't work, I'll be replacing the plugs and wires on the 30th (Thank GOD for paychecks!), and will report back with what's what.

Mr. Cynical · #13 08-22-2004, 10:46 PM

Still no clue as to what's going on. I noticed today that the transmission fluid is a little high. Not like CRAZY high, but enough that I wondered if that could be a problem.

According to what I'm reading, when the transmission fluid is high, it can get frothy, and thus lose its ability to function in both shifting and cooling.

Since there's no drainplug for the transmission, I'll be dropping the pan anyway. I'll change the filter at that time, and see if that fixes things. I'd rather not have to try and find the TCC solenoid if I don't have it!

richtazz · #14 08-24-2004, 09:32 AM

if your fluid was too full, you'd see bubbles on your trans dipstick. I would still look at the tcc, as they don't always trip a code when they start to stick intermittently.

Aqualls1 · #15 08-25-2004, 10:34 AM

I have the same problem, I subcribed to all data yesterday and found that the ho2s is the first thing to check. If its response is too slow it will cause this problem. I have some checking to do I have a problem with my ignitions switch (which supplies the power) so I'm going to make for sure it is getting power before I replace it.

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