My wife's 2001 Grand Am GT acts sluggish when pressing the gas pedal. Has trouble going up hill sometimes (sluggish) and feels like it's slipping. When she took it to Midas for an inspection and to have the tires rotated, they told her that she needs to have the throttle body intake replaced and that would solve the problem. When it comes to engines, I'm not the sharpest knife in the drawer but once I have an idea of what needs to be done, I have no problem doing the work myself. Any ideas about this and recommendations for replacement? If this is the problem, and needs to be replaced, I wouldn't mind spending a the money on something that will add performance to the engine (vroooooom vroooooom )

In case anyone needs to know the engine is a 3400 SFI
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[This message has been edited by F-I-E-R-O (edited 06-10-2006).]

The 2001 Grand Am GT doesn't have throttle body fuel injection. It's sequential port fuel injection. So, they might mean the throttle body, or they could be talking about the MAF sensor. Or they may not know what they're talking about at all. I can't imagine why the intake would need to be replaced. And if so, which one? It's a two piece intake, with an upper and lower, very similar to how the 2.8 Fiero V6 is set up.

I checked the car computer with my actron and got a code P0442:

The main function of the Evaporative Emissions (EVAP) system is to minimize hydrocarbons (raw fuel vapor) from escaping into the atmosphere.

The EVAP system is a closed/sealed system that traps and stores fuel vapors using a charcoal carbon activated canister. These vapors are then introduced into the combustion chamber to be burned when conditions permit.

The powertrain control module (PCM) controls this process, by opening and closing the purge solenoid and using engine vacuum to retrieve the gas vapors.

The system may also monitor the oxygen (O2) sensor and fuel trim to determine quantity of fuel vapors retrieved, to avoid excessive fuel.

The main components in the EVAP system are the canister, fuel tank, filler cap, pressure sensor, purge solenoid/valve, vent solenoid/valve, etc.

SYMPTOMS............

Raw fuel odor.
Fuel saturated canister.
Possible rich/lean trouble codes.
MIL on.

Diagnosing leak (small and large) codes:

The powertrain control module (PCM) performs periodic tests looking for EVAP system leaks. Vehicle manufacturers primarily use two methods; vacuum and/or pressure to check the system. Understanding your system is essential when determining the source of a leak. The PCM will set DTCs and illuminate the malfunction indicator light (MIL) for gross and small leaks. A gross leak is defined as a leak that exceeds 0.040 inches in diameter. Finding a leak this small can be virtually impossible without specific equipment; i.e. smoke machine or gas analyzer.

A common gross leak issue may be caused by a loose or poor sealing gas cap. Check the tightness of the gas cap. If loose, tighten cap, using a scan tool clear the DTC and retest the system (Note: Meeting the criteria needed to run an EVAP test can be difficult, refer to the factory service manual for specific test requirements.) If tight, remove the gas cap and inspect the condition of the gasket/seal. If the gas cap is ok, the next step is to visually inspect system components; vacuum lines, hoses, connections, canister, purge solenoid, vent solenoid, etc. Check for leaks, cracks, loose connections, etc. Repair as necessary. See diagram for typical EVAP system.

Other possibilities include; sticking purge or vent solenoids, fuel tank seals and gaskets, etc. Following a visual inspection, if no problems are found, then more sophisticated diagnostic tests may be required to detect the leak. Again, the most accurate test method is using an approved EVAP Smoke Machine that introduces smoke into the system to find the leak. Intermittent EVAP leaks are possible, so testing at different temperatures and conditions may be necessary.


Whooooooo boooooy...

Check your gas cap, then clear the codes. That may not have anything to do with how the car's running, though.

http://www.obd-codes.com/trouble_codes/generic/p0442-evaporative-emission-control-system-leak-detected-small.php
P0442 OBD-II Trouble Code

What does that mean?
This indicates a fuel vapor leak in the EVAP control system.

Symptoms
You likely won't notice any drivability problems.

I looked at the gas cap- seems OK, and something that I can replace myself without professional guidence (AutoZone guys can help ).


About the throttle body. Looks easy enough to replace, though I'm wondering if that will fix the hesitation problem. Seems like the car is pulling a tractor trailer when going up hills, kicking in then out again when it feels like it, almost like the transmission is bad.

If it feels that bad, I'd probably take it to a dealer or another garage for another diagnosis. You could have transmission problems. You don't want to waste money throwing parts at the problem. The throttle body doesn't have much on it to go bad except the TPS. A Haynes/Chilton book should have a test procedure for it. Test it with a volt meter and make sure you get a smooth transition from low to high voltage. The manual would have the actual voltages. I believe on a Fiero it goes from around 0-1V to about 4.5-5V. If it's not a smooth progression, or the voltage jumps around, that could be your problem. Otherwise, I'd look elsewhere.

I think the dealer will charge you $65 for a diagnosis. I would definitely get a second opinion, either at a dealer or somewhere else.

How's the coolant and oil look? The intake gaskets on those engines are notorious for cracking. It can let oil and water mix. Sometimes it just leaks coolant out of the engine, and other times you get coolant in the oil. If your Dexcool looks like brown mud, you may have a bad lower intake manifold gasket. I just had that done on my '99 Grand Am. It's about an $800, but the dealer will charge about $1200-1400.

I wouldnt go putting a new anything on there yet, til you have it diagnosed by someone other then a brake and muffler expert!!! The evap code not likely a gas cap. that is usualy a code p0440 large leak detected. You likely will need a new vent solinoid. In my experience that is 95% of what causes a p0442. Have someone with a smoke machine smoke it for you. Then you will know. Midas may have been aluding to the an intake gasket failure, which is common to the 3400 before the newer gaskets came out. Check too see if there is any whiteish sludge under the oil cap, or coolant at the back of the engine, just over the tranny. If that does need to be replaced, make sure they use GM gaskets as they now have a metal insert that prevents them from being over torqued, and that they use the GM revised torque values to torque the intake down.

After doing some more research I found this: http://www.pfyc.com/store/merchant.mv?Screen=PROD&Store_Code=PFYC&Product_Code=GA3003&Product_Count=2&Category_Code=GAUNDER



Throttle Position Sensor Enhancer - $84.99

The Throttle Position Sensor Enhancer maintains maximum horsepower by optimizing the throttle signal sent to the PCM. At about 70% throttle, the TPS Enhancer locks into maximum voltage which assures maximum power enrichment meaning once you hit 70% throttle it tells your car's computer that you're at 100% throttle. This should help initial acceleration by providing more fuel to the engine when you first accelerate hard. This unit also corrects for dead spots or flat spots in the throttle position sensor. Simple 5 second plug-in installation.

Any thoughts?

Your "mechanic" sounds like a 'tard... No offense.

I jsut picked up and installed one of these:
WELLS THROTTLE POSITION SENSOR for a 2001 PONTIAC GRAND AM
Unit Price: $38.99
Core Value*: $0.00
Part No.: TPS140
Weight: 0.088 lbs.
Warranty: 3 MO

from AutoZone- seems to have doen the trick. The wife has yet to give me the final OK though.

Don't bother with the TPS enhancer. All it does is tell the computer you've gone to wide open throttle when you're at about 70% throttle. It's like you go immediately from 69% to 100% throttle. Doesn't help WOT performance at all, and can hurt driveability under heavy throttle.

It's not much different from the intake resistor "mod." Dumping more fuel does no good if the engine doesn't need it.

I hope the TPS sensor fixes it. That's what it was sounding like, and easier and much cheaper if you do it yourself.

At least they had one in stock. The alternator just went out on my Formula, and NAPA doesn't have any in stock. It'll be Monday before I can get it back on the road. (at least it's a lifetime warranty, so it's free)

CRAP! That didn't fix the problem. It started acting up again, especially when in cruise control mode. It felt jumpy, like it had bad gas then got progressively worse when we got off the highway. There were times when Linda had the accelerator pushed all the way down and there was no power. That comes and goes- sometimes catches, sometimes not. jeez this is frustrating.

I started looking for loose or damaged hoses and connections but it's too dark out to get a good look around so I'll look harder in the morning. I did notice that all the spark plugs but one seemed brand new, with one having a bit of oxidation on it and looking almost original. I'll replace that one in the morning and make sure that all the others have that conductive grease stuff on them. I'm not really sure where to go now. Maybe I'll have Linda push on the accelerator while in neutral to see if the throttle works OK (at least on the outside) .

I just confirmed with Linda that the tach/engine does not respond when the accelerator is pressed at times. I guess that's a good thing, in my mind at least that rules out the transmission as the culprit.

Sounds like a dealer diagnostic may be required. There's enough computer controls that just about anything could cause it. I really like my Grand Am, when it's running right, but I've not been impressed with the build quality.

Here's what I come up with, Cat converters always use a factory one. This car has 2 crank sensors, a 7X and a 3X need a scope to check this one out. Ign switch. and My thought is the Mass air flow sensor With all the problems I saw with the clogged converter that's where I'd go first. I'm surprised Midas didn't check there first, by the way stay away from franchises, I'd go to the dealer or a good driveability shop.

[This message has been edited by Kekipi (edited 06-11-2006).]

Ding...Ding...Ding...Ding!!! We have a WINNER!!! I went to AutoZone and repalced the mass air flow sensor and WHOA! what a difference that made. Like driving a new (used) car! Thanks for your help!

Were you getting any codes on the MAF?
Were any of the wires inside it visibly damaged (or was the screen on it removed?)

The MAF is very easily damaged, but they typically don't fail that early unless something damages it.

What the heck is MAF?

Mass Air Flow, Measures the air by weight in grams as opposed to Map, Manifold absolute pressure that uses engine vacuum to verify how mush air is going into the engine.

[This message has been edited by Kekipi (edited 06-11-2006).]

quote Originally posted by F-I-E-R-O: What the heck is MAF?

That's what you replaced: The Mass AirFlow sensor.