Question about 1998 Pontiac Grand Am

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1998 Pontiac Grand Am GT 3.1 V-6 Engine RPM Surge

Rpm surge, with steady gas pedal pressure, of about 200-300 RPM ,most often while cruising at 70 Mph on level road. Surging will occur continuously unless gas pedal pressure is changed either up or down.

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  • Anonymous Mar 22, 2014

    driving on hwy at 60 mph, car starts to hesitate on slight incline

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  • 328 Answers

Might be ur throttle position sensor

Posted on Apr 08, 2009

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1 Answer

2002 intrepid engine surge at 4000 rpm at neytral and park.?


Be careful, could be dangerous, and similar to the Toyota problems before. Gas pedal and or linkage sticking? Last time serviced?

Feb 28, 2015 | Cars & Trucks

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What is causing my truck to surge when it is in od


not uncommon for it to jump out of overdrive at that speed tire pressure weight in truck incline in road dirty air filter how is it at 60 mph? no problems

Feb 20, 2015 | 2004 GMC Canyon

1 Answer

Car surging


Is the car equipped with the Automatic Transmission?
If so, read on.
Otherwise skip to the end and answer some questions.

POSSIBLE SCENARIO:
I have observed a condition where my car surges slightly when the torque-converter clutch (TCC) cycles between lock and unlock when driving on an uphill grade.
First some basics and history that will explain why the TCC is used.

Engine, Torque Converter, TCC, and Transmission relationship--
The TCC allows for a solid connection between the engine and transmission which allows the input to the transmission to rotate at the same speed as the engine.
Without a TCC, there is slippage between the engine and automatic transmission. The slippage is greatest at low engine RPM. That is what allows the engine to run with the automatic transmission in gear, like when you first shift into gear or stop at a stop sign. When the throttle pedal is depressed, the engine RPM begins to increase and the torque converter begins to slip less and less the more the engine RPM increases. The car moves. But even at cruising speeds the torque converter slips slightly. Engine RPM is greater than transmission input RPM, which is realized as slight decrease in fuel efficiency.
When acceleration is complete and a constant speed is being maintained, the engine power output is reduced to the point where the TCC can engage and eliminate any slippage between the engine and transmission. If the car has a tachometer the engagement of the TCC can be verified when a slight reduction in engine RPM observed without a corresponding change in vehicle speed.
One method used to test the operation of the TCC is as follows:
Find a flat section of road where it is safe to perform the test.
Reach a steady speed and keep the gas pedal depressed with one foot. While observing the tachometer (or listening for an increase in engine RPM), with the other foot depress the brake pedal enough to activate the break light switch but not enough to engage the brakes. When the brake light switch activates, the TCC receives a signal to disengage. With the gas pedal being held steady, release the brake pedal and the engine RPM should decrease when the TCC engages.
Old cars with Automatic Transmissions did not use a TCC. I believe the TCC was put in use in an attempt to increase fuel economy.

MY EXPERIENCE WITH SIMILAR SYMPTOMS
The condition that causes that issue on my car is this:
- A slight uphill grade increases the load on the engine.
The car tends to gradually slow and it is necessary to depress the gas pedal to maintain speed.
- Depressing the throttle pedal (manually, or automatically with cruise control engaged) signals the torque converter clutch to unlock when the load increases slightly. (A more drastic load increase would signal the Transmission to downshift to a lower gear.) The corresponding increase in engine RPM and output is enough to compensate for the reduction in speed. When the vehicle speed, engine RPM, and throttle position stabilize to the point that the TCC will engage and the engine RPM will reduce in correspondence with TCC engagement. Now, if the road conditions have not changed, power output is not enough to maintain vehicle speed. With the increased load caused by full engagement between engine and transmission, and the cycle (surging) repeats itself until the road conditions change.

Does that help?
If not:

QUESTIONS
Please define the symptoms.
What are the road conditions when the surge occurs? (A slight uphill grade?)
What is the frequency of the surge?
Does the engine power output have a noticeable surge?
Is there a speed change related to the surge?
Does the tachometer move up and down with little or no change in vehicle speed?
Are all instrument indication in the normal range?
What else has changed?

Good luck!

May 24, 2014 | Subaru Impreza WRX STi Cars & Trucks

1 Answer

2002 Pontiac Montana trans problem


no I don't think so , it is only the torque converter clutch engaging and disengaging due to engine load. if you want to test this. go on steady speed over 50 mph no gas pedal movement. touch lightly the brake pedal but not braking and release . during this see the rpm drop down and raise

hope it helps

Mar 24, 2014 | 2002 Pontiac Montana

1 Answer

1999 Silverado has an engine surge of 200-500 RPM at 45 to 55 MPH


sounds a little like a cruise control problem.
they used to have a centering adjustment that kept the speed within a range. If the range somehow shifted to the high end this would cause your surge. it would be a screwdriver slot on the outside of the case.cw increase ccw decrease. yours is set too high or cw.
I work the screw back and forth several times in case dirt entered the cruise module.

Jan 30, 2013 | 1999 Chevrolet Silverado 1500

1 Answer

Drive cycle


Here is the OBD2 emission system drive cycle test procedure.
Engine coolant temp must be below 70c (158f) before starting the engine for either the first or second trip
The fuel level should be less than 1/2 full
First trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" for at least 10 seconds (not more than 5 min)
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary.
End of first trip. Turn the key off the begin the second trip.
Second trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" add four gallons of fuel
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary. I especially like the part where they want you to add four gallons of fuel. Not three gallons, not five gallons, four gallons. Gotta love those Nissan engineers. ...and of course they state that if the trace is not followed exactly (i.e. you botch the acceleration/deceleration) you have to start all over again from scratch

Feb 09, 2012 | 1996 Nissan Pickup

1 Answer

It has started to accelerate.up to 35 mph without any pressure on accelerator and revs up to 3 rpm's when idling. could this be a stuck gas pedal? will some WD40 do the trick


the idle control motor could be opening up causing the rpm to increase(acting like a vacume leak),by either sticking or the(ecm)computer, is commanding an increase in rpm.a bad throttle position sensor ribbon could be the problem(must be replaced no repair).if it was a sticking gas pedal then at idle when you move the gas pedal the rpm`s should increase alot.its possible that a vacume leak could cause this like a hose,although this should show up at idle with a high idle.

Apr 13, 2011 | 1999 Pontiac Grand Am GT

1 Answer

2002 grand am ecotec Rpm bounce 400-900 when engine is cold


Try and clean the throttle body. Carbon will gum up on the blade and the vaccume passages, which will cause a surge and stall.

Oct 28, 2009 | 2002 Pontiac Grand Am

1 Answer

Engine surges under load at 3800 rpm


yes it could be. have fuel pump pressure tested, fuel pump pressure should be. (key on engine off) 1999 to 2000--with egr--41 to 47 psi without egr--52 to 58 psi,

May 30, 2009 | 1999 Pontiac Grand Am GT

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