RPM's jumping up while driving... [Archive] - GrandAmGT.com Forum

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GA Nightmare
02-23-2007, 04:05 PM
As the title states, I notice that when I hit 80mph my RPM's have been jumping occasionally from 2500 to 3000. It's only a split second that it does this, but I'm afraid its going to throw a code. I lower my speed below 80mph and theres no problem. weirdest thing. Anyone have any insight into potential problems, and any experience with this issue where RPM's just jump up unexpectantly?

andrewe77
02-23-2007, 06:08 PM
Lack of fuel maybe? How long since a fuel filter change?

jackal2000
02-23-2007, 06:52 PM
bad throttle positioning sensor perhaps?

GA Nightmare
02-23-2007, 07:36 PM
fuel filter change has been a while....along with needing a new inverted cone filter for the CAI. I just wanted to see if anyone has had this same issue before I went about fixing stuff.

drumking1721
02-23-2007, 09:46 PM
mine jumps while still...i think its bc i need a new fuel filter like whoa

gectek
02-24-2007, 10:38 AM
well it depends on alot of diff things, but have u tried cleaning the maf to see what that does, sometimes itll do that, also you could be on the borderline of a failing output shaft speed sensor on the trans. or maybe some RF interference from another wire

GA Nightmare
02-24-2007, 01:34 PM
well it depends on alot of diff things, but have u tried cleaning the maf to see what that does, sometimes itll do that, also you could be on the borderline of a failing output shaft speed sensor on the trans. or maybe some RF interference from another wire

Okay, that would suck if it the case. I haven't noticed any problems with the car driving. Its a 99' with 95K miles. Probably been 30K miles since a tune up (i.e. plugs, wires, etc). Oil change is every 5k with full synthetic, Seafoam injector cleaner used at the same time. I might just have to wait for it to finally throw a code so I know for sure what the problem is. The only other time I've seen the RPM's do anything out of the norm, was twice I was parked with the car running and all of a sudden the RPM, MPH, GAS, and TEMP gauges went all the way to the right then back again. Like the car rebooted itself or something.

gectek
02-24-2007, 01:51 PM
sounds more electrical than anything really, u might have a wire grounding, sounds like they went into self check mode to me, but also if you ground out a gauge it will usually peg out, and the output speed sensor on the trans isnt a big deal, just take conn off, take 1 bolt out, put new one in, replace bolt and conn, tada thats it, but it sounds more complicated than that. i would look for a common point where these components intersect, like a splice pack or ground or something like that...best place to start.

Sprucegagt
02-24-2007, 11:01 PM
I might just have to wait for it to finally throw a code so I know for sure what the problem is.

That's exactly what I would do. Until then you really don't know what's wrong.

Ajaxus
02-24-2007, 11:18 PM
Actually ive had this problem for awhile and it never threw a code..i figured out it was my casper tps tho and pulled that today, no more issues. Not everything throws a code, sometimes old fashioned intuition can go a long ways... (or common sense in my case)

gectek
02-24-2007, 11:35 PM
chuck norris is so bad azz that he can slam a revolving door...haha

GA Nightmare
02-25-2007, 01:41 PM
thanks for all the insight on this problem. I have had the Casper TPS off the car for sometime, since it really never made a difference in performance. I'll just let it go for now, and change small things like fuel filters to see if it helps any.

GA Nightmare
02-26-2007, 12:29 AM
okay to add to this thread....I noticed today that the RPM's only increased drastically under hard acceleration. But again the RPM's only jumped from 4500 to 5000 once I hit 80mph??? There's something with this 80mph that is throwing the engine crazy. Would airflow be a cause? I do need to replace the cone filter.

TDRDevelopment
03-05-2007, 03:53 PM
Sounds to me like its a problem with your torque converter clutch. The TCC engages and disengages based on engine load and demand from the TPS. Its controlled by the PCM and generally causes a jump in RPM when it engages/disengages. The TCC problem could be a result of your TPS so I would start there.

jackal2000
03-05-2007, 04:17 PM
Sounds to me like its a problem with your torque converter clutch. The TCC engages and disengages based on engine load and demand from the TPS. Its controlled by the PCM and generally causes a jump in RPM when it engages/disengages. The TCC problem could be a result of your TPS so I would start there.

this could be true.


nightmare, are you saying that you are flooring it (100% throttle) all the way up to 80mph and the rpms jump while its floored?

gectek
03-05-2007, 07:02 PM
well you car doesnt run at 4500 rpm at 80 mph unless its accelerating, and the TCC doesnt engage until you are cruising

02GAGTinprogres
03-06-2007, 06:18 PM
can you send me the sheet as well i am interested in fixing this problem. furthermore, my rps jump all around and what not when i get in the gas. it also seems to stick in gear from time to time. if i disconnect the IAT sensor all together, where it boosts the line pressure it shifts ok, but the rpms still hop around. it threw a p1374 code which was Manufacture control system or ingition misfire but thats all it told me. i called a friend with a lot better scanning program and he said it was a cam position sensor. i replaced that last night along with a new, connected, IAT sensor. still does the same thing. i have flowmaster exaust and it sound like puffs of air in it. could it be the crank position sensor or what...any advice from ANYONE will be appreciated. thanks

gectek
03-06-2007, 07:04 PM
well the IAT usually controls timing advance, but not overall timing, i would look to a bad coil probably or a bad ICM...if you have another friend with an oscilloscope, then i would use that to look at the wave form patterns... if you are getting RPM jumps, then it might be the crank sensor(s) or the reluctor wheel for the front sensor...either way the DSO should show that as well. and it may not be the cam sensor, it could be the cam itself...but those are just a few areas in no specific order.

its prob the bad ICM.

also to send u my trans sheet i would need your email address.

slacker 32
04-17-2012, 07:47 AM
Ok my 2000 Grand AM 4DR GT it has 180,000 miles on it is for some reason the tach will jump up and down if i go to give it gas to pass someone or to go faster or go up a hill it shifts fine under normal driving but the min. i give it gas the tach jumps like it is gasping for air or something im guessing the maf senor but i dont want to start replacing stuff and it still be there .

zukiracer19
04-17-2012, 10:36 AM
Try the IACV?

slacker 32
04-18-2012, 05:34 AM
no i havent checked that yet

zukiracer19
04-18-2012, 02:03 PM
It's located in throttle body I believe.