WOT performance

Conman · 06-09-2002, 08:57 PM

my car runs pretty good and and pulls pretty hard at 80% throttle but if I go full throttle it feels like it actully looses power
I can take it right to redline smoothly if I don't mash the gas
If I do go full throttle it doesn't feel as fast and it starts to stutter at about 4000 rpm.
you guys have any ideas?

bobtodd · 06-09-2002, 09:33 PM

My car seems to do the same thing...mash on the throttle and it goes, but it seems that when you gradually push the throttle you feel the pull alot more. I was curious why it does that myself.

Conman · 06-10-2002, 08:42 AM

so that's two of us with the same problem
anyone have any ideas?

Mr 5 0 · 06-10-2002, 08:55 AM

Weakening valve springs could be the culprit but you could also check for the TPS to be out of adjustment, a binding throttle linkage or a binding TB butterfly due to accumulated goo on the edges (common). A weak coil might possibly do this, too.

Just a few thoughts to get you started.

joe4speed · 06-10-2002, 11:43 AM

I agree with the TPS
Get a voltmeter and check to see that the volts go up smoothly when you open the throttle.
My daily driver olds is the same way, if you floor it the service engine soon light comes on and it doesn't want to go... 80% throttle acts like it's floored. When I hooked up the voltmeter the volts jumped all over the place. actually reads 0 volts at WOT. I haven't been able to change it, since the geniuses at GM put a weird bolt on the throttle body and I have to take it off to get to the TPS!

bobtodd · 06-10-2002, 08:05 PM

So what do you do if you take a reading and the voltage is jumping all over the place? How hard is it to change valve springs?

joe4speed · 06-10-2002, 08:21 PM

Quote:

Originally posted by bobtodd
So what do you do if you take a reading and the voltage is jumping all over the place?

It just means that it's telling the computer that the throttle is opening/closing when it's not.
closed throttle is a low voltage, open throttle is a larger voltage, if it's not smoothly going up as you open the throttle then the computer is getting very wrong readings and will throw a code. I just changed the one in the olds today, it's amazing how much better that car runs, I just need to figure out the idle volts for that GM. (I'll post a thread)

*Edit* I read that wrong.. all you do is buy a new TPS! LOL

Conman · 06-11-2002, 09:12 PM

well I lost my volt meter, no idea where it went, so I just borrowed one off of a guy at work to test the TPS. At idle it was at 0.82 V and went smoothly up to exactly 4.5 V at WOT. So I took it right off and can see the little plastic bits wearing so I elongated the holes and rotated it so that it is at 0.98 V at idle and 4.65 V at WOT
It's getting late so I guess I'll see if this makes much of a difference tomorrow

how much difference should this adjustment make?

thanks for all the help guys
I got the specs and process from PEKRWUD in an old thread

bobtodd · 06-11-2002, 09:36 PM

I changed my TPS and it definatley made a difference...just make sure it is set like what you were talking about...at .98

sn95gt19 · 06-12-2002, 12:27 AM

when i went to the dealership to buy my 95gt i took it for a test drive, and the thing would not rev past 4000rpms when you floored it. i eventually got them down to 5800 from a asking price of 10000. the reason that i got them so far down is cause they could not figure out why the car ran like &h!t. i have had the same problem on 2 previous mustangs and it ended up being a bad mass air sensor, sure enough when i got the mustang home i switched the sensor with one i had and went for a drive and it ran perfect. the problem was a little different on my 89 though, when i would part throttle it, it was faster than when i would floor it. anyways, what im getting at is try the mass air, that is if the tps adjustment is correct.

Conman · 06-12-2002, 07:14 AM

well my '88 is speed density so I'm pretty sure it's not the Mass Air Sensor
It is raining and really shitty so I can't harass the car too much today unless I want to end up sideways in a ditch
Although this morning on the way to work it did seem to work alot better at WOT. I had it up to about 5700 RPM in second gear and she was still going. Hopefully on the way home it will be all dried up and I can try redline in the first 3 gears
All I did last night was adjust the TPS
Thanks alot guys

sn95gt19 · 06-12-2002, 08:43 AM

my mistake i didnt read what youve got.

jimberg · 06-12-2002, 09:06 AM

Since you don't have a MAF sensor, I would say that you should check the MAP sensor which would lead to the same symptoms as a bad MAF.

Conman · 06-12-2002, 12:28 PM

well the weather is getting better so I went for a little blast at lunch time and the car is deffinately working a lot better

it's pretty shitty how 0.15 V can make such a difference
I don't think the computer was getting enough voltage from the TPS to put it into open loop (or closed loop? whatever the WOT one is)

well my problem is solved and I think bobtodd's problem is solved so that is great

06-09-2002, 08:57 PM	#1
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	WOT performance my car runs pretty good and and pulls pretty hard at 80% throttle but if I go full throttle it feels like it actully looses power I can take it right to redline smoothly if I don't mash the gas If I do go full throttle it doesn't feel as fast and it starts to stutter at about 4000 rpm. you guys have any ideas? __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

06-09-2002, 09:33 PM	#2
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	My car seems to do the same thing...mash on the throttle and it goes, but it seems that when you gradually push the throttle you feel the pull alot more. I was curious why it does that myself. __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

06-10-2002, 08:42 AM	#3
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	so that's two of us with the same problem anyone have any ideas? __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

06-10-2002, 08:55 AM	#4
Mr 5 0 Conservative Individualist Join Date: May 1997 Location: Wherever I need to be Posts: 7,487	High RPM bog Weakening valve springs could be the culprit but you could also check for the TPS to be out of adjustment, a binding throttle linkage or a binding TB butterfly due to accumulated goo on the edges (common). A weak coil might possibly do this, too. Just a few thoughts to get you started.

06-10-2002, 11:43 AM	#5
joe4speed He said Member...heh, heh Join Date: Sep 1999 Location: Jupiter, Florida U.S.A. Posts: 3,718	I agree with the TPS Get a voltmeter and check to see that the volts go up smoothly when you open the throttle. My daily driver olds is the same way, if you floor it the service engine soon light comes on and it doesn't want to go... 80% throttle acts like it's floored. When I hooked up the voltmeter the volts jumped all over the place. actually reads 0 volts at WOT. I haven't been able to change it, since the geniuses at GM put a weird bolt on the throttle body and I have to take it off to get to the TPS! __________________ *Joe!* 1988 GT, 13.58@101mph Check out my listing! Click here! Or my website:www.joe4speed.com

06-10-2002, 08:05 PM	#6
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	So what do you do if you take a reading and the voltage is jumping all over the place? How hard is it to change valve springs? __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

06-11-2002, 09:12 PM	#8
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	well I lost my volt meter, no idea where it went, so I just borrowed one off of a guy at work to test the TPS. At idle it was at 0.82 V and went smoothly up to exactly 4.5 V at WOT. So I took it right off and can see the little plastic bits wearing so I elongated the holes and rotated it so that it is at 0.98 V at idle and 4.65 V at WOT It's getting late so I guess I'll see if this makes much of a difference tomorrow how much difference should this adjustment make? thanks for all the help guys I got the specs and process from PEKRWUD in an old thread __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

06-11-2002, 09:36 PM	#9
bobtodd Registered Member Join Date: Dec 1998 Location: WI, U.S Posts: 255	I changed my TPS and it definatley made a difference...just make sure it is set like what you were talking about...at .98 __________________ 91 LX - 10.5:1 pistons, ported 289 heads, Ultradyne 588 cam, Cobra upper/lower, MSD, JBA long tube headers, Flowmaster, Richmond 4:10, roll cage, monster tach...FUN!! 95 SHO - K&N filter

06-12-2002, 12:27 AM	#10
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	when i went to the dealership to buy my 95gt i took it for a test drive, and the thing would not rev past 4000rpms when you floored it. i eventually got them down to 5800 from a asking price of 10000. the reason that i got them so far down is cause they could not figure out why the car ran like &h!t. i have had the same problem on 2 previous mustangs and it ended up being a bad mass air sensor, sure enough when i got the mustang home i switched the sensor with one i had and went for a drive and it ran perfect. the problem was a little different on my 89 though, when i would part throttle it, it was faster than when i would floor it. anyways, what im getting at is try the mass air, that is if the tps adjustment is correct. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

06-12-2002, 07:14 AM	#11
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	well my '88 is speed density so I'm pretty sure it's not the Mass Air Sensor It is raining and really shitty so I can't harass the car too much today unless I want to end up sideways in a ditch Although this morning on the way to work it did seem to work alot better at WOT. I had it up to about 5700 RPM in second gear and she was still going. Hopefully on the way home it will be all dried up and I can try redline in the first 3 gears All I did last night was adjust the TPS Thanks alot guys __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

06-12-2002, 08:43 AM	#12
sn95gt19 motors done......woohooo Join Date: Mar 2002 Posts: 799	my mistake i didnt read what youve got. __________________ 95gt lazer red (98 cobra clone) Rice Haters Club Member #116

06-12-2002, 09:06 AM	#13
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Since you don't have a MAF sensor, I would say that you should check the MAP sensor which would lead to the same symptoms as a bad MAF. __________________ 351W 89 Mustang GT Convertible

06-12-2002, 12:28 PM	#14
Conman Registered Member Join Date: Apr 2002 Location: Kingston, Ontario Posts: 351	well the weather is getting better so I went for a little blast at lunch time and the car is deffinately working a lot better it's pretty shitty how 0.15 V can make such a difference I don't think the computer was getting enough voltage from the TPS to put it into open loop (or closed loop? whatever the WOT one is) well my problem is solved and I think bobtodd's problem is solved so that is great __________________ '88 lx, Black on Black, check it out here Spent all my money on school, what a dumb mistake I'm old enough to know better, but still too young to care.

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