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fixed my idle problems, backfiring, bucking and more...

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fixed my idle problems, backfiring, bucking and more...

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Old 03-27-03, 01:21 AM
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fixed my idle problems, backfiring, bucking and more...

For those of you who already know how to adjust your idle and tps, you don't need to read this ... its old news :-)

Ok, I want to be vary careful here because I don't want to get anyone's hopes up that what I did will fix similar conditions in your car, but it may....

Basically my car ran like crap after I got it all back together from the winter updates. I had re-done the hoses, totaly removed double throttle system (except solenoid is plugged in for the ecu), totaly removed AWS, totaly removed fast idle cam and thermalwax rod housing. After my car was back together it had the following problems:

- Idle
idle was really bad, hunted, minibackfires, airpump was coming on at funny times, it stalled a few times, sometimes it would idle high

- Rev sticking
It would stick around 3500-4000 when downrevving, it made it really weird to drive because it would not decelerate right away when you let off the gas, after a few seconds it would eventually go down

- Deceleration backfires
I would get all kinds of backfiring upon deceleration or gear shifting

- Bucking
It would buck when trying to keep a constant speed and buck very bad deceleration.

I know my car is in great shape and had the potential to run perfect so I was determined to get it straight. I did searches here, and on all the normal tech sites and I was able to solve ALL of the issues above and it runs perfect, I mean PERFECT...perfect idle, smooth rev up and down at any load or speed, NO BUCKING and NO BACKFIRING anymore, and proper airpump operation. It is running smoother than when I had all that double throttle/AWS crap on there!!! :-)

The magic egg = TPS!!!!
The throttle position sensor was the key to it all, but it also was the proccess in adjusting the idle in general that I read from a post. This is what I did.

Get all the tools needed to do the TPS adjustment, the details are at the top of this link: http://www.fd3s.net/TPS_adjustment.html

I HIGHLY suggest a digital voltmeter. I got a realy nice one for $14 at radio shack. Make sure it can give you good resolution at 0-14 volt range. (2 decimal maybe)

Before checking the TPS, first set the throttle body to ground zero, what i mean by that is totally close the air adjustment screw that is on the underside of the throttle body, and also adjust the scew on the top of the throttle body so that is does not hold the butterflies open, in other words, so that it just touches the throttle linkage just as the butterflies are fully closed. I got this idea from erics info on this thread: https://www.rx7club.com/forum/showth...threadid=52710

(much thanks to the thread by supercell and great info posted by eric)

Now its TPS time, follow the proccess on the link above, it is a PIA to get to the darn tps screws, but take your time and DONT strip the screws (some new ones may have allen bolts)...mine was WAY off (obviously, by my problems listed above)....but I was able to adjust it to these settings:

Green/Red wire (2nd from top)
Closed = 1.00 V
Open = 4.99 V

Black wire (bottom)
Closed = .4 V
open = 4.3 V

So I got it set just about perfect, and that is exactly how it ran after I started it...well almost. It idled a bit low (500 rpm) so, since I closed the adjustment screws fully, I had plenty of tweaking room. All I did was un-screw the air adjustment (one below throttle body) until I got the idle to 700-800 rpm and that was it.

Drove it all around with a BIG AZZ SMILE on my face....no hunting, perfect idle, no backfiring on decel or shifting. I love it when it all comes together....and this was one of those times.

By the way, my flow mods are catback, DP, and intake...manual boost controllers (running at 9lbs until I get a power FC in here)

Last edited by dgeesaman; 01-07-06 at 11:02 AM. Reason: fixed links
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Old 03-27-03, 01:33 AM
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Great post, I have many of these symptoms and will definitely try this sometime soon.
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Old 03-27-03, 01:55 AM
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Originally posted by gnobesav
Great post, I have many of these symptoms and will definitely try this sometime soon.
thanks gnobesav, good luck and let me know if you need any help..
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Old 03-27-03, 04:51 PM
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by the way, I wanted to calrify on the 'bucking'.

there are 2 kinds of bucking people talk about, ignition bucking caused by a messed up idle controls, tps, ISC, et... and the suspention bucking caused by word motormounts, diffmoutns et...

the idle adjustmentsi mentioned above removed all my ignition bucking...however, since my motormounts are definetly broken, I still have a ton of play in the drivetrain, that causes mechanical bucking between decel-accel
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Old 03-27-03, 05:38 PM
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you mean jumpiing between 1k and 1.5k rpms?

mine does that, pisses me off
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Old 03-27-03, 05:45 PM
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Originally posted by 93BlackFD
you mean jumpiing between 1k and 1.5k rpms?

mine does that, pisses me off
mine does non of that anymore :-)
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Old 03-27-03, 09:47 PM
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I'm going to start this project as soon as my friend gets his S14 out of the garage. My symptoms have been a hunting idle at start, and it occasionally stalls immediately after start. Also, I had light-throttle bucking which was fixed by adding extra grounds. The only remaining bucking is from on-throttle to off-throttle. I'll let you know how well it fixes these.
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Old 03-28-03, 03:25 AM
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let me know if you need pics or anything
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Old 03-28-03, 10:10 AM
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How could the TPS change when you worked on the car damian?
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Old 03-28-03, 10:34 AM
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well apparently mine did too
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Old 03-28-03, 12:41 PM
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Originally posted by TobiasRX
How could the TPS change when you worked on the car damian?
good question, it should not have, however I did have my UIM sent away to be polished and it may have been 'bumped' out of adjustment...also, I removed the AWS, thermal wax rod and cam, and double throttle shaft and butterflies, these changes may have tweaked the idle airflow in some way so that it was off enough to be out of the 'play' range of the TPS.
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Old 03-28-03, 12:55 PM
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I have some trouble with my car wich i have explained in a thread a litle bit further down.

But then it couldnt be my TPS since i havent done anything near there.
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Old 03-28-03, 01:32 PM
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post a link to the thread for me...
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Old 03-28-03, 02:09 PM
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Old 03-28-03, 02:20 PM
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ahh yess, dunno, ur issues might be non-TPS/idle related?
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Old 03-28-03, 03:31 PM
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i have the samething i think . my those that when i hit 2 pounds of boost on the turbo meter gauge. can the cause that too.
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Old 03-28-03, 03:59 PM
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yes i dont think it's TPS either since my idle is good.
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Old 03-28-03, 04:48 PM
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Had an idle problem of when I reved it it wouldn't slowly settle at 700-800 rpms for idle. It would go all the way down to 300-400 rpms, shutter, then come back up to 700-800 rpms. I tightened the throttle cable and adjusted my dash pot was sticking, got that fixed. It would buck under cruising speed I would eithe rhave to accelerate or decelerate for it not to buck. Put some ground on the car and that went away.

Easy fixes, gotta love'em.
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Old 03-28-03, 04:58 PM
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well checked my TPS yesterday since i have the same symptoms...

and found it VERY loose, as in i could swing it by hand with no force...

tonight im going home to adjust it.

interesting huh?
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Old 03-28-03, 05:40 PM
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let us know the results tedder1
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Old 03-28-03, 05:41 PM
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tedder1, what could have caused your TPS to be loose?
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Old 03-28-03, 06:51 PM
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the torque for the scewes is not very much, so it could be possible they just ratteld loose
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Old 03-28-03, 07:15 PM
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but it's hardly likely it could have rattled looose when my car just has been sitting though

I will look for something tomorrow. thanks for all help and plz post if you come up with something
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Old 03-29-03, 03:06 AM
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do this apply to second gens also?
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Old 03-29-03, 09:15 AM
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gonna try revving the engine while standing still.

When i drove i couldn't come over 3000 rpm, but i don't know if it's because i pushed the pedal too little.
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