you see i fixed the whole TPS thing the way you did, but my car is still surging. i was told that it was because my motor was ported and the stock maps on the PFC needs to be tuned via Datalogit. how did you get your to stop surging?

Well, it's possible that your maps are so far out of whack that the PFC can't find the proper setting for your car. I'll share what knowledge I can to help you, but you'll need either a datalogic or a commander.

im using the base map right now that comes with the PFC. i have a commander, but not really sure what setting would really help the surging. i can fuel tune, but i am not experienced tuner like that by all means

bump

try posting in the power fc forum...

just wanted to bump a good thread.

i have a 92' efini fd and the car had problems idling steadily, and was a real bitch to drive at slow speeds in 1st gear. it would also pop like crazy on deceleration coming off of boost.

getting the screws out was a pain, the bottom one you have to be careful with as it's easy to strip it. the top one i began to strip and then just decided to use pliers to undo it, i got it loose enough to finish with a screwdriver.

adjusted the voltage to the correct readings and then tightened the screws up again.

fired up the car and instantly it idled smoothly at 750rpm and stayed there. took it for a couple spins around the block in 1st and 2nd gear and it's now silky smooth, no bucking at slow speeds.

a must-do maintenance item for every fd owner with idle surging and bucking problems.

while you are adjusting the TPS, you should take a look at the MAP sensor hose going into the back of the engine. Mine was in pretty crappy shape so I just cut a new piece of 4mm ID rubber hose and slapped it on. That solved some of my unstable idle problems as well, and also reduced backfiring slightly.

bump an excellent informative thread for quick question.

brief history. i just started another thread so ill give the very basics real quick.

idles at 1100 rpm usually. occasionally will go down under a 1000 but not often. i dont really care about that part.....

VIOLENT bucking at WOT in 1st, and sometimes second gear. should not be fuel cut as im not making 10psi.


i have a similiar scenario as many in this thread. my UIM was off, and ive removed double throttle completly, and disconnected the AWS hose to install greddy elbow, left other end open(bad idea?) and that seems to be when all this started!


so what i wanted to ask. i have a PFC ready to install. however i dont have access to a commander right now. BUT i do have datalogit. ive never used any of this. can i see VAT1 and VAT2 reading from datalogit, like i could from the commander?


p.s. if anyone thinks they know what my problem is(not TPS) please chime in.

I know this is an old thread but I have found it very helpful. Here is my question: In the first post to this thread, Damian listed the following symptoms of his out of whack TPS sensor:

My question is, I am having EXACTLY the same issues with my FD. Unfortunately, my readings on my TPS are all within range. Is there any chance that my TPS sensor is still bad even having gotten good readings?:scratch:

im having idle issues also. my car fully warm idles at 1100 and when i drive and hit a light and stop its idling around 1300-1400 then i depress the clutch throw it into first then it drops down fast to 1000-1100 then put it into neutral and it stays. also while driving at about 30mph and i approach a stop light and while the car is moving in neutral the rpms go up and down from 1100 to 1400 until i stop. would this be the tps? i also will need pictures =( it looks so complicated and i dont know which is what yet. thanks.:Wconfused

thanks this really helps!

Hi all

I also read this thread because i guess i have also a bad TPS.

I got all the tool from robrobinettes site.
Then i put a needle into the connector to read voltage, but i only get about 0,200 - 0,300 volt, also when i move the TPS up and down ( i pulled the screws out a little bit so i could move it ). Do i have a bad TPS?

To work easier with the screwdriver, i put off the throttlebody. After the reinstall, my rpms are higher then before, like 3000 - 2000 rpm. The fan-relay has been pulled to get good voltage readings.

Problems yesterday and today:
I let the car warm up, suddenly a lot of steam came out of the cabin --> the heater core blew and a lot of coolant was on the passengers side.
Today, i pulled of the hoses for the heater core and put them together. The heater core has to wait for now, i want to fix these other problems.
Then today, i let the engine warm up again, suddenly the small hose from the AST went off and hot coolant came out.
So i guess i did three mistakes:
1st: the fan relay wasnt in for warmup
2nd: the small hose on the AST wasnt secured with a hoseclamp
3rd: i have one 0,9 bar ( 13psi ) radiator cap and one 1,3 bar ( 19psi ) radiator cap.

Ok but i guess the major problem is the TPS. But how can i be sure its the TPS and not the signal to the TPS ( because i dont want to buy a expensive TPS and then i will find out, it wasnt the TPS... ).

Thx a lot for your help!!

any1?

if you have a pfc you can check the tps voltages from there. if not , i think the only way is to use needle on the wire behind the connector terminal. the 3000 rps i think is too much to be caused by a tps. did you checked for air leaks? all the air hoses are ok?gaskets?

Thx for your answer, Achilles.
Suddenly i dont have a PFC but good to know that you can read it with the pfc.

Hoses are new and double checked, no air leaks - i built that pressure adapter for the air intake hose. Gaskets are new.
The 3000 are only there when you move the TPS up and down.

My car electrician will check out if he can read that TPS out, i will inform you what he says.

Ok, i have a bad TPS, i got following trouble codes: 11, 12, 18.

My car electrician thinks, that my grounding problem in the past could be the reason for the damaged parts, because the engine took grounding from every part with a grounding cable. That may be the reason for the damaged parts.

I guess i have to order again...

My problem is the TPS too. The car electrician thinks that it has been damaged with my grounding problem in the past. This means the engine took grounding from everywhere else, because there wasnt a good grounding connection to the engine.
So this could be a reason for the damaged TPS. I also got an error code for the air intake sensor...

Could this be the cause of my car idling at 3500 rpm?

My FC had a bad thermowax that caused it to idle very high.

it idled perfect before i took it apart and went simplified sequential...never mess with something that works...

Really old thread. . .still really good and current advise. Adjusted my TPS (I was within spec but at the very high end of the low end settings). After adjusting, 90% of popping on decel is gone, all popping between gears on upshift is gone, and slight "bucking" while maintaining constant speed on "nuetral" throttle is gone. This is such a simple thing to do, and yet i hadn't thought to check it in years!
PS. Replace the original screws with socket head screws -- the next person to work on the TPS will thank you:-)

Sorry for yet ANOTHER resurrection of a zombie thread - It's a great one and shouldn't be dumped out to the thread graveyard.

I just looked at mine, and given the skew inside and outside of the whole shibang, here're my numbers:

O>1.35v C>4.99v

O>.6v C>4.46v

Now.... These numbers represent the numbers of a known working TPS (I'd gone through all of this crap before and verified that it's working) and so I came up with a solution for short-cutting the whole test, in it's entirety:

Back out the idle adjustment screw, all the way, so that it isn't touching the throttle-stop (it's the adjustment screw on the fronside of the TB), so that the TB is sitting at a non-altered position.

Do the same voltage checks that you'd normally do when checking the TPS (green+red and then Black).

If your numbers are what mine are, then your TPS should be fine, though I'm certain that someone's going to give X, Y, or Z reasons as to why this won't work as a good base-logic but doing it this way is a really quick identifier to see if you need to take on the PITA task of the entire endeavor.

Someone who's gone through the entire TPS adjustment process (therefore KNOWING their TPS is in good adjustment) should try this and post their numbers, just as a fail-safe/ redundant test.

Like I said, this IS NOT a shortcut to doing it right, just a quickie test for baseline numbers.


If these numbers are off by a bad margin, then there's probably something amiss and you should go through the entire ordeal.

Hope you dont mind me resurrecting this thread again. A lot of good info in it.

Im having a couple problems setting my TPS

I had a lumpy idle, with TPS values outside of spec. Measurement taken last Novemeber. I stored away my FD for the winter months and went working on it last weekend to get it ready for spring. I took off the tps and replaced the bolds with cap head bolts to allow for easier adjustment.
I warmed up the car, then shut it down. Turned on the ignition to check the values on the PFC - values are something like 0.1V and not changing when I rotate the sensor. If I rotate the sensor when the engine is running The idle changes - bounces higher, closer to stalling etc.
The fact the PFC is not picking up any values does this mean Ive a dead TPS sensor? Any help is much appreciated

Thanks
John

So I checked my TPS voltages and the bottom wire is about 1 volt low at the upper range and a smidge low at the bottom of the range. So now to get the friggin bottom screw loose so I can adjust it. I have the phillips head screws and the bottom screw is nearly stripped from me trying to get the thing out. I disconnected the hoses as suggested as well as unscrewed and removed the oil filter to try and come from underneath with an elbow phillips. No luck.. the thing just won't budge. I even got some needle nose pliers wrapped around and it still can't get it.

Any suggestions?

Pb blast? Seems like overkill for such a small screw, but I just can't get leverage. I know one thing. If that screw comes out it will not be going back in. I picked up some hex bolts that fix perfect. Top one is good to go.

Ok,

After reading through this entire thread and the links posted, it seems that I'm having some of the same problems with mine as well.

Whenever I'm in low speeds, (parking lots mostly), it's bucks pretty wild if I'm trying to hold a low speed. It requires me using my clutch to keep it from bucking back and forth. Also my idle is around 500 when fully warm.

I'm not familiar with the TPS or adjusting anything that has been mentioned, but I'm needing to fix this. I'm glad I'm not the only one with this problem.

If anyone can dumb this down a little for me, I got tools on hand, no voltmeter but I can pick one up. I'm wanting to fix this asap.

Thanks in advance.

Also I'm stock other than Intake and exhaust.

any help please! This is all I can notice now when I drive

^^

Just do a forum search or a google search for "RX7 TPS" and there are about six different versions of the same instructions.


Essentially, there is a plug on the TPS... slip a safety pin into the second wire down on the plug between the wire's insulation and the plastic plug itself. Clip your meter onto the safety pin and a ground on your car. Now check that voltage with the car's power switch on but the engine not running. You'll want to open up the throttle by hand to see the upper and lower voltage ranges. Do the same for the bottom wire on the plug. Others have identified these wires by color etc in their instructions as well as noted the acceptable ranges.

To adjust either voltage loosen both screws on the TPS. The bottom one is a @#$ to get loose so be really careful not to strip it if you have the old phillips screws. Don't ask me how I know.... The loosening of the screws allows you to tilt the TPS by a couple degrees at the bottom like a pendulum to adjust the voltages. You'll want to find the sweet spot to where all voltages are within range then tighten everything back down.


For more detail the below set of instructions is nice in that it has a pic that'll help you identify the screws etc.

http://www.rx7.org/Robinette/tps_adj.htm

Keep in mind this isn't the end all miracle solution to all idle problems. It's worth checking though.

Good Luck!

Just wanted to bump a very informative thread.

I've been having similar problems and i'll be using this thread to help troubleshoot tomorrow, if it ever stops raining.

Basically, it's starts up and revs to about 2k, then when it settles in it'll idle at ~1.6k and bounces between 1.5k and 1.8k. Sometimes it bounces fast(like in the vid) but most of the time it bounces about twice as slow.

It also lowers the rpm's when the ac is turned on, but only to about 1.4k, and it stops bouncing when the lights are turned on.

Idle problems

So im attempting to fix my idle and at 3g ( Bottom (black wire with green strip), this goes to the 3G ECU connector. Closed throttle +V range is 0.1 to 0.7. Fully open throttle +v range is 4.2 to 4.6.) i can only get the open position to 3.36v.... any idea what i should do? i have every emission delete possible...

Keep adjusting it. I played with mine for 3 days and couldnt get it to the right numbers. Then I realized I wasnt going to get the right numbers with only one bolt in the bracket to adjust it so I got a new bracket from a throttle body at a show and it was replaced and now idles fine. Id say keep adjusting.

i know this thread is older then most users, including me, I just found then modified this picture which I personally find a lot easier to "read" if needing to adjust the TPS


http://img89.imageshack.us/img89/882...swithvolta.jpg


hope this is a bit easy to understand, and faster then always going back to some written dialog....


J.

hey, i havent read threw all the post idk if im repeating anything but i had the same EXACT issue everything down to the turning the AC on, my fix was a couple vacuum lines where cracked from under, i couldnt see the crack till i took the UIM and check each one, good luck!

So today a new chapter started on my rx7 I call it the bucking chapter , this past weekend I fixed my fuel level sensor as the float had somehow fallen off and it only read empty after fixing this I started and the car started fine

But today I took the fd to work just to make sure everything was working and it wasnt...


If I gently accelerate the car reaches red line , but sometimes not always but sometimes if I give the car gas more than half throttle it will buck as if it hit fuel cut , I tried doing this at idle while out of gear and same thing happened but it only happens sometimes ...

I rechecked all the fuel lines for leaks and nothing

I did a search on bucking and read a ton of threads on tps adjustments

Since I have a pfc I said why not it's quick to check

After the car is warmed up and it was doing the miss fire / bucking issue

I checked the tps

Vta1 reads .4 closed and 4.45 wot

Vta2 reads 1.00 closed and 4.97 wot

But I did realize something and I'm not sure if this is normal or not

When Vta1 is at 1.98
Vta 2 is at 4.97 so at half throttle Vta 2 is already at 4.97

So I started the car and pressed gently on the gas and it reached 8k than I gave it more than half throttle where vta2 was at 4.97 and bam it bucked at 4k it misses for a second than resumes for a bit there is smoke and alot of backfire when I do this

Is that 4.97 vta2 while vta1 is at 2.0 normal????

No thats not normal. Sounds like you have a dead spot or something like that, you can take off the tps and clean the tabs, if that doesnt help you might have to replace the sensor. Unless anyone else has a better idea.

I am currently having an issue where Vta 2 reads 4.8x closed and 4.9x wot. I cant seem to get the closed values any lower. This is the second tps ive had, dunno if its a fluke or if something is making the sensor think its wot.

bump.

Current issue:

Car would hesitate like hitting a wall or getting fuel cut.

Throttle position sensor VTA2 or narrow range on power fc (green wire with red stripes) was reading 4.8v+ at closed and open throttle. Full range or VTA1 was correct .5v

I changed the tps and still had the same issue.

Followed the green/red wire back to the power fc and found it was unplugged (someone cut the wire and put in male/female ends that were disconnected). So i connected them back together and the throttle position sensor finally started to read the correct values.

So i start the car and it idles/runs and revs like crap. Running extremely rich almost sounds like its skipping a beat.

Why would the car rev and idle fine when the green/red wire (VTA2 or narrow range) is unplugged and reading 4.8v+ but run like crap when its plugged in and reading 1v?

So if I'm using my PFC to adjust the voltage, should I ignore the values on a cold engine? If I pull up the PFC, the voltages for VTA1 is a bit high but if I start the car, warm it up, and then read them both, they are within the suggested range.

Yes, you want to look at the adjustment warm.

Dale

TPS Adjustment
 

This is a great discussion, 17 ys old still helping us today. I have had my current car about 2 weeks, pulled the upper intake off and blocked off everything but the BAC, Air pump had already been removed and the car has a 3" M2 down pipe, Racing Beat cat back, with the stock cat.
Still has the twins. It was bucking and hesitating but once I checked and adjusted the TPS it now runs a lot better, better idle and no hesitation. The TPS had a white paint mark on it to show that someone had previously checked it out but the adjustment was way off.
Anyway, this site is full of very useful info and I just want say thanks to everybody who has contributed in the past.
Dave

Since this is related and I followed this thread to get my TPS within spec I suppose I'll ask my question here. Thank you everyone for the valuable information -

My second screw on the bottom was mangled before I started so I ended up taking the throttle body off. Put everything back on, connected everything I disconnected I think. TPS is now within spec (was reading high previously) but now my idle is hunting between 1.2 and 1.5k RPM.

Did I spontaneously crack a vacuum line while fixing the TPS? Any ideas would be helpful..

You've got a vacuum leak somewhere. Read my guide on idle troubleshooting -

https://www.rx7club.com/3rd-generati...ncing-1147118/

Dale

In looking around I can see under the intake runners what appears to be a vacuum tube just sitting there not plugged into anything. How would taking off the throttle body cause this.

Either way, in order to see where that should go to, I'm assuming I have to take everything off including the intake manifold? ugh...

Post a picture up of what you are seeing.

Some of the vacuum lines can be plugged back in with long needle nose pliers. Harbor Freight has a nice set with straight, 45 deg, and 90 degree. I use them all the time.

Worst case pull the upper intake manifold. Get used to doing it, it's something that gets done more often than not on the FD :)

Dale

on a manual transmission car there is an unused pipe/tube.

Hard to get a good pic but it's on the right side of the manifold. No idea if it's always been this way or not.

Thanks,

https://cimg3.ibsrv.net/gimg/www.rx7...23686ce4be.png
https://cimg4.ibsrv.net/gimg/www.rx7...5967c0fa9a.png
https://cimg5.ibsrv.net/gimg/www.rx7...20fe33ab02.png

That's most likely the empty pipe that is only used on auto trans cars.

Dale

So its something else randomly great. On cold start the air pump seems to keep the idle steady then once that kicks off it hunts for idle. Even under acceleration it seems to be cutting fuel and the revs dip every second or so. So odd that this wasn't a thing before I was only working in a small area near the throttle body..

Go back over what you just worked on. You missed something. If it was working perfectly then you got into it and it's being goofy you missed something.

Start a thread and post pictures if you need help on it.

Dale

When you say the revs cutting n dipping are you in neutral or on the road? Asking because I’m having the same issue on a 95 import it’ll bounce if I try to keep revs at a constant for anything 3k n above in neutral. Under high load on the road it’ll hesitate at random spots in the rev range. Got TPS within spec and idle screw adjust eyeballed to 750 rpm with bac/isc disconnected. I guess my point here is trying to see if some else has had this same experience.

I read this whole thread and am having a issue with my car. hope someone can help.

rywire engine harness ( only has wire for vta1. vta2 is empty)
haltech 2500

so i checked and set my voltage. vta1 at rest, i have set for .75v, wide open reads 5.1v

my main concern is that ive noticed when pushing the gas pedal, when its about 50% the actual haltech is showing 4.96v and 100% throttle. After that point i still have what feels like 30-40% travel left in the pedal. Ive tried adjusting the sensor multiple times and recalibrating the ecu with no luck. Has anyone else experienced this?

There are 2 outputs on the TPS. One is only part range, one is full range. You may be tapped into the wrong output.

Dale

with the rywire harness it only has 3 wires going to tps instead of 4. So im measuring voltage from the pin thats 2nd from the top.