camajo

iTrader: (3)

^^

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!

Commoner

iTrader: (2)

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

muibubbles

iTrader: (36)

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...

MazdaSpeedDan

iTrader: (4)

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.

Prôdigy2nd

iTrader: (3)

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





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


J.

okevin

iTrader: (1)

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!

Tem120

iTrader: (5)

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????

Josh&fd

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.

Josh&fd

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?

Djseto

iTrader: (2)

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.

DaleClark

iTrader: (55)

Yes, you want to look at the adjustment warm.

Dale

david93fdr1

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

dubbs693

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..

DaleClark

iTrader: (55)

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

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

Dale

dubbs693

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...

DaleClark

iTrader: (55)

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

j9fd3s

iTrader: (3)

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

dubbs693

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,

DaleClark

iTrader: (55)

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

Dale

dubbs693

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..

DaleClark

iTrader: (55)

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

lordofpalms

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.

Unkachabull

iTrader: (7)

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?

DaleClark

iTrader: (55)

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

Unkachabull

iTrader: (7)

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.