I have yet ANOTHER problem with the S4 TII, at first I thought it was something with the clutch, now I think it is something with the Throttle cable or TB.

I depress the accelerator about half way and all it wants to do is suputter and die, the only way I can get it to rev is to lay on it only about 10-15% at most. It will only rev to 2k then fall down to about 3-400rpm. During that time I let off the accelerator then when it falls I feather the pedal to bring the rpms up. I check the linkage is and everything seems fine, no blockage and everything connected properly. I had adjusted the TPS last night so I cannot see how it can be off already.

Heres a list of the parts that could be the possible problem:

1. Plugs - used but were cleaned when put back in
2. Wires - used but no arching or toching of one another
3. Injectors - were sent to RC Eng. to be clean/balanced
4. Timing was adjusted properly when reassembaling the block
5. I have a straight exhaust, so there is no clogged cats
6. I have checked the vacuum lines about 100 times and can't seem to find a problem
7. New OEM fuel filter

The only thing I can see as being the problem is that I had put in premix, because I was not sure if the MOP was working properly (could not see the oil in 3 of the lines), since I was unsure I only put in a 150:1 mixture in.

 

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If the spark was breaking up, you'd be getting backfires.

I'll bet the TPS resistor has a bad spot in the plunger stroke.
It will set at idle just fine, but as you open the throttle part way, the TPS value will drop out.
The ECU sees RPM >2K & the TPS value briefly says idle so you get a short fuel cut.

 

I do get back fires on engine decleration and most of the times it dies, if not it reving around 200rpm and then dies or I can tap the gas in time and it will come back to life.


What do you mean by rpm>2k and the TPS value?


I had just adjusted the TPS again, its just about spot on. The idle is just about perfect as well. But again when I depress the acclerator it revs to about 1800rpm then wants to die, but I quickly let off the acclerator and hit it a agin then it will go over the 1800rpm mark. Also when I go to try and drive it, like I just stated it revs to about 1800rpm then I release the clucth ans it stumbles to 900-1000rpm then I try to accelrate the engine and it does not move... I then depress the clutch pedal and it dies immediatly....

I went back to check the TPS and it was off by about 400 (at about 0.560) ohms readjusted and went back at it. Came back it was off 500 (at about 0.440) ohms again.... I was readjusting it and this time when I was slowly opeing the throttle I saw that the meter went dead at about 3.95 ohms, then at WOT it was at about 5.25-45. Tried it again and I got the dead reading at about the same 3.98 ohms....

Could that little dead spot be the problem? I sorta hope it is the cause of all my problems, but then it sucks at the same time. Is there any way of fixing it other than replacing?

Oh one last thing, I was looking at both the Haynes and FSM to double check I have the spark plugs/wires correct. Haynes says the Leading is the top and Trailing is the bottom, but the FSM says the oppisite. Was this a mess up on the Haynes? The block has the T on top and L on bottom. Let me get this right the leading coil is the one on the front strut tower and the trailing is by the clutch/brake cylinders...

 

The golden TPS test:
Use a cheap needle type multimeter.
Set the meter to the 1K ohms scale & zero it.
Unplug the TPS.
Clip the multimeter on the orange & green wire pins.
Hold off the throttle & work the TPS plunger in & out.
The needle should sweep smoothly from ~0 to ~5K ohms.
If it jerks around, goes high, or low during the sweep - it's bad.

If the ECU see a short or open as the throttle opens, it will cause a fuel cut.

The block is gospel - T on top L below.
Leading coil near the battery, trailing near the firewall.

Spray contact cleaner (Home Depot- CRC QD contact cleaner- electric Dept) will sometimes rescue one.
Spray it in, work the plunger, blow it out, test with meter.

 

What do you mean hold off the throttle? I am using a multimeter, but everytime I go back to re check it it is off.

 

Oops - I was adding to the previous post as you were typing.

Hold the throttle enough to allow the TPS plunger a full stroke.

It's not repeating - a good sign it's dirty inside - try the contact cleaner (above).

 

Video of a really bad (worn out) TPS:

click here

 

Ok thanks! I went back to check the readings and it was at about the same 1k then I pressed the plunger all the way in and let it out and all the way in it read like 226k and 5.5k all the way out. I released the throotle to check the 1k vlaue again and it was at 2.2k.... I guess I will tyr cleaner or if not by a new one...

Watched the video, whats it mean if it is worn out?

 

If I'm reading this right, it may be exactly what my problem is...

Could the RPM ranges shift? Could the dead spot be mobile? I watched the video, but I'm not exactly sure where the TPS is to remove it and test it like that.

I'll be excited if this solves my problem...

 

One other thing I would like to add. Opun deceleration of the engine, I get slight to moderate back fire...

And when I clean the TPS I should have it removed?

 

I had cleaned it ALOT then tested it. I was getting values all over the place.... Well I thought at first, I have a digital multimeter and I was not paying attention but when it is under 1k ohms it drops the K and reads just the actual ohms. Anyways the lowest it would go was about 130 (thats about an average, it would fluctuate between 78-200 ohms). Then when I would slowly let the plunger out there wer 2 spots it would be dead (no reading) around 4-500 ohms and 3900 ohms give or take a bit. Basically my scale went from 130-5680 ohms. It would not stay on a constant number, it would always fluctuate maybe 5-15 ohms, i think that is because its digital/sampling rate...

Does that mean its bad?

 

If the needle (or digital) value is inconsistant & jumping high & low, it's just plain worn out.

FWIW all RX-7 narrow range TPS sensors are the same, only the brackets & plugs are different.
If you have a different model available & it meters good, you can bend open the 4 tabs on the retainer & swap the sensor to your bracket.
Then splice (solder & heat shrink) the wires to your plug.

 

Hmmm thats a good thought. Thanks! But I am leaning towards shelling out $154 for a new one..... don't really want to but I am sure it would be best..

Also I decided to try and put it back in and this time I hooked up my LM1 WB and I was watching the dispaly as I TRIED to drive it and it was reading about 14.1-15.9 :1 which is REALLY bad, the worst was at about 1500rpm where it was in the 15.9:1 range, upon decleration at times I saw as high as a 20.3:1, that is when the engine wants to die completly. At idle it is VERY rich right around 11.5-8:1, don't forget the Reman has only been run for maybe an hour and a half to two haours at the most. While driving it or attempting to do so, again the car would sputter and pretty want to die, I would also get alot of bucking....

So if I understand what you said before, that dead spot in the TPS causes the ecu to lean out (fuel cut) hence the reason I am getting such a high AFR reading. If so god love WB meters!!! I shoul dhave had it connected sooner.

One other thing, if I were to get a Standalone (haltech or microtech). Do I need the TPS?

 

You could also monitor the voltage the ECU sees from the TPS (either at TPS plug or at the ECU) when you are driving.

If you see 1V or so, when you're not idling or not letting off the throttle, the TPS is misadjusted or bad.

If you see anything other than 1V or so at idle, the TPS is misadjusted or bad.

Do you have emissions control (air pump) ? If yes, your AFR reading should read sligthly lean at idle. So, AFR readings also depend whether or not you have air pump or not.

Hugues -

 

How do you monitor the voltage at the TPS or ECU? Is that when it is plugged in and running? The TPS might be hard to get to because of the TMIC.

I have the airpump on, but no cats, just a midpipe, the WB sensor is mounted on the DP so it would never see the clean air from the air pump.