1986.5 Runnning rough, sputters/misses on acceleration

[NiGMa]

So, car has been running fine for last couple of years. Then the other night, let my younger brother do some learner driving, car was bucking like a bull while he was learning to use the clutch, as you do. Then as he is driving it, I notice it is missing when he accelerates/puts the pedal down. I drive it home and it does it for me also. Is fine when driving at a constant speed, but accelerate and it sputters/misses, it still does manage to speed up, but not very well and it sounds terrible.

Sounds perfect when idling, can put in neutral and rev it all the way up let it go, all sounds great, but try drive it(load), its horrible.

Some kind of Air/Fuel mixture, ignition problem by the sounds of it.

I have checked, vacuum lines, timing(10d BTDC), TPS(which is not up to spec as per TSRM), electrical grounding of ecu.

I get code 51. which is related to the TPS, since i can get it to go away by shorting E2 and IDL on the harness.

Could the bad acceleration be caused by a TPS? does anyone know what a supra runs like with their TPS disconnected?

Any ideas?

 

[AJ'S 88NA]

Fix the TPS. It is a wear item.

 

[NiGMa]

Fix the TPS. It is a wear item.

Okay, but any idea what it would run like if it was disconnected?

 

[AJ'S 88NA]

Okay, but any idea what it would run like if it was disconnected?

Don't think it would run at all.

 

[NiGMa]

Don't think it would run at all.

Well, I checked my broke TPS with a DMM as per the TSRM and only signal between the E2 and IDL terminals isn't working properly. The throttle position other than at idle is sending a continuously increasing resistance signal to the ECU so from this I would assume my broke TPS only has an issue at idle. I'm pretty sure about this because at any throttle position above 0.75mm(7M-GE) the E2 and IDL terminals should not have continuity, which is what mine do since they never make continuity at any position.

 

[NiGMa]

Found this interesting tidbit from jetjock at this thread: http://www.supramania.com/forums/showthread.php?19142-code-51&p=220269&viewfull=1#post220269

"It sure can. Remember, the IDL contact is what enables and disables the ISC system. Code 51 signifies no IDL contact close, thus no ISC operation. Unplugging the TPS always results in an altered idle. In fact that's about all it'll result in other than a slight enrichening of the mixture."

 

[NiGMa]

Another post about running without a TPS: http://www.supramania.com/forums/sh...PS-unplugged&p=1621383&viewfull=1#post1621383

"+1^... on a side note though, I drove my car for almost a week to and from work with the TPS disconnected and didn't notice any additional driveability issues (it was definitely not running 100% anyway). I took the intake manifold off for a starter replacement and missed the plug when I put it back together (oops). Still not recommended though."

Doesn't seem too bad.

 

[NiGMa]

Good news,

Sorted the problem out today. It was the spark plugs! just changed them with some spares I had lying around. =)

This thread helped: http://www.supramania.com/forums/showthread.php?104519-Splattering-Missing-under-load-gt-10-vacuum