I haven't been able to find anything about the TPS issues that I'm having. My setup consists of a 96 hatch with a 94 b18c with a p28 OBD1 ECU tuned by Crome according to the guy I bought it from. Anyways, at first the idle started to oscillate here and there and then it would just oscillate all the time; I heard that it might be a Crome issue as the 880 cc injectors might be too big for it? Anyhoo, I replaced the IACV and it continued to do it even tho it wasn't throwing that code anymore. Thats not the biggest issue however, as I was driving, apparently the stiffer then stock hasport mounts rattled out the TPS screws and the TPS just fell out... No biggie I thought, until I put it back in and the TPS code got thrown and the car just wants to hit the rev limiter anytime I start it now. I checked the voltage and the ECU is seeing 0.0005 volts with no throttle and 3.44 volts at WOT... I replaced the TPS with a new one and it still does the same thing. I'm at a loss. I am not sure if the exposed (TPS) wires touched and shorted or what, but I corrected that problem as soon as I saw it. So what I'm trying to figure out is what the problem is.... I don't see any wires coming out of the OBD2 to OBD1 harness conversion and the ECU is seeing a voltage so I'm really not sure which direction I should go? Or what the problem could be other then the wiring, which has continuity...

Any help is appreciated guys and yes, I have searched and came up empty handed.

 

Anyone have any ideas?

 

Adjust the TPS until it reads .5 closed ad about 4.5 volts on WOT....

 

Well, I can't adjust the TPS to read 0.5 closed or 4.5 at WOT because the range of 0.5 is pretty much at 1/4 throttle and even at full throttle, the damn thing will only read 3.4 volts... and its not the sensor as I replaced it with a new one AND I even tried my buddy's known working one....

 

This is odd. Nobody has had this problem before? Could it be the ECU? Is there some sort of resistor or something in the OBD harness that could have fried? Anybody?

 

i broke a tps sensor and it did the same thing that your talking about... what i did was buy the BBK 68mm throttle body with TPS sensor and it solved my problem. I dont have a chipped ECU though so i dont know if it could be that.

 

Thats the thing. The sensor got rattled off the throttle body and that's when this problem surfaced. I've tried 3 different TPS sensors so thats why I'm thinking its gotta be something else...

 

Check your voltage supplied by the ecu to the TPS. Should be close to 5v
Your voltages should be(as started above) are correct .5v and 4.5v @WOT

If you are not getting the proper voltage in then you are not going to get the proper voltage out.

This might also be a ground problem too. Your TPS can be affected by voltage drop on the ground side.

 

So what exactly is the problem if there isn't 5v going into the ECU?

 

which wires r u testing to get the voltage?

 

broke my tps a few months back.. i just checked voltage for 0.5..

i dont this this might do anything but maybe reset your battery.. i always run my plugs when the battery disconnected

 

I had some corroded pins in my TPS plug a while back that caused that problem. I replaced them with some pins from my cruise control plug and fixed it.

 

As far as voltage goes, I have the 5v going into the TPS and a good ground (the outer most wires as the middle is the signal) and at the TPS, the signal is at a 0 to 5v resolution but I'm thinking that either the harness is bad or the ecu is, because at the ECU I'm only seeing a max of 3.4v (at WOT)... I'm gonna play with it some more later today and keep everyone updated...

 

you said that you just got a new chipped ecu... why dont you put in your old one to see if you have a faulty ecu? i think that'd solve one problem or maybe all your problems if you TPS is fixed and you just have a bad ecu.

 

What do you mean by good ground? You're only aloud .050v on the ground side. More than that and it will mess up the signal wire.

 

sorry .

 

yeah,.should be at 4.5 volts..try adjusting like stated before...if the code goes away...and stills idles bad....could be a vaccum leak..or needs a retune..

 

You have to adjust the TPS to get it to .5v at idle, correct?

Do you leave everything off or do you turn the key to the "ON" position?

 

Ok. New info. Apparently, the JG throttle body that's on the car, somehow bent on the TPS side.... a little rebending and we were back in business. Having said that, I adjusted the TPS to read dead nuts 0.5v at idle (0.501 to be exact) but it will only read a 4.3x at WOT now... no biggie I thought. Well, anytime I go WOT, I get a TPS code again... and somehow I am magically getting an IAT and water temp codes as well.... Does anyone know what the ECU is looking for as far as voltage goes, for both the IAT and water temp sensors? Also, its interesting that this only tends to happen after I do a WOT pull. Since the ECU has CROME on it and was "tuned" by someone that knows the system, the ECU shouldn't pull any codes under boost, right? Basically, I'm thinking having the car boosted is part of the problem but am not sure yet....

 

i think you are not getting full voltage to the ecu, thus some of the sensors is not getting the voltage it needs to operate. check the groung at the thermostat see if it has a good contact. if not you might not be getting full voltage to the ecu.

 

if that only happens after a WOT pull you might have weak mounts that cause the engine to rock that far to bend the TPS sensor enough to cause problems

 

try ur mates ecu

 

tuned w/ crome, IAC duty cycle not dialed in especially for the 880cc injectors, and ignition timing not in sync.

i garentee you have atleast one of the problems above, if not all of them.

not many people know how to properly tune for VERY LARGE injectors.

 

Any hints, tips, or tricks that you can share on the whole Crome tuning philosophy? I have a copy of the map thats currently in my ECU so if any knowledgable people would be willing to help, I'd be more then glad to send them the bin.

 

w/out a burner its pointless, but i can tell you that your injectors are WAY too big, and probably working at 50% duty cycle at max, which isnt going to give much room for error when trying to get it to idle.

my suggestion, raise the idle using crome to atleast 900rpm, drop the duty cycle to somewhere around 33% and just adjust from there. make sure you have all the idle cells in sync for timing and fuel and you should be able to get it stabilized.