Need help with my TPS

[c-rad]

Ok, I am at my wits end here. This is the symptom with my car--

If I am at a dead stop, and I go to accel, the car falls on its face and sputters. Any time I give it a quick blip of the throttle in neutral, it does the same thing (just sputters and won't rev). It drives pretty decent once I am cruising and over 2000 rpms. The MAF checks out good, I just put a brand new O2 sensor in there, fixed all my boost/vac leaks. I removed the TPS when the manifold was all cleaned up and I did not mark its position. I am sure that it is my problem. Thing is, I cannot for the life of me figure out how to test it/adjust it. I have a multimeter here, and I have the FSM. Here is the page from the FSM for testing the TPS-- http://www.escic.com/240sx/tps-chart.jpg Now, if someone can hold my hand and tell me EXACTLY how to adjust it/test it, I would greatly appreciate it!
Modified by c-rad at 7:54 PM 5/30/2006

[Swedish Mike]

Ok, I am at my wits end here. This is the symptom with my car--

If I am at a dead stop, and I go to accel, the car falls on its face and sputters. Any time I give it a quick blip of the throttle in neutral, it does the same thing (just sputters and won't rev). It drives pretty decent once I am cruising and over 2000 rpms. The MAF checks out good, I just put a brand new O2 sensor in there, fixed all my boost/vac leaks. I removed the TPS when the manifold was all cleaned up and I did not mark its position. I am sure that it is my problem. Thing is, I cannot for the life of me figure out how to test it/adjust it. I have a multimeter here, and I have the FSM. Here is the page from the FSM for testing the TPS-- http://www.escic.com/240sx/tps-chart.jpg Now, if someone can hold my hand and tell me EXACTLY how to adjust it/test it, I would greatly appreciate it!

Maybe a stupid question but you got no marks in the TPS after the screw heads? They often leave a small mark.

I can´t remember the pins you measure but you can figure it out by measure them two by two and flip the butterfly.

/Mike

[c-rad]

Maybe a stupid question but you got no marks in the TPS after the screw heads? They often leave a small mark.

I can´t remember the pins you measure but you can figure it out by measure them two by two and flip the butterfly.

/Mike

I measured the resistance of every single combination and I get nothing. But, when the TPS was on the car, I loosened the screws and adjusted it while the car was running and my idle would change. I know there are pretty much two sensors in the TPS. One for the closed throttle/idle switch and the other for the TPS voltage value. On my old car, I could hook up the multimeter to two of the pins, and turn the tps and watch the resistance value change. Which two would I check on this TPS?

[NismoBgt]

C-rad just thinking out loud here but have you checked the cam timing?

[c-rad]

C-rad just thinking out loud here but have you checked the cam timing?

Yeah, its dead on at 15* (had to set it as the motor was just put back together).

EDIT: Ok, I get a resistance reading while testing continuity between the red and white wire on the harness. And it changes while moving the tps. Now, how do I adjust it properly on the car?
Modified by c-rad at 9:21 PM 5/28/2006

[NismoBgt]

C-rad what you quoted is ignition timing. Im talking about CAM timing. It sounds to me like your exhaust cam might be one tooth off... Maybe even 2

[c-rad]

C-rad what you quoted is ignition timing. Im talking about CAM timing. It sounds to me like your exhaust cam might be one tooth off... Maybe even 2

I don't think it is... I counted the ribs between the marks like 5 times before I put the covers on. But, I guess its always a possibility.

[knightrider]

iirc you dont adjust the tps by resistance, you check it for voltage, and i think .5 v is idle, i will double check and get back to you

edit: ok, so i looked through my ca manual, and its saying with the throttle closed you should measure .5v, and at full throttle you should have 4.0v. i believe its pin 38 on the ECU. now as far as checking the tps and idle switch for correct operation, when the throttle is closed, you should have continuity between pins A and B on the idle switch, which is the plug on the unit itself, now on the tps harness which is the plug that has wires coming from the tps. you should get about 1k ohms with the throttle closed. now at full throttle, you should not have continuity between A and B on the idle switch, and you should be reading about 9k ohms on the throttle position harness. now the idle switch, you should get a reading of about 8-10v at idle from the + and - wires. and at partial throttle you should get 0v from the negative, and battery voltage from the + side.

lemme know if some of this doesnt make sense, or doesnt help at all. oh yea, all the information i just gave you is on ef and ec 122 and 124 in the manual
Modified by knightrider at 10:02 PM 5/28/2006

[damesta]

I'll second that, iirc check the voltage on the middle pin of the 3 pin plug with the ignition switch in the "on" position, voltage should be around .5v when throttle is closed and around 4.5v when its fully open, if its not, adjust it until it is.

[NismoBgt]

C-rad Im only saying this becouse your symptoms sound just like what I had. The timing between the cams is correct but the teeth between the crank and exhaust cam.. 99% of the timing belts out there have marks on them. They even have an arrow on them to tell which direction to install them.

I had good idle, the engine would rev just fine but when you tried to drive the car it was weak. Low power off the line and just overal low performance. I checked every sensor. including the tps. I replaced Almost every sensor before someone pointed me to the cam timing.

[NismoBgt]

Oh yea and only time I had any power was on boost above 3000 RPM

[c-rad]

Oh yea and only time I had any power was on boost above 3000 RPM

Well, that does sound like my symptoms, so if this TPS situation doesn't resolve it, it's off to the t-belt I guess.

God... I REALLY don't want to pull that crank pulley off... grr...

[c-rad]

Ok, I adjusted the TPS and it is right at 0.5v with the throttle closed, and it goes to 4.12v a WOT. The car drives a LOT smoother now when starting from a stop, but it still doesn't feel like it has much pull. Of course, my AFR is still at 10.0 whenever I give it any throttle. It's KILLING me.

One thing I did notice though, and maybe this relates to the "one tooth off" theory... my CAS is retarded a significant amount (physically). I was under the impression that the CAS should be about in the middle for a 15* setting. Here, look for yourselves... this is where my CAS is set and according to the timing light, its right at 15*

EDIT: Oh, and vacuum at idle doesn't seem to want to go below 10" Hg which I guess is common when the timing is physically off by a tooth.

[NeedCAforS13]

go recount the ribs between the belts chris. that looks like cam timing is off... cas should be pretty well centered, or even just slightly the other way.

[rico05]

When mine was off, I had my CAS to the opposite extreme as yours to get 15*. I reset the cams and viola! The CAS wanted to live in the middle again.

[c-rad]

Well, I just went out and popped off the upper timing cover. I wanted to see where the markings lined up... I set the motor to TDC and took pics. This is where its at-- It seemed when I was putting it on, that no matter how I did it, the markings wouldn't line up EXACTLY where they should be. And I am 99% sure I counted the cogs right. I am waiting to get a 26mm socket for the crank pulley from my friend. Probably tomorrow. Anyway, here are the pics--

[datsunboy]

To get the cam pulleys to line up when I did my belt, I had to get someone to turn them slightly from where they naturally wanted to sit, and hold them there as I put the belt on.

[NismoBgt]

I would say thats one tooth of my friend. and the one that realy counts is the mark on the belt pully not the one on the pulley. It does take a little time to get it correct but it does make all the difference in the world.

[rico05]

I tried and tried to set it up by myself, but because of the valve springs and the lack of tension, every time I went to tension the belt after setting it, it was off. I had to get an extra set of hands and eyes to get it right. Took me an hour GRRRRR

[c-rad]

What I don't get, is that there are still 39 cogs between the cam gear markings. I can't count the cogs from the exhaust cam to the crank sprocket yet as I am still awaiting a 26mm socket. But still... 39 across the cam gears should still be good though, right? Did I mention how much I hate the stupid timing belt on this motor?