SumTinWong

iTrader: (2)

I've searched the jumping idle problem and it doesn't totally encompass my problem but some of the symptoms are the same. I was a dumbass and broke a bolt off of my throttle body by over torqueing it. Bought a used TB and installed it. I have a PFC so I reset the idle and turned the idle screw all the way in and back half a turn. Start the car and it spins up to about 2k rpm. Drops to about 500 and bounces between that and 1500. Now this is where it gets complicated. Tried adjusting the TPS and it will only affect how high the car jump to (500-1500vs 500-2200). Sometimes through my fiddling the car will stabilize at about 1100 RPM and when I turn the car off and start it again it starts back up. The reason that I am more concerned that when I cannot get the car to go past about 3k RPM. The throttle body opens all the way. The double throttle is removed and I dont know what else could be causeing the proble. The car was 100%, changed the throttle body and now it no go.

datz

10 bucks says vacum leak
check: TPS, BAC, water thermo sensor, and replace intake gaskets(3) and the o ring on the oustside of the TB.

SumTinWong

iTrader: (2)

Granted. I replaced the O ring on the TB and everything else was working the 10 mins before I replaced the TB. The TPS is the same so I know the sensor isnt bad. Water sensor was fine before. I didnt take off any other gaskets so there isn't any real way for them to become damaged. I checked the vaccuum lines going to the MAP sensor and the rest of the lines around that side of the TB. Even if I assume its a vaccuum leak what line would cause the car the be unable to accelerate?

SumTinWong

iTrader: (2)

Also while doing the TPS check while the throttle is both closed and open it reads .01V if I disconnect the sensor then it reads 4.98V . Having the sensor connected or not does not have any effect on my problem. If I adjust the fast idle cam I can make it spool up to redline on start up, but after it comes back down it still bounces around.

datz

i have always tested the TPS's resistence in ohms, or the two light method. the fsm has values for that.

same problem with my 90, after replacing intake gaskets, vacum lines, i will be willing to bet the bouncing goes away.

also get a auto stethescope(or piece of vacum line, or similar)and listen around the gaskets and vacum lines(youll hear it leaking) and its a cheap way to narrow the problem down.

datz

also the holes in the side of the TB that held the double throttle plates are not plug good(or at all), huge vacum leak.

SumTinWong

iTrader: (2)

The holes from the Double throttle plates are blocked. I was doing the TPS test and since I didnt have ready access to a multimeter I used the sensor read out on the PFC. Looking at VTA1 and VTA2 when the key is in the on position I get ~.01V on both. At WOT I get the same readings leading me to believe the TPS is bad. Strange since it was working fine beforehand. I'm gonna try taking it apart and taking a look inside since I've read about them being vented and corrosion on the inside.

datz

with those readings the tps is prob bad.
but if that doesnt fix it i would suggest a vacum leak or somthing telling the ecu(incorrectly) to keep the rpms a little higher.

LikeThunda

iTrader: (1)

yes, i remember that being a TPS issue. replacement, always worked for me.

gracer7-rx7

iTrader: (16)

VTA1 plays a bigger role in idle and low rpm. Both values need to be in spec in order to have a smooth idle. The TB mechanical settings (there are 3 if I remember correctly) should also be checked and adjusted as they will affect the position of the TPS.

The 3rd gen fAQ has a couple of good threads on the topic of adjusting TPS and TB settings. There are also a couple of good threads in the 3rd gen archives.

I used the PFC sensor check to review TPS readings also. Much easier than trying to get a voltmeter on the wires.

SumTinWong

iTrader: (2)

Got the replacement TPS. Put it on and same issue. This leads me to believe that there is a problem with the wires. I was trying to find what the voltage readings should be with the key in the ON position and the throttle body closed. I checked the wires at the sensor to see if there was an open in the wire and my brown wire with black stripe was open. Pulled that out, stripped it and re did it. Tested it out and thats g2g. I've narrowed down that this is an electrical problem (atleast one of the problems are). I'm trying to find out what my readings should be at each of the wires but there seems to be some conflict between Damians FAQ on adjusting the TPS and fd3s.org. Even if I find that one of them is bad I tried to trace the lines back and they seem to dissapear either underneath the UIM or behind the block. Where do the signals that go into the sensor originate? From what I read it should be a ground and a +5V and the position of the sensor acts as a potentiometer for VTA1 and VTA2. Where else can I check to see where the electrical fault is?

SumTinWong

iTrader: (2)

Fixed the TPS problem. Took everything apart and put it back together. Voila. Most likely a bad connection or I missed something on the initial hookup. Got the car to idle correctly and everything was gravy. Took it for a spin. Throttle would stick so I went back under the hood. The primary throttle plate is sticking open. Adjust the throttle cable, same problem. Tried to clean the throttle body out didnt fix the problem. Did some adjusting and the cable seemed to be snapping back shut. Started the engine and the idle is now bouncing. Did the reset to perform the idle learn and still wouldnt idle. More suggestions?