rough idle. stumped...please help

[grlsk8co]

My car is a 92 civic hatchback w/ p28 (obd1). The engine harness is from a obd2 ls. running s100

The motor is a 95 ls block with a 2000 type R head. brand new fully rebuilt. At first start up there was a problem with the iacv, where (from cold start) it would roam aroun 2k-2.5k. once it warmed up it would drop to about 1.5-2k and still roam/surge etc. we changed the iac and from a cold start everything is okay, then once it warms up and drops to normal idle levels it begins to roam again. 600-800rpm). everytime you hit the throttle and let off, it drops off to the point right before the motor dies out, but then regains and goes back to 600-800rpms. Ive tried 2 different map sensors, and 2 different tps sensors. Ive tried so many different things and im just lost as to whats correct and whats not by now. Can anyone confirm the wire colors for the 3 connector pin on the TPS and the 3 wire colors for the MAP on top of the throttle body?

I also have a 3 wire plug that has yellow/green, green/blue, pink/white wires. If this is not plugged into something, the car will not start. i have been plugging it into the firewall map sensor. (if im correct, i dont need that sensor correct?)

I have tried to set the tps with a multimeter set at DC 20v and get readings like .33-.88 at closed throttle. and much more spastic readings at WOT. both tps do this..I am almost positive that I have it in correctly, positioned in the groove.

I just tried to change the plugs and see if that helps..which it did, but the problem still persists. There is no CEL code being thrown


if anyone has any ideas please let me know. thanks a lot.

-Keegan

 

[raysee]

I am having a similar issue so I know for a fact that you are doing at least one thing wrong. On the TPS, you can swivel it in the throttle body to get the correct readings (or at least on mine you can). Loosen the screws a little bit, and with a volt meter attached, swivel the TPS front and back until it reads 0.5 volts with throttle closed. When you have that correct reading, then tighten the screws holding the TPS in the throttle body. Now test it again to make sure the TPS still reads 0.5 volts. If it does, move on to the next step. With the volt meter still hooked up (this is easier with two people), slowly twist the throttle to fully open. As you turn the throttle, the voltmeter reading should smoothly increase to 4.5 volts when WOT is reached. I am not saying this will fix your issue (it sure didn't fix mine), but at least you can mark one more item off of your list when the voltage is correct.


You are using the positive probe on the volt meter to the signal wire correct?

 

[grlsk8co]

Yes.

im having a little trouble making sure the intake manifold plugs are correct.

1) the harness is an obd2 LS harness.
2) i checked d11 on my plugs and the color is pink black...unlike the multiple pinouts i read that said its red black.
3) on the few plugs that go around the manifold ( there are 3 of the same style plugs) there is only 1 with the middle wire as red/black which i assumed is for the TPS.
4) there is another plug with the above mentioned colors that im not sure of its location, but i think it was on the car as a firewall MAP.
5) however now i have a vtec head which utilizes the TB MAP and im not sure if the plug should go there, or if the plug that is next in line from the TPS wire bundle is correct ?

I KNOW, confusing haha.


I tried to set the tps. again im almost positive it is positioned correctly (if it is positioned wrong it moves the butterfly right? and the correct way is to start it with the plug facing downward and rotating it counter clockwise until it "clicks" into place, and then continue cc until the holes line up to mount it correct?

following that ^^^ when the tps is as far cc as it can go, the reading was .33, and when as far clockwise it was .88 (both at closed throttle)


i can also unplug the tps and get almost no reaction out of the car...but when plugged in it will only run half decent if i turn it all the way cc.


making any sense to anyone?

hope u get ur problem fixed man, thanks for the reply

 

[grlsk8co]

ok i got the TPS sensor voltages set correctly. the problem did get a little better. From a cold start, it idles around 1200rpm VERY VERY nicely. then as it warms up it slowly drops off until 500-750rpms, still nicely, and then it begins to misfire very slightly. at this point in time, if u hit the throttle and release, the rpms will go up and then drop off and the motor dies ? any suggestions.. ignition problem?? i was also told that it could be my engine coolant temperature sensor?

 

[raysee]

Sorry I haven't been on in awhile. Unfortunately, I am not a very reliable source of good information when it comes to troubleshooting. All I know is what I have experienced, and that is very little when it comes to diagnosing problems. I too have some unused plugs from my swap and am also missing a plug for the IAT sensor. I have no clue where it is, if it is needed, or how to fix the issue. I wish I could be of more assistance, but at least I might have helped a little bit...kinda sorta. Good luck to you. I don't know why someone more useful hasn't replied to this thread, these all sound like valid questions to me, but what do I know? haha Have you tried searching for the answers in the search engine?