I did the swap in my car and it was running good but with the CEL on because my TPS was broken, replaced the tps with a known good one and set the tps at .50 at idle, started the car and when cold it will idle just fine at 2k and work its way dow, but once it warms up my idle jumps up and down from 900-1500 rpms. now sometimes it will stop jumping up and down and idle at 900rpm but it is verrry rare that it happens. I replaced the TPS again but this time swapped a complete GSR throttle body and the issue is still happening. if i unplug the tps it will idle fine at 1,300 rpm.. here is the info and list of things I have tried..

1993 civic CX hatch
2000 b16a sir2 motor
usdm b16a2 intake manifold
stock intake
Chipped p28 (p30 base map)


2 different TPS sensors set at .50 at idle, still jumping up & down
cleaned out the IACV, still jumping up & down
replaced IACV, still jumping up & down
tried 2 different ECU's, stock and chipped, no fix
topped off the coolant and "burped" the system
new throttle body gasket, still jumping up & down
new intake manifold gasket, still jumping up & down
new map sensor, still jumping up & down

I am 100% stumped on this, any help would be much appreciated, thanks.

 

Any CEL codes?

Does your throttle body have an FITV attached at the bottom?

Have you tested the ECT sensor?

 

the code 43 "fuel supply system" will come up well I am driving but im sure its because of my o2 sensor, but if i turn the key off then back on it go's away for the whole day.. with one of the TPS sensors it will also pop up the code 7 with the code 43 but also go away if i turn the car off and then back on and stay off all day..

as far as I know my ECT is fine, I replace the one for the ecu and the one for the gauge cluster a few months back and there is no cel coming up for it.

the b16 throttle body is without a FITV and the gsr has it but with or without the idle still jumps up and down.

 

If you unplug the primary O2 sensor, does the idle problem stop?

 

Ill try it right now, gotta put the TPS back on and set it to .50.. but why would the jumping idle go away when the tps is unplugged?

 

I believe that unplugging the TPS causes the ECU to put the engine into limp mode.

 

tps back in and set at .50 idle, o2 sensor unplugged and the idle issue is still there but now I have a constant CEL and the code is #41 "primary 02 sensor heater element"...

 

You are thinking of code 41. Code 43 indicates a problem with either the O2 sensor itself or a fuel system problem (e.g., fuel pressure, FPR, injectors).

 

yea sorry, that was a typeo.. before it was code 43, now with the o2 unplugged its code 41..

 

Check your FPR and injectors.

Also try adjusting the idle speed.

 

is there a way to check the FPR or will I have to swap in a different one? also how do I check the injectors? the idle screw on both throttle bodies are stuck/ stripped..

 

Measure the fuel pressure with and without the FPR vacuum hose attached.

Check whether they are dirty.

This could be the cause of the idle problem, but you also need to fix the code 43 problem.

 

the motor is the same with/ without the fpr vacume line on, I dont have a fuel pressure gauge hooked up but Ill get one if you think that will help..

the injectors are fresh, had them sent out to RC and they came back with good numbers on all 4.

so do you think the code 43 is because of a bad o2 sensor?

 

Measuring the fuel pressure may help you solve code 43.

It could be, if the fuel system is fine.

The idle problem may be separate. Inside the throttle body are ports/holes leading to the IACV or FITV. When the engine is warm and having the idle problem, use your finger to cover the IACV or FITV port. Does this cause the idle to settle down?

 

I will try again tomorrow, im too tired to mess with this stupid car anymore. Thanks again for all of your help ron.

 

i just did a b series swap on my cousins car and it was doing the same thing as urs turns out it was the timing did u check to see if urs was correct?

 

timing is 100% spot on, checked it 4x when I replaced the water pump but ill check that agin too. thanks.

 

*UPDATE*

I replaced the o2 with a good used one and it fixed it, KINDA..

it still jumps up and down once it warms up but only a few times then idles fine..

no more CEL on at all.

RON do you think if I re-chip my ecu and delete the o2 sensor it will fully fix this issue?

 

ttt

 

Stupid question..... Whens the last time you cleaned/recharged or replaced your airfilter? That can have an effect on it if its blocking a little airflow.

 

I had the same problem and I tried absoultely everything, it turned out to be a warped intake manifold. I replaced it and it ran perfect. Sometimes the idle still does it but it's the iacv now. I tested for vac leaks before the switch and it was a bolt closest to the vtec solenoid that it was leaking by, after retorque it still leaked so the only option was changing the whole IM. probably not the same problem for you but thought I'd share.

Good luck getting it to run perfect!

Edit: forgot to mention this was on a JDM D15B.

 

It will do it without the intake even on the car as well.


its not a vac leak cause after I replaced the o2 sensor it ran way better but still has a funky idle for a lil bit then stops.

 

spray some intake cleaner all over your TB, your intake plenum, and your vacuum lines. If the engine revs up, then you have an air leak, which COULD make your engine do that.

Bubbles in the coolant system can also cause your engine to rev up and down i've heard (in hondas). So bleed yours just to see if you have any.

Also, clean out your IACV, could be some dirty clogging it.

 

By you saying that it does it a couple times when it warms up it made me think vac leak, as you warm up everything expands and a vac leak could present itself, which would cause large bubbles in the coolant, little ones are just from the thermostat opening and closing. It could be a number of things, the o2 sensor helped so that was the first fix, this may very well be the second.

No harm in running it without the radiator cap and letting it go through a few fan cycles to look for air, also did you reset your ecu after changing the o2 sensor? Relearning the ecu might help, after the relearn test for bubbles in the coolant, if none, then on to the next one lol.

Edit: run heater on full blast while cap is off the radiator.

 

did all of that and still no fix...

when its cold and idling at 2k its fine, once it gets warm it is fine at 900rpm.. as soon as i drive off and come to a stop it will rev a few times then sit at 900rpm.. before I changed out the o2 sensor it would rev up and down as soon as it warmed up and then never stop.