I recently swaped a b18b1 into my 95 civic and when i started it up everything ran and sounded good except for a bad fluctuating idle which surges between about 1000 to 3000 rpm. Any ideas on what might be causing this? Thnx

Brady

 

Vac leak, air in your coolant, or a bad IACV would be my top 3 guesses. Other than that, it could also be an electrical problem, but unless your headlights are dimming or you're experiencing some other electrical problems, I would focus on the first 3 things I mentioned. Check all your vac hoses, ALL OF THEM. Sometimes there's one on the back of the intake manifold which you may have forgotten about. If all the Vac hoses are accounted for, and are not leaking, move on to your coolant. Bleed your coolant by running the car with the radiator cap on loosely with the heater blasting full-hot for at least five minutes(preferrably until the engine starts to come up to operating temp), and then shut the car off and top off the coolant if needed. Repeat the process and put the cap on tight. Now check your idle again. If it still fluctuates, then try letting the car run with the IACV disconnected. With the IACV unplugged, your idle should drop to whatever your idle adjuster screw is set at. If it does, and stays constant with the IACV unplugged, your IACV is probably toast. You can try taking it off and cleaning out the little mesh filter and see if that helps. If it doesn't, look for another IACV. I have an extra OBD-II, but I don't think it'll work with your setup.

 

first check you TB gasket, this is the culprit like 80% of the time. Most people over look this. Cost $5 from Honda(do not use a cheap autozone one) takes 10 minutes max to install. I would recommend that one first.

 

TPS? Vacuum leak? IACV?

 

My car setup is 1992 Honda Civic VX w/ 1995 GSR swap.
I seem to have a similar problem, but is more extensive and will need experienced tech help. Thanks to all who help out.
The problem is 3 consistent problems. They happen every time I drive my car, and it happens the whole time im driving my car.
- The first problem is the idle. It idles really high. 1500rpm's. And it idles roughly between 1500-1200rpms. But, whenever I pull back on the gas pedal, it sets itself back down to 1000rpm's and stays there. As soon as I start to press the gas again, it idles again a t 1500-1200 back and forth. I put a brand new GSR throttle cable on the car as well.
- The second problem is my speed stability. For example, I cannot cruise at 45mph. I have to either have the foot off the gas pedal, or going faster. It won't let me go inbetween keeping a constant speed. It will only speed up or slow down. There is like a gap. I was thinking maybe there is slack in the cable or something like that because I can press the pedal and nothing will happen and then it engages and I speed up. I put my foot off the pedal a bit to keep a constant speed, and it will hop out of giving it gas. So its either speeding up, or slowing down because it stops giving gas. (Hard to explain) I cannot keep a constant speed
- The final problem is my fuel. The fuel is in excess. Whenever I give it WOT, there is a cloud of black smoke out the back of the motor. I never concluded what the problem was because there could be so many probabilities. But, the mpg is really low. I was thinking maybe dumping excess fuel from injectors, but someone told me to just get an adjustable fpr and that would fix it. I don't see how because the fpr that I have on is from the vx so wouldn't the current setup give less fuel?

By the way, when doing my swap, I took out the IACV and cleaned the mesh. Seems to be fine. Also, all the sensors are hooked up correctly, but I believe that my Heated O2 sensor is bad. Can't be for sure. Also, I have no intake as of right now, its just the filter on the throttle body. And, I have a breather on the valve cover where a vaccum line is suppose to be, so I have a couple extra hoses not hooked up b/c of no intake and the breather. Don't know what I should do with the vac lines.

That should do it, please help as this is damaging the reliability of my car.
Thanks,
Turtle

 

Are you using the right ECM? Any mods to the fuel system? Have you tried adjusting the idle with the adjuster screw on top of the tb?

 

if your puffing black smoke out the back under WOT, your running to rich, thats why your MPG sucks or you just have a heavy right foot, my friends civic did the same thing, till he had the FP dropped 7lbs, and now it has less lag in vtec and NO BLACK SMOKE out the back, that may be why they suggested the FPR for the GSR they may have different pressure adjustments

 

yes I tried the adjuster screw and nothing. Also, I did make one change to the fuel system, I got a new ecu with a chip in it. That could also be the problem but I have no way of fixing that.
I already know that I am running rich. I already stated that fact. I also already stated the fact that I should get a fpr but I didn't. Anyways, is there any help with the idling problem I am having. That is the worst of my problems.