Vehicle: 95 Vtec

If there is a leak between the 3 FITV orings what can happen? I assume they block off air and coolant from each other. Can coolant get into the intake air system ??? If so, what would I see or should I check into?

I recently removed, cleaned, adjusted, and reinstalled the FITV, without taking the TB off the manifold. The middle triangle oring was more flattened that the other two, but my local Honda dealership did not have the triangle oring in stock. It may have shifted position when I reinstalled it.

I tested the bottom hole in the TB for vacuum at full OP temp, and there is a very small amount of suction there. If I put my finger tip over the hole for 5 seconds or longer, then I can feel the suction when I try to remove it. I understand that there should not be any suction. But oddly covering the hole does not eliminate the hunting idle.

 

Orings do not cause any idle problems. They dont wear out and you can just put more gasket dressing on them. Its probably a bad throttle body.

 

did you tighten down the white screw while you had it apart? and might be a vacum leek. use some intake cleaner to make sure you don't have a leak or bad gasket

 

I took have removed, cleaned, and adjusted my FITV.

Like you, if I leave my thumb over the FITV port inside the throttle body at full operating temp, over a period of several seconds I can feel a minimal amount of suction. According to the FSM, there should be NO suction. before i cleaned it, the same amount of slight suction existed, so I don't think my tampering had anything to do with it.

I have no vacuum leaks anywhere. I have tested with a vacuum gauge and also with carb cleaner all over the entire IM area. all the hoses are new. new TB gasket, new IM gasket.

If you figure anything out, please post back!

 

yes, that's why i removed the FITV. i tested all possible areas where there could be a vacuum leak with propane but i did not hear any rpm increase or idle hunting.

 

Are you having idle problems, or are you just wondering how you could have suction without an idle problem?

If you have an idle problem what's your symptoms? give details. your problem may be different from mine.

If you just have suction without an idle problem, my guess is that the small amount of air being sucked in is not significant enough for it to mess up the ECU and/or the ECU is compensating for the leak.

 

well i know that with mine it idled at 2k rpm and would drop down to 1k back and fourth most of the time and sometimes it would just hold at 2k rpm. after taking the TB off and cleaning it and tightening everything down and replacing the TB gasket even though the old was fine,it now idles at 1200 rpm and if it sits for a minute it lowers ti 750 rpm. it has a slight float in it every once and a while still from 1250 to 1500 rpm but it is slow unlike before you think it was going to die the way it dropped so fast. but yet the second i start moving it went away

 

I'm having a very persistent code 14 and major idle problems. Stumbling and bogging. Have replaced the FITV and IACV with known working units, been all the way through the flowchart, replaced the ECU etc etc. I just can't get it figured out. There are no vacuum leaks. It's very, very annoying.

 

well sounds like a bad sensor of some sort like a MAP or O2 or maybe even your TPS

 

First, is your vehicle the 93 Civic Coupe? If so, what engine is in that vechicle? If not, let's start there. Do you have the Helms or Honda Service Manual?

 

D16z6, 1993 Honda Civic.

I have both.

I have been all the way through both flowcharts for code 14. Everything tests out 100%, yet the code is still there. I have tried two known-working P28 ecu's, two different known working IACV/FITV combos, and have wired the IACV straight to the ECU to rule out any wiring problems. Still there!!!!

Compression is good, so no bent valves messing things up.

I even went as far as swapping out the entire intake manifold/TB/FITV/IACV/IAT as a complete unmolested unit [so as to rule out the TPS/MAP/Adjustment problems etc] from a known working vehicle, and still have the exact same problem. I did install a new IM gasket and torqued everything in sequence.

 

well i will be honest with you and say the obvious you have a weird problem. i would go back and check out the basics, air filter, plugs, wires cap rotor etc. might even check out the fuel injectors. obviously if you have replaced the TB and all that and you haven't resolved it maybe it's time to look other places. unless you have a vacuum line backwards but i hope you would have noticed that already

 

I took the liberty to edit your thread to read easier, a list of the work done. Sorry to hear of this level of frustration. Cant blame you if you never want to see another Honda again. But things like this can happen with any car, since the epa took over engine emissions design. Well, I assume you deleted the code 14, via the fuse, or battery cables to reset the ecu. I assume you probably bled the cooling system too. There is no fuse for the IACV that I am aware of [not usre which engine you have], but if there is check on how tight the fuse is fitting. So, this dumb, OBDI, programmed ecu is essentially saying, "Hey, I have either too much or not enough air going into the engine, and all I know is that I was programed to blame the IACV, or I cannot control the current to the IACV and since I do not know why that is, then it must be the IACV's fault. And the irony of it all is that is how it was programmed, the damn thing cannot think outside of its programming [Japs = classic under engineering]. So, forget the code completely, forget the # 14, dont obsess. Since we know what you did, then what's left. Well either the ecu cannot control that IACV for some reason, or there is extra air getting into the engine that the ecu is blaming the iacv for. What are the other sources of air -- the PCV system and related tubing, the EVAP system and tubing, the EGR system and tubing. That's where I would start now.

If possible, could you put your original IACV wiring back in place correctly, then we can take it from there. You have the Honda service manual, correct? Follow that for now. Also, if Helms has a more detailed manual for the electrical, intake, or fuel systems for your vehicle, I wouldn't spend another dime until I got them too.

One other thing that comes to mind that might help you figure this out, is the vehicle history? Did you get it with a code 14. What was happening right before you got the code? Were you working on it, or was someone else doing something? Its of paramount importance to retrace those steps at that time period. Sometimes the hardest thing to fix is the one that wasn't correct to begin with -- meaning, people tamper with vehicles and really screw them up and then lie when they sell them, and then you get stuck with their problems, and you dont know that something is put together wrong. That takes a keen eye and lots of detective work, though. Was it a private owner or purchased from a dealer? Quite frankly, your problem is frustrating me more than my own. Gee, I also hope that this car has not been modded. I wouldn't have a clue where to start with such a vehicle.

Btw, it would help to know what your exact symptoms actually are. I dont recall reading that specifically, only that I started the thread asking if the FITV could leak inside itself somehow, and then you said yours was doing the same thing. So, besides the code, what are the symptoms exactly.

 

wow well written LOL

 

Jonathan, one other possibility, but your going to have to ask an engineer or seasoned mechanic about this idea. I was thinking about how a clogged up exhaust system can totally shut down the intake air of an engine, and shut an engine off [example: clogged CAT]. But can the opposite thing happen ... where the exhaust is flowing too much [beyond capacity], possibly a leak, and as a result more intake air than is needed is going into the engine, and the ecu blames the iacv? Its just a long shot, because my understanding about exhaust is that the greater the flow rate [called breathing] the better the engine runs. Of course, there is also something called back prressure. I don't know much about it, but mechanics say it is neccessary for proper engine operation. When it comes to dumb computers and glitches and things like that, well you can see my train of thought on this.

 

You are correct in that there is no IACV fuse. I have reset the ECU nearly every time I tinker with the car, both via the back-up fuse and by disconnecting the negative cable itself.

I have bled the coolant system properly according the FSM guidelines.

In my earlier post by "I have both", I meant that I have both a Helms and the FSM. I have been all the way through the flowchart for both. Of course, the end of all flowcharts is always "If problem persists, take vehicle to a qualified service technician."

I put the engine into the car myself. I bought the d16z6 from a H-T member several years ago. It was completely stock out of a '93 Si. He only took it out to go B-series, and I believe him that nothing was wrong with it. I forget his name now, but at the time he had a very good reputation here on H-T.

The entire wiring system is stock OBDI Civic wiring that worked perfect with a d15b7 in there. The car itself is bone stock aside from the engine. The only thing I had to do was add the two wires for VTEC, and I did those proper with the correct plugs and at the correct terminals, soldered all connections etc.

The injectors are working properly - both with regards to resistance and receiving proper voltage from the ECU.

When I first put the engine in, I had 3 codes. IACV, TPS, and VTEC Oil Pressure.

The TPS only needed adjustment to clear away. I had put a new TPS on the throttle body, and didn't adjust it until after I got the engine running.

The VTEC code was due to low oil level.

The symptoms I have now are that the engine won't idle. When it does eventually find an idle, if you gun the engine, when the revs fall back down it won't level back out at idle. Engine speed falls all the way down and cause the engine to die. Then the engine has a very hard time starting back up. And when it does start back up the engine has a bad idle. There is also a dead/flat spot between idle and about 2500 RPM.

When I first time on the car, the IACV code comes on nearly immediately. Sometimes it takes 5 seconds, but more often than not it appears instantaneously with starting the car.

Thank you for all your help! I've really run quite totally out of ideas.

 

Jon, uh, I see now why you said yours was doing the same thing [Re/my question about the fitv thread], but now I see yours is doing quite a bit more than just having an idle problem. It sounds like a clogged exhaust somewhere, because when the exhaust clogs, it shuts the engine off, and causes idle problems on restart. There is no code for a clogged exhaust system, other than the EGR part of it, and that part is limited. Also, bad O2 sensors can destroy CATS and cause all kinds of havoc all without setting a code until they completely go bad [check into it, Jon, but dont go right out and buy new parts]. Do you know how to test the O2 sensor and the CAT. Well, one quick test is to disconnect your exhaust before the cat and see what happens, if it runs ok, or stays running at least. You might have more than one part bad by now -- a compounded problem, but maybe not?

There is a temp test you can run on the cat, but it can fail to pass the temp test and still not be clogged, so the test is limited, but its still useful as an indication clue. Your problem is really now starting to sound like an exhaust/emissions system issue. The ecu is trying to control the air thru the iacv, and another bad part of the air system is just making it confused, and the darn exhaust, if it is clogged up is just shutting you down. There is also an O2 sensor test that you can run on OBDI systems with a multimeter, I assume you know how.

I've had another OBD1 car that had symptoms like yours and never got a code for the O2 sensor until it was completely dead. I was getting a general air/fuel codes though, again computers cannot reason, and I believe they are the equivalent of the Honda code 14.

About the idle to 2,500 rpm issue, there is a valve called the fuel injection air control solenoid valve (FIA), and it [is supposed to be] active in that rpm range.

But this sound like either the exhaust is clogging causing too much back pressure and shutting you down and/or that O2 sensor is creating havoc by itself. But I would start there and not focus on the FIA for now. Lets get it and keep it running first and then see what else happens.

 

gee didn't i say before sounds like a bad sensor?

 

For the record, the car has no exhaust on it right now.

When the car did have an exhaust, the exact same problem existed.

I will test the 02 sensor. I have the info in the FSM.

 

Wow, new facts coming in all the time. But if you have a known good O2 sensor, put it on and lets see what happens -- dont forget the "nickel" antiseize for the threads. Btw, you didn't ever put copper seize on the sensor, since you had the car, did you?

 

Did you ever figure out your problem? I'm having this exact same issue.