When i start my 95 civic ex up cold it runs fine but just as it starts to almost reach normal operating temperature, it starts sputtering and losing power for at about a minute.

Then, when it reaches normal operating temperature, it runs normal again.

Doesn't do it everyday but pretty often.

I've replaced the idle air control valve with an eBay item to no affect.

what could be causing this?

 

Maybe do a couple quick checks of your spark plugs cond., gap, inspect the distributor cap and rotor for build up and wear?? Check ground wires conditions and contact surfaces. Battery terminals clean of corrosion..
Has the fuel filter ever been replaced to your knowledge?
Some simple things to do to narrow it down..

 

Your car has multiple idle control systems - to me it sounds like there is an issue when transitioning from one to the other. At full cold, the idle control is primarily handled by the fast idle thermo valve (FITV). As the engine warms, the FITV begins to close, dropping the idle, and the IACV takes over. Maybe when the car is warm enough for the FITV to be out of play, but not fully warmed, the IACV is sticking closed? Then, once the engine fully warms, that's enough to heat soak and free up the IACV and it starts working properly.

I haven't personally tried any of the aftermarket IACV's, but I've seen lots of folks have issues with them on this forum and in the Facebook groups.

 

I was also thinking of the iacv aswell but since it being replaced to have no change I thought a bit different. Coukd be something to do with the thermal expansion of a valve working incorrectly, resistance/voltage change of a sensor possibly.. I also had the thought of possibly there may be an issue with a dying sensor like the o2, when the ecu is switching from closed loop to open loop its giving a bad reading while warming up?

 

I noticed I forgot I don't have an FITV because i have a Skunk2 Racing 309-05-1030 Alpha Series Silver 66mm Throttle Body that seems to have deleted it. What should i check.

 

You can also test the Engine Temperature Sensor the 2 pin one. It tells the ECU the engine temperature. May also just be a byproduct of the 66MM throttle body, no FITV and stock ECU tune. Might just need a tune to your modifications.

 

Kinda reminds me of back in the day of slapping on a b18 throttle body to my old d16a6 thinking I was going to make more power.. Nothing but a problem. Did you install the throttle body or was it on the car when you bought it and it's always had the issue?
If that's the only mod you have on a stock motor, the bigger TB is not doing much for you at all. Seems like the motor is choking on all the extra incoming air. Maybe grab a stock one from a wrecker and try it out.

 

Yes i also have and installed skunk2 Pro Intake Manifold - D Series 307-05-0260 on the car, as well as a skunk2 alpha series exhaust manifold with tanabe 60mm exhaust.

I'm about to install

AEM 30-0300 X-Series Wideband UEGO AFR Sensor Controller Gauge.

and Hondata S300 v3 and take to dyno, but i want to fix this issue first.

could a dying speed sensor on 5spd cause my problem?

owned car and dd since 2003

 

So aftermarket throttle body and intake manifold on a stock ecu.. That doesn't help. Tuning the ecu may be your only resolution to make it run "right" or converting back to stock until then..

 

I think it's a dying speed sensor.

 

How long have you been having this problem? If you haven't any problems with your couple mods in the past and now a issue started arising out of no where then those probably are not related to your problem.
Since your car is not a automatic, and if your speedometer is working properly I would highly doubt that speed sensor being the issue.
As mentioned earlier, the ECT sensor would be a suspect since it does affect how the engine operates based on temperature change.
If I were in your shoes, first off keeping things simple I would make sure all connections are on clean and tight- chassis grounds, battery terminals. Then look into which sensors have an affect to engine performance based on temperature changes. Bonus if your the type of person who is able to go to a wreckers and grab a bunch of them off other cars for dirt cheap or free and swap one out a time to see if it solves the issue instead of testing and possibly gets mixed results or inconclusive but if your good at testing, save yourself the trip and test away.. I know it sounds silly to just swapping parts but if you can get them for basically free and have time and space why not have some fun and get dirty! There's a gremlin in there somewhere causing it so good luck on finding it.
I'm just a dad in the garage who likes to tinker and hates electrical problems or I could be a robot holding sticks in the air, wearing a tinfoil hat and just throwing out ideas on here when I get bored.

 

Lol either way I appreciate it. I've had this problem for months and my speedometer I've been having problems with on and off for longer than that i would say. But recently my speedometer completely died and i got that engine code and the sputtering seems to have stopped. I have a rock auto speed sensor should be here feb23 i will see but in meantime I'll look at ECT sensor

 

Sure is a strange issue you were having also nice to know the new missing info, hope it all ends well once replacing that sensor. Wouldn't really think that had something to do with the sputtering but hey, I'm not expert as you can tell!... Was also thinking something inside the distributor could be going wonky as they can sometimes produce odd symptoms without throwing a cel.

 

I replaced the speed sensor and cleaned off the coolant temp sensor and the issue went away.

I would still get the speed sensor check engine light but no issues so probably just needs code cleared.

then it came back but with engine fully cold like it started almost as soon as I started driving. so i was giving it some gas to get it to straighten out like it usually does

then I started hearing clanging and power steering went out. I had to drive like half a block to where i could park it. The crank pulley / harmonic balancer bolt came nearly completely out. When I pulled it off i found the little key piece. I'm waiting on a new crank pulley bolt just because the threads got messed up. The timing belt looks ok , my upper cover is see-thru but that's as far as i looked.

will i be ok to just slap the crank pulley and belts back on and fire it up? Thanks.

 

If the crank snout threads got mangled with the crank bolt, then probably not. Also usually when the crank pulley wobbles loose the key and key way on the snout tend to get mangled. You will have to inspect ALL of that before you know if you got away unscathed.

 

Threads are fine but the keyway is kinda damaged but new key fits in pretty snug. Also replaced the crank pulley. I used jb quik weld in the damaged spot and drove it home, it made it ok. What should i do now

 

Slap it back together for what it is.. I doubt you will notice any problem. Could probably use a heat gun and fix that warped cover a bit before putting the pulley back on though...

 

Ok thats what i did and I replaced my belts and crank pulley bolt which came with instructions which had me tighten the bolt by degrees which i followed exactly. ended up being about 150 ft/lbs

I drove it hard like 40 miles just now and it was ok. Next time i do water pump or something with timing belt I will probably weld in that missing chunk. because suppose i went turbo or a certain hp that missing chunk would become an issue?

does the keyway not just align the crank pulley, doesn't the bolt and some light teeth on the pulley hold it down? Not much pressure is on the keyway, correct?

 

Now the sputtering problem is back, this time it recovers all power once the check engine light comes on. The code is 43, Fuel Supply System.

I tried a new o2 sensor and fuel filter but the problem persists.

Look at the 95 Civic Workshop Manual and I can't follow it because it says to go to Fuel Supply System (page 11-89)




but that takes me to this page, 11-89 is the middle of a flow chart. is there a mistake?

 

Bump

 

Bump

its also not temperature based, it's just random. Fuel supply system check engine light keeps coming back. Replaced o2 sensor and fuel filter and no change. Car runs fine but when you're cruising it bogs suddenly bogs down randomly and if you hold the gas steady for a minute, the CEL comes on and it starts running normally again and it won't do it again until you turn engine off and start again. I usually reset ecu by pulling back up fuse to get it to hopefully stay gone but it keeps eventually coming back.

and the workshop manual flow chart seems to have a mistake idk

 

Bumpity

 

Get a remote fuel pressure gauge from Autozone or wherever, hook it up to the test port on your fuel filter, tape the gauge to your windshield, and go drive around.

You have all of the symptoms of a slowly failing fuel pump.

Check the fuel pump voltage at the pump connector, with the car running. Do a voltage drop test between the fuel pump fuse and the fuel pump connector.

 

Pretty sure what's in there now is amazon from june 2019. I will put the old one back on with new sock i guess. I will try to do those other tests u mentioned first.
but why does the manual direct me like it does though what's up with that

 

Looks like a misprint?