Here is a video of another person's prelude but my car has the same EXACT problem. It will sometimes start perfectly and idle normally or do this like in the video below, or just start-up and run like its running on 2 cylinders and shake quite a bit until I give it some gas to wake it up. But even then sometimes it will still die on me. It mostly happens when I have the car warmed up all the way or occasionally it will happen when I first start it up in the morning when its cold outside. I have replaced almost everything I can think of sensor wise. I have replaced my map sensor, IACV, TPS, coolant temperature sensor on the head, fuel pump, and my spark plugs and rotor in my distributor. I will also be replacing my intake air temperature sensor on the manifold. I am chasing my tail here and I do not know what to do anymore to fix this issue. I do have an extra Main relay in my tool box to test out and see if that is the issue. I just want some feedback from you guys or some ideas on where to look or check next.

 

Starting Problems

 

It could very well be the only thing you haven't replaced, the iat.

For starters, take it out and look at it. See if it's caked up with carbon or even melted.

 

Here is what my IAT looks like and before the picture was taken there was a slight smell of gas and oil residue on the threads plus on the tip of the sensor. I just replaced my catalytic converter as well today and my car seemed to do a little bit better no start-up issue yet. The only reason I replaced is there was a knocking or rattling sound going while driving and it boiled down to the cat making that noise. This car has been giving me hell lately.

 

Its possible your cat was clogged up. If you've never replaced your iat it might be good maintenance to swap it out anyhow.

 

Yeah the cat could have been clogged up how can you tell though, when you can barely see daylight when you look through it? When I took the cat off yesterday to install the new one I was expecting to see something fall out of it like the honeycomb that is in those things and nothing came out so I am stumped on that because that is 100% where the rattling noise was from. I haven't replaced the IAT since I bought the swap and that was almost 3 years ago. Might as well replace it since its a $17 part. I started reading the starting problems thread that Tamboo left for me, but it says for my issue the coil is bad on prelude, I have an extra coil in my toolbox so maybe today I will swap it out and see if that helps anything at all. I heard that those external coils rarely go bad.

 

I had a coil go bad before but it was very very intermittent. I had random misfires and occasionally my car would stall. It took me forever to track down. On a whim i swapped out my coil and immediately i got a 2 mpg bump and no more random stalling and misfires. However my coil is internal and i think the heat is indeed what kills it. I think the external coils might indeed last longer by being outer.

 

Today I will change out my coil for the other one in my toolbox and see what happens. Its just odd when I start-up the car it either wants to start-up normally and idle or just idle like crap then die or just die period as soon as I turn the key. Yeah you are right holmesnmanny the internal coils are more or less likely to fail compared to the external coil. I really am thinking my car is choked up also from having a stock exhaust on it from the headers back to the muffler. I know for a fact that I should be running larger diameter headers since that is what the euro-r and type-s engines came with from the factory in Japan. And I am honestly shocked all our cars can run with those damn catalytic converters there is so much honeycomb in those things its ridiculous. Damn tree huggers in the state of California making things to difficult.

 

I think a stock exhaust is more than adequate for any n/a car.

 

Even a stock header? Well thats what im saying though is my euro-r came with a bit bigger header then my stock prelude header so that is an issue with my car not breathing well enough.

 

Honestly i dont think its going to be noticeable.

If you want, remove the oxygen sensor and see if the car runs any better on some WOT pulls.

 

Remove it completely? I will just leave them in there, pretty sure the basemap tune I have on my p28 is using the o2 sensor. I will just save up my money for a full 2.5 header to match my 2.5 cat-back exhaust that is sitting in my room.

 

If your exhaust is clogged or slowed down as you suggest you would temporarily remove the oxygen sensor to test. If it doesnt run better then the exhaust isnt an issue.

 

So just take out the o2 sensor and leave the hole open? I just think me running stock headers with a magnaflow cat is restricting the exhaust flow a bit.

 

Are you not understanding that I am not saying to remove the oxygen sensor forever ?

 

No I understand I will remove it this week and post back my findings. Thanks for your ideas on this holmesnmanny.

 

Please tell us if you solved it, and how. I have the same problem.

 

Have not solved this issue yet, still chasing my tail on it and trying to figure it out. For now the problem is intermittent, it for sure is not how it use to be which was all the time when I went to start it up no matter if it was cold or fully warmed up. Trust me when I figure out what it is I will post the solution.

 

Since I have an extra main relay I bought a long time ago I will swap it out and see if the issue persists. Plus my startup issue seems to happen more so when the car is already up to temperature and on warmer days.

 

Have you read the different scenarios on the link provided above?

 

Oh yeah I have read it a few times and changed out my coil with better luck but my issue is intermittent it will happen sometimes not always.

 

We definitely share the same problem. I bought a relay than took it back because It hasn't happened in so long, then there it goes.

A suggestion i would give you, is to do a idle relearn procedure. I have seen a thread where a 7th gen civic suffered from the same thing, and this was the fix. This did not fix my problem tho.

Unplug your IACV connector, adjust the idle screw accordingly, shut car off, plug the connector back in, and unplug the neg battery terminal or ecu back up fuse for 5 mins. Start up car and let it idle until adjustments are within spec.

 

Unfortunately that is not my issue at all. And to top it off I don't have an idle adjustment screw on my throttle body since its an h22 euro-r. Im actually just stumped on this issue. It hasnt happened but only once in two weeks since I changed my coil for another one and installed a new catalytic converter. But I will still install the new main relay and see what happens.

 

a bad map sensor would cause it to stall out like that, or a bad vacuum leak.

 

Thanks for the reply I have already replaced the map sensor and the issue still exists. I will check out all my vacuum lines again and see if there is a leak or bad hose some place.