Engine acted funny today - Check engine light came on - Honda Prelude Forum

vtec-prelude · 11-22-2002, 07:12 PM

Well, it's been kinda "chilly" around here and the Prelude has had it's idle problems with the rpm jumping up and down. I believe it do to the TB coolant bypass mod I did this summer. Anyways, today I go with my girl to look at our house that's getting built and I leave the car running while we look around. Anyways, like a half hour later we get back in the car to leave, and the check engine light is on. WTF?!

I reverse the car out of the driveway and back out. As soon as I start to go forward the car begins to hesitate, jumping forward, like the gas pedal wasn't working. I pull over, shut off the car for like a minute. Turn it back on, check engine light still on, and I drive it gently about a mile down to where I currently live. The motor didn't act up on my way home. I get home and pull out my trusty check engine codes. I do the thing to see what code it's throwing and it's code 14, Idle Control System Malfunction. So what's causing this? Could it be that the ECU thinks there's something wrong since it's been cold and I did that TB bypass coolant mod? I don't know what to think, but I doubt that a lil mod like that would cause this. Anyways, on the www.hondaprelude.to site it says these could be the cause: IAC Valve, Fast Idle Thermo Valve, Throttle Body. Well, I reset the ECU just so I didn't have the CEL on and I haven't driven the car since. Can anyone help me with their inputs?

red98lude · 11-22-2002, 07:39 PM

The possible problems listed would be the cause for a stock prelude. I would almost gurantee that the problem is the bypass that you did. Try going back to stock because the mod you made causes big problems with cold weather.

Sticks · 11-23-2002, 06:59 AM

If you do the coolant bypass mod, you also have to close off the fast idle thermo or you'll get exactly what you're experiencing in cold weather! I had the same prob, researched, closed off the fast idle thermo and no more probs!!

ludikris · 11-23-2002, 07:24 AM

Sticks is correct. Around here it's 30s in the morning and I have the TB bypass with the fast idle thermo valve block off mod and no idle problems at all.

Here's a link:
http://hondata.com/downloads/gasketh22ainstallation.pdf

vtec-prelude · 11-23-2002, 11:26 AM

Yeah, thanks for the help everyone. Ludikris thanks for that link. Car is running good so far today, I thought that was the problem. Just to be safe I pluged the coolant lines back how they're supossed to be, atleast until winter time is over. Maybe I'll close off that fast idle thermo valve whenver I have time.

jnkoh · 11-23-2002, 03:11 PM

I have the same problem, but I haven't done the bypass mod. I got a code 14 too. Is this a real fix, or is it a bandaid?

ludikris · 11-23-2002, 05:24 PM

It's a real fix.

jnkoh · 11-23-2002, 09:13 PM

So it's the fast idle thermo valve to block, not the IAC valve. I don't have the TB coolant bypass mod done, but I am getting the same symptoms.

vtec-prelude · 11-23-2002, 10:32 PM

Well after I put it back to stock the car has been fine. I drove around town all day and it drove just perfect. I don't know what could be the cause to your probs jnkoh, I wish you luck.

jnkoh · 12-06-2002, 04:37 PM

When you guys say block off the fast idle, do you mean putting the cardboard gasket in there?

sharkcohen · 12-06-2002, 06:03 PM

Quote:

Originally posted by jnkoh
When you guys say block off the fast idle, do you mean putting the cardboard gasket in there?

Yup. I have a Kellog's Special K gasket

DudewithaLude · 12-06-2002, 06:53 PM

i got the cheerio's gasket

jnkoh · 12-07-2002, 03:07 PM

cool, that's what I thought. Well I just used a piece from a cardboard shipping box, but it might be leaking or something. It was fine for the first 20 minutes. And then I started driving real hard. The idle started to bump up and down again, but not as bad. It might be that I had changed the idle speed screw before this trying to fix it. I will put it back and see what happens.