Hey all, for awhile now I have noticed a problem with my idle when applying the brakes. It doesn't always happen when I apply the brakes, but generally it does.

I searched on here and read that cleaning the IACV(intake air control valve)may resolve the issue, I did this on Monday but I noticed the problem again today. The idle drops to about 250 and then spikes to about 800 and keeps doing this until I give it gas.

This is a 1990 accord with a manual transmission.

What can I look at next to hopefully resolve this?

Thanks,

 

if it's constantly fluctuating between 250 and 800, I would say it's the iacv...or maybe a small vacuum leak.

 

Good news: This problem usually has a simple solution.

Bad news: It is sometimes EXTREMELY hard to find out what the problem is exactly.

The reason being that it could be a many number of things. I've been hunting for other threads and posts looking for people with this same problem (my friends Civic has had this on occasion). However, I haven't found a single person who has solved all their idle problems. I'll let you know what I have found though.

Items I notice that come up a lot are the ignition (distrib, plugs, wires, etc.), Throttle Position Sensor, any of the idle controls (I include IACV in that, along with the various other valves), vaccum lines, radiator/coolant hoses, and O2 sensor(s).

These are the top things people recommend checking when having any idling issues. Your particular problem is one that I haven't seen solved (on forums at least) and would like to see someone finally get it.

I'd start with the easiest and check your plugs and wires to make sure they are in good shape. If you haven't had to replace the distrib, you definitely should check that out next as well. Hondas tend to have a problem with moisture getting in them. I'd then check the vaccum lines and the TPS.

I wish you luck!

 

Stupid question, but where is the throttle position sensor? I have had the car for about a year and a half, and I noticed this idle problem about this time last year. The car has never died, but it just fluctuates. I will replace the dizzy wires and spark plugs, as the car could use it anyways.

Even if there is a pin hole tear in a hose, would it cause this problem, or does the hole need to be larger in a hose to cause an issue?

 

No, a pin-sized hole is not usually enough to cause real problems. Usually something like this is caused by one of them being loosely connected or a bigger tear.

The TPS is on the throttle body. Here is a picture. The TPS is the black piece on top.

 

Thanks for the reply. What exactly would I check on the TPS? I hate to sound like an idiot, but I really don't know.

 

Get a haynes manual and perform the tests on the iacv and the tps etc. It also has test for the plug wires dizzy etc. This will tell where to look instead of replacing a bunch of crap.

 

accord99power is correct.

The haynes/chiltons manual is well worth the money. Will tell you just about everything.

No need to just replace it if something just needs to be adjusted.

Let us know what you find out.

 

Okay. I will order that Haynes manual and start from the top and see what happens. I already cleaned the IACV on Monday, but I noticed the problem again on Wednesday. It is pretty inconsistant to when it happens, nothing really triggers it.

 

Same with my friends Civic. Thats what has had me puzzled, and has led to me not checking anything out right now.

It hasn't done it in a week or so now so I'm not gonna mess with it unless it starts again.

 

i have probleme too, but voltage on MAP sensor is downing from 1.04 to 0.92 and engine is shuting down

 

Next time it happens, I will take a video of it and post it up here. This sounds like a pretty common problem and I would like to find a resolution for it.

 

Just as a helpful update, my friends Civic started having the idle problem again so I checked out his TPS and MAP sensor voltage. MAP was fine, but the TPS was NO WHERE near the correct idle voltage (I believe it should be 0.48-0.49v and it was reading almost nothing). The WOT voltage (which you need to set first) was only off by 0.2v, so that just needed a slight adjustment.

After correcting this is runs just fine; no idle problems whatsoever for almost 2 weeks.

So I'd check that out if you haven't yet!