Idle problem, tried cleaning IAC... also jerky/vibrating ride - Toyota Nation Forum : Toyota Car and Truck Forums

tsqr · 09-26-2011, 11:31 PM

I posted earlier that I am new to car-owning and maintenance, and that I thought I had a clogged IAC in my 1999 Camry 4 cylinder with manual transmission. Well, today I sprayed about 5-10 seconds worth of carb cleaner down the throttle body hole per the numerous instructions out there (and cleaned the throttle body to boot), TWICE, to no avail. It still idles around 600-800 rpm, and is erratic, sometimes jumping up to 1000.

More specifically, I seem be having a slightly different experience than others have described, in that when I start the car cold, i.e. after several hours of being shut off, the idle is normal, around 1000-1200 rpm. However, pretty much as soon as I put it in gear and start driving, the idle goes down. (Others seem to describe having low idle when starting cold, with the idle improving as the car warms.)

Another issue that I'm having, and I'm not sure if I'm hallucinating or what, is that the car seems to vibrate ever so slightly. Vibrate might be the wrong word, because it's not really small, rapid vibrations, but more like a lumpy, jerky, generally unsmooth feeling when I'm cruising along.

Based on my research, my utterly uneducated guess is that it's a bad transmission mount, or possibly a bad motor mount. That would account for the jerky ride. However, I don't hear any kind of bang or thump when I change gears, which others have said is a sign of bad mounts. It just... feels unsmooth and jerky.

As for the car history, I just bought it a few days ago. It has been serviced regularly sinced it was bought, according to the copious service records the previous owner kept. The engine came from another Camry after the guy drove it for too long without changing the oil. The clutch was replaced a few thousand miles ago. It has 180K on it now, with about 30K on the new engine. The only thing I've done to it since I bought it is plug in a power thing to charge my phone with...

Other than all that, the car drives ok. I mean, it doesn't make any weird noises or stall unexpectedly.

I'd like to try to tackle this myself before bringing it to the shop, partly because I am in the process of moving to LA and need the car to get around, and partly because I'd like to avoid paying hundreds of dollars to fix something I only paid 3 grand for. Of course, if I can't solve this within a few days, I'll bite the bullet, but here's hoping that it doesn't come to that.

Help? Thanks!

bolink654 · 09-27-2011, 01:33 AM

Quote:

nother issue that I'm having, and I'm not sure if I'm hallucinating or what, is that the car seems to vibrate ever so slightly. Vibrate might be the wrong word, because it's not really small, rapid vibrations, but more like a lumpy, jerky, generally unsmooth feeling when I'm cruising along.

Way you describe that, it sounds like it could be a random misfire. Do the records indicate spark plugs? Type and mileage? Plug wires?

tsqr · 09-27-2011, 03:49 AM

After 45 minutes reading about what the heck random misfire means, it certainly sounds like it explains both the idle and the shaky ride. I'll look into the service records tomorrow.

But one thing that's not happening is the check engine light is not coming on...

bolink654 · 09-27-2011, 04:16 AM

I recently fixed my brother in laws 98 4cyl Camry, so that I could drive it while I fixed the wife's 98.

I'd heard it run once... VERY very rough. Wouldn't move on it's own, it'd die when you put it in gear (automatic) Me and Bro-inlaw thought it could be - timing belt skipped, clogged CAT, and worse case - a blown engine (head gasket? bearings?)... No check engine light was on.

Well I had my money on timing belt, since my grandparents had a Hyundai once that had a bunch of teeth missing on the timing belt, and it ran similarly to this Camry.

So the first thing I did was check the timing. Was spot on. So I had the wife check out the FSM... she came back with "plugs or plug wires"... I thought "yeah right... those go bad very slowly, not all at once"

But to convince her, I pulled a plug wire off the plug... WHOA. There was white dust all on the plug wire boot. And a burnt spot. Upon further investigation, another wire was the same way. I placed the wire on the engine and had the wife crank it... Sure enough, spark shot out the burnt part. This must be what is wrong, I thought.

Ran to auto parts store and got a set of wires. And it's been running fine since.

Now, another story! I had a Nissan Stanza. It was running fine. Then I noticed one day that while in drive, but stopped, it was misfiring. But not in neutral or park, or while driving down the road. That's really odd, as these things are not really connected (transmission vs. ignition system). I didn't bother with it though.

But one night I had come home and was working on it, and for whatever reason I had it running, and I had a screwdriver. I bumped one of the plug wires with the screwdriver and spark shot out the side of the wire.

Long story still long - when the engine was in drive and stopped, the engine tilted just a tiny bit, as they all do, which allowed the bad plug wire to move 1/4inch closer to the engine... which allowed it to get close enough for the spark to jump to the engine. But in park, or in drive down the road, the engine hadn't tilted enough to allow this.

Anyhow, none of this is really related to your problem, well maybe a little. What I'm trying to get at is from my first story

Check Engine light wont always come on with bad plugs and/or wires, in these Camrys. The Bro-inlaw had 2 totally fried plug wires, but the check engine light wasn't on.

From the second story: Even the weirdest problems could be something very simple.

Not saying you should run out and change the plugs and wires ASAP... wait until more people comment, I'm just a shade tree mechanic, but if they haven't been done in forever, it couldn't hurt. Heck even if they are new... maybe they nicked one putting the engine in. Maybe one got too close to something hot and melted it or made it brittle.

Edit: A random misfire while driving down the road will be kinda like "boom...boomboom...boomboomboom..boom...boom" just totally random. Maybe replace the "boom" with "thud" or "jerk"

garytho · 09-27-2011, 10:47 AM

"It has been serviced regularly when it was bought"

Was that before or after the 1st motor was blown from not changing the oil???

If the wires are indeed toast,...than maybe the top "dogbone" motor mount is moving the engine excessively and arcing the wires if touching it as bolink suggested. Or it may be the dogbone itself??
Using carb cleaner for 5-10 seconds to clean the IAC valve really isn't going to clean it properly. You should really go back and research the threads on "IAC valve" again for proper instructions. Seafoams Deep Creep is the right product for the job without removing the valve itself. Doing the job right takes about a half hour or so,...not just a few seconds or minutes.
But to be honest,....it doesn't sound like the IAC valve if your getting vibration/jerking while driving. I'm leaning towards the top motor mount as a starting point.

toovira · 09-27-2011, 06:45 PM

First off, you cannot rely on check engine light. You can pull one plug wire out and runs rough and CEL won't come on.

Measure the resistance, assure good contacts on both distributor side and spark plug side. Inspect physically. Check your rotor and cap (3 small bolts). Inspect condition of the plugs (lean, rich, etc.) Measure the resistance of the throttle position sensor.

The function of IAC is to bypass air when the throttle body is closed. The problem is when IAC is dirty, the engine is not getting enough air, causing rough idle. So if you ever slightly hold the throttle open (press the pedal a bit), your engine should idle as air can bypass....and it should be smooth idle if no other issue is going on - which is not your case.

Here's a good example:

You Tube

You may also have old timing belt as previously suggested, which causes cam/crank timing to be off.

bolink654 · 09-28-2011, 01:55 AM

One other idea on checking plug wires (but this wont tell you if the boot part is bad) is to pop the hood at night while it's running. Any spark shooting out the wire will be clearly visible at night. Should be visible in daytime too, just not as much.

tsqr · 10-07-2011, 12:14 PM

hey guys, thanks for your responses. just thought i'd update and confirm what many of you said: it was a random misfire caused by bad plugs. turns out that the plugs that were in there were copper, and should have been platinum. the mechanic just put in a whole new set and all is now well again.

what's strange, and i should have asked this of him but didn't, is why this problem just seemed to materialize. most likely i just didn't notice till i drove it for a while.

bolink654 · 10-07-2011, 03:16 PM

As far as I know, you can run these on copper plugs just fine. Just that they will burn up quicker. I was very low on cash once and needed plugs. Asked a guy at a local auto parts store and he said the copper would be fine but they'd only last like 20,000 miles. I got a set and they seemed fine. Got the same MPG and all. But I put in a proper set of plugs only 10,000 miles later.