High idle until I blip throttle, then it's normal

[Mty Mous]

Hey guys,

I'll start off with the car's specs
1988 Camry with 4cyl engine and manual tranny with 175,000kms.

So here's what's happening, once the car is warm, as I'm driving, every time I press the clutch in, to either downshift or just get into nuetral and coast, I notice the idle is anywhere between 1100rpm ~ 2400rpms. As soon as I blip the throttle, it drops down to 1000rpms.

Oh, and btw, I have the idle set to 750rpm, but I hardly ever see it idle at that, but it has been known to happen in a blue moon.

This has pretty much happened since I bought the car (about 20000kms ago) and I had the timing belt changed about 10000kms ago.

Not sure if this is a seperate problem or if it's related to the above problem, but since the timing belt service (which included the water pump and all other belts and several seals\gaskets) my milage has dropped significantly, ... I used to get average about 13.5km\liter of gas, and now I'm averaging about 10.5km\liter, and my driving style has not changed. I replaced the O2 sensor myself (along with new plugs and air filter as well as a fresh oil change about 2000kms ago) and still no change in fuel economy.

My guess is that the timing belt might be off a tooth and is throwing my mileage outta whack, but I don't know cause my mechanic is who did the service and I'd hope he did it right.

Any help or suggestion would be appreciated.

Thanks
Thuwa

[OBwan]

Probably a good guess on the belt. I would take some intake cleaner and spray the butterfly valve in the throttle body. Sometimes the crud in there builds up and makes it stick.

[ghost_ryder35]

do you have access to a timing light? you should check to see if the timing is off. check to make sure throttle cable is not being interfiered by anything in the engine bay.

[timebuilder]

If you are comfortable doing it, check the cam timing. If the spark timining was set AFTER the belt was installed, you can be dead on with the timing light and still be a tooth off on the belt.

Have you approached your mechanic about the change in mileage? As a tech, I would be willing to check the timing myself to assure that nothing was overlooked. But, that's me.

[Kep]

I would encorage you to thoroughly clean the throttle body and try to clean the IAC valve. Afterwards you might want to run a fuel system cleaner (Techroline, Sea Mist, etc) through your gas tank once or twice. But definately pull the air supply hose and clean the throttle body by hand first.

Kep

[Mty Mous]

During the summer months, I thought maybe there was too much slack on the throttle cable, so I adjusted it. But didn't seem to help the situation all that much.

I then had a treatement done to my car (Terraclean) which helped for a while and also boosted my mileage from 12km\liter to 14km\liter for a good 5000kms, but after the timing belt service, it went all to hell and now I'm getting a measly 10.5km\liter. Might as well get my summer car on the road with that kinda mileage, atleast then I can enjoy some boost while I'm at it.

I do have access to a timing light (buddy's tool), so yeah, I'll check that this weekend, ... or atleast when it warms up a bit here in Toronto.
My fear though is that one of the CAM might be the one outta whack and is creating too much overlap, (the reason I say this is due to the lack of power I've noticed ever since the timing belt service), ... will this still show up when checking the timing against the crank pulley?

As for spraying some Intake cleaner down the TB, ... is Intake cleaner the same as TB cleaner?

Also, I wish I knew where to look as well as what to do, to diagnose the EGR valve on this car, cause I wonder if that's all clogged up too?

Thuwa

[timebuilder]

Because the cams are geared together, overlap will not have been changed due to a belt replacement.

Check the timing of the belt visually, not with the light, as explained above.

Also, make sure everything is clean. That's always good advice, but a dirty TB or IAC would not explain the immediate change that you have identified as happening after the belt change. The TB and IAC would not have suddenly become dirty due to the belts.

[IvanHoe]

Dude, your problem is VERY simple, trust me on this one.
The manual transmission gen2s are prone to this.
Your throttlebody is worn out.
The Timing belt has NOTHING to do with this, neither does the timing itself!
My current 5 speed has the same issue, I also had a 1990 Camry 5 speed a few years back that also had the same issue.
And after doing some research on this, Ive heard of many other 5 speed guys with this as well.
With a manual transmission, your constantly on and of the gas pedal as you shift through the gears. Over years of this, tend to wear out the TB, allowing air to hitch up the butterfly a little.
So far I left my throttlebody alone, but when it gets warmer, I plan to swap in a TB from a automatic gen2.
The slight problem is that it's NOT a direct swap, but it can be done by using some of the parts from your current throttlebody.
To be honest with you, it's not really a big deal, you can drive it forever like this.
Im choosing to fix it cause Im a perfectionist and I love doing this kind of stuff.
The way I deal with it now is, when I get to a red light, I blip the throttle to kick it down to where it belongs.

[TBayToyotaBoy]

Yeah, my tb has been doing this for a couple of years now...just keep cleaning it every so often, and the sticky throttle problem should go away. When you clean it, make sure to spray-out the side chamber (towards the firewall) in which the Idle Speed Control sensor is. They get really gummed-up as well.

As for your fuel mileage, it should improve with thorough and frequent cleaning (every 3-6 months).

[IvanHoe]

Originally Posted by TBayToyotaBoy

Yeah, my tb has been doing this for a couple of years now...just keep cleaning it every so often, and the sticky throttle problem should go away. When you clean it, make sure to spray-out the side chamber (towards the firewall) in which the Idle Speed Control sensor is. They get really gummed-up as well.

As for your fuel mileage, it should improve with thorough and frequent cleaning (every 3-6 months).

Cleaning it is not the issue. In fact, when I cleaned out my TB, the worn out throttle body symptoms were increased for a little while. It's a good thing in general that you clean out your TB and IAC, but that's not what's causing the idle to be high.

[timebuilder]

I just re-read the original post, and it appears this symptom did not have the sudden onset I understood from the timing belt change.

I'm an automatic user, and if what is posted above is true, you may want to visit a yard and see if you can find a used TB.

[TBayToyotaBoy]

Originally Posted by IvanHoe

Cleaning it is not the issue. In fact, when I cleaned out my TB, the worn out throttle body symptoms were increased for a little while. It's a good thing in general that you clean out your TB and IAC, but that's not what's causing the idle to be high.

My apologies, my experiences on the 2VZ were different...I too was getting a high idle, because inner spring plate on the ISC was not being allowed to rotate fully closed (to the idle position), and the butterfly valve was sticking slightly open at times. Cleaning thoroughly worked for me. But I defer to the judgement of those with personal experience on the 3SFE.

[IvanHoe]

Originally Posted by timebuilder

I just re-read the original post, and it appears this symptom did not have the sudden onset I understood from the timing belt change.

I'm an automatic user, and if what is posted above is true, you may want to visit a yard and see if you can find a used TB.

Right, make sure it's from an automatic WITHOUT ECT(electronically controlled transmission),the TPS (throttle position sensor) is incorporated differently into the TB, making it much harder to swap.

Originally Posted by TBayToyotaBoy

My apologies, my experiences on the 2VZ were different...I too was getting a high idle, because inner spring plate on the ISC was not being allowed to rotate fully closed (to the idle position), and the butterfly valve was sticking slightly open at times. Cleaning thoroughly worked for me. But I defer to the judgement of those with personal experience on the 3SFE.

Don't get me wrong, you made good points for both engines , but the 3SFE 5 speed is especially prone to having a worn out TB

[Kep]

Thuwa,

You may have several issues going on here. It sounds like you made some adjustments first and then had the timing belt replaced (as well as other service?). If the prior adjustments were correct and you adjusted them before the timing belt and other items were serviced then you may have to readjust them back to original specs (did that make sense??). It would be helpful if you could list which items have been adjusted/replaced and maybe in what order. I can't say that I'll notice anything but someone may.

IvanHoe's point is interesting. It makes sense but I, too, am an automatic type and haven't experienced this kind of wear. I guess that I would suggest waiting until you are ready to replace the throttle body (and know that you can get one) and then try cleaning the system out. If it works, great. If it gets worse then go ahead and replace it.

Do a search on this forum for "throttle body", "EGR" and "IAC" and you will get lots of hits. There have been a lot of posts detailing how to find them and clean them. Since you're going to be in that area of the engine you may as well make sure that they are right.

It won't hurt to check the timing but remember that you need to manually bridge two contacts in that OBD plug.

Kep

[IvanHoe]

Originally Posted by Kep

IvanHoe's point is interesting. It makes sense but I, too, am an automatic type and haven't experienced this kind of wear.

Kep,
It's a common thing with the 5 speed Throttle bodies and not really the automatics, that's why your auto Camry doesnt have this issue.