Normal for Engine to Idle Rough during Techron Treatment?

[Jonny Z]

My car, a 2002 Camry 4 cyl, had seen cheapo gas for first 20K of its life. It had a very slight rough idle 'attacks' problem, with the AC on. It will idle smoothly, and all the sudden shake more for a second or so, RPM dips, and back to normal. I think probably a cylinder misfires and causes the 'shake attack'.

10K miles ago I used Chevron gas by chance once, and the situation improved. I have been on it since - for the most part, the idle is silky smooth.

A few days ago, I filled up with Chevron and a 20 oz bottle of Techron Concentrate (18.5 Gal tank). I am 1/4 tank into the treatment, and the rough idle is back.

Is this normal? My idea is the Techron probably loosen up additional gunk in the fuel line and it is clogging up the injectors a little, causing a little misfire ever now and then. Any thoughts?

 

[stogiedude]

Do yourself a favor. Get a gallon of Fuel Power and put some in your gas every time you fill up. Your car will like it. While you're at it, get a gallon of lube Control and add some to your oil every 1000 miles or so, your car will like it. I learned this right here at BITOG, good advice, it won't cost you and arm and a leg and your engine will run better and last longer. It will save you money in the long run. You'll have a cleaner engine that runs better and smoother for longer.

 

[Quest]

Get some throttle cleaner spray and clean your throttle plate.

Also replace your PCV valve, adjust your idle and replace your spark plugs.

 

[kenw]

even techron will take the full tank to work on realy dirty injectors, but if it is dirty injectors, that will clean them. Don't refill until under 1/4 tank or less to maximize the concentration as long as possible. Techron won't do anything until it gets in the injectors so I'm virtually positive it didn't cause any problem.

If that still doesn't do it, it's probably something other than fuel. it really sounds more like a dirty throttle body and/or MAF anyway.

Save your money on the Fuel Power and do a real throttle body/MAF cleaning.

 

[Jonny Z]

This only happens with AC on. Otherwise, this motor is silky smooth at idle, impossible to detect the motor is running w/o looking at the tach. Even when the shake attack happens, the magnitude is small. Maybe I am too picky?

I doubt I have a real problem - I am going to run this tank dry and see what happens next.
I don't think the idle can be adjusted - it is all computer controlled, even the throttle is drive by wire.

 

[Steelhead]

these small 4 cyls love LC and FP, has made noticible difference in wife's Honda's. smoothness at idle and rpm, engine noise level and power on hills -doesn't shift down as often, more pulling power. Techron concentrate is the right stuff for cleaning the injectors and intake valves, every 5-10k is enough, can overuse per Chevron's directions.

 

[DaveJ]

I wonder if its an AIS valve in the Throtle Body? When the AC kicks in the AIS is susposto open a wee bit and raise the RPM to handel the extra load. The AIS needs cleaning on my Mopar 2.5's every 10K miles if I run cheap gas. Adding 20 oz of Techron to the Cheveron's gas that has Techron in it is overdosed. DaveJ

 

[jorton]

When I used 20 oz. in 12 gallons last week, there was no noticable difference in the idle. Now with a fresh tank of gas, when i'm coasting with my foot off the peddal, it sounds and feels like the engine is off.

My other car gets the same "shake attack" you described, even with the a/c off. If your Camry is auto trans, how many miles on the trans oil? That could be related to the shake attack when the RPM raises, with old trans oil.

With modern drive by wire cars there aren't too many parts to adjust. Only things left to do are cleaning or replacing parts. If these parts are too dirty, sometimes engine RPM at idle increases which affects overall drivability.

I keep the throttle body, plate and IAV(idle air valve or motor) clean in my cars but I know it will be an adventure if you're doing that the first time. DON'T USE ANYTHING BUT ELECTRO PARTS SPRAY ON THE MASS AIR METER FILIMENT.

Good luck!

 

[Alex P.]

quote:

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Originally posted by jorton:
My other car gets the same "shake attack" you described, even with the a/c off. If your Camry is auto trans, how many miles on the trans oil? That could be related to the shake attack when the RPM raises, with old trans oil.

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Torque converter shudder? Wouldn't that occur at a given condition (RPM?) regardless of the A/C being on? IA valve sounds like a candidate to be cleaned, while you're cleaning the throttle body. Give the PCV valve a shake too while you're at it.

 

[jorton]

Yes. After I come to a stop, the idle RPM gradually slows. When the shudder starts I go to neutral.

 

[kenw]

You may have a fouled plug or a bad plug wire. They do fine when in neutral or little load, but the AC or in gear accellerating makes them misfire ever so slightly.

Look for a fouled plug or a bad plug wire (look under the hood, in very dark conditions for faint blue arcs from any plug wire.)

 

[DriveHard]

I think you all are over anlyzing this problem. To me it just sounds like your A/C compressor is cycling on/off. It is common to notice a dip in idle when the A/C kicks on. My guess is that maybe the compressor is starting to draw a little more juice than when it was new and when it kicks on, it simply bogs the motor a bit. Probably no need to do anything other than normal maintenance.

I doubt you can adjust your idle as someone else suggested...but maybe I am wrong.

 

[gogozy]

quote:

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Originally posted by DriveHard:
I think you all are over anlyzing this problem. To me it just sounds like your A/C compressor is cycling on/off. It is common to notice a dip in idle when the A/C kicks on. My guess is that maybe the compressor is starting to draw a little more juice than when it was new and when it kicks on, it simply bogs the motor a bit. Probably no need to do anything other than normal maintenance.

I doubt you can adjust your idle as someone else suggested...but maybe I am wrong.

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i agree, RPM dips and rough a bit when A/C compressor kicks, also you may notice the brake sink too. i would think this is normal. will slowely more noticeable as engine mount aging.

 

[Alex P.]

quote:

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Originally posted by jorton:
Yes. After I come to a stop, the idle RPM gradually slows. When the shudder starts I go to neutral.

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But in his case it only occurs with the A/C on at idle. It didn't sound like torque converter shudder.

quote:

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Originally posted by DriveHard:
i agree, RPM dips and rough a bit when A/C compressor kicks, also you may notice the brake sink too. i would think this is normal. will slowely more noticeable as engine mount aging.

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I can't say that I agree entirely. This isn't a old vehicle that you can just easily set the idle low/idle high speeds. The computer should handle all that. Also, shouldn't it increase the idle in response to the increased load? At 2002, it is certainly NOT old, and the engine ****ed well better not be worn.

Let the techron run its course, clean stuff with some spray, etc. Go from there.

 

[Ken2]

It isn't that unusual for some engine roughness when cleaning out carbon in the combustion chamber. The cleaner removes part of the carbon and leaves rough edges that interfere with good flame propogation. Continue the cleaning until the engine runs better than ever.


Ken

 

[Jonny Z]

UPDATE:
The car just finished the Techron tank - 1.5 weeks, 475 miles and 17.15 Gals. About half tank into the treatment the car was back silky smooth.

The car usually get 31+ MPG, but it dipped for the treatment tank. I did drive it to red line a couple of times to "flush things out". Am I just being silly?

The car is manual, with CoP setup and NGK iridium plugs and just rolled over 30K.

I think my new found roughness was indeed Techron related. But it runs fine now. Thanks for all the comments.

 

[Jonny Z]

So the AC compressor cycles on and off on its own? I don't have automatic climate control. I have always thought that cars w/o auto climate control will engage the AC clutch anytime the AC is turned on and the light is green.

Now that Techron is done, next step is a new PureOne, 4 qts M1 5W30, a new Wix cabin air filter, and a tire rotation. This completes my 30K service.

The tranny BTW, received fresh 75W90 Penzoil Full Sync gear oil at 20K. I am going to leave it alone for a while. (Manual says lifetime oil under normal service).

 

[Titan]

quote:

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Originally posted by Jonny Z:

So the AC compressor cycles on and off on its own? I don't have automatic climate control. I have always thought that cars w/o auto climate control will engage the AC clutch anytime the AC is turned on and the light is green.

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Yes, the compressor cycles on and off, even without automatic Climate Control.

 

[kenw]

even with ACC, the compressor cycles. The ACC usually (not always, just usually) operates baffles to vary the blend of air over the cooling and heating coils.

 

[kang]

quote:

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Originally posted by Jonny Z:

I did drive it to red line a couple of times to "flush things out". Am I just being silly?

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Not at all. The “Italian Tune-up” is an excellent way to “flush things out.”