So my car now has the dreaded carbon shudder. But only after the temp needle gets to the halfway point (just a hair below it) which seems to be the normal engine operating temperature. At least what I presume it to be because that's where it has always been since I bought the car with 89K miles on the odometer. It now has 103K miles on the odometer. Until engine warms up, car runs beautifully. No carbon shake and bake. But then like clock work, the minute the needle reaches the normal op temp spot, car starts flashing the check engine light and goes in to limp mode with a horrible shake when trying to accelerate. It does it every time now. I can shutoff the car and re-start it immediately and it will drive normal again for a mile or so and then repeats the shake and bake. But if I let the engine cool down, I can drive for 10 miles or so before the engine get to operating temp without any problems. I am not an internal combustion engine guru so I am trying to figure out what is different when the temp needle gets to the normal operating temp? Are injectors spraying more fuel when engine reaches operating temp and not enough air being let in due to carbon build up causing these misfires?

Any thoughts that this could be a different issue instead of Carbon build up?

 

https://www.bgnebraska.com/need-know...n-fuel-ratios/

 

Hi MikeFig82,

Thanks for the link. It explains why the carbon build up happens.I am not disputing that fact as to why it builds up. But What I am not getting is or trying to figure out is, what changes the minute the engine reaches warm-up temp? The same carbon was present when I started the car when it was cold. One would assume injectors would have behaved poorly if they had build up in them even when the car was cold. If the plugs were bad, they would act up as well and not wait until the car warmed up. Problem starts the minute the temp needle reaches the normal operating temp region regardless of the speed I am driving in. It could be 5 miles per hour or 40 miles per hour. What changes in the Air/fuel map when it reaches operating temperature vs 60 seconds prior to that? Just curios. Because prior to that, car runs perfectly at city or at freeway speeds.I am no longer driving it on the freeway until I gut it and get the carbon clean-up and a tune up done.

Thanks again.

 

 

Well, that still doesn't explain "WHY THE CAR RUNS GREAT WITH "ALL" THAT CARBON BUILT UP ALREADY IN PLACE WHEN THE ENGINE IS STILL COLD EVERY MORNING.
WHEN IT IS FIRST STARTED-UP. IT STARTS AT THE VERY FIRST PRESS OF THE BUTTON. RUNS PERFECTLY UNTIL IT GETS TO NORMAL OPERATING TEMPERATURE.

Then, Game over.

Flashing check engine light and car in LIMP MODE shaking horribly upon trying to accelerate but still runs OK at 40mph..

OPTION 1:
Shut off the engine. Re-Start immediately. Good for several more miles of normal driving before the next shake episode that can get triggered at any time, randomly and without warning..

Or,

OPTION 2:
Shut off the engine and wait for it to fully cool down.
From a cold start, can do 80 on the freeway w/o issues until engine reaches operating temp.
Once there, Limp mode and no more than 40mph.

So what gives or what takes place when the engine reaches operating temp to make it shake and shudder and go in to limp mode?

That is all I am trying to figure out/get educated on.

Cheers.

 

This thing double posted so I am trying to get rid of it. But unable to. Please ignore post #6.

Cheer's.

 

I may have missed it, but did you pull the code to see what the actual check engine is for? I would start with that. May not even be carbon build up related for all we know

 

From the cheap OBD II scanner that I have, no codes show-up. If I disconnect the battery and reconnect it, The VSC warning, Check engine light, and the annoying exclamation point is all gone from the dash. Until the engine warms up again the next time that is. I will take it to a local Auto-zone and try to get a reading tomorrow after the car warms up and lights up the dash again. I did buy the Tech-stream software CD and a cable last year but never had a reason to use it. That is until now. But now, I can't remember where I put it. I am sure it is with the rest of my Barry Manilow CD collection which I have tried purposely to forget of ever owning.

 

A couple of things are in play at cold start. For one, the engine runs in open loop mode being told what to do with fixed fueling and fixed ignition maps from the ECU. During the warming process, the O2 sensors heat up and begin reporting data, at this time it goes from open loop to closed loop mode where the data from the O2 sensors is fed into the ECU and the ECU adjusts the fueling to maintain emissions.
When fully warm, the engine advances the timing more and leans the AFR to make more power. Lean and more ignition advance creates the shake as one or more of the cylinders are misfiring which should be captured in the Freeze Frame data. What hardware and software are you using to read ECU data?

Off hand, if you have to live with this for a while, I would replace the spark plugs and clean the MAF sensor, verifying there are no vacuum leaks. Most ignition failures occur when warm and under load. But with out seeing any stored codes, you don't know which plug/coils are misfiring so you don't know which to replace.

That's the snap shot. Look up key words and read up. It make more sense.

 

Thanks 2013FSport,

That was the information I was looking for.

Where is the temperature sensor that is keeping the engine in open loop mode located at? Is it more than one sensor? I was thinking of attaching a dummy temp sensor (with a fixed resistance value) so the car will stay in open loop mode until I can get around to fixing it. Could that cause any lasting damage? I am no longer driving it on the freeway and hardly go above 45 during my 25 minute commute to work. Luckily, it just gets to normal running temp just as I reach my office. So I only have to shut the car off once and then restart again. I have bought all the parts (Plugs, Gaskets, Valve cleaner, walnut shells etc.), but I am not going be able to start on it for at least two more weeks. I plan to dedicate a whole weekend for carbon cleaning, Tune-up, Oil change etc., and I want to take my time to do it properly (rather than spraying thru the intake), since I have no idea how bad the carbon built-up is. As far as cleaning the MAF, I hate to mess with it if it doesn't need it. These things are delicate and like to avoid tampering with it if at all possible. In case if it has any visible dirt build up, MAF cleaner that you find at Auto parts stores good enough? Or should I just clean it off with using a can of air or use compressed air at very low pressure?

This is the OBD II scan tool I have. It did not pull any codes with the Check Engine light and VSC lights set. Disconnect/reconnect battery clears all warnings on dash.



I also bought a Tech-stream Scan software and a cable from Amazon. Not sure how legit that was now that I find out it is a subscription service. I have no Idea where I put them so I have not been able to Install and use them.
I will try to get Auto-zone to read the codes sometime this week.

Thanks again for your help.

Cheers.