Our Community is 705,000 Strong. Join Us.


What Are Signs Of Misfiring?


bcook
08-25-2006, 10:43 PM
I'm wondering what are the sign of misfiring?

I have a 2000 Monte Carlo SS. It's maintained well. It has 67312 miles. It's all stock besides a K&N filter and a Gatorback Serpentine belt. I use premium octane. I recently drove it back to school (MI to KY to GA to FL). I just had an oil change before I made the 1000+ mile journey. On the way I experienced my car doing some type of shaking that I had never felt. One time I remember I was on the highway doing like 70. I need to pass someone. So I stepped on the peddle slightly. The car accelerated, but very slowly. It accelerated maybe 1MPH per rock. I noticed the tachometer moved between 2400 and 2800RPM during the rocking. I pushed the pedal further down and the rocking stopped and my car begen to accelerate normally. This occurence has arisen several times now. Most recently, this evening. I had just put some fuel treatment in this afternoon also.

If not misfiring, are there any other ideas as to what may be wrong?

Rally Sport
08-26-2006, 12:08 AM
I would run regular unleaded.. not premium, one of the most things that people think is that running a higher grade means more gas mileage or better engine response.. but that isnt true because the higher grade fuel burns longer, so im pretty sure if you run regular unleaded the problem would go away. If it doesnt then im sure the problem is in your throttle position sensor. But try going with the first suggestion.

bcook
08-26-2006, 09:22 AM
I just filled up on 93. But when I go to fill up again I'll go to 89. I had been using 93 since I felt it'd reduce the chance of water being in my gas, which I hoped would extend the life of my fuel tank and fuel filter. I had a multipoint inspection a few months ago. They recommended that it'd be good preventative maintenence to install a new fuel filter. So I'm going to go ahead and get one of those put on.

What effect does the gas burning longer have on the engine?

G-man422
08-26-2006, 09:26 AM
It is harder for the engine to combust the higher octane gas, and is really only suitable for high compression engines. As stated, i would use regular unleaded, and if that doesnt help, you can try a new fuel filter.

bcook
08-26-2006, 09:39 AM
Is 89 ok? or should I go to 87?

G-man422
08-26-2006, 09:44 AM
Yeah, I think that your V8 should be able to handle 89 fine, but i wouldnt go any higher.

bcook
08-26-2006, 09:56 AM
Ok I'll move down.

I went to AutoZone this morning and got a scan done. My CEL still hasn't come on and the guy said that if the CEL wasn't on then it wouldn't read. And it didn't. Is it true that some misfire codes get stored but don't kick on the CEL? If so how would I go about getting those codes read?

MT-2500
08-26-2006, 10:10 AM
Ok I'll move down.

I went to AutoZone this morning and got a scan done. My CEL still hasn't come on and the guy said that if the CEL wasn't on then it wouldn't read. And it didn't. Is it true that some misfire codes get stored but don't kick on the CEL? If so how would I go about getting those codes read?


Missfire codes may not set light on but usually are stored in memory.
You need a real good engine capable scanner to get into history and history missfire codes.
A real missfire will give a flashing or blinking engine light.
If you have a K&N filter clean the maf sensor real good.
If they get k&N oil in them they throw off fuel mix and can cause missfire or engine running problems.
As said go back to reg gas and check fuel filter and MAF sensor.
Is it still act like it is missing or has it came out of it?
MT

bcook
08-26-2006, 10:25 AM
The problem has only occurred about 3 or 4 times now. I've been trying to reproduce it but I haven't had any luck yet.

I doubt I'd be able to check/clean the MAF on my own. I can call my uncle and see could he walk me through it.

MT-2500
08-26-2006, 11:00 AM
The problem has only occurred about 3 or 4 times now. I've been trying to reproduce it but I haven't had any luck yet.

I doubt I'd be able to check/clean the MAF on my own. I can call my uncle and see could he walk me through it.


It is not that hard to do.
They make a good spray type cleaner for them now.
CRC and some others may have it.
Remove it first.
All you need to do is spray the little wires that have the little sensors on them.
Spray and let dry about 3 times for a good clean.
And go real easy on the oil in that K&N filter. A little dab will do you.
If it keeps on doing it would have a look at the spark plugs to and only use The good AC delco plugs that the good book calls for.
If you can narrow it down to one cylinder check the coils and or wires on that cylinder to.
MT

Mickey#1
08-26-2006, 11:39 AM
What engine do you have?

Rally Sport
08-26-2006, 12:15 PM
If it is a 00 Monte SS then its just the V6.

I would go ahead and step all the way down to 87.. cheaper that way. :lol:

bcook
08-26-2006, 01:05 PM
I have only had the K&N for about 10k miles, so I have never had to oil it. They are supposed to be reoiled every 15k?

I have a L36. *sighs cause he wants a V8*

Do you all know of any venues that have good scanners that scan for free?

Rally Sport
08-26-2006, 01:10 PM
To scan for codes? I'd just try autozone or O'rielly auto if you got either around.. they do it for free.

BNaylor
08-26-2006, 01:20 PM
The first thing you should do is get rid of the K&N air filter. They are worthless unless you are running a CAI or FWI with a cone style K&N filter. Nothing beats the stock AC Delco in airflow and filtering efficiency.

On oiling K&N filter that is called a recharge and you get the recharge kit with the cleaner and spray oil not the stuff in the squeeze tube. Kits runs around $10.

Once the filter oil gets on the MAF sensor hot wire elements a cleaning may not help because the damage is already done.

Since you have a SII 3800 just disconnect the MAF sensor and take it out for a test drive. It your problem is resolved then the MAF sensor is bad. If there is no change then don't waste any time on the MAF sensor and look for another issue. With MAF disconnected all the PCM does is use pre-programmed MAF/VAF tables, TPS setting, rpms and MAP. The idle may be a little erratic until the engine is warmed up.

bcook
08-26-2006, 09:13 PM
I think I may have found a way to reproduce the problem. Gonna try it some more tomorrow. It seems to happen when I try to accelerate(with a gentle pressure on the pedal) from a steady speed while going up hills. Tallahassee is a hilly place so I got a lot of places to try tomorrow.

bigd2006
08-27-2006, 03:40 AM
hey i have a 2001 monte carlo ss with the v6. i seem to have the same problem except it happens between 20mph-45mph i feel it happens when the car shifts but im not sure i went to schucks and i poulled up a code 7402 or something with t he transmission. my cars symptoms are the same bogs up and shakes my engine and if u push down on gas it will slowly continue. if u find anything out please gimme advice.

bcook
08-28-2006, 06:43 PM
Still haven't reproduced the problem yet. I'm about at 3/4 of a tank so it may be a minute before I run out all the 93.

Question. What causes oil to come off of the K&N filter? Just regular use?

bcook
09-09-2006, 09:27 AM
I've been reading around. I believe what I had been experiencing was a surge. My symptoms were very similar to those posted in this thread about a Regal. http://www.automotiveforums.com/vbulletin/showthread.php?t=590602

I haven't experienced the problem lately. I haven't been up many hills either. I have moved down to 89 octane as well. I am going to change the fuel filter ASAP as well, I'm just waiting on my refund checks to come in.

If it is a engine surge what should I do?

BNaylor
09-10-2006, 12:44 PM
hey i have a 2001 monte carlo ss with the v6. i seem to have the same problem except it happens between 20mph-45mph i feel it happens when the car shifts but im not sure i went to schucks and i poulled up a code 7402 or something with t he transmission. my cars symptoms are the same bogs up and shakes my engine and if u push down on gas it will slowly continue. if u find anything out please gimme advice.

On a 4T65E tranny the P0742 DTC you are getting is of concern. The torque convertor clutch (TCC) is stuck on indicating you have a valve body related problem. Possibly the TCC-PWM solenoid. This DTC is a type A fault code and stored in PCM memory for retieval. It will disable shift adapts and commands the TCC on at maximum capacity. It is consistent with the bogging and shaking effect you are getting.

Add your comment to this topic!