Engine misfire

Hello,

Well agon813, I sure will do my best.

Okay, first, thanks for the info on the car. . ...I just want to make sure though, what I am looking at is a 2.3L VIN 3. So the 8th digit of your VIN is a 3. . .. . .yes?

Now you have a miss. Is this all the time, at idle, just while driving, when just starting out and the engine is cold, when it is just warm, all the time?

When was the last time you changed your air and fuel filter?

Did you clean your MAP sensor?

Was it missing and that is why you replaced the parts you did?

So you and I are saying the same thing, you

When you put new AC plugs in, you did gap them to .035 inches? NOTE: Check the gap specifications given on the Emissions Control Label. If the gap is different from what is listed here, use the information on the label.

The spark plug type for VIN 3 is AC FR3LSK - make sure you used these plugs. Other VINs use different ones, that is why I asked what the 8th digit was of your VIN.

Next, please go to Auto Zone or O'Reilly's and for FREE they can pull the codes to the car. Most important: Once they check your codes, if they find something and you don't get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad. Then make sure you give us all of that. While there for FREE also they can bring their tester out and check your battery, alternator and starter.

Now we may end up needing to check your fuel pressure also. . ...if you can, then get that done or you can wait until we gather the data from above.

Okay, I don't have a good pic to show certain things so you may need to ask the parts department. I have attached the pic I am talking about.

First on the ignition cover, the bolts #2. . ..they look like they have rubber washers under them. Do they? If you are not sure then please call the parts department to verify. If yours has them on it make sure they are okay and metal is not touching metal.

Item #3, the retainers, did you make sure those were in good working condition - no tears, holes, burn through marks or burn marks.

Basically what we are checking for is a way for sparks to travel ANYWHERE other than your plugs. I worked a Grand AM not to long ago and the miss was the rubber washers were not installed. So as we go over these things, that is what we are looking for.

You replaced #4 - the plugs. . ...again, please make sure you used the correct plugs.

You changed the boots - #5

The springs #6- they are all in good working order and have good contact with the plugs.

Item #8 - more bolts - check for rubber washers - again, call the parts department to verify.

Item #9 you have replaced.

Item #10 - did you look that over really good for chaffed wires, burn marks, anything defective and the plug ends were clean - no cracks or any defects?

Item #11 - I don't show, but is this insulator rubber and is it in good working order, clean making contact in all of the required places?

Items 12 and 13 - are these in good working order - especially that 13, the seal?

Number 15, the retainer, no cracks or defects?

Now number 14 - the module - it may be heating up - pretty pricey so we will try to look at that last. I did want to provide you with what it does. As you see it sends a signal to the PCM so the correct spark and fuel injector fire. Special point here, I have attached a pic, there is supposed to be grease between it to help with the heat. White lithium grease. You can pick that up at AZ while you are there getting the free checks. I also attached the note on the module and coil about the grease.

PURPOSE
The Electronic Ignition (EI) control module monitors the crank sensor signals and based on these signals sends a reference signal to the PCM so that correct spark and fuel injector control can be maintained during all driving conditions.

NOTE
Do NOT wipe grease from module or coil if same module is to be replaced. If a new module is to be installed, a package of silicone grease will be included with it. Spread the grease on the metal face of the module and on the cover where the module seats. This grease is necessary for module cooling.

Okay, lots here - I need many questions answered and if you would get these checks done and make sure you check the things I asked. Then get back with me so we can get this miss gone.

Last, looks like you may have some recalls on your vehicle. The dealer may fix these for free. Please contact the dealer service department, give them the VIN number of your car and have them check on these to see if they apply to you.

Hello,

Thanks for the update.

On those items I asked about the rubber washer it did not have oneÂ. Were you able to contact parts department to see if they came with them?

Look all the wires over really good going to the coils... With the car running take a spray bottle of water and mist all over the wires and see what happens.

Look at your vacuum hoses for any slight tears, holes, loose connections.

Get a can of BG44K and pour in the tank. This will clean the fuel system.

Did you ever go to AutoZone and check the codes?

Just putting my 2 cents in. Have you checked your Ignition Control Module and crank shaft position sensor?

Hello,

Jnovack provided some excellent input.

I included information on the ICM farther back in the posts when I talked about that may be getting hot and checking that last. I told you to ensure there was lithium grease on it and gave a pic of it.

I put to check that last because I do not show a check that you can do with that with normal volt meters etc, if you have to have certain test equipment. You can pick one up at AutoZone for about $140.00.

Thanks for the assistance jnovack.

Heres how to test the crankshaft position sensor thodle position sensor and map sensor

TESTING

See Figure 1

Fig. 1: Attach suitable jumper wires between the CKP sensor and CKP sensor harness. A DC volt meter can then be attached to the necessary terminals to test the sensor as the engine is being cranked

Typically, when a crankshaft position sensor DTC is set, checking the integrity of the wiring connecting the sensor (using a digital volt meter) to the PCM harness connector is the best way to determine if the sensor is faulty. If the wires all have continuity, and a DTC is set, it is probable that the sensor is faulty.

Although a procedure is given here for testing of the crankshaft sensor itself, it is generic, and may not apply to every vehicle. Typically, the crankshaft position sensor harness connector wire leads are labeled. However, it is advisable to use this procedure in conjunction with the wiring diagrams in to identify the terminals on the crankshaft sensor before connecting test leads.

Turn the ignition key OFF.
Unplug the sensor electrical harness and check the terminals for corrosion and damage.
Check the sensor wiring harness wires for continuity and repair as necessary.
Attach the sensor harness making sure it is firmly engaged.
Using a Digital Volt Ohm Meter (DVOM) set on the DC scale, backprobe the sensor signal terminal (terminal A) with the positive lead of the meter and backprobe the sensor ground terminal (terminal B) with the negative lead of the meter.
Have an assistant crank the engine and observe the meter.
You should have approximately a 5 volt reference signal pulse. If not the sensor may be defective.

Fig. 2: The TPS is located on the side of the throttle body

Fig. 3: Inspect the voltage of the TPS when the linkage is closed, then ....

Fig. 4: ... check for change when the TPS linkage is at WOT

Disconnect the TPS harness from the TPS.
Using suitable jumper wires, connect a digital voltmeter to terminals A and B on the TPS.
With the ignition ON and the engine running, the TPS voltage should be 0.450-1.25 volts at base idle to approximately 4.5 volts at wide open throttle.
If the reading on the TPS is out of specification, replace it.
Turn ignition OFF, remove jumper wires, then reconnect harness to throttle position switch.

TESTING

See Figures 2 and 3

Backprobe with a high impedance voltmeter at MAP sensor terminals A and C.
With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
If the voltage is not as specified, either the wiring to the MAP sensor or the PCM may be faulty. Correct any wiring or PCM faults before continuing test.
Backprobe with the high impedance voltmeter at MAP sensor terminals B and A.
Verify that the sensor voltage is approximately 0.5 volts with the engine not running (at sea level).
Record MAP sensor voltage with the key ON and engine off.
Start the vehicle.
Verify that the sensor voltage is greater than 1.5 volts (above the recorded reading) at idle.
Verify that the sensor voltage increases to approximately 4.5. volts (above the recorded reading) at Wide Open Throttle (WOT).
If the sensor voltage is as specified, the sensor is functioning properly.
If the sensor voltage is not as specified, check the sensor and the sensor vacuum source for a leak or a restriction. If no leaks or restrictions are found, the sensor may be defective and should be replaced.

Fig. 2: Using jumper wires and a high impedance voltmeter test between MAP sensor terminals A and C with the key ON and engine off. The voltage should be approximately 5 volts

Fig. 3: Next test between MAP sensor terminals A and B with the key ON and engine off. The voltage should be approximately 0.5 volts

Agon813

You sound frustrated and you have good reason to be. But try to relax. There are many vehicles that sit at many shops for days, people pay hundreds of dollars to locate what you are trying to locate and they have tons of expensive test equipment and many times they can not find these things either.

You do not have all that equipment and are doing the best you can. Same here. So as we provide you with suggestions unless we just know for sure or you are able to perform a test and see the problem, it is the best answer/guess/suggestion whatever word you want to try to track this down.

So we keep trying. Again, I understand the frustration been there.

As for replacing the ICM that is no guarantee that is the problem either. The only test you can do on it is remove it, visually inspect it for anything that may not look right, apply some grease and try it again. If you replaced it that is not a 100% guarantee either.

It may be a vacuum leak too very slight. Try inspecting all the vacuum lines to include the one to the brake booster. Push, pinch, squeeze each one do it and hold it for a second to give time for the car to react. For the brake booster remove the hose and plug it with your thumb and see if that makes a difference. The other hoses use pliers to pinch them closed and see. Make sure all connections are tight, hoses are not split etc.

I have troubleshot things for weeks. Then finally, there it is. Try not to let if frustrate you. The more you can look at the positive side that keeps your mind clear to think on what it may be.

Hang in there we will keep doing what we can to suggest.