1999 Pontiac Grand Am Intermittent engine missing, hesitati

Hello

There are a couple of things. First, run by Auto Zone or O’Reilly’s and for free they can pull the codes on the car. This is extremely important to know.

Next, have them for free, they can hook a tester up to the car and check your battery, alternator and starter. Pour electrical output can cause all types of problems.

If the above doesn’t show anything, take a spray bottle of water, and spray a mist over the plug wires from one end to the other and see if this causes the car to run ruff at any time. Sometimes even though you have replaced the wires you will have sparks jumping. Many times it is best to only use OEM wires to prevent sparks jumping. Make sure you spray down by the boot where it connects to the plug too.

Next is the ignition module: The electronic Ignition Control Module (ICM) monitors the CKP sensor signals and based on these signals, sends a 7X reference signal to the PCM so that correct spark timing and fuel injector control can be maintained during all crank and run conditions. Since the PCM controls spark timing and ignition control during crank and run, there is no bypass mode.

The ICM is not repairable. When a module is diagnosed to be faulty, it is replaced as a separate component

The other strong possibility is the fuel pump. You do have 130,000 on the car. You need to check the fuel pressure. The pump can be intermediate for some time and cause you problems.

Bob

I will do as you suggest, checking at Autozone for the codes and the electrical system. The ICM was replaced by a local mechanic in an attemtp to solve the problem. It didn't help. Also, several times in the past few days, rough running and hesitation of the engine has caused the "Trac off" warning light to come on and stay on for a while. On the 99 Pontiac there is an electronic traction system. I don't understand why a rough running engine would trigger it. Perhaps this symptom is a clue that would help you to diagnose the problem? Or maybe it's not related at all. Also, I have found that rough running of the engine can be temporarily "fixed" by simply flooring the accelerator. The engine smooths out immediately and runs fine until the next time it misbehaves. It sounds like a fuel pump problem to me, but I'm not a mechanic. Finally, there is no fuel pressure test port on the 99 Pontiac. How do I test the fuel pressure?

I took your advice about Autozone. Their computer hookup said: "Misfire, cylinder 1." I also had Sears check out the electrical system, battery, alternator and starter. Everything is OK.

Next, I sprayed the wires and boots with the engine running, looking for sparks from hidden breaks in the wires. I saturated the wires and the boots, but it produced no effect on the engine. It kept running smoothly.

What next?

Hello

A miss fire could be several things. Faulty spark plug or wire, Faulty coil (pack), Faulty oxygen sensor(s), Faulty fuel injector, Burned exhaust valve, Faulty catalytic converter(s), Running out of fuel, Poor compression, Defective computer.

My suggestion. You have replaced many of these things. I would think if it were a oxygen sensor, you should get that code. I don’t think it is a faulty catalytic converter or defective computer. You are going to have to be able to clear the code and check each time for this or end up taking it somewhere. Auto Zone or O’Reilly’s may let you buy/return under the tool loan program the tester for codes.

First since you have replaced numerous things, do a compression check on all the cylinders. If number one is really low, then you probably have a burnt valve. If all okay or close to the same, then I would do the below next.

Starting simple, you can crack a plug putting it in. I would clear codes, swap #1 plug with another cylinder. Drive it see what you get. If you get number one again, then swap the plug wire, clear the code and try it again. If you get number one, swap fuel injector. If any of these moves to the other cylinder then you have found the problem and you replace that part.

From what I see to test the fuel pressure you would need disconnect the fuel line, hook the pressure tester to the end, have a tester to turn on the fuel pump and then see what the pressure is.

It appears you need some test equipment for some of this. Why don’t you do the easy things above and let’s see what you come up with from there.

If it were a steady misfire and running rough, you could isolating the misfiring cylinder the old-fashioned method for finding a weak cylinder is to temporarily disconnect each of the spark plug wires, one at a time, while the engine is idling. When there's no change in the idle speed, then you have pinpointed the weak cylinder. Careful though, if the spark jumps to you it isn’t going to feel good.

My bet with that many miles is a bad fuel injector or fuel pump. But let’s see.

Thanks for the suggestions. I will pull the plugs tomorrow, run the compression check and move the wires around. Hopefully I will find something amiss. I think we are moving closer to solving this problem. Thanks again for your help.

ted

Hello Ted

Please when you do the checks write down the info you have to let me know the specifics.
Also, when you encounter codes, please provide the number also, like “code P0301 – Misfire cylinder 1.” Sometimes the info is only by code number. Sometimes codes are different.

You also might consider picking up some injector “O” rings before you remove them. The few cents will save a leak. Put a dab of Vaseline on them to go in smooth.

Good luck on the checks

I ran the compression test as you suggested. Cylinders 1-4 read 197, 196, 200 and 197, respectively. The car ran perfectly on the way to the mechanic, but terrible on the way back. I put the trans in neutral, floored the accelerator and it smoothed right out. The mechanic did find that I had the wrong plugs. The plugs I have are for a 99 Pontiac 6-cyl engine. Mine is a 2.4L, 4-cylinder. I have ordered the right plugs and will install them tomorrow. What now?

Ted

I forgot to say the code is PO301 Misfire Cylinder 1. Also, I could not switch spark plug wires around because my car has a plastic housing with the four plug boots imbedded in it. The whole thing goes on as a unit and can't be switched around.

Ted

Hello Ted The compression looks good. No cylinder is supposed to be less than 100 and the lowest one should not be less than 70% of the highest.....which is 140. So I would think that would rule out the valves. Having the wrong plug - make sure when you put the correct plugs in the gap should be 1.27mm or 0.050 in. Since you will have that stuff apart, really look the plug boots....inspect really good. Put a little ignition grease in the boot. When you take the plugs out, really look at the ends that were in the cylinders and see if number 1 looks any different that the others. Compression is the same as 4 and higher than 2.......but still look really good. Also, they have a technical service bulletin out on misfire, rough idle. When you have it apart really look to make sure the spring is there. I have attached the bulletin. Bulletin No.: 00-06-04-009 File In Section: 06 - Engine/Propulsion System Date: February, 2000 Subject: Rough Engine Idle, Misfire, Possible DTC P0300 (Replace Spark Plug Boot Assembly) Models: 1999 Chevrolet Malibu 1999-2000 Chevrolet Cavalier 1999-2000 Oldsmobile Alero 1999-2000 Pontiac Grand Am, Sunfire with 2.4 L Engine (VIN T - RPO LD9) Condition Some customers may comment on a rough engine idle and/or misfire. The Check Engine Light (CEL) may or may not be illuminated, and DTC P0300 may or may not be set under rough idle conditions. Cause Condition may be due to a missing spark plug boot spring. Correction

Legend (1) Spark Plug Boot Spring

Check for presence of the spark plug boot spring (1) by removing each boot and checking for spring presence at the boot to coil tower connection If the spring is missing, replace the spark plug boot assembly Also there was a important note for the ICM cover bolts. Make sure you follow that. Install the Ignition Coil and Electronic Ignition Control Module assembly to the engine while carefully aligning the spark boots to the spark plug terminals. IMPORTANT: The ICM cover bolts must be installed with isolator washers with the rubber side facing down You said you took the car to the mechanic...........are you able to do these things yourself or have to take it to someone? If you are using a mechanic, then have him do the fuel pump pressure check. I have attached a pic. It is an inline fuel pressure gauge.

FUEL PUMP PRESSURE With the ignition switch "ON" and the fuel pump "RUNNING", the fuel pressure indicated by the fuel pressure gage should be: With EGR 284-325 kPa (41-47 psi). Without EGR 358-405 kPa (52-58 psi). Once you change the plugs, see how it does. If it is still there, my earlier suggestion was to swap the number one fuel injector with another. Again, don't forget new O'rings with a little vaseline on them. Then make sure there is no codes, run it and check for codes and let's see how it does. It would be nice if the code jumped to the other cylinder. Then you would know the injector is bad. Also the TRAC light - not to go too much into this right now but did it come on when you would floor it and then the car smoothed out for a little, or just normal driving......or when it starts to run rough......light comes on? Here is some info on the TRAC light for your reading enjoyment though for now. The amber TRAC OFF indicator will illuminate in order to alert the driver of an existing malfunction with the Enhanced Traction System (ETS). In this situation, enhanced traction will not be available. The ABS VI/ETS must be serviced in order to regain enhanced traction ability. The amber LOW TRAC indicator illuminates in order to alert the driver when the ABS or ETS is active. Whenever the EBCM determines that the vehicle has entered a braking event that requires the ABS or an ETS event is occurring, the amber LOW TRAC indicator will turn ON. The amber LOW TRAC indicator will remain ON for approximately 3 to 4 seconds after the ABS/ETS event is completed. The ABS VI with the ETS includes the following components: "¢ The ABS modulator/motor pack assembly "¢ An Electronic Brake Control Module (EBCM) "¢ Four wheel speed sensors "¢ An electronic brake control relay "¢ An ETS OFF switch "¢ An amber ABS warning indicator "¢ Amber TRAC OFF and LO TRAC warning indicators "¢ The interconnecting wiring Okay Ted..........let us know............

I will check for the boot spring tomorrow when I install the new plugs. The isolator washers for the ICM cover bolts are all in place and in good condition. I took the car to a mechanic because I do not have a compression testing guage. I also asked him to do the fuel pressure test, but without a test port on the fuel rail he said he could not do it. The inline fuel pressure guage shown in the diagram: Is it a standard unit that can be bought off the shelf or is it a homemade rig? My mechanic said he has no idea how to read the fuel pressure on my car, without a test port.

The material you attached on the Trac warning light was not helpful to me. It tells me a lot about Trac lights, but nothing about why the light would go on while my engine is running rough.

Hopefully, the new plugs will help and perhaps I will discover a missing boot spring. But if not, can you think of other possible causes of the symptoms on my car? What about a bad injector? How about a bad coil housing? Are there any sensors in the fuel, electrical or exhaust systems that might cause these symptoms?

Ted

Ted

I believe it is an inline with a T-fitting. Not sure if off the shelf or not. Snap on may have them.

When you have time review my questions about the TRAC…..I did not want to transfer a lot more data over to the post right now due to space. Rapid acceleration affects timing, fuel etc that the TRAC system picks up. So when you have time, please review the questions and pass on what you can.

Please review what I suggested about swapping the injectors – Once you change the plugs, see how it does. If it is still there, my earlier suggestion was to swap the number one fuel injector with another. Again, don’t forget new O’rings with a little vaseline on them. Then make sure there are no codes, run it and check for codes and let’s see how it does. It would be nice if the code jumped to the other cylinder.

It is possible a bad coil, but the same coil runs #4. They are only about $35 at Auto Zone. For another test you could clear the codes, swap the coils and see if the problem transfers to another cylinder. That would isolate the coil.

I think I've fixed the problem!

Today I installed the OEM spark plugs, whose tips looked very different from the ones I took out. In the process of installing the new plugs I noticed that the coil and ICM housing is held in place by four bolts, each of which is electrically isolated from the housing by washers that are metal on one side and rubber on the other. But on my car, one of the OEM washers had been replaced with a plain old steel washer, making metal to metal contact between the bolt and the housing. I installed a rubber washer under the metal one, gapped and installed the plugs and reassembled everything.

Before I did all this the car had been acting up constantly for 3-4 days. It was misfiring, hesitating and running rough at all speeds from idle to highway. After installing the plugs and adding the rubber washer, the car has been running perfectly at all speeds. No misfires, hesitations, coughs, stutters or anything else. The engine runs smoother than it ever has.

Here's my theory: I think the metal washer (which was located only inches from the ICM) created an electrical path that was never intended by the factory engineers. I think electrical charges built up and intermittently interfered with the ICM, causing misfires, etc. I don't think changing the plugs made the difference. They are exactly the same length, only the tip on the OEM plug is much smaller than the one I had been using.

Last night I ordered four rebuilt fuel injectors, in case that was the problem. It appears to be fixed now, but I'm going to install the injectors anyway since any car with 130K miles probably needs new ones anyway.

What do you think of my theory about the rubber washer?

Ted

Ted......That's great news! I think you are right on. It is hard to believe sometimes that a little rubber washer would cause a problem.....or in this case a lack of one, but it can. As you said, the current travels. I am excited you got it fixed. Great job! I know you didn't ask for it but I wanted to send you the info on the injectors since you are changing them tomorrow. Review the info really good. It has a caution using the correct ones, speaks about 2 different rubber O rings and make sure you put just a drop of clean eng oil on them so they slide better into the port. Again, great job and good luck on changing those out! How to Relieve Fuel Pressure

CAUTION: Refer to Vehicle Lifting Caution in Service Precautions. Raise the vehicle. Disconnect the fuel pump electrical connector. Lower the vehicle. Start and run the engine until the fuel supply remaining in the fuel pipes is consumed. Engage the starter for 3.0 seconds in order to assure relief of any remaining pressure. Raise the vehicle. Connect the fuel pump electrical connector. Lower the vehicle. Disconnect the negative battery cable in order to avoid possible fuel discharge if an accidental attempt is made to start the engine. This Procedure is With EGR

REMOVAL PROCEDURE Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure. Remove the fuel rail assembly (1) from cylinder head. Spread the fuel injector retainer clip (3) to release the fuel injector from rail extrusion flange. NOTE: Use care in removing the fuel injectors in order to prevent damage to the fuel injector electrical connector pins or the fuel injector nozzles. Do not immerse the fuel injector in any type of cleaner. The fuel injector is an electrical component and may be damaged by this cleaning method. Remove the fuel injector assembly (4). Discard the fuel injector retainer clip. Remove the injector O-ring seals (2) (6) from both ends of fuel injector, and discard. INSTALLATION PROCEDURE CAUTION: In order to reduce the risk of fire and personal injury that may result from a fuel leak, always install the fuel injector O-ring in the proper position. If the upper and lower O-rings are different colors (black and brown), be sure to install the black O-ring in the upper position and the brown O-ring in the lower position on the fuel injector. The O-rings are the same size but are made of different materials. IMPORTANT: Different fuel injectors are calibrated for different flow rates. When ordering new fuel injectors, be sure to order the identical part number that is inscribed on the old fuel injector. Lubricate new fuel injector O-ring seals (2) (5) (6) with clean engine oil and install on fuel injector assembly. Install the new fuel injector retainer clip (3) on fuel injector assembly. IMPORTANT: Position clip on right side of the fuel injector electrical connector. Install the fuel injector assembly (4) into fuel rail injector socket with electrical connector facing outward. IMPORTANT: Push in far enough to engage retainer clip over rail extrusion flange. Install the fuel rail assembly (1). This Procedure Without EGR

REMOVAL PROCEDURE CAUTION: Relieve the fuel system pressure before servicing fuel system components in order to reduce the risk of fire and personal injury. After relieving the system pressure, a small amount of fuel may be released when servicing the fuel lines or connections. In order to reduce the chance of personal injury, cover the regulator and the fuel line fittings with a shop towel before disconnecting. This will catch any fuel that may leak out. Place the towel in an approved container when the disconnection is complete. Relieve fuel system pressure. Refer to Fuel Pressure Relief Procedure. CAUTION: Refer to Battery Disconnect Caution in Service Precautions. Disconnect the negative battery cable. Remove the fuel rail assembly. Remove the fuel injector retaining clip (1). IMPORTANT: If the fuel injector is difficult to remove from the fuel rail assembly, use J 43013 Multec II Injector Removal Tool. Visually inspect the fuel injector to see if the upper O-ring was also removed, if not, remove the O-ring from the fuel rail assembly. Remove the fuel injector. INSTALLATION PROCEDURE IMPORTANT: Each fuel injector is calibrated for a specific flow rate. When replacing fuel injectors, be sure to order the correct fuel injector for the application being serviced. Lubricate new fuel injector O-ring seals (2) (3) with clean engine oil, and install on the fuel rail assembly. IMPORTANT: When installing the fuel injector, care should be taken not to tear or misalign the fuel injector O-rings. Install the fuel injector upper O-ring (3). Install the fuel injector lower O-ring (2). Install the fuel injector to the fuel rail assembly. Install the fuel injector retaining clip (1). Install the fuel rail assembly. Connect the negative battery cable. Inspect for leaks through the following steps: 8.1. Turn the ignition switch ON for 2 seconds . 8.2. Turn the ignition switch OFF for 10 seconds . 8.3. Turn the ignition switch ON. 8.4. Check for fuel leaks.

Thanks so much for all your help. When I fired up the engine after changing the plugs, I just couldn't believe how smooth it ran. I honestly don't know if it was the plugs or the rubber washer. One way to check would be to reinstall the sold steel washer and see what happens. In any case, it runs fine now and I don't really want to mess with it.

Thanks again.

Ted

Ted

I am really, very happy your car is running as you want. You are more than welcome for the help, but let’s not forget, you were the guy turning the wrench. Fantastic job. Great teamwork I think. You are right. The rule is, if it works, leave it alone.

You have a great weekend and enjoy driving that car around and feel proud you fixed it!

Bob

I'm baaaaaack. Just for insurance, and because the car has 130,000 miles, I changed all the fuel injectors. I bought remanufactured ones online and had them installed by a mechanic. The car continues to run beautifully, silky smooth, with great acceleration and gas mileage, but a new problem has now popped up.

Immediately after the new injectors were installed, starting problems began. I've never had a starting problem with this car before, but now it will not start unless I give it a tap or two of gas while the starter is cranking. When it finally does start, I occasionally get a puff of grey smoke out the back end.

Any idea what's going on?

Ted

Hello – Ted

Glad to hear back from you……..sorry about the car though.

Well it could be a couple of things……first though remove the brake booster vacuum hose and see if it is wet inside from brake fluid? I would check it at the booster end and the manifold end.

As for the having to pump the pedal after the injectors were installed, look them over really good and see if there is any gas leaking around one of them. It sounds like one or two are bleeding down therefore you are loosing gas pressure. Since that is the only thing that was changed and the car was running great before, that is what I would think. Next your fuel pump….you do have 130000 miles on it so it may be coincidental that it did this at the same time as the injector change. You might try running a can of BG 44K injector cleaner through and see if you do have an injector sticking maybe that will clean it.

Also, next time, turn the key on and wait until you hear the pump totally stop…..then try cranking and see what happens. The only way to know for sure what is going on with the fuel is put a gauge on it and let it sit. If the pressure drops to say, 35 after sitting for a while it is leaking.

Last have you pulled the codes or checked to see if there is any?

I made a donation and I will check all the things you suggested, as soon as election day passes. I'm working as a pollworker tomorrow so i won't be able to get to the car until later this week. Talk to you about results later.

Ted

Hello – Ted

Thanks for the update…..good luck working the polls tomorrow….sorry again about the way it runs….you really seemed happy when it was running so good.

Don’t loose faith in it….things happen.

It will be running great in no time.

Keep me posted….

I believe I have found the cause of the hard starting problem. I took the air breather off and found the plastic electrical connector on injector number 3 is broken (probably by the mechanic who installed the new injectors). I pushed the connector parts together to make the tightest possible fit, then taped the joint with plastic electrical tape. The car started right up with no problems. It appears to be starting and running fine now. Should I replace the plastic connector or just leave well enough alone?

Ted

Well Sir My suggestion is to definately replace the connector. I wouldn't always say that by my concern is what it is connected to and where it is at....fuel..........sometimes they leak, if for some reason it decided to spark then hard to start is the least of the problems.......putting it out would be the main thing. I have attached two different pics of the plug....one is part number 12129140 and the other is 15326179. If it were me, I would pick up the connector, if you don't have the pin extractor tool, then stop by a auto electrical shop and they could swap the connector out for you. Glad you found it and it's back up and running. Have a great day Ted...