Review Quad 4 Engine Problems

Quad 4 engine problems are very common and discussed here, but first some background and history of this General Motors engine. The engine started as a high rpm dual overhead cam 2.3-liter 4 cylinder.

GM created it to provide a balance between horse power, weight and fuel economy. For many years the long term goals remained to streamline production, improve quality and deploy it across all car lines. They introduced the motor in 1988 using the Oldsmobile and Pontiac car lines. Finally it made its way to the Buick line in 1990.

The General later punched out the engine to a 2.4 Liter version. The first thing people wonder when they see a Quad4 is where are the spark plugs and wires located. At the very bottom of this page is large picture of the hidden valley under the coil cover. You can use this as a point of reference for component location.

We call the ignition system a first generation distributor less ignition (DIS) and it’s completely unique to this engine. There are no old style plug wires running to spark plugs in this set up.

In fact, it’s in this system where a few common problems develop on older engines. We’ll talk about them here and point out inexpensive replacement parts.

The coil housing becomes responsible for delivering the high energy spark from the coils to the plugs. They locate it in the top center cover of the engine that says Quad4 on it. You remove this cover to access the spark plugs. Inside the coil housing exists copper strips that act like ignition wires. They run the spark from the coil to the plugs.

Auto Facts repair manuals
Auto Facts Repair Manuals

Here is an e-mail I fielded about a quad 4-engine misfire coupled with a check engine light. You can read through this and look for a link at the bottom for a PDF you can save to your hard drive about other quad 4 problems that are common.

Question or Comment: I have a 2001 Pontiac Grand Am with a 2.4L and Auto Trans, 74000 miles. Last week it started running very rough. Also the service engine light came on. I recently purchased an auto scan tool. At first there were (2) codes for the same thing. P0303 Cylinder #3 Misfire detected. I pulled the spark plugs and they where severely worn so I replaced all (4) plugs gaping them to the recommended specification.

Upon re-starting the car it ran great for a short time before the check engine light came back on. The engine also started running rough again. I plugged in my scan tool; this time the code was P0300 Random/Multiple Cylinder Misfire Detected.

I tried doing some research all I could think of trying was to replace the coil packs. However, it didn’t make any difference at all. Any help you can provide me with concerning this matter will be hugely appreciated. Thank you for your time and keep up the awesome work.

Answer to this Quad 4 Problem

I would like to say that your car questions website is awesome! I learned a lot of fundamentals about the automobile and plan to learn more. With that said, I did not use the factory service manual to check for technical specifications as you recommend. Also, would you know how many TSB’s are out for this motor?

Scott: I do not know exactly how many bulletins they issued, but I traveled down this road with a grand am (quad4) myself. The Quad 4 engine I worked on was a 1999 2.3 Liter so things might be a bit different on your 2.4L model. I had the same codes and also replaced the plugs and the coil packs.

To make a long story short the engine misfire turned into what the quad 4 uses to replace the plug wires. The plastic housing that holds the coil packs and fits down over the spark-plugs. On the bottom of the housing they use little boots that connect to them.

U480 CAN-BUS code readerThe coil housing itself contains copper (thin) runners to carry the high voltage spark from the coils to the plugs. My housing was bad because the copper strips had hairline cracks I could see with the naked eye when I busted it open. These cracks acted exactly like bad plug wires.

The engine would miss hot or under load. When I went to the Pontiac dealer parts department they new all about this Quad 4 problem! They called this part the battle ship (Available on the right) because the gray plastic housing held upside down looks like a battle ship. Yes replacement parts are white.

It sounds to me you are having the same problem causing your grand am to run rough. When I replaced my coil housing I also replaced my boots the dealer called it a boot kit. These parts are rubber and exposed to tremendous heat that can make them brittle and weak.

Sorry I don’t remember the prices, because this all happened 4 years ago. However, I will never forget the battle ship. Note: Your newer quad 4 2.4L may have a slightly different set up? You may want to take a look at a professional auto repair manual. Pontiac provides diagnostic steps for other Quad 4 problems. now offers factory technical manuals for mechanics and do it yourself people. Watch the free demo of the online service manuals system. Once you find the demo it walks you through how to find the tech tips and bulletins sections for specific automobiles.

I put together a helpful video that shows you some features and benefits that are exclusive to the PDF program. This next page also gives you more information about the auto repair manuals available online.

As this engine ages into oblivion there aren’t many people writing about Quad 4 engine problems anymore. However, I did find a small piece in the urban dictionary calling it the 4 cylinder engine of the future that never lived up to it’s potential. This is an accurate assessment in my mind. I think its worth a read, but the  article talks more about the pro’s then cons on the Quad 4 subject.

I have more articles in the DIY section that is meant for at home mechanics or motorists that would like to learn more about cars. This next link takes you from Quad 4 problems to Diy auto repair articles.

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Common Failed Quad 4 Engine Parts