The 2.3 liter Quad4 was developed by GM's Oldsmobile division in the mid 1980's. It was created in order to fill in the gap between performance and economy. It is an improvement over the 2.5L 4-Tech and 2.0L Turbo engines which it replaced. The discerning automotive enthusiast may also note that it's offered as a performance upgrade in GM's small compact cars. In GM's compact (an inch or two short of midsize) and midsize cars, the Quad 4 is offered as an economy item in lieu of a V6 (the V6 runs a little smoother, has little more torque-but not much more.)
"So, what's so special about that?" you may ask. Well, the Quad is quite a strong little engine. Compared to other 4 cylinder engines of similar displacement, it comes out on top. (Well, maybe if you consider a Japanese engine or two-not exactly. But look at how many RPM they have to rev to. How often will a normal person do that? So there.) It uses a timing chain and is fairly reliable. Its efficiency is decent, on average it gets above 30 MPG highway and 23 MPG city.
Other stuff... Some may not realize it, but the Quad is also the precursor to the more famous Northstar and Aurora engines. All the technology used in them was more or less derived from and improved on that developed and researched upon the Quad4.
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What's a FAQ?
FAQ stands for Frequently Asked Questions. Got it? OK.
Where's dem plug wires?
The Quad is unique in that it uses a completely integrated ignition system. With the exception of the timing pickup and the computer that controls timing, all ignition components are placed in an easy to service assembly. This is that cover plate on the very top of the Quad 4 engine. It contains the ignition coils and module and all associated connections. The sparkplugs attach to boots on the underside of this assembly. To be specific, GM calls it an IDI ignition.
What is that black box in the middle and towards the front?
That is an oil vapor seporator. It has the equivalent funtion to a PCV valve found in most other engines.
I know a lot of engines have emissions controls on 'em. What does the Quad have?
The Quad 4 is one clean, lean, and mean machine. Emissions equipment on it is minimal. The earliest and latest Quads have no EGR. This may have to do with the fact that the spark also fires on the exhaust stroke. It has the vapor separator in place of the PCV. A fuel vapor canister scavenges from the gas tank. Make sure it works since its operation can affect the idle. The catalytic converter is only there if something goes wrong. The Quad (believe it or not) in good running condition doesn't even need one. That's how clean it burns. The 'cat' is just there to make the EPA happy.
I have an engine in my GM car that has DOHC or Dual Cam on it, is that a Quad?
Well, it just might be. If it has four cylinders and a displacement of 2.3 or 2.4L, then what you have is a newer generation of the Quad. For some reason, GM stopped using the Quad 4 name. Why? I have no idea.
What does DOHC mean?
It stands for Dual OverHead Cam.
So what's that?
It's a type of engine design. In most cases it's used to increase air/fuel flow through the engine. In general, this is a good thing.
I have an engine that has SOHC Quad 4 on it, what's up with this?
Well, ahem... I hate to say it, but you've got the only true lemon that's growing on the Quad family tree. Either go easy on it and accept its lackluster ability and what few more MPG you're getting, or let it go and rebuild it with parts from a DOHC Quad. I'd recommend finding the parts and rebuiling as a DOHC, the improvement in reliability and performance is quite remarkable.
What's a cam?
If you didn't know this, well you're not the most auto literate. But I'll tell you. It's a long metal rod with lobes machined into it. These lobes are what push the valves open when the cams turn.
Where can I get performance cams?
If you're into tinkering and have the knowhow... Performance cams can be had through GM (W41 spec), MantaPart, and Comp Cams. Price is around the $200 range. Not too bad. You may need the proper EPROM chip to get the full use of it though.
What's a valve?
I'm not going into that kind of detail here. Ahem... Get an encylopedia or better yet, a book on automobiles or engine repair.
I heard someone say that Quads had trouble with cylinder heads and/or overheating.
Well, for a while they did. This was no fault of the engine itself. This was due to improperly stamped head gaskets. These didn't allow proper flow of vital engine fluids through the head and caused problems. This problem had been fixed quite a while back. If you were one of the unfortunate few, getting it rebuilt with a good head gasket will definitely fix this. There is an exception to this, it's the SOHC Quad. Remember seeing it mentioned before?
What's this cryotreating I've heard about?
It's a process of slowly cooling something to less than -400° F or so, and then slowly warming it up. This is usually done by professionals and takes time (about a month, if I remember right.) That's why it costs $$$ and notice the emphasis on the word slowly.
Why would I want to do something like that to engine/powertrain parts?
It allows the atoms in a metal alloy to seat themselves in a matrix or something like that. If you're into performance, it greatly enhances the durability and strength of metal (especially aluminum) components.
What's this stuff on VIN-whatever Quads?
This is refering to the 8th VIN number of the VIN number code. Believe it or not, there's more than one kind of Quad. The core of the beast is still the same, but a few key parts are different. Intake, exhaust, and computer/fuel management components vary. This results in the SOHC(BAD), DOHC(GOOD), H.O./W40/W41/W42 DOHC (PRETTY DANG AWESOME) versions of the Quad 4. A VIN-D Quad is the most common run o' the mill DOHC (which is pretty decent-it's the one I have.) VIN-A's are the H.O. Quads. There are some more codes for the performance and SOHC as well as the newer DUAL or TWIN-CAM engines. I don't know all of those codes yet.
What's H.O. stand for?
It stands for High Output. Any Quad that's truely H.O. puts out around 180 HP.
Somebody says Quads have an oil leaking problem/I have an oil leaking problem-what's with this?
Normally this is no true fault of the Quad itself, just a quirk in its design. There's a gasket that goes on the timing chain cover (if I remember correctly) that happens to look the same from either side. However, it only goes in correctly only one way. If the person working on the Quad puts this gasket in wrong, it's probable that it'll leak. This has something to do with the seating surfaces on each side of the gasket being slightly different.
Where the heck is my air filter!?
Heh. (<- My little been there-done that laugh.) You probably have one of the cars in which they stuck it on the bottom. In this case, follow the big rubber air hose from the throttle body. It's kinda near the battery. Remove the rubber air hose (being careful as not to tear it.) There will be a canister down there with a thumb screw on it. That's where they put your air filter. I believe they put it there in order to get cooler air or more airflow. This design does have its problems, believe me I know! If you have this setup, be careful driving through water more than 1/4 the height of your wheels. If you do so, be prepared to grab a screwdriver and temporarily disconnect that rubber air hose.
What should I do for a tune up?
Make sure it's clean. Change the oil. Perhaps use some throttle body cleaner. Change the coolant if the schedule requires it. Not much more than that usually. All the stuff's electronic or permanently set at the factory. Odds are that nothing's going to need adjusting. If you're unsure, consult a professional.
My "Check Engine"/"Service Engine Soon" light came on. Should I have reason to worry?
Not necessarily. If you have a definite change in performance, a low oil pressure and/or high engine temp light come on-then you'd better find a place to stop soon. You really do have a problem. This light doesn't, however, require anything major to happen in order to come on. The problem may be elsewhere in an emission control system or powertrain component (transmission.) Sometimes it comes on due to an electrical fault of some sort, like a short to ground caused by a worn wire or poor connection. These problems don't warrant the most immediate attention, but should be addressed in a timely manner. Sometimes they go away on their own or are intermittent. Anything that will cause this light to come on will be stored as a code in the engine management computer. See codes section for more details. As a reminder, it is better to be safe than sorry if you're uncertain - go to a trusted mechanic.
I heard somewhere that there was an injector problem with Quads.
This was in fact true on the earliest of the early Quad 4s. They used needle type injectors which were prone to fouling with low quality fuel. A change to disc type injectors fixed this. All current Quads use fuel injectors which don't foul up easily. You'd have to use some really crappy stuff to mess them up.
Are there any problems common to the Quad 4 engine? As a matter of fact there are. It's a nifty and compact powerplant, but it's not without its faults. One is with the headgasket. It usually fails on engines with over 100K mi on them. Usually you'll lose power in one or two cylinders. A check of compression and the cooling system in in order to be sure. Another problem to look for is cracking on the actual cylinder head between the spark plug hole and valves. One more thing to watch for is failure of one or both of the coil packs, as they're subject to heat and vibration due to their tidy placement in the IDI assembly. Other problems are less common, and vary due to individual differences between cars and changes in design.
Hey! I'm quite sure I'm mechanically adept. I've done work on cars before. Where can I find performance parts? I'd definitely like to beef that little sucker up!
Well, in most normal cases performance parts are a bit tricky to find. It's not like you can go to the dealers and just ask for that stuff. OK-you could, but they'd just look at you funny-since it doesn't have 8cyl (and therefore isn't important to them.) However, I'm glad to say that there is a growing trend supported by enthusiasts of American compact cars. (yes I did say that.) So this situation isn't completely bleak. (Yey!) Now the good part. I have a few links here and there. I'm not biased, so what I have is more or less what I've found. Also the other websites that I've linked to have plenty to offer for the serious. If you don't have the list on the left of the screen click here. And there's the quadfourm at egroups.com. Yes it's quadfourm-that's how it's spelled. Be nice to everyone there-and I'm sure you'll learn what you need to know Quad 4 wise.
Hey! I don't have a Quad 4 car but I'm interested. What are the Quad 4 cars?
Click here and you can jump to my list of Quad4 cars.
Just curious, how much would one cost?
It depends... New, about 18 to 20-something grand. Used... How old you're willing to go with and how many miles you're willing to have on the odometer. A good one can be aquired around $3000. One that runs can be had for under $1000. Of course, it may have some faults to it.
Displacement: 2.3 Liters (141 cid)
Type: dual overhead cam with naturally aspirated port fuel injection.
Horsepower: approx. 155 on average (standard output) 180 (high output)
Torque: approx. 155 ft-lbs on average (standard output) 165 (high output)
Ignition: Integrated Direct Ignition (Electronic, distributorless, twin coil)
This is a list of the cars available with a Quad 4 (as far as I know.) It shows the main body styles available. The Fiero body type is listed as modified since it was never originally available with the Quad 4. The little picture should give you a general idea of how each body type/style looks. The underpinnings of all cars in each body style are essentially the same. Of course there are further refinements that make a Buick a Buick, an Olds an Olds, etc. Brackets ( ) denote a performance variant of the listed car.
|Chevrolet: Beretta (GTZ)|
|G-Body (Years 1990 and 1991 only):|
|Buick Regal?, Pontiac Gran Prix, Olds Cutlass Supreme|
This is a list of common engine computer trouble codes. These can be obtained easily with a tool called a jumper. It can be made from a paperclip or a piece of wire. To get the codes, make sure the engine is off. Then you just put the ends of the jumper in terminals ? and ? on the diagnostic connector on the underside of the dashboard. Then taking care as not to actually turn the key to the start position (bad stuff could happen.) you put it in the on position. The codes are obtained by reading the check engine/service engine soon light. It will blink out the numbers associated with each code three times. This cycle repeats itself, just in case you think you missed one. It always starts with code 12, this tells you that the engine computer is actually working.
|Quad 4 computer stored fault codes|
|12||Computer check (shows that it's working)|
|26||Quad driver module fault|
There'll be more later this page is still under construction and subject to change.
I will get this up and running as time permits...(been quite a while-I'll get around to it.)