| The AW11 FAQ V1.2
Last Updated 07/13/03 This AW11 (MKI MR2) FAQ is a supplement to go along with the MR2 general FAQ. This FAQ is designed to provide more in-depth information pertaining to the MKI only. For more Detailed information on all MR2's and other MR2 information please visit http://www.mr2.com Especially the regular MR2 FAQ at: http://www.mr2.com/FAQ_html.html
Section one: Basic Info
1.1 What does MR2 mean? From the MR2 FAQ: Toyota originally explained the name "MR2" as
meaning "Mid engined, Runabout, 2 seater" however, they now claim (and
most owners prefer) the explanation of "Mid engine, Rear drive, 2 seater."
The car is also informally known as the "Mister Two." The MR2 is actually
known by a different name in France. Rather than the MR2, it is known as
the "Coupe MR," because "MR2" in French sounds a lot like "merdeux," which
means "shitty." Australian MR2's come in two flavors, the "MR2 Bathurst"
and "MR2 GT"
1.2 What is the history? A more detailed explanation can be found in the
History
section of the page, but in short, the Mr2 was a pure Toyota design, this
sometimes being contradictory to the rumor that it was an abandoned Lotus
design. Rather, Lotus helped in the suspension tuning. It was
introduced in Japan in 1984 and to the rest of the world in 1985.
1.3 How many were made? From the MR2 FAQ: There were roughly 30k sold in the US in 1985. 1986
1987
1988
1989
1.4 Where is the Gas tank? It is right between the driver and passenger in
the center hump of the car.
1.5 Where is the lock code? If a perfect copy of the key to you car is needed,
the lock code for the key can be found underneath the passenger side door
panel on the lock cylinder.
1.6 How do I subscribe to the MR2 list? Send a message to mr2-interest-request@mr2.com with subscribe in the body. For the digest do the same, but send the subscribe command to mr2-digest-request@mr2.com. To post once you have joined, send messages to
mr2-interest@mr2.com.
Section 2: Common Problems: 2.1 Why does my temperature gauge peg? This a very common problem for many MR2s. Since the MR2 is a mid-engined vehicle, the coolant has to flow from the radiator in the front of the car to the engine behind the driver. As a result, a sending and return pipe must be plumed underneath the car, along with many other pipes that are not found on front engined cars. Therefore, it is very easy for air to get into the cooling system. When this air is heated by the car it turns into a very hot steam that freaks out the temperature sending unit, thus making the gauge peg. A separate very comprehensive FAQ written by Tim
Kingsbury, covers this subject to help you get rid of the air, and figure
out what is letting the air get in. See the Repairs
section.
2.2 Why does my idle bounce? The same reason as the gauge pegging. There is
air in the system. See section 2.1
2.3 Is it important to Torque down my wheels to specifications? Yes! The hubs to the MR2 are very picky about
how tightly the wheels are tightened down. If tightened down to hard, the
car will shimmy, and/or, will eventually warp the rotor. The specified
amount for the MKI is 76 ft/lbs. The 85-86's also have a greater tendency
to warp their rotors than the 87+ which have upgraded brakes, thus making
the wheel torque specifications even more important.
2.4 Why does my 88-89 MR2 have a weak AC? Due to customer complaints, it was rumored that
Toyota reduced the load the AC puts on the engine to increase HP with the
AC on, thus less cold air.
2.5 Why is it hard to steer? Oh come on! Hard to steer? The MR2 due to its
mid-engined design, the MR2 was given no power assist to decrese steering
effort. The car really doesn't need the added complexity and weight of
a power steering system due to it's low weight and rear weight bias.
2.6 How do I fix my rusted rear wheel arches? With alot of cash. Unfortunately if your rear
wheel arches have rusted out, there is little chance of being able to save
them. To have them replaced right, takes a great deal of time and preparation.
Many parts must be taken off. This is the most common place for rust to
show up so watch out when buying.
2.7 Why does my parking brake freeze? A common problem for MKI owners during the winter
is that the parking brake will freeze in it's locked position overnight.
This is usually due to water that has frozen in the cable. A temporary
fix is to either leave the car parked in gear if it is not on a steep grade,
and/or place a stone in front of the tire. You can also (*gasp*) drive
it until the heat from the engine unfreezes it. The only permanent
fix is to buy new cables.
2.8 What is that "thunk" noise when I steer? A common problem on the MKIs is that the RH bushing
inside of the rack and pinion goes bad, leading to a thunk noise. It can
be cheaply replaced for about $6. It can be changed both while in place
or if taken out. Do not let Toyota tell you your whole rack and pinion
is bad, and charge you $$$. Remove the boot and unscrew the inner tie rod
from the rack. Turn the rack all the way to the left, and then snap out
the old bushing and pop in the new one. There is a lock washer you will
want to replace also.
2.9 How do I fix my electric windows? The Nylon drive cogs on electric window motors
can strip causing the window to not work. Sometimes the switch is just
full of crud, and a good cleaning will fix the problem.
2.10 I cleaned my engine and the car will not start! The spark plug wires do not make a good seal with
the valve cover, and as a result, water can easily get in the spark plug
wells. Somehow get the water out, and be careful in the future.
2.11 Where is that Exhaust Leak? More than likely you have the #4 cylinder cracked
manifold problem. Quite often, the exhaust manifold will crack right by
the #4 cylinder, causing the exhaust leak. It could also be loose EGR bolt
or a rusted out muffler.
Section 3: Engine upgrades 3.1 What can you tell me about the engine? We as MR2 owners are very lucky to have the engines that we do. Both the MKI NA and SC have race bred engines that are very suitable to their task of letting us zing them up to redline. ;) The 4A-GE is currently used in competition in the Toyota Formula Atlantic Racing series in a heavily modified state. The block from the 4A-GZE is used, as it is a heavier more robust block, that can handle more abuse. In 1987 the 4A-GE engine received a few minor modifications to increase it's strength and reliability, none which improved horsepower however. Late in 87 a a new dual spray injector and ECU was added to bump up HP to 115. When the 4A-GZE was introduced, Toyota added more nickel content and significant strengthening to the block so that it would be able to handle the rigors of forced induction. All of the NAs also received this block, despite rumors that it is different block from both the 85-86 NA blocks and from the 4A-GZE blocks. There was also a change in the heads with corresponding valve cover color change. The red hat is the later model while the blue hat is from the 85-86 and some 87 cars. The different hats also signifies a different ECU. Currently no one knows the exact date change of the block or the color hat for the NA. My current MR2, which was manufactured in Feb. 87, has a blue hat and the 7-rib block. The head design is a non-interference design meaning that if the timing belt (which is recommended to be changed ever 60k miles) breaks, no damage will be done. 4: stands for the 4th major version
Z: stands for supercharger
The 4A-GE which is found in the MKI NA has the following specs: 4A-GE:
The supercharged MR2 introduced to the US in 88 had the 4-AGZE engine: 4A-GZE:
This along with a vast amount of additional Toyota
drivetrain information can be found at Matti
Kalalahti's page, who has painstakingly put together one of the best
information sources available for us Toyota owners. Past, present, and
future orientations of the A series engine can be found there. Also please
check the 4A-GE section, along with the Links
section for much much more info.
3.2 What is the best route to power? While it may seem difficult to increase the power of the already well tuned 4A-GE engine, it can be done by starting with simple modifications leading all the way to performance engine rebuilding. Dave Aucott from the MR2 list had built one of the most potent streetable 4A-GE engines in the US, while spending much dyno time evaluating what parts are best for the most power. My suggested route to more power is as follows: 1. Start off with an engine that has good tolerances
and specifications. Have a compression test done to check the health of
your engine, replace the fluids, and in general just make sure the car
is in good health before mods are made, as a healthy car has a significant
advantage over one that is not. Especially seeing as this engine has come
from the factory in a relatively well tuned state.
The SC follows a similar route, but has the added
advantage in that they can use an aftermarket pulley SC pulley which will
increase boost, along with intercooler mods that can be made.
3.3 Is synthetic oil worth it? Many MKI owners, including myself, feel that Mobil
One usage will smoothen out the engine, while making it easier to rev.
I have also seen studies that has shown that synthetic will indeed give
a very slight power increase. After use of Synthetic many owners find spotless
engine internals when they are taken apart. Others however feel that it
is not needed. Either way, the most important thing to remember is that
the if the oil is regularly changed there should be no engine trouble for
many many miles. The one drawback is that after switching to synthetic
after using regular oil for many miles, there is a very good possibility
for new oil leaks. The reasoning behind this is that, while regular
oil may not have picked up some crud that may be blocking an oil leak,
synthetic will.
3.4 How much HP will a K&N Filter give? Despite K&N's advertisements about more power
by using their filter, this is usually not true for filter alone.; In general,
HP is only gained when modifications are done to the intake tubing and
air filter boxes, not just the filter itself. By simply replacing the stock
filter with a K&N on a MKI, you may actually lose power. If you have
an 87+ car open your trunk and take out the gray panels. Follow the intake
tubing and be appalled like the rest of us as to how far the air has to
go before it reaches the engine. And then follow along to section 3.5:
3.5 What is this powermax setup? Remember all that intake tubing you saw? The powermax setup gets rid off all that. In short, a filter is directly mounted to the MAF in the engine bay, which is then connected to a piece of 3 inches of tubing that is directly connected to the intake runners. Dave A. has dynoed this setup, and it has shown a 5 hp gain across the board. More detailed info can be found under the Modifications section. IMPORTANT NOTE: When doing this mod, don't touch the screws on the MAF. The harness on the MAF disconnects with a metal clip on the harness. If you loosen the screws on the MAF, you will be breaking solder joints in the MAF that will be VERY difficult to fix. 3.6 What can I do to my exhaust? The good news is that there is a TRD header and
many different exhaust systems. The bad news is that the TRD header gives
maybe 1-2 extra hp and the exhausts give only about 3-5 hp. The stock exhaust
manifold is quite good, and there is not that much HP to be made by replacing
it if your overall engine modification level is low. The benefits of the
TRD header may be more pronounced if many mods are made to the car, but
it does not do much until then. One other note about the TRD header is
that if you do buy it, DO NOT use the included gasket, it is very flimsy
in comparison to the stock one. Buy a new gasket for the stock manifold,
or you will be in about a month after the TRD one breaks. TRD has also
said that equipping the MKI NA with an SC exhaust is good for a few hp
as it is a less restrictive design. Once again, like many other modifications
that can be made, there are many more headers and exhaust systems that
are available in Japan that may be worth the effort for you to try and
locate. Once again, check the Mods section
to find out more.
3.7 Can I supercharge my NA engine? If you really want to, it can be done, but is
not advised. A much easier route is to find a used 4A-GZE and transplant
it into you NA. It is not very hard to do, and has
been done so by Steve Bagdon from the MR2 list.
3.8 What is this I hear about a "Twincharger" or Turbo for the MKI? There indeed is both a Twincharger kit and a Turbo kit for the MKI. Both were made by HKS and are now impossible to find. The twincharger kit is very unique in that it is the only one of the few engines in the world that utilize both a turbo charger and supercharger on the same engine. The Twincharger kit starts off with a MKI SC and basically a turbo kit is added on. Much tuning must be done, as a great deal more fuel is needed, along with many other concerns. An estimated 350-400 hp can be obtained with a properly tuned twincharger system. There are very few twincharged MR2s in existence. The turbo kit for the MKI is very similar to the twincharger with the difference being that there is no SC. It too is now very hard to find. The most important piece being the turbo manifold. Properly tuned Turbo systems, can yield approx. 250+ hp. A great deal more info can be found in the Major
engine mods and swap section.
3.9 What is "TVIS"? The MR2s equipped with the 4A-GE engines have
what is called a TVIS intake system. Each cylinder in the engine has two
intake runners going to it. There is a valve that is controlled by RPM
that opens the second set of runners at approx. 4300 RPM. This was done
so that at low rpms, the engine would breath through one long runner to
increase torque, while at 4300 rpms, to increase high end hp, the TVIS
valve opens up to increase engine breathing. This system is very similar
to the one used in the Acura NSX. Later incarnations of the 4A-GE (post
AW11) however, dropped this option, as a single small port was used to
increase velocity of the air entering the engine.
Section 4: Handling: 4.1 What size tires/wheels do I have? The MKI NA came stock with 14x5.5 steel rims, with optional 14x5.5 alloy (large three spoke 85-86, or basketweave 87-89) rims. Both wore 185/60 R14 tires. The MKI SC came stock with 14x6 alloy "teardrop" rims with 185/60 R14 tires. Bolt pattern: 4 lug 100 mm spacing
4.2 What are the best high-performance struts for my car? The most commonly used high-performance struts used on the MKI are the: Tokico: Tokico offers both a high-performance non-adjustable and adjustable strut. The non-adjustable runs approx. $50-70 while the adjustable runs approx. $115-140. The adjustable strut adjusts both jounce and rebound. Koni: This legendary company offers an adjustable
strut. The adjustable Koni Sport runs approx. $150. It adjusts jounce only.
4.3 What are the best springs? There are many different companies that offer
springs for the MKI. Some of the more commonly used are Eibach, H&R,
and Suspension techniques. I have not heard of any negative reports on
any of these. DO NOT cut your stock springs as there will not be enough
spring travel to absorb bumps, thus wearing out the bump stops on the car.
It also NOT recommended that you put on lowering springs without changing
the struts to a high performance design, as it will increase wear on the
stock struts. Also, it is very wise to replace both spring and strut at
the same time, as it will be easier to take it all apart once instead of
twice.
4.4 Why does my SC not handle as good as my NA? Due to the added weight to the rear of the car,
and also because of the greater power, Toyota when designing the SC dialed
in more understeer so that the car would not be as tail happy. This can
be offset by the owner by upgrading suspension components such as tires,
struts, and springs. The SC however will never out handle a similarly tuned
MKI NA as the NA is simply lighter.
Section 5: Transmission 5.1 What is the best gear oil? Despite Redline's suggestions, the list has found
that MT-90 is the best choice. It significantly reduces noticiness, and
helps the syncros work better. MTL has also been found to work good as
well. In general the MTL is better suited to colder climates, whereas
the MT-90 works better for hotter ones. The MTL will sometimes have
a slight amount of gear rattle in hot conditions.
5.2 Can I switch my auto for a manual? Yes, it can be done, the procedure is outlined
in Modifications section.
5.3 Why does 5th gear pop out? The 85-86 Mr2 had the C-50 transmission while the 87+ NA models had the C-52, which was an upgraded and strengthened version of the C-50. This included stronger input and output shafts with larger diameter bearings on some of the gears, along with updated syncros. The C-50s are notorious for having what's been described as the 5th gear popout. This is where 5th gear will pop out engagement when the throttle is applied. Some C-52s also have this problem. The trannys will also sometimes have bad 2nd or 3rd gear syncros. While one might think that these trannys are not that great because of all these problems, this is not entirely true. If treated correctly, with a somewhat periodic changing of the tranny oil, a C-50 or C-52 can handle great amounts of power and last a long time. If you have the 5th gear pop out problem, first check your tranny and engine mounts to see if they are worn out and causing too much engine movement. After that, some have been able to stop the problem by replacing the 5th gear and synchro, others have not. John Welch gives the following:
The cause of the pop-out is not the syncros, hubs, or gears.... it's
from
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