Tech Articles

Contents
TPS Adjustment
IAC Cleaning & Adjustment
Base Idle Reset
Timing Belt Replacement
Timing Adjustment
Timing Adjustment/Reset w/o Timing Cover
Manual Cooling Fan Switch Wiring
91-93 Oil Pan Removal
79-90 Oil Pan Removal
A/F Gauge Install
VAM Testing Procedure
Future Articles

Throttle Position Sensor (TPS) Adjustment
Symptoms: high idle, won't idle, dies when throttle is lifted when slowing down

These sensors show as no longer available at most parts stores but if you choose the right application, you can still get them from us here: 2.3 Turbo Adjustable TPS

1. First bring the engine up to normal operating temperature.
2. Turn the engine off and unplug the Idle Air Control (IAC). This is located on the backside of the Throttle Body near the firewall. This device is a round cylinder approximately 5 inches long with a (2) bolt flange and 3 wire male / female plug connector (see pic).
3. Start engine and using a screwdriver adjust the base idle to 700 – 800 RPM using the screw on the throttle body (see pic)

Idle Air Sensor (IAC) Cleaning & Adjustment
Symptoms: wandering idle, hanging high idle, idle problems when at operating temperature.
Note: This is normally done in conjunction with the TPS adjustment above to get the idle set properly.

1. Bring engine up to operating temperature.  This is located on the backside of the Throttle Body near the firewall. This device is a round cylinder approximately 5 inches long with a (2) bolt flange and 3 wire male / female plug connector (see pic above).
2. Turn the engine off and unplug the Idle Air Control.
3. Remove 2 screws near the plug.
4. Remove two bolts holding the cylinder on the throttle body.
5. Push "piston" inside canister in and out to see if it moves freely.
6. Spray carb cleaner into piston area and move piston to clear out carbon deposits, repeat.
7. Blow out the excess cleaner and carbon deposits with compressed air (your mouth will suffice if it must)
8. Install cylinder with bolts.
9. Install plug with screws.
10. Start car, if it won't stay running then turn the idle adjustment screw on the throttle body towards the driver's side until it will stay running. 
11. Turn the idle screw until it reaches 600-700rpm at idle.
12. Plug in 3 wire connector, if the IAC is functioning the engine should smooth out and the idle should jump up to 1000-1500 RPM.
13. Turn the idle screw until it idles at 1000rpm.  Rev engine a few times to be sure it stays at 1000rpm at idle.
14. Remove tools, shut hood, and go for a drive.

Base Idle Reset

1. Bring car up to operating temperature.
2. Unplug the IAC.
3. With the IAC disconnected and the idle adjusted to 750 RPM, shut off the engine and plug the IAC back in.
4. Unplug the battery cable and let it sit for 30 minutes.
5. Hook the battery back up and start the engine.
6. Let the car idle for 10 minutes and then go for a drive.  It may take up to 75 miles for the computer to fully reset and learn the new settings.

Timing Belt Replacement
Use the pics below to reference what is stated here.

Removing the belt:

1. Set the engine at Top Dead Center (TDC) on compression stroke (crank pulley mark should be at TC on the timing cover and the cam notch should be visible through the little hole in the timing cover, see pic below).
2. Remove the timing belt cover. This involves removes anything in its way (pulleys, etc.).  This is a real pain to remove if it's not already broke.  Take your time and remove whatever seems to be holding it on.
3. Mark the cam, crank, and auxiliary pulleys "straight up" with some chalk or a marker.  Make sure that they stay "straight up" throughout this procedure.  If they get moved slightly, move them back.
4. Find the tensioner hold down bolt (see pic below) that's located next to the tensioner pulley and loosen it enough to move the tensioner.
5. Put a breaker bar between the tensioner and the crank pulley or between the tensioner and water pump and push upwards to release tension on the tensioner pulley.  It takes a good bit of force to release the pressure.
6. Once you release the pressure, hold the breaker bar and tighten the hold down bolt in it's new "loose" location.
7. Now you can remove the belt.  The easiest way is to just cut the belt and pull it out of the way.

Installing the new belt:

1. Wiggle your belt back onto the pulleys.  It may take some work to get it around the crank timing belt pulley.
2. Once the belt is routed properly, remove all the tension from the DRIVER'S SIDE of the belt.  You want to get it as tight as possible on that side.  Make sure the belt teeth are lined up with the cam and crank pulley teeth and all the slack is removed.  You may have to VERY carefully move the cam back a little bit to get the belt on, then move it back again to tighten it all the way up.  The tension on the other side doesn't matter because the tensioner will take care of it when it's released.
3. Check to make sure all marks you put on the pulleys are still positioned "straight up".
4. Release the tensioner hold down bolt slightly and the tensioner will spring back into place.
5. Put the breaker bar back under the tensioner and hold enough pressure on it so there is approximately 1/2" of slack in the belt on the driver's side.
6. Once the correct slack is obtained tighten the hold down bolt.
7. At this point the hard work is complete and you can now install everything in the reverse order of how you removed it.  Once that is complete, check to make sure everything is correct and then start the car.
8. Now you can proceed to the Timing Adjustment below to set the timing to factory specs.

Timing Adjustment
Follow these steps after completing timing belt install above or to set timing to factory specs.

1. Make sure you have the timing belt cover installed (or at least the lower part around the crankshaft pulley)
2. Put timing light connector on #1 spark plug wire (nearest the front of the car).
3. Locate distributor hold down bolt and use a 12+" long 3/8" extension and ratchet to loosen bolt.  You only need to turn it a small amount...just enough to release the tension.
4. Unplug spout connector (small gray plug located within 6" of ignition module that's bolted to the side of the distributor, the plug is located within the ignition harness). 
5. Make sure the timing light wires are out of the way of the engine pulleys.
6. Start car.
7. Point timing light towards the timing marks near the crankshaft pulley on the timing cover.
8. Locate the 10* BTDC mark on the cover (factory setting) and turn the distributor slightly until the "notch" in the pulley lines up with the desired timing (10*BTDC).
9. Once the desired timing marks are lined up tighten the distributor hold down bolt.
10. Recheck timing to make sure the distributor didn't move when tightening it down.
11. Plug in Spout Connector and check timing, it should be advanced to 20 degrees or more now and move with rpms.
12. Shut off engine, remove tools, close hood, and enjoy your new found power.

Timing Adjustment/Reset Without Timing Cover
Follow these steps if you don't have a timing belt cover and have thrown the timing belt.

1. Turn over the auxiliary pulley if you can't see the timing mark that is on it.  Sometimes the aux pulley is reversed so that you can't see the timing mark that is on it.  The aux pulley is the same part as the cam pulley but everyone that I have seen is turned over so that you can't see the timing mark.
2. Turn the crank so that the crank bolt, the TDC mark (on the compression stroke, not the exhaust stroke), the auxiliary pulley bolt and the auxiliary pulley timing mark form a straight line. The crank and aux pulley timing mark's will not be next to each other but both will be pointed in a straight line with the crank and auxiliary bolts towards the driver's fender.
3. If you can't or haven't turned over the auxiliary pulley just check to see that the rotor button is pointing to the Four O'clock position
4. Check the distributor. The rotor should be at about the 4 o'clock position, if not move it now.  The crank and auxillary pulley and distributor are now aligned.
5. Now put a straightedge or piece of wire in a straight line between the cam pulley bolt and the auxillary pulley bolt.
6. Turn the cam until it's timing mark is in line with this straight line.
7. You're done.  If you are stuck somewhere this method will set the timing to Zero Degrees BTDC. This is an emergency method only. It will get you home however.  Once you get home, adjust timing to 10* BTDC as shown above.
 
Manual Cooling Fan Switch Wiring
Reasons for doing this: Fan doesn't work, allowing manual control of fan (useful for pulling air through the IC when getting ready to race)

Run a heavy (10-12 gauge) wire from the positive side of the fan through the firewall and to the location you choose to mount the switch.  Attach it to the positive (+) side of the switch.  Leave the negative (-) wire on the fan in its stock location.  Run a black wire from the negative (-) side of the switch to a screw on the fuse panel frame.  Run a small wire from the (acc) plug on the switch to a spot on the fuse panel that comes on with the key at the accessory (acc) position or the on position and shuts off when the key is off.  Turn the key to (acc) and flip the switch to (On).  Make sure the fan is operating.  Turn the key to (Ign) and make sure the fan is operating again.  Flip the fan switch to (Off) and see that the fan quits.  If it worked as described then you are done.  If not, start tracing your work to figure out what you screwed up.

91-93 Oil Pan Removal
To remove the oil pan "in-chassis", follow these steps:

1. Raise the car and place it on jack stands.
2. Drain the oil.
3. Remove the motor-mount bolts and raise the motor as high as you can with a winch.  Support it under the crank pulley with a stand and a block of wood.
4. Disconnect the steering shaft from the rack and pinion at the "rag" joint and tap it upward and out of the way (it's telescopic to prevent you from being impaled).
5. Take all 8 bolts out that attach the front crossmember to the "frame" (it won't fall - trust me). The bolts have a torx head, but you can use a standard 6-point socket.
6. Remove the four bolts holding the anti-sway bar brackets to the frame and let the bar hang.
7. Drive a wooden wedge between the rear of the crossmember and one side of the frame (this will not only lower it, as it compresses the suspension springs which is what's holding it up, but it will usually slide forward as well.
8. Remove the starter.
9. Drop the pan down low enough to disconnect the oil pump from the block, allowing it to drop in the pan (you'll need an 8mm 12-pt socket for the pump body and a 14mm for the pickup support.
10. Slide the pan out the back.

79-90 Oil Pan Removal
To remove the oil pan "in-chassis", follow these steps:

1. Raise the car and place it on jack stands.
2. Drain the oil.
3. Remove the motor-mount bolts and raise the motor as high as you can with a winch.  Support it under the crank pulley with a stand and a block of wood.
4. Disconnect the steering shaft from the rack and pinion at the "rag" joint and tap it upward and out of the way (it's telescopic to prevent you from being impaled).
5. Remove the four bolts holding the anti-sway bar brackets to the frame and let the bar hang.
6. Remove the starter.
7. Drop the pan down low enough to disconnect the oil pump from the block, allowing it to drop in the pan (you'll need an 8mm 12-pt socket for the pump body and a 14mm for the pickup support.
8. Slide the pan out the back.

Compression Test
Be sure to bring the engine up to full operating temperature before proceeding.

1. First, take an air compressor or shop vac and clean the area around each spark plug recess BEFORE removing the plugs in order to prevent any dirt/sand from dropping into the cylinder. 
2. If turbocharged, remove the intercooler.  Be sure to cover the turbo inlet hole with a towel or cup.
3. Number each spark plug wire with clothes pins or tape and a pen so you can return them to the proper location when reinstalling them.
4. Remove the spark plug wires.  You should twist them while removing them to try to break them lose before yanking on them.  Try to pull on the rubber boots, not the wire itself.
5. Remove the spark plugs. Use the kind of compression gauge that screws into the spark plug holes for best results. 
6. Install the Compression tester into the first spark plug hole and then crank the engine over with the starter and allow enough time for the gauge to hold at a given pressure (probably 4-6 compression strokes).  Repeat this process twice for each cylinder.  Record the results for each cylinder for comparison after completion.
7. Ideal results would give you 120-150psi in each cylinder for a turbo motor and 140-170 for a N/A engine. If your lowest psi is more than 20psi from the highest psi (140 and 120 for example) then you have a problem.
8. If you get a low reading on a cylinder, try adding about a tablespoon of oil to each cylinder. If the readings go up significantly the second time around, you know the rings are weak/bad. If the compression is low and doesn't go up significantly in round 2, then compression is leaking past the valves or the cam lobes are worn significantly. A lower compression reading in one or two adjacent cylinders can be sign of a blown head gasket.
9. After you have tested all cylinders, reinstall the plugs and wires in the proper order. 

Air/Fuel Gauge Installation
Used to detect lean/rich engine conditions.

1. Disconnect negative (-) battery cable.
2. Mount Gauge into whatever location you have chosen (pillar, etc.).
3. Wire gauge as follows:
Red Wire: 12v power source that is powered on/off with the key.
Black Wire: Ground to chassis.
Violet Wire: Oxygen sensor signal wire.  You can connect directly to the wire coming off pin 29 on the computer in turbo applications (and many n/a).

Note: A/F Gauges are set up for N/A engines that run an ideal ratio of 14.7:1.  If you are using it on a turbo motor you must remember that the ideal ratio is 12.5:1.  This means the ideal range when under boost is 3-4 lights into the green lights (rich zone).  When not under boost it should be in the yellow (Stoich) range.

VAM Testing Procedure
Used to detect faulty/out of adjustment VAM.

Testing for DC Voltage with your negative (-) lead on the signal return wire and probing wires below with the positive lead:
VREF (orange) = 5.0-5.1v
VAT (light green/purple) = ~2.8v @ 70*F
VAF (white/black) = ~.25v @ 0%, 4.5v @ 100%, .8v-1.0v at warm idle (this varies on idle speed)
You must also make sure that there are no dead spots (0 volts) when the door sweeps from .25v to 4.5v.  If this is the case then the VAM is shot.
 

If you have any questions about any of these procedures feel free to contact us HERE  

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