Task list for tomorrow's class

Re-measure current drain from battery when car is off. Check spec. Typical is 20 mA.
Remove airbox
Clean grounds
Add extra ground wires
Check intake hose, intake manifold gasket for leaks


Measure MAF sensor voltage
Clean MAF sensor
Clean throttle plate
Measure resistance of IAC valve terminals with connector removed
Clean IAC vavle
Inpect cap and rotor
Measure spark plug cable resistance
Check spark plug gap

ATF fluid condition

Tools/Supplies:

Anti-Seize
Brake Cleaner
TB cleaner
MAF cleaner
5' #6AWG wire
5 ring terminals
sandpaper
clean rags
T25 security bit
extra extensions
a known, good DMM
incense - probably not allowed in autoshop

Ah Ha

I suddenly realized why the rough idle/stall problem occured after the transmission rebuild and after each time the battery was disconnected. The battery was probably disconnected when the transmission was rebuilt, therefor wiping the ECU's "learned" parameters.

If I had disconnected the battery prior to the transmission rebuild, the problem probably would have manifested itself.

Fixes for 626 rough idle, stalling

I posted the rough idle and stalling problem on mazda626.net. From the responses I got and posts from people with similar problems, I'll clean the MAF and IAC. I'll reprint my post here:

I have two problems with my 1997 626 (2.0L, ATX).

1. When I come to a stop and the transmission is still in "Drive", the engine rpms drop below 650 rpm and stumbles a little bit before recovering.

2. When I change from "Drive" to "Park" or "Neutral", the engine rpms drop below 650 rpm and usually does not recover. The engine stalls.

My current problem may be related to a transmission rebuild done earlier this year and possibly the things that I did in an auto shop class. I'll use a timeline to summarize the background.

March 2006 - Rebuilt transmission. After rebuilt, problems #1 and #2 occur intermittently.

April 2006 - Replaced battery. After replacing the battery, both problems occured regularly. I took the car back to the shop for repair under their warranty. The shop had it for several days and found nothing wrong with the transmission. They did fix the problems and told me the cause was due to a corroded ground connection. I didn't asked them where it was. I only spoke to them over the phone because this was my wife's car who was a student in another city.

Summer 2006 - Replace spark plugs, air filter, flushed coolant, checked PCV valve.

October 4, 11, 18, 25 - I'm taking an introductory auto shop class and take the car into the shop to do basic maintenance and test procedures: engine compression test, cylinder leakage test, battery load test, alternator test, measuring manifold vacuum using the PCV vacuum line, cleared CEL for "warm up cat efficiency". If anyone is interested, I blogged about the tests and results.

I've noticed problem# 1 occuring again about 1-1.5 weeks ago.

In yesterday's class, I removed the battery and the battery tray to get a better look at the "driver side upper" transmission mount. When I removed the battery tray, I saw a ground connection that didn't look original. A bundle of 4 wires came off from a thick cable assembly and all four wires were crimped together onto a single large ground lug. The connection looked a bit corroded, so I used some sandpaper to buff it a little bit.

After the class, problem #2 occured repeatedly and #1 got worse.

Is it coincidence that problems #1 and #2 are happening again or caused by something I did during the shop class? The weather has been getting colder lately.

Problem #2 seems to occur regularly whenever the battery is removed and reinstalled. Is this stalling problem due to some parameter being lost in the engine/transmission controller's memory when the battery is removed?

I did test the resistance measured between the lug and other points on the chassis, result was 0-1 ohm. I'll go back and clean up that ground connection that I disturbed in the class.


I have browsed some related threads about the engine stalling and poor idle. Most of the posts suggest to clean the MAF, IAC. I don't know if doing these things will help because it just seems that problem #2 is related to r/r the battery. Perhaps some wires inside the cable assembly got affected when I disconnected the battery cables.

Thanks for reading. I appreciate any advice to diagnose this problem. I shudder to think that it's a transmission problem again because then I have to take the car back to the transmission shop that is located 360 miles away.

Rough Idle, Cutoff

The rough idle, park engine cutoff problem has returned. I'll write more later.


1. Engine Mount Inspection Results

Confirmed Right engine mount is cracked.

Suspect Rear and Top mounts may be damaged. The Rear mount is by the firewall below the intake manifold. It seemss very difficult to r/r. The Top mount is under the ignition coil.


2. Cooling System Test
Radiation cap test result was 13 psi, but cap spec is 16 psi.
Pressurized cooling system to 16 psi, and found no leaks.

3. Driver side inner CV joint
Found a slight dab of new grease near CV boot end. I'm not sure if this is really new or a spot that I missed cleaning last week. I cleaned it up very carefully this time and will check it again in 2-3 weeks.

4. System Current Draw = 390 mA with ignition key OFF. This is OK.


5. Found broken wire clip just above passenger side inner CV joint. Replaced with tie-wrap.

6. Found non-OEM looking grounding point under battery tray. Four wires were connected to one lug. I sanded the chassis and lug to remove corrosion. Maybe this is what I shouldn't have touched and lead to the park stall problem. If it ain't broke, don't fix it.

Mazda 626 inspection plan

For tomorrow's class, this is the to-do list in order of priority. There's no way I'll get all these things done, but the list will help me focus.


1. Jack up engine and inspect crack in top engine mount (passenger side)
2. Inspect driver side upper engine mount, below the ignition coil.
3. Inspect driver side inner cv joint to see if there's fresh grease.
4. Cooling system pressure test
5. starter voltage drop test
6. alternator wire resistance or voltage drop test
7. Ignition coil test
8. Measure spark plug wire resistance
9. Cap and rotor inspection
10. Adjust tire pressures
11. Find jumper location to do measure timing


I also ordered the replacement shifter bushing from Jerry on Ebay.

edited 11/1/06

Saturn Shifter Bushing

A month ago, the shift lever suddenly became loose and could no longer shift gears. The lever was floating. The instructor for Auto 50B thought it might be a shifter bushing. I did further research on the saturnfans.com forums and learned that this was a common problem for the Saturn S-series.

I removed the console and parts of the lower dash to view the shift cable and shift lever linkages. Sure enough, I found the broken bushing for the cable that sends the up and down lever motion to the transmission. Thank goodness the problem was not due to a broken shift cable or broken linkage at the transmission end.

The bushing looks like plastic spindle that is pinned to the shift lever to allow it to spin. The spindle part is wrapped around by the shift cable's eyelet. The cap end of the bushing broke off so the cable eyelet was no longer secured to the bushing.

Unfortunately, Saturn does not sell this plastic piece by itself. I have to buy the shift cable assembly (~$200) to get it. The good news is that there is a guy on Ebay who is making and selling the bushings from Delrin or stainless steel. Here is his webpage.

Engine Mounts and CV joints

Fluid levels

ATF level - ok. Color is light pink, which is normal. I'll be worried if it turns dark or has silvery particles in it.
PS level - ok. Orange color. I don't know if that's normal or not.
Oil - ok.
Coolant - ok.
Windshield Washer - Need to add.

Alternator Test

I can't conclude whether the alternator is ok or not. Measured battery voltage with engine off = 12.9V.

1. Using VAT40, placed a 20A load across battery terminals. Voltage at battery dropped from 14.2V to about 13V and alternator made a noisy whining sound. RPM at around 2000 rpm. By this test, alternator is no good. Alternator should provide 80A at 12V according to spec. But this spec doesn't make any sense to me. Should the alternator voltage remain at 14.2-14.7V at 2000 rpm with a load across battery? How much of the voltage drop is due to the resistance of the wire between the battery and alternator? It's hard to access "B" terminal on the alternator.


2. Alternator is good according to Haynes manual test. Turned on AC, defrost, radio, lights, and fan. Then measured battery voltage. 13.2V at idle and 14.2V above 2000 rpm.
I could not measure the "L" terminal voltage on the alternator with the connector on.

Inspect Engine Mounts

Used inspection mirrors.

1. Rear mount appears to have crack or large cavity above the thrubolt. Check new OEM mount to see if there is a cavity there by design. This mount is very hard to access.
2. Right mount has crack.
3. Front mount looks brand new. This is the one replaced by Wabbit Wepair earlier this year.
4. Bottom mount is aged and has some light wrinkles. I don't think it has cracks.
5. Top (Left) mount is hard to access and I didn't have time to check it.

CV Joints

I discovered fresh gobs of grease deposited around the driver side inner CV joint. Boot did not appear to have crack. Perhaps boot was a universal one and doesn't fit well. Gas station monkeys replaced this axle 2 years ago. I cleaned up most of the grease and will monitor it.

On passenger side outer CV, I found some old grease and dirt along edge of boot. I didn't see any obvious cracks.

Got New Tires

I got new BFG Precept Touring tires on Monday. $317.30. I didn't get the optional full replacement warranty for $40 extra at America's tires.

It was about time to get new tires. The car had 3 different makes of tires for the past 3 years. The sidewalls were beginning to crack on two tires and very low tread depth on the third tire.

Tonight I'm going to auto shop class!

To do next week

Inspect engine mounts
Redo Alternator Test
Check ATF fluids
Inspect underbody -cracks in boots
Starter Voltage Drop test
Verify if front struts need replacement


check all fluids
pressure test cooling system and cap
adjust tire pressure

Edited 11/1/06

Cylinder Leakage, PCV valve, Manifold Vacuum

I used the lift outside the main indoor area. These lifts were a bit strange. There was a center column and 4 movable arms. At the end of each lift arm was an adjustable metal pad. These pads can be adjusted so that there is a slight upward angle to keep the car's underbody from impacting the lift's arms.

Cylinder Leakdown Test

21mm crankshaft bolt

Measured 12%, 24%, 14%, 6% for cyls 1,2,3,4


Firing order 1-3-4-2

The nice feature on the Mazda is that there is already a hole in the wheel well cover to access the crankshaft bolt. I turned the bolt until the timing mark lined up with the TDC marking for cyl 1. The timing mark is found on a ring between the two concentric crankshaft pulleys.

To put the next cylinder in the firing order at TDC, I turned the bolt 180 deg. (720/# cylinders). Putting a long screwdriver down the spark plug hole helps indicate when TDC is reached. It's hard to estimate if I've turned the bolt 180 deg because of the limited room to turn the rachet.

As for the leakage, I couldn't feel or hear any air from the exhaust, oil filler hole or dipstick tube. I also didn't see any bubbles in the coolant at the radiator cap. I didn't take off the air filter (intake valves) because it's too troublesome to remove the air box cover. So I don't know the source of the leakage. The only hissing air sound was from the spark plug well where the air hose was plugged in. What's that from? Was it from the other cylinders since I had removed all the spark plugs at the same time?

Manifold Vacuum

Use PCV vacuum source

20" vacuum

Needle varies between 20-21". Needle steady for about 0.5 secs, then vibrates for 1-2 secs, and repeats the entire cycle. Applying pressure to the vacuum fitting could make needle steady at 20".

PCV Valve Check

PCV valve check. It's OK.
Why does air come out of the oil filler hole?

Compression, Battery Load, Starter, Alternator

Compression Test

To disable fuel and ignition, remove fuel pump relay and ignition coil (primary side) connector. Haynes manual says it can be done by removing HV side cable and grounding it to chassis.

Measured 185, 185, 185, 190 psi for cyls 1-4

Battery Load Test
Car is off
Connect VAT40 to battery terminals and set load current to 150A. Measure battery voltage 10.9V. This is greater than min limit 9.6V. PASS

Starter Draw Test

Disable fuel and ignition (see above)
11.4V at 80A

Alternator Test

Reg. Voltage 14.1V-14.7V

At 2krpm, voltage = 14.2V with no extra load

As I increased the load from 0A to about 20A, the voltage drops below 14V!! Is this normal?
Instructor said this indicates alternator will go bad. Typical life is 80,000 miles. Car has 123K miles. But alternator puts out enough current to charge up battery, so it's ok to not replace it if car is not used frequently.

Redo test with lights on, rear defrost, heat fan, radio on. See if voltage is below 14.1V at 2Krpm.



It's better to do the compression check and alternator test with 2 persons.