Last post on May 08, 2012 at 4:17 PM
You are in the Mazda 626
What is this discussion about?
Mazda 626, Sedan
#1924 of 2044 Mazda 626 V6 Rough Idle & Acceleration Hesitation
Mar 28, 2006 (8:07 am)
This posting reports back on a successful solution. The 1993 Mazda 626 with V6 & 110,000 kilometers would hesitate when trying to accelerate at highway speeds, and idle rough, only when engine was warm. It was known that oil was in the speark-plug wells, both front and rear rockers. There were no Codes to assist diagnosis. Problem solved when both gaskets replaced which necessitates the inlet manifold gasket replacement also, plus changing out all six HT leads. Dated March 2006. Noted that a slight hesitation occurred just before the 5 year Warranty expired, and HT leads replacement was successful back then too. Replacing the rear rocker cover gasket is time-consuming. My repair bills were $90 CAN for diagnosis, and $782 CAN to implement the solution. Hopefully this repair will last for the next 5 years.
#1925 of 2044 Re: Mazda 626 V6 Rough Idle & Acceleration Hesitation [dolby]
Mar 28, 2006 (11:40 am)
I replaced the valve cover gaskets on my 99 626 V6 when I changed the timing belt at 105K miles. I did this work myself, and yes, it is time consuming becuase you ened to remove the intake manifold to get to the rear valve cover. And to remove the intake manifold, you need to unplug practically the entire engine electrical harness, which is attached to the manifold.
Anyway, even the gaskets were expensive: $ 30/piece for the valve cover gaskets, $ 80 for the valve cover bolt sealing washers, and $ 30 for the two intake manifold gaskets. Note that my valve covers were not leaking when I replaced the gaskets, but I figured that they might after 105k miles. If I keep the car I hope not to touch the valve cover gaskets or the timing belt until 210k miles (140K miles or 210,000 km on it now). I change the spark plugs and plug leads every 60k miles. I always use the OEM plugs and leads. Change oil and filter religiously every 3k miles, use Castrol GTX 10W30 and Mazda OEM filters. Cheap insurance, and so far the engine is running like a champ. In fact, it feels stronger than it did when it was new.
Don't forget to clean out the EGR passages just behind the throttle body in the intake manifold. These passages clog with carbon on these cars after about 100k miles and cause improper EGR circuit operation.(you get a trouble code). Fortunately, the solution is simple cleaning, and usually no need to replace the EGR vavle which is very expensive ($ 360 for the part alone, and a nightmare to get to on the V6 engine).
#1928 of 2044 mazda 626 1997 2.0L, check engine light on, code 0171
Apr 14, 2006 (2:56 pm)
the check engine light is on for 2 months. the code is 0171, - bank is too lean. i have replaced fuel filter, spark plug, changed oil and oil filter, flushed engine when I did oil change.
right now, I filled up with gas #91. the normal use is #87.
after I changed fuel filter, the check engine light will be on again until 30Km or so. then 3 days later, after the code is cleared by code reader, the light will be on after 5-8 km again. the code is still 0171.
the gas that I use is still #91.
I need to get it pass the emission test as my sticker will be expired in May.
wonder if anything else that I can do to clear the issue?
would it be possible to pass emission test if I just leave check-engine light on?
#1929 of 2044 Re: mazda 626 1997 2.0L, check engine light on, code 0171 [brandnew]
Apr 14, 2006 (2:57 pm)
and the mileage is 185,000KM so far
#1930 of 2044 Re: mazda 626 1997 2.0L, check engine light on, code 0171 [brandnew]
Apr 14, 2006 (4:37 pm)
air filter is also replaced.
next I will try to clean MAF by TB cleaner.
I went to Ford's forum and on Ford Expedition, PCV hose was reported to have a hole in a few cases, which causes 0171/0174 . not sure if it will help Mazda 626 as well?
#1931 of 2044 Re: mazda 626 1997 2.0L, check engine light on, code 0171 [brandnew]
Apr 17, 2006 (12:28 pm)
There is a possibility that you have clogged EGR valve passages in the intake manifold just past the throttle body. These passages cake up with carbon after some time. To clean them, you need to remove the throttle body. With insufficient or nonexistent EGR flow, the mixture will be too lean.
You cannot pass an emission test with a lit engine check light.
#1932 of 2044 Re: mazda 626 1997 2.0L, check engine light on, code 0171 [p100]
Apr 17, 2006 (5:05 pm)
Thank you very much.
I cleared the CEL before I went to the garage for emission test. The readings are all in very good range, much below the limit. so I got the sticker renewed. but after a few km later, CEL came up again.
I will read the book and try to clean them.
also, last time, I used electronic cleaner to clean MAF sensor. today I just bought a Carb cleaner and will try to clean the sensor again.
#1933 of 2044 Pls bear with - dumb blond 626 question
Apr 26, 2006 (1:30 pm)
Hey, guys! I have a big problem with my much-driven, much-loved '84 626. The carb squirts major amounts of gas up into the air cleaner, and it's all wet inside. She wants to run, but there's so much gas, I have to hold the pedal down all the way to even make it start. It kind of runs, but not very good. Anybody got any ideas?