2002 Mazda - Run poorly at low rpms

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Old 08-28-10, 03:16 PM
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2002 Mazda - Run poorly at low rpms

2002 Mazda 626 4dr 5 speed 2L


Lack of power, boggs down and lurches, maybe misses at very low rpms such as when starting off, going up steep hills, shifting into higher gears.

But runs like a charm at normal to high rpms.
 
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Old 08-28-10, 03:59 PM
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So it runs poor under low engine vacuum conditions/under load.

Do you have any theories or have you looked at certain things on the car already?
 
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Old 08-28-10, 04:12 PM
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Has routine maintenance been done on this vehicle as recommended in the owner's manual or factory service manual?

Like at certain mileage intervals change oil, filters, spark plugs, etc.

Or has not much of anything been done?
 
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Old 08-28-10, 04:34 PM
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Scan for error codes. Pretty sure you’ll find that codes PO300 through PO304 are set.

(Quote) But runs like a charm at normal to high rpms.

Higher rpm’s means greater fuel flow, pressure and volume. At this point the problem is “Self Explanatory. The engine is telling that the problem is related to a lack of fuel flow, pressure and volume. Let’s begin slow and easy.

Has the fuel filter been changed recently?

Pull the rubber vacuum hose on the fuel pressure regulator. If fuel is present inside the hose it means that the diaphragm in the regulator is fractured, and the regulator must be replaced.

Check back at about in about an hour for additional troubleshooting and repair info.
 
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Old 08-28-10, 05:35 PM
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The car has 100K miles on it, had for two years have routinely changed oil. Looked at the air filter and plugs, didn't see anything notable. I pulled the vacuum hose on what I think was the fuel pressure regulator and didn't note any gas or other substance. Don't know, but guess its the original fuel filter.
 
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Old 08-28-10, 06:35 PM
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Kennn,

Since you pulled the plugs describe the burn at the electrodes to us. BTW are the plugs “NGK”. Since this is a Japanese car only “NGK” plugs and ignition wires must be used. Many chain type stores like Auto Zone read computer error codes. Having a scan done is free at these stores. The first chance you get have a scan done and post any codes. Sounds like the fuel filter has never been changed. Changing it now would be a good idea.

Attach a fuel pressure gauge and drive with the gauge attached. Confirm psi values below, and post the results.

Fuel system pressure at all engine speeds. (38 – 46) PSI

Another possibility is that one or more fuel injectors are “Partially” clogged. Pour in the fuel tank cleaners are a waste of money. The best way to clean fuel injectors is to remove them from the car and clean them on a injection table. Problem is, it’s very expensive. The second method is very effective and much less expensive. This method allows the injectors to be cleaned while they remain installed on the car. Look for repair shops in your area that clean fuel injectors, with the cleaners, tools, and equipment found in the links below.

CAMP // Products // Fuel Service Products

BG Company
 
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Old 08-28-10, 09:04 PM
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2 things to do first:
1. clean or replace PCV valve
2. locate, remove, and clean EGR valve.

for a mazda, 100 000 miles is not much of a mileage. i'd recommend general tune up. it's simple DIY procedure.
of course, read codes, good starting point.
 
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Old 09-05-10, 04:40 PM
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OK I changed the fuel filter, seemed to help but problem still continued. I checked the PCV it was good. Disconnected the egr valve and problem stopped. Apparently it needs to either be cleaned or replaced. I have looked at the egr valve and it is very difficult to get to. It appears to be attached to manifold by two bolts that are difficult to reach. The top is covered by a black plastic lid secured by four star type screws. How would you clean or further evaluate this valve. Is it possible to clean it on the engine by removing he four star type screws.

Thanks
 
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Old 09-05-10, 08:28 PM
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take it off the engine, shoot few squirts of carb cleaner into it, reinstall.
normally, those have metal or metallized gasket that is prone to breaking during valve removals. might be a good idea to have a spare one. i messed up a few before and they are hard to mend. exhaust is running through it, it must be high temp resistant material.
no need to replace it, it's a very simple valve usually operated by vacuum line. cleaning works well.

sorry, that's what DIY is about - small hands, esp if you own a Japanese make. be glad it's not an older Honda with 96 vacuum lines, or a Mitsubishi, with kitana sharp sheetwork. or a Ford with special tool for any coupling, or a Volvo, with special tool required for EVERYTHING.

btw, the cheaper gas you use, the sooner you get EGR filled with soot.
 
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Old 09-07-10, 05:58 AM
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It didn't turn out to be near as difficult as it looked. Runs great. Thanks for your help
 
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Old 09-07-10, 06:12 PM
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good. i learned this on my galant. unfortunately, from now on, you are destined to do this cleaning every 30 or so thousand miles. every Japanese make we ever owned, ends up with this.
 
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