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8

I had this same issue. The PCM and fuel pressure regulator is the correct fix. It is not cheap, but it does address the problem. If i recall, the issue has to do with ethanol having a lower boiling point than traditional gas. This causes it to vaporize on the fuel rail when the car's warm, but no long pumping gas because it's off. When you go to re-start ...


7

A defective ignition switch, which has been attributed to several deaths, and caused several models of GM cars to spontaneously shutdown during operations. These reports very accurately describe what we noticed. The purge valve solenoid and vapor canister were contaminated with fuel. Update: So the above is what the dealership said was wrong, and we got ...


7

Most likely, one of the engine mounts are 'torqued'. You can try and neutralize the mounts. Loosen the through bolts of all mounts several (4-5) turns. Then start the car, and drive back and forth several feet (using quick taps on the gas and not just idling) over and over, and let it rest at idle a few seconds before turning off the engine. Now tighten all ...


5

My first thought is to clean the throttle body and Idle Air Control (IAC) motor passages with carburetor or throttle body cleaner. They get a black buildup on the edge of the throttle plate and IAC passages that interferes with the idle speed regulation.


4

Unfortunately, there are many, many things that can cause a rough idle. I'll try to cover a few things that might help with the diagnosis. I'm sure that there are many others that could be added. Like I mentioned in my comment, it's definitely not the fuel filter. If a fuel filter was bad enough to affect idle it would stall instead of accelerate. A ...


4

As Larry said, check the throttle body and the IAC, but I'd also check for vacuum leaks.


4

So the problem seems to go away if manage to get the car into gear and move, but not if you rev it? "fuel ressure regulator and PCM!?" Sounds like they haven't bothered with the slightest bit of diagnosis. It sounds like a fuel pump problem to me. An electrical fuel pump problem at that. I think you have a mechanical fuel regulator, so i wouldn't expect it ...


4

Looks like I may have answered my own question last night. I did a deep clean on the throttle body (and as far back in as I could access). The idle is HUGELY improved, though still not perfect on this 28° morning. Is that really all it was? I'd love to hear your comments if you've had the same experience.


4

It might be the intermittent failure of an idle speed solenoid. They go by a bazillion different names and have just as many variations. For example: Fast Idle Valve Idle-up solenoid Accessory Valve/Solenoid Auxiliary Air Valve Et cetera... It may also be, as noted in your comments, an air leak somewhere. Seeing as how it works fine above a certain RPM, ...


4

Ahh, cold starts. In the DIY ECU world, this is always the most difficult part of tuning a vehicle. One reason is that the engine is horribly inefficient at low temperatures, and requires a very narrowly defined amount of fuel. Too much and it eventually bogs down and dies. Too little and it dies as well. Then if the engine's warmed up at all during this, ...


3

Aftermarket tuners/PCM flashers (such as HP Tuners) will allow you to do this. However, HP Tuners costs about $600, so your best bet would be to find a friend or shop who already has one, unless you see yourself using such a tool often. Also, worn motor mounts will put more stress on other mounts in the driveline (transmission, rear diff, etc.) so it might ...


3

The factory plugs should be good for 100,000 miles / 160,000 km or so. They're ridiculously easy to change on a Zetec. If you can handle a screwdriver and a socket wrench, you can check / change them yourself. They're easily accessible from the top of the engine through holes in the valve cover. The plug wires are also easy to inspect, just keep track of ...


3

An AC compressor puts a big strain on an engine when it's engaged. This is especially the case with low horse power 4-cylinder engines. What makes matters worse are high mileage engines which are in poor running condition. I experienced this with a Saab I used to have. I could only run the AC when I was moving at highway speeds. Otherwise it was too much ...


2

I'd check for vacuum leaks and malfunctioning idle controller valves. Cold air is more dense (contains more oxygen for the same volume) so I'd expect a vacuum leak so show up worse as you get more unmetered air introduced into the engine and the ECU tries to compensate for the air/fuel mixture being off, which leads to the idle surge.


2

On a Mitsubishi, it would be either a failed Idle Air Controller, or the Base Idle Set Screw has backed out and needs to be reset (and sealed into place). Look for something similar to start with.


2

Is this an automatic or a manual? The idle speed should be higher for an automatic. Do you have an engine light on? A bad misfire will sometimes turn one on, because your emissions go up with a misfire. (Unburnt fuel is being sent into the exhaust, which can destroy your catalytic converter.) Either way, this car is new enough to have a scan tool plugged ...


2

I had the same problem you have to change your control box more or less $ 100. Hope this helps, mine runs perfectly since replacement.


2

I have a 1997 626 Mazda 2L (manual) and it shook at idle and got progressively worse. It turned out to be the intake manifold seal. Its cheap to fix about $12 for a new gasket. To diagnose it is simple too, spray where the intake manifold joins the engine with a can of "jump start" or similar and if the idle picks up you have an air leak. Mazda's are prone ...


2

Could be many things, but I'd start with what it gives you. Have the alternator checked. It may not be putting out enough to keep the car powered at idle, slowly draining the battery, causing the idle to lower do to low sparking ability. Just a wild stab in the dark, probably wrong. It could also be other problems that didn't trigger a code causing a low ...


2

This hardly sounds like a problem for which the whole vehicle needs replacement. The symptoms could be explained by a misfiring cylinder, in which the vibrations are most obvious at idle and with the drivetrain engaged. Common causes for misfires include ageing spark plugs/wires, absence of spark or improper fuel delivery (usually a clogged fuel injector). ...


2

The slightly high idle and roughness at idle sounds like a symptom of a vacuum leak in the intake system. It also would cause it to go away when the throttle is slightly depressed taking the engine off idle (~1000RPM) Here is how you can test that theory: A common trick I used in the shop is to spray the intake area from the throttle body to the cylinder ...


1

Took it to the shop, broke an engine mount bracket which is causing the shake. Also, the tubes are torn on the AC. – Cody Bennett just now edit


1

Not surprised it shakes, being under 700 rpms sounds a bit on the low side for an engine that small. I'd expect it to be around 750 rpms normally. You may have a faulty Idle Air Controller (or something similar, not familiar with Saturns).


1

In my experience, this type of issue is usually related to the EGR system - EGR valve starting to fail perhaps. There are some great videos on YouTube on how to test the valve. I would almost think to check the MAF sensor or IAC valve but the operation of those shouldn't change much as the car warms - the EGR valve might have the clearance to operate ...


1

It's most likely a bad engine temperature sensor. (common problem) When the car is cold the computer uses a cold start fuel map. If the engine temperature sensor is bad the computer won't know the car is cold and will not activate the cold start fuel map. More information: http://blog.bavauto.com/8178/bmw-e30-e28-engine-temperature-sensor-m20-engine/ It ...


1

These motors were plagued by problematic cylinder heads. Usually the end result in cases like yours are replacement of the Cylinder Head. Most likely there is either a blown head gasket or burnt exhaust valve. If there are no vacuum leaks and MAF is good then you need you start looking deeper into the engine.


1

It could be caused by ignition cables, coils, plugs, I have had the same problem in my Skoda Octavia ´00, in the morning it was like one of cylinders is not having a spark, combustion was very bad and power was reduces but only for max 5 minutes, then after engine got heated a bit it disapeared, also this problem is related to damaged gasket under the ...


1

Replace fuses that go to computer shutdown, #11 &14 I think. Or re-seat all fuses in the fuse box under the hood. The spades on the fuses build up a thin corrosion that gives a voltage drop.[they got me for $1200] new computer and new plugs in my 2006 300c


1

Try idle speed sensor or spraying throttle body cleaner into throttle body or removing it entirely and cleaning it,especially where the idle air port entry.


1

I had the same problems and a forum somewhere told me that there was a Mazda 626 directive telling a Mass Airflow sensor going bad after a certain mileage. This islocated in the airflow tube coming from the airfilter. I pulled the 3 prong connector and the rough idling stops but it now runs on a higher idle . When I took the sensor out I broke the wafer ...



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