Hot answers tagged rough-idle
6
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
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 ...
5
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 those parts fixed (several hundred $ IIRC). Unfortunately, the problem resurfaced. By that time we'd moved, so we took the car to a totally different dealership. They also could not reproduce the problem reliably ...
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.
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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
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, ...
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
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 ...
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
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 ...
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
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
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 ...
1
I would suspect that this is the problem:
I have absolutely no idea what can be causing this. I recently cleaned the carb and rebuilt it with all new needles and everything. Any help is greatly appreciated.
Rebuilding your carb is a tricky thing that if you don't get right could lead to the types of problems you have. I would take it to a bike shop ...
1
the oxygen sensor needed replacing
You may have identified the root of all of your issues. Depending on exactly what is happening with your faulty O2 sensor, it could affect any aspect of the intake-combustion-exhaust cycle. I would expect exactly the sort of symptoms that you cite; specifically, rough idle and reduced performance are to be expected.
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 ...
1
Given that this started when you replaced the exhaust, the likely culprit here seems to be that one of the o2 sensors starts to fail when it gets hot and your engine starts to use too much fuel. My second guess was going to be your MAS, but as you say, you don't have one.
Have a car shop scan for and OBD II code and see if there is a code being thrown, the ...
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
I was having the same problem with my 2000 Accord coupe v6. Has always been an intermittent problem. Just got it from dealer I experienced shaking on highway one day cruising at 75 mph, freaked me out. Check engine light came on and was P0108. Map sensor was somehow not fully connected. That took care of that. Regarding the no start after "hot soak" they ...
1
I would check belt tension and rotation of the pulley on the compressor.
The compressor may be exerting more drag then it is supposed to causing a further drop in RPMS then the IAC is compensating for and so causing it to stall.
It may be the pulley itself seizing which you may be able to recover with some corrosion cleaner, lubricant etc. Otherwise it ...
1
I had a similar problem on 2 vehicles, a 03 mustang and a 99 bonneville. When the car would come to a stop light the engine would idle too low and stall out. The problem (in both cases) was the mass air flow sensor. Its a piece of electronics that determines the amount of air to let in to the engine from the throttle based on inputs. You could test it by ...
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