Hot answers tagged

10

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 ...


9

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 ...


8

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 ...


6

Possible Answers We were hoping for a little feedback regarding this issue prior to attempting an answer. A few things come to mind regarding the problem description and we'll run through a few of them for you. Regarding Stalling Fuel Filter - Your fuel filter may be impeded and require replacement. Since you have not indicated this happens at higher ...


6

You need to check for leaks in the air intake A leaky air intake can explain hunting idle and I don't think spraying carb cleaner is always conclusive as some cracks can be really hard to see/detect. There are several ways to check this: block the air intake completely The easiest way to do this is disconnect the airbox and cover the piping before the ...


6

This wont do any damage to your engine until you have an accident making a mistake with the pedals:) The IAC would only doing the same function that you are doing manually. I do think you have more of a problem than the IAC being faulty, since it should just add extra air when you switch things on like the lights, air con etc. Maybe your throttle ...


6

Your data logs tell me the following: Fuel trims are fine Here are some plots I generated from your data for both short-term and long-term fuel trims. The plot above (Bank 1 STFT vs Bank 2 STFT) show that there is no bank imbalance and most of the data points hover around zero STFT correction, which tells me that feedback from the O2 sensors is ...


6

The fact that you can smell fuel in the exhaust is a strong indication that the engine is running rich. This means that there is more fuel than required by the engine. There are many things which could cause this and the sensible course of action would involve hooking the engine computer to a scan tool to retrieve data about fuel trims, and O2 sensor ...


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.


5

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, ...


5

I know this vehicle as a Yaris; 1NZ-FE engine, and that is the vehicle I am commenting on. Toyota does not mention a specific procedure for an idle relearn in their official service information. Even the procedure for throttle body replacement does not mention a relearn procedure. The info does not state that a procedure is not needed, it is silent on the ...


5

Not familiar with your vehicle/engine specifically, but familiar with carbed engines in general. I would think the #1 thing to look at would be the choke. Pumping before starting a carb vehicle is normal. It gives it a squirt of fuel and sets the choke. The low RPM indicates that the high idle is not set, which likely means the choke is not set also. ...


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

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, ...


4

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 ...


4

Your Golf should have two fuel pumps: one for the injectors (high pressure) and one which feeds the injector pump (low pressure). The low pressure pump would reside in the fuel tank. I'm thinking the low pressure pump may be going bad, as in getting weak. If it were starting to overheat, it may not pump fuel like it is supposed to and would cause the loss of ...


4

The Problem can be with the engine not getting enough ventilation. Problem: In your car the ECU is programmed to raise the rpm when it detects a stall or the RPM dropping down so if there is problem with your air filter which is not allowing much air into the engine and causing a stall but not noticeable your ECU will fight it to keep it in working ...


4

Thanks for the great detail. Considering this is a bit of an odd issue, I'll try thinking outside the box a little. But first I would use a multimeter to test the coolant temp sensor, then o2 sensors. Perhaps even a quick check of the upper radiator hose to make sure the thermostat isn't stuck open. I say to check these first because it sounds like ...


4

My suggestion is that your IAC valve is sticking. This would mean it is jutting in/out and not providing the amount of air for the computer to get the engine to settle. Since you've already cleaned it and the passageways, about your only other recourse is replacement.


4

As HandyHowie said, this won't cause any damage. However, there is a better way, based on the assumption that you have a foot on the brake because you leave the car in D at the lights. If the car will still idle in N with a bad IAC, select N as you're coming to a stop and put it back in D as you press the gas pedal to set off again. Make sure the revs are ...


4

The stalling issues point toward problems with an engine control system (air, fuel, or spark), but again short of replacing the fuel pump, you have already replaced the parts most likely to cause those issues. The idea that the car will act normally on short trips is also strange. The problem that stands out to me is that the car has trouble accelerating, ...


4

First of all, the 5.3l engine (could be all of the Vortec LS engines, don't know) is thirsty. It drinks a bit of oil. Be aware you could be looking at up to 2 quarts between oil changes. I don't know exactly what the issue is, but it does have a bit of an oil control issue whether it has to do with leakage or burning. My '06 is this way. It has never ran bad ...


3

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 ...


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

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 ...


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

I had the same problem with my car last year, problem only occurred when idling and not while driving. This is why I immediately suspected the IAC. Removing and cleaning the IAC did the trick for me. Hope this will help you.



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