Log in or Sign up. Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself. Recent Posts Contact Us. Just Commodores. Feb 5, 1. Hey guys! Runs fine when im driving etc. But when sitting at the lights the tacho goes almost down to 0 rpm then back up to rpm then goes to rpm etc.
And keeps doing that over and over until i start driving again. Now the guys that installed it said i need to change my O2 sensor. Is this the problem? I have check all vacum hoses etc. No problem there. Plus the car idles properly while using ULP. Any advice would be appreciated! BoofeFeb 5, Feb 6, 2. I had it al taken out. I had nothing but trouble. When i got it it was all working, but had plenty of issues. In the end i had it completely removed and the car has been fine since.
I was given no explaination to the problem, so i just put it down to LPG being no good. Don't know if this will help.Also the idle drop when running on petrol could be something to do with a particular vacuum pipe it had weakened on the bend of the pipe and was collapsing when on idle As for the LPG its a very specific thing and i'd get it checked Ive heard of the zetec engines suffering from burnt or sticking valves, could be a cause of bad idle?
I've got a 1. Bought with k miles, now k and just started misfiring on lpg. I'm almost certain its fuel, maybe the LPG pump, I think its in the middle of the donut tank. I'll try the pump connections like andy. Finally, I've got ideas on fitting a traction control brake valve off a scrap car. Anyone ever done this.
Does the computer need resetting do you reckon? Then raise the suspension with longer springs and some proper snow tyres. You can post now and register later. If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed. Display as a link instead. Clear editor. Upload or insert images from URL.
Ford Focus Club Search In. Reply to this topic Start new topic. Recommended Posts. Posted February 11, Thanks for taking the time to read this post. Share this post Link to post Share on other sites. Posted February 12, Posted February 16, Posted August 30, Posted August 31, Posted December 16, Hi, I've got a 1. Anyone know where it is located? Join the conversation You can post now and register later.
Reply to this topic Insert image from URL. Go To Topic Listing. Sign In Sign Up.The idle of a car engine is kind of like a human heartbeat: You can tell what shape it's in just by listening.
Problems with idle speed —things like slow idle, fast idle, rough idle, or stalling after idling for a few seconds—are symptoms that something is wrong with your engine. These should be investigated, diagnosed, and repaired as soon as possible. Some of these repairs you can probably make yourselfwhile others will require a professional mechanic to sort out.
It's a cold day and you're stopped at a stoplight. You take your foot off the gas pedal to apply the brake, but your engine begins to idle very roughly, and then it stalls. Yet, when you restart the engine and run the car at higher speeds, it seems to run fine, or at least more smoothly. Here's what could be wrong:. If you're having the same problem as you did in the cold, only your engine is warm, even hot, this could indicate the following problems:. Even after the engine has run long enough to become warm, the idle speed does not come down to normal but continues to idle at a fast pace.
You really notice it when you come to a stop, after which you have to push hard on the brake pedal to keep the car from moving. Here's what could be happening:. You are driving along and everything is just fine—until you let off the gas pedal and apply the brakes.
At that point, the engine starts shaking and may even stall. Here are some possible causes:. Remember to always check your engine idle with the air conditioning and defroster turned off, as both of these systems are designed to change the idle when they are on due to the demands they place on the engine. Matthew Wright. Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles.
If you have a carburetor, you may have a bad accelerator pump or power circuit. The Fix: Replace accelerator pump or replace the carburetor.
Is Your Car Idling Too Rough?
There may be a vacuum leak. The Fix: Check and replace the vacuum lines as required. There may be some type of ignition problem. The Fix: Check and replace the distributor cap, rotor, ignition wires, and spark plugs. The ignition timing may be set wrong. There may be a fault in the computerized engine control system.
They'll test the circuits and repair or replace components as required. The EGR valve may be bad. The engine may have mechanical problems. The Fix: Check the compression to determine the engine's condition. The idle speed is set incorrectly. The Fix: Set idle speed to the car's original settings.
The fuel injectors may be dirty. The Fix: Clean or replace the fuel injectors. The Fix: Check and replace vacuum lines as required. The fuel pressure regulator may be operating at too low a pressure. The Fix: Check the fuel pressure with a fuel pressure gauge. Have your fuel pressure regulator replaced. Idle speed is set incorrectly. The Fix: Check and replace distributor cap, rotor, ignition wires, and spark plugs.Fun, Friendly and Free.
VP Commodore rough idle when running LPG
Welcome, Guest. Please login or register. News: Many thanks to everyone who donated to the running of the forum! Long may we prosper. Author Topic: Misfire The plugs were changed about 1, miles ago, and the leads last year. Any ideas please! Electrics, change the plugs, leads, dizzy cap and rotor arm if it's got em - landies aint my thang again.
If it runs fine on petrol then Try hotter plugs and pull the gap in about 0. Quote from: morson4x4 on February 08, I love my LPG, it has saved us so much money over the nearly three years we've had the motor. Ordered a new cap and arm and will fit those first to see if that will sort the issue. Thanks for the replies. And you did buy a Genuine cap and Rotor arm?
Not cheap but will work. Having a gassed V8 means having to have top notch Ignition system. My website Searle Safari Info source. Well, replaced cap and arm. The old cap and arm looked OK, but put the new ones on. Still backfiring.
VP Commodore rough idle when running LPG
They are 12 months old. Should these be next on my list? Ive Had the same issue on a single point system. It would be backfire after initial burst of acceleration, Ok on motorway stretch. Just turned the mixture up a bit, seemed to have cured it. Built for Everything. Check compresion on the engine too, backfiring can be a symptom of a burned out valve.
If you can get one, a Gunson's flashtester will check the strength of your sparks. OK, thanks. It runs perfect on petrol, the problem is only on LPG. I have ordered new leads. Changed the leads and Good to hear it was a simple fix. That's why i run Magnecor. I still get a rare misfire The leads certainly helped.
The only thing left to change now is the plugs, so I will do them this week. Octane is a measure of how hard it is for fuel to self-ignite under compression and as spark ignition works by causing auto-ignition due to a shock wave, the octane rating of the fuel relates directly to how hard it is to ignite.
Also the burn temp of LPG is different and it takes longer to burn.Jump to content.
4.7 V8 running rough
Posted 26 May - PM.
I have just had a head gasket changed as well as spark plugs. The power is also down but I have a feeling it is just bad lpg as i filled a whole tank at mobil the other day and started running sluggish.
Any ideas on the rough idle or hard starting? Posted 26 May - PM I am unsure of how much the motor has done but i do know that the previous owner had the motor reconditioned a few years back by people he knew he was around 80 years old so hopefully he would have picked his friends by now.
It had a reco head fitted when the head gasket was changed a few weeks back. I am unsure how old the leads are but new plugs were fitted 2 or 3 weeks back when it also got a tune mechanic fiddled with the mixer and flow rate.
Im running an wierd brand lpg converter woldoff or something like that i think its an impco copy its raining heavily i cant check right now and running a dual fuel snorkel on top of the weber carby. Posted 26 May - PM check to see all the hoses are connected tight, no vac leaks. Posted 26 May - PM yea i heard about hoses coming loose as well. The vacuum hose from the inlet to brake booster is slightly cracked from touching the hot egr pipe but im not sure thats the problem as it could have been cracked before.
It also has a small crack on the pcv hose near the hose clamp at the carby dont know if thats leaking or not. I suspect there is an inlet manifold leak somewhere as the idle can be anywhere between The mechanic also noticed this but said he couldnt find the leak. Im suspecting carby gaskets. Is there anything that can be done about this?
The last time the car ran on petrol was before the head gasket and tune. The car will no longer start on petrol so i just dont use it. Back to LPG Discussion. Need an account? Register now! I've forgotten my password. Remember me This is not recommended for shared computers.Log in or Sign up.
Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself. Recent Posts Contact Us. Just Commodores. Sep 10, 1. My VT Commodore factory dual fuel. If anyone has any idea then I would appreciate it. Plugs have been changed and it made no difference. Sep 11, 2. Yip I hear you, mine does it to on the odd occasion, revs bounce up and down I changed plugs leads, coils, ICA, gave the throttle body a clean and still at times plays up, it did become much better with new ICA and a clean.
I think the car ecu at times gets confused with mixture. Lpg is very sensitive everything has to be in tip top shape, leads and coils too, one weak coil while running on gas can do funny things, also read 02 sensors or even low pressure from your regulator, mine does it more on hot days. Last edited: Sep 11, Trevor loves holden. Sep 11, 3.
Found this old thread might help. There is a wire that the LPG installers route to one of the spark plug leads. And it wasn't picking up the signal good enough through my heavy duty 10mm leads. So all i did was re-route the wire into my tacho signal wire, same thing! And the idle is all sweet now Just like running on petrol! It now gets a direct signal Sep 11, 4. EYYSep 11, Sep 11, 5. Sep 11, 6. Seems a really cheap solution fraught with warranty claims for a manufacturer to do such.
More likely to see such cheapness in after market LPG system to be honest. If your LPG was factory, maybe it was modded by a previous owner as a cheap fix to a wiring problem? SkylarkingSep 11, Sep 11, 7. Sep 11, 8. Higher octane requires better spark intensity to burn quicker it also needs more advance in the timing.
So as LPG has a high octane, usually around the mark. They can appear to be perfectly serviceable, but cause problems when running on LPG. Don't be fooled into thinking that the surrounding air is too warm for freezing to occur, outside temperatures do not have to be down to freezing level for this to happen.
Sep 12, 9. SkylarkingSep 12, These diagnostics also apply to older Ford factory Tickford LPG systems where the balance line is in a different position to the vehicles featured in this story.
The oxygen sensor should have 0 to 1 oscillating voltage if it is working OK. The stepper motor count should be about to at idle if all conditions are OK.
If the engine is running lean, the 0 sensor 2 will be showing lean around 0. Now check the PCV positive crankcase ventilation valve that can often be damaged by an engine backfire. Check for air leaks within the intake manifold system, from the air box through to the manifold gasket. If the fault is still apparent, test drive the vehicle with the scan tool hooked up and record the stepper motor count.
If the mixtures go lean as indicated by the 02 sensor being below 0. To check the balance line remove it from the air filter end and, using a smoke machine, check for leaks but use only very low pressure. Alternatively just seal one end of the flexible line and blow in the other. There should be no pressure loss. Due to the design being like a convoluted tube, complete removal and a thorough visual check for splits must be done.
If no splits are found, the sensitivity diaphragm in the converter may be split. This pressure balance system must be completely sealed. An easy way to help diagnose this is to test drive the vehicle in a safe area, accelerate up to 40 to 60 kmlh and shift the gear to neutral while coasting. The balance line must be completely sealed as the incoming ram air is required to draw the correct amount of LPG through the idle circuit. Note: Stepper motor count- the higher the number, the richer the mixture.
The lower the number the leaner the mixture. Car diagnostics software like TOAD can help diagnose common engine issues. Did you find out what your problem was mate as im having same with bf falcon with factory lpg. Stalls soon as take foot off accelerator. Lol, it had me scratching my head for a little while. My point is you all need to check your whole gas system. Hi Alex. My name is Carl. I have a ford Falcon dedicated gas.Mercedes 6 Cylinder Gas Rough Starting and Running Problem Solved by Kent Bergsma
I have been having backfiring issue for three months. When in backfires. It blows off a vacuum hose need the manifold and I need to take the air filter cover off to fix it. Annoying when it does it twice a day. I have it to two mechanic. First one decided it was the starter motor. Still have the issue. Second mechanic Ford dealership said it was the ignition coils.
I still have backfire. Any suggestion.