very rough idle

[jcasey007]

My shoulder will be fine thanks, too many years as a rugby prop means both shoulders have been out at least twice.

Bloody inconvienient as I had planned on replacing all my front bushes this weekend but can't now as I can't raise my arm above waiste height. Still I still have to get it sparking.

With respect to power on gas, I can't honestly tell the difference when switching from petrol to gas and mine will rev as cleanly and as high when running on gas. It has taken an awful lot of tinkering to get it to this stage including having to learn how a gas vapouriser works! Having installed an O2 meter in the dash is the only way imho to get gas system set up correctly for all conditions,loads and throttle openings as you can see exactly what is happening and can replicate settings.

Keep plugging at it, I have realised that the explorer looks like a BTH truck but the systems are complex and nothing short of taking a step by step approach to test and diagnosis on each sub system will find the faults. I don't think I have every spent so much time with a multimeter on a car

cheers

Jim

 

[wetdog]

all posts refering to the bad running of my explorer are based on it running on petrol. it runs the same on both, but before you can sort the gas side you muist have the petrol side running correctly.

both my shoulders, among other things, are bu66ered. this too is down to playing rugby

mick.

 

[jcasey007]

Testing the common Sub-systems on petrol and LPG

Hi Wetdog

you are quite right, when I bought my EX it ran what I thought was OK on gas (as I did not have a reference) but ran like a dog on petrol.

The fact that yours runs the same (as bad) on both, tells me that it is a fault(s) on the common components of both Gas and Petrol. I'm assuming it is a single point LPG system (with a closed Loop?). If that is the case then the fault has to be one of the following.

1. Lower Manfold Seal Leak - I ran mine for 6 months (25k miles) with an inch of gasket missing until it failed the MOT on high NO. Yes fixing it improved things no end, but the engine still pulled like a train with the missing gasket.
2. Upper mainfold leak - again poor sealing will not make it run as bad as you describe, I tried to run mine without the gaskets using liquid gaskets (bloody disaster) as I couldn't wait for the dealer to get them.
3. IAC Valve - depending on your system it will either be blanked off by a sheet of metal so there is no idle control other than the butterfly or like mine you will have a manually adjustable voltage regulator that is switched on when on gas only. I found that unless I had the butterfly slightly open and then adjusted the voltage regulator when on gas for a good idle speed it would not idle properly. You should have one of these if you are running injection emulation as the PCM will interperate the emulation as static and have the IAC contol Voltage to low. The give you an idea my IAC voltage on petrol was 4.01 Volts and the Voltage regualator is set to 4.35 when on gas.
4. Throttle potentiometer - a bad one of these will screw both systems up
5. Tacho Input - again incorrect or a ragged input will not only mess up the ignition but also the gas control map as the stepper motor that regulates the gas is driven by this input. My regmatic takes RPM input from one of the ignition coil feeds.
6. ERG control - Again how much impact will this have. In diagnosing mine I ran it for 3 days with the ERG valve disconnected.
7. Ignition system- Plugs, leads, Crank sensor

That's all the common controls, anything else does not have any impact on the running of the gas (i.e. MAF, Engine temp, Air temp, Petrol pump etc)

These seven common systems can easily be tested and and discounted.

If I was a betting man, I would test the common components in the following order 4, 7 then 5.

Get it running well on GAS as the inputs are less and then tackle the Petrol subsystems if still needed.

cheers

Jim

 

[wetdog]

i'm running on an early AGI sequential system, the model evades me at the moment.

i have a meeting with work on thursday, and have it on good authority that i am to lose my job. so, that will give me and a multi meter plenty of time.
i'm just gonna put up with it then til next week, or when it thawes, then crack on with it.

thank you to all who have helped, i will post back on this thread when i have started work and have some results.

mick.

 

[RammaR]

Did you ever get this resolved? After I replaced the cylinder heads, my '96 4.0 is acting very similar to the way you describe yours.

I've been toying with it for about 2 weeks and am baffled.

 

[DuncanOfEngland]

Mick

There are a few tests which you can do which may give a pointer to what's causing the rough idle and loss of power.


1. Vacuum test. Test the engine vacuum at idle. It should be steady in the 15-20 in. hg. range.

2. Compression test. This will give a good indication of the state of the valve. Readings should be in the range 160-170 psi

3. Spark test. With the engine running, using insulated pliers, pull off one spark plug lead at a time from the coil pack. Each one should change the engine note.

4. Fuel pressure test. This should be 30psi on idle rising to 40 when the throttle is opened.

5. Spark plug condition. Look at the colour of each of the spark plugs. They should be greyish (Haynes manuals show a colour chart). Most of all, look for differences between plug which may give a clue.

I have encountered 2 Explorers with LPG which have suffered with severe valve seat recession, necessitating replacing the heads.

Duncan

 

[wetdog]

cheers duncan. i had been informed both on here and by LPG specialists , that explorers dont burn valves on gas. but it looks like they do.

i am on a couple of retraining courses at the moment, so the car hasnt yet been touched. buti will report back as and when.

mick.

 

[Aspire]

Hi wetdog,
Hope things improving on the work front. I have the same model as you running on gas. When I bought it the gas system wasn't working so had the vapouriser replaced only to discover that the head gaskets were gone. So had them done and the valves were fine, but one of the heads was split. On monday this week I was in Scotland and was running low on gas so switched to petrol as gas station 5 miles away and engine died wouldn't start. " hours later the AA turned up and spent 2 hours saying it was head gasket as when they got engine going clouds of white smoke. They checked to see if I had run out of petrol gauge saying 1/4 tank. So we went to get more petrol 20litres jerry can and when trying to fill her we noticed filler nozzle full of mud. So cleaned that out and started to fill only to find petrol all over floor and that the filler neck had fully rotted away and as a result petrol contaminated. Car wont start and runs rough so petrol being drained tanked taken off and cleaned and put it all back together. New filler neck from Duncan that I picked up yesterday. Worth a look.

Regards

 

[wetdog]

Hi wetdog,
Hope things improving on the work front. I have the same model as you running on gas. When I bought it the gas system wasn't working so had the vapouriser replaced only to discover that the head gaskets were gone. So had them done and the valves were fine, but one of the heads was split. On monday this week I was in Scotland and was running low on gas so switched to petrol as gas station 5 miles away and engine died wouldn't start. " hours later the AA turned up and spent 2 hours saying it was head gasket as when they got engine going clouds of white smoke. They checked to see if I had run out of petrol gauge saying 1/4 tank. So we went to get more petrol 20litres jerry can and when trying to fill her we noticed filler nozzle full of mud. So cleaned that out and started to fill only to find petrol all over floor and that the filler neck had fully rotted away and as a result petrol contaminated. Car wont start and runs rough so petrol being drained tanked taken off and cleaned and put it all back together. New filler neck from Duncan that I picked up yesterday. Worth a look.

Regards

hhmmm.............funny you should say that mate. i was putting my monthly tenner's worth of petrol in the other day when i heared a splashing sound. i looked down and the fuel was going straight on the floor.

when and if i get my car back from the parking nazi's , dont ask, i will investagate further.

cheers,
mick.

 

[Aspire]

yes water in the petrol gives white smoke and engine runs rough!

 

[fastwalker]

Hey there,
Im new to all of this, im having the same problem as everyone... i had the recovery chaps out to have a look at it as i dont have the money for a code reader... told them i broke down and voila a free code reader he said that their were about six codes telling us that it was running "lean"...? could this be due to water in the petrol as i too have a rotter petrol filling neck??? and even better than that when i lifted the single seat in the back to lay it flat i saw some little pieces of carpet... i lifted them only to find myself looking directly at the petrol tank... some little s%*t has cut a cirle in the floor panel to get to the petrol pump... yeh really a hole... in the floor panel because they couldnt be bothered... comon mann!!!! so i dont think its the petrol pump ha haa.
ive cleaned the egr and have noticed that the pipe leading from the egr runs back to a small black plastic cylinder and out towards the manifold inlet, now between the inlet and cylinder is great vacuum but from the cylinder to the egr no vacuum but the pipe is clean so whats the cylinder??? and does it open at a certain temp??
anyways got to hit the sack ill be keepin an eye on this one
Speak soon
Fastwalker