Please Help, New User 4.0 SOHC stuttering problem - Totally stuck!

[Advan]

Hi folks,
I have also posted this in the technical section so i hope i have not pi$$ed anybody off by doing that!
Im a new user to explorer forum (so apologies for this being my first post, grovelling for help) I live in Beaconsfield, Buckinghamshire and I purchased a Ford Explorer a few months back. It’s 1997 4.0 SOHC model. The car has a six point sequential LPG system and has done 102,000 miles and has always been well maintained. It’s in very good condition indeed!

Here is the problem:
The engine stuttered on LPG when it came on load between 2000rpm and 3000rpm and would randomly cut out at will. It would not accelerate away from standard and popping sounds came from the airbox, which I am sure is bad ignition or backfiring. It wouldn’t pull cleanly and the performance was reduced across the rev range. I figured it was old plugs (LPG systems are especially hard on the ignition system) So we changed the plugs to what ford recommended and gapped the plugs to 1.3mm (as ford recommended)

The new plugs have actually made the problem worse.

The car now also stutters (very slightly) between 2000rpm and 3000rpm on petrol (didn’t do that before) and on LPG it won’t cruise on the motorway and is almost un-drivable between 2000 – 3000rpm while under load. HOWEVER: It does pull away much cleaner from a stand still (LPG) and is much better around town.

Im stumped – it seems like an ignition problem but I don’t know where to go from here. Does anybody have any other ideas? I am quite frankly fresh out.

Apparently the previous owner said that the system needed a second LPG regulator for the 4.0ltr engine. But I have spoken to the LPG system manufacturer direct and they say that the system that is installed is designed for large capacity V6 and V8 engines. So the large single regulator should be fine.

My Gut, tells me that it’s not the LPG system as the back firing indicates a lack of/poor ignition – rather than a malfunctioning system with poor fuel delivery.

HELP! The explorer is my daily driver and running it on petrol (at the US equivalent of $2.00 a litre, £0.99) is killing me.

Thanks 

Chris

EDIT: I forgot to add that the engine check light is on (small yellow engine shaped light in the bottom right hand corner of the dash) im just looking up how to check the fault codes now...

 

[Howard]

We need to find out why the light is on before guessing as to what the problem is. You need a code reader then post the code and we will try and help from there. BTW plug gap is listed as 0.054 inch with a plug # AGSF-22PP. My guess would be leaking lower inlet gaskets but it is only a guess.

 

[Advan]

We need to find out why the light is on before guessing as to what the problem is. You need a code reader then post the code and we will try and help from there. BTW plug gap is listed as 0.054 inch with a plug # AGSF-22PP. My guess would be leaking lower inlet gaskets but it is only a guess.

Thanks for your reply howard!
Where would i get a code reader from? I have done a limited amount of searching on here. But im at work!

If it was leaking inlet manifold gaskets - would it cause a worse problem while running on LPG rather than petrol?

The engine has recently had the cam chain/tensioner/guides replaced. Which im told was an engine out rebuild. (however im not 100% sure)

Many thanks again sir!

 

[Howard]

All you need is an OBDII code reader from a good tools place. Something like http://www.gendandirect.co.uk/product_GDEOBD.html this. Or you can get your local garage to read them for you (but they will charge). I have one lol if you fancy a visit. They would have to take the engine out to do the rear chain but not if they only did the front one.

 

[jays1]

ok not sure how much help this will be but the engine check will come on with lpg it is the engine telling you the fuel is to lean (mine was on for a long time) even after several resets'

Have just had the regulater ect changed on mine and the engine still overpowers my multi point injection lpg (had to have the strongest spring they did put in it to allow the gas pressure to keep up (it would be fine until i kicked down hard then the gas would turn off and the petrol kick in.) now it just does it sometimes.

i would stay with there being a fuel prob it could be the gas (have you had it checked ) my engine light is now off after having all the lpg parts sorted,these cars really do not seem to like lpg it seems.

jay

 

[Advan]

All you need is an OBDII code reader from a good tools place. Something like http://www.gendandirect.co.uk/product_GDEOBD.html this. Or you can get your local garage to read them for you (but they will charge). I have one lol if you fancy a visit. They would have to take the engine out to do the rear chain but not if they only did the front one.

That's mighty generious howard!
Your not far away from me (in south bucks - beaconsfield, J2 M40)
Are you around this weekend at all?

 

[Howard]

PM sent.

 

[DaveFuk]

LPG problems.

Hi i had basically the same problem last year, after having my x converted (third x to be converted) having had diffrent problems with both prevoiuse cars i new what to exspect.

1, the back firing came down to bad plug leads look for slight black marks like stripes down the plugs. but we did change plugs, injectors (lpg), (it feels as if the timing is retarrded but not)

2, the lpg turning off and jumping back to petrol when you exsellerated hard was fixed after 2 things increased the bore of the lpg injector by 0.5mm using a drill bit and a larger lpg filter, still ocasionallt happens if i have the caravan on the back and try to gun it going up hill. it's basically the gas kit not supplying enough gas.

is the code a 171, side 1 lean as far as ican tell this is reasoably normal,

 

[BIGHVM]

I dont know if it would work on this, but in the past when i suspected and inlet manifold leak I would run the car to temp and then using a can of wd40 I would spray the inlet manifold where it joins the engine, if it suddenly runs better then you have an air leak and the mixture is way too lean as a result.
Hope this helps. In your case you would need some one to hold open the throttle at the suspect rev range.

 

[DuncanOfEngland]

Advan

Above 2000 rpm, the engine is gulping in vast quantities of air, so a manifold vacuum leak is unlikely to be the cause. I would look for something which can become stressed as the engine demands more power. Something like the coil pack, spark leads or spark plugs would be a good starting point.

You are losing power in the 2000 - 3000 rpm band. This is when the engine is working hardest. Fuel delivery might be a problem. Perhaps one of the fuel injectors is misfiring, or its associated LPG valve is intermittant, pointing to an electrical problem. LPG intstallations are notorious for introducing problems of this nature, due to the way the fuel injector signal wires are cut and joined, as is the fuel pump control.

It's just possible that you have a complete misfire on 1 cylinder and haven't noticed it. Tickover will be a bit lumpy on 5 cylinders, but the engine will smooth out at anything over about 1100 rpm.

One way of isolating a misfire would be to remove the HT leads one a time, with the engine running, to see if they are each contributing to the tickover. Insulated pliers and a steady hand are a must

If you find a misfire, then you need to track down the cause. If it's not electrical or fuel, then a cylinder compression test may give you a clue.

Another possibility is that one or both oxygen sensors (lambda sond) are playing up, although normally this will cause the orange "check engine" light to come on.

Another possible cause of power loss could be that the camshaft timing has shifted. This can be due to slack tensioners or guides within the engine.


Duncan, Aylesbury, England

 

[Advan]

hi guys,
Just an update on this -
I have had a good dig around with the system and took it into a garage just up the road from me who specilise in the Romano LPG system. They said that the ECU wiped it's self and that's why it was running so badly. They re-programed the LPG ECU charged me £70 for the privilage and gave me the car back. It ran "alright" for the first 10 miles or so, but then it got worse and worse and by the time i got to work, it was worse than ever!

It's now un-drivable on LPG - it backfires and is VERY down on power. It's also started to hesitate (as if it's not pulling and getting stuck) between 2-3krpm on petrol also, this is only when you put your foot to the floor tho.

The whole engine sounds like it's got a bag of spanners rolling around inside it, when i first picked it up, the car sounded smooth and nice, now it's horrible to listen too.

When you blip the throttle, there seems to be a sucking sound coming from the inlet manifold and the exhaust has started to sound like it's blowing! Bah, im going to investigate some more tomorrow.
Merry Christmas and thanks agaiN!