Lumpy Running V6

[Guest djdoylie]

I have a P reg 2.8 V6 Auto Galaxy. It has an LPG conversion - though this is something that has happened whilst running on petrol only (I was waiting to fit a new LPG tank). It's been running fine for a year. I had to sort the brakes out for an MOT a couple of weeks ago, in filling the fluid resevoir I had to move the Air intake hose. After doing this I drove about 20 miles. And parked up for a beer. Upon returning to the car it started fine but when accelerating the rev counter would reach 1,800 revs then fly up to 3,000 revs drop down / up / down / up etc. I then found that when the engine got warm I could 'blip' the throttle and it would then run fine. For a week I would use the car by starting up and driving around the side roads until the engine was warm then 'blip' the throttle and then use the car as normal. I then got the time to take the car to a Ford dealer who reported "hooked up to WDS and carried out checks, found DTC - air fuel ratio fault - suspect caused by LPG system". I used the car a few more days in the same warm up manner. Today I took the car into my LPG specialists to get the new tank fitted, I told them about the 'cold running' problem. They had a look and found a plug (sensor?) fitted to the air hose system that had a broken wire / connection - they said thyat this was a 'sensor that would normally be fitted in the airbox, but because the airbox was replced with a KN type filter when the LPG conversion was done, the sensor had been fitted to the pipework. they fitted a new plug unit for me. This still did not cure the fault, in fact it seemed worse as instead of 'just hunting' as before, it now caused a few of blow backs when trying to accelerate. Even when it has got warm the car will not respond the the 'throttle blip' cure. I need this fixed by tomorrow .... PLEASE HELP if you can. Steve (djdoylie@ntlworld.com)

[Guest marcusheawood]

...Just a thought, have you tried unplugging the MAF? If not drive with it disconnected and see if it's any better.

[Guest djdoylie]

I have tried running with the sensor /plug (I assume that this is the MAF) unplugged. No difference detected. Thanks for the suggestion though. Steve.

[Masked Marauder]

This sounds like an air leak after the MAF and before the inlet manifold to me. Check all your air piping for cracks and secure fitting.

[seatkid]

they said thyat this was a 'sensor that would normally be fitted in the airbox, but because the airbox was replced with a KN type filter when the LPG conversion was done, the sensor had been fitted to the pipework.

sounds like yet another bunch of hapless mechanics.

 

 

There are no sensors fitted in the "airbox", the MAF sensor is fitted between the airbox and the turbo in the pipework - always has been.

 

I take it you've checked plugs/leads/coilpaks. These are always first suspects on spark ignition engines with running problems.

 

Otherwise it sounds like some dogdy electrics in this "LPG" conversion....

[galaxychap]

yup i had same symptoms which turned out to be a split ht lead so i replaced all 6 got them from gsf car parts i also changed the spark plugs as i only had the car for 4 wks and thought may as well go the hole hog i also removed the coil pack and sealed it with epoxy resin from halfords. been running fine since

 

Regards

 

Galaxychap

[Guest vr6galaxy]

Sounds like and intake air leak? check all the air hoses to the throttle body, pay particular attention the main hose from the filter to the throtttle body! check in the folds for cracks and splits? also there is a spare connector that is located in the section between the air box and the throttle body, it does nothing and is usually clipped into a blanking plug on the intake hose

have you noticed an increase in intake noise since this problem occcured? not that you could possible tell having an induction kit fittted :huh:

[Guest djdoylie]

UPDATE: Yesterday I started the car expecting the same old story - but it started just fine. No rev problems, no lumpiness, all ok. (but ..... wait for it)

I drove around for 20 miles with no problems, so I thought I'd try switching over to gas, I did so and it immediately died. Tried a couple more times, same thing. So I took it to my LPG garage - they found the problem (the air inlet pipe had come away from the engine).

They told me that my running problems would probably appear again when I put this back, saying that the 'sensor' after the air filter was probably kaput.

So I drove back home with the 'disconnected' air inlet pipe.

In the morning I refitted the air inlet pipe and IT RAN FINE.

I drove about 15 miles without a hiccup, then thought I'd switch over to LPG (as I was on my way to a gig in London. Bugger ..... it lost power, I quickly switched back to petrol but to no avail, I was stuck doing 20mph. I pulled over to a layby. Stopped and started a few time, but still had no power. So (having to get to work within an hour or so) I loosened the air inlet pipe at the engine again. This got me to work and back without a problem.

I am not a mechanic, but have a bit of common sense which usually helps me sort stuff out, but this has me flummoxed.

Can anybody tell me how comes the engine runs ok the above way, and doesn't otherwise/

Could I bypass this 'sensor' and just run an inlet hose to an air filter?

If this helps anybody here is how my air intake is currently arranged:

The standard airbox is removed (LPG can sometime 'blowback' and this blows up the std box), in it's place in a KN type filter.

The pipe from this goes to a 'plastic pipe with an electrical connector in it' (is this the MAF sensor?).

More flexi pipe goes round to where the 'gas ring' is mounted (there is another connection before the 'gas ring' where a smaller pipe joins into the big pipe.

This smaller pipe comes from the engine and has a join with another sensor built in to it before it goes into the big pipe (what is this sensor?).

After the 'gas ring' the is a short bit of flexi pipe that goes into the engine.

As said at the satrt of this thread, I have had the car for nearly a year and been running it on LPG and petrol with no problems at all - until I had to bleed the brakes and to do that I had to remove the bulkhead and move the 'air intake pipwork', obviously I must have dislodged something somehow then.

Thanks to everybody that has replied, I really do appreciate it.

[johnb80]

they said thyat this was a 'sensor that would normally be fitted in the airbox, but because the airbox was replced with a KN type filter when the LPG conversion was done, the sensor had been fitted to the pipework.

sounds like yet another bunch of hapless mechanics.

 

 

There are no sensors fitted in the "airbox", the MAF sensor is fitted between the airbox and the turbo in the pipework - always has been.

 

Come on Seatkid, pay attention it's a V6 and doesn't need a Turbo, it can waste enough fuel all by itself :o

[Guest vr6galaxy]

Ok remove all the hoses, maf, air filter and work back from the throttle body connecting things up and taking test runs till the problem occurs, with a couple of blow backs it's possible you have taken the MAF out! or even scorched the inside of the air filter and blocked it slightly? when you do reconnect the MAF dont plug it in, try running the engine with out it as the ECU will drop back to preset parameters and makje do without it

another thought is that you have taken out the throttle body sensor! in one of the blow backs! I hope not as they are not cheap! although my spare only cost me

[Guest vr6galaxy]

another thought! the loose plug they found? is it the one for the crank case breather valve? if this valve is duff? or the pipes are open to the atmosphere it can cause running problems! rough tick over, variable tick over speeds, and possible air fuel ratio fault as this air is inserted into the loop after the MAF sensor!

[Guest djdoylie]

Firstly a BIG thankyou for help here.

I have now made some progress.

I took the entire Air filter to air intake (on engine) components off. I put some silicone in the joins to the 'gas ring' pipes. I then put jubilee clips around every part where pipes joined.

SUCCESS!!!!!!

The car now runs fine on petrol, I even THINK that the MAF sensor still works as I have plenty of power at all revs. ....... mind you, when i disconnect it, it still runs ok, so maybe I am wrong here.

Is there anyway to test if a MAF unit is working properly?

 

I am still having a problem with running on LPG. It switches over just fine, and if I am featherlike in the accelerator it's ok too. However if I accelerate medium to hard I get a blowback (at the front). I have not had the spare time to be able to get it booked into my local LPG specialists as december is very busy for me (I'm a dj). Anybody have any ideas?

 

A couple more thingies (you guys have been so good, I may as well try to take advantage of you again) .......

 

When removing the air filter piping I found a rubber pipe 'underneath' which has a palstic / nylon 'T' piece joined in it, the leg of the 'T' is a small nozzle (a vacuum nozzle - as when the engine is running and I put my finger on the hole of the nozzle I can feel the 'suck'). This looks like it should be joined to something. I've looked for a loose pipe and things, but can't find where it is supposed to go. Anyone got any ideas?

 

The other thing is, on the left side of the top of the engine (looking from the front of the car) is a black box unit, this has a pipe coming out of it that goes into my 'air ducting pipe' after the MAF filter but before my 'gas ring' (this MAY have originally gone into the airbox? I am only guessing). Anyway, this pipe has a plastic / nylon 'joiner' which has an electrical connection on the top of it (two wires in the connection). Now when I took this off to put the jubilee clips on the joins I took a look at it .... it looks directional as it has 'arrows' in the moulding (so I put it with the arrows in the direction of out of the black box and towards the 'air ducting', the problem is that I did not see any electrical connectors for the connector to make contact with - the whole thing looked like a nylon 'dummy unit', when you look through the 'pipe' it is not fully round though - it is flattened off at the top, again this all looks like it is just nylon. Anybody know what this is? What does it do? Is mine a 'real' unit?

 

Once again, MANY thanks for your help. You guys are great. Steve.

[Guest djdoylie]

I've been told that the plastic 'T' piece is part of the fuel tank venting system, but the guy that told me was unable to say where the 'open' part of the 'T' was supposed to be connected to. Any ideas?

[Guest vr6galaxy]

Carbon canister, tucked up behind the wheel arch liner drivers side wheel arch, the canister collects the fumes from the petrol tank, stores them and via a valve switched by the ECU allows the fumes to be sucked into the engine and burnt off :( sounds like who ever did the LPG install and fitted the filter kit had no idea of what they were they doing! and unplugged hoses left right and center with no idea of where or what they did and no clue of where to stick them afterwards!

[Guest djdoylie]

Thanks vr6galaxy - you are a hero!

 

Thanks another thing out of the way .... shouldn't be too long and I'll be all sorted.

 

I've found some old paperwork from when I bought the car showing who did the LPG conversion. I am hoping to find out the makers of the control unit which, when found, should allow my local LPG place to sort out the LPG flow rate.

 

How about the nylon pipe / sensor thingy mentioed a couple of posts above? Any idea what that is anyone?

 

Thanks to all that read this, Steve.

[Guest marcusheawood]

A nylon thingummy with arrows on it? Not an NRV is it?

[Guest djdoylie]

NRV (non return valve?) It does not have any moving parts to it, so I am assuming not.

Thanks.

[Guest vr6galaxy]

Any chance of a picture of the engine bay and the parts you need to know about?

[Guest djdoylie]

I'm a bit too busy to be able to do any pics at the moment.

I've done a bit more to the system.

I have completely taken hosing from the air filter to the input off.

I cleaned the MASS sensor 'blades' with electrical contact cleaner then a bit of WD40.

The 'gas ring' bit is a cheapo looking nylon/ plastic setup that looks very heath robinson.

Does anybody know if this eBay Variable Piston Mixer ( item 4597556630 ) would be a better choice.

I have removed the 'gas ring' and made sure all hose connections are tightly fitted back on.

I disconnected the battery earth for half an hour. I beleive that this resets the ECU. I will now run on petrol only for a week for the car to be (hopefully) setup right.

If the VPM mentioned above is recommended I will fit that.

What about the standard airbox - does anybody have recommendations / comments about that ... I had a couple of Scorpios that ran better with after market K&M cone type filters (the original boxes caused rough running at slow speeds when hot and would fall apart if you got a 'blowback'. Are the airfilter boxers for the V6 the same as those for the 2.0 and 2.3 petrol engines?

The little plastic 'T' piece vaccum connector does indeed go to a carbon cannister, but not the 'open leg' of the 'T' ... one of the pipes from the top of it goes to the cannister and the other side of the top goes to the 'engine' .... I cannot see wher the 'leg' is supposed to go (and there is not a lot of options due to the length of the pipe) Any ideas?.

The other 'Plastic sensor pipe' does indeed look even more like a 'dumy unit' .... I'll try to take a pic of it sometime.

Thanks for reading this guys, any answers always appreciated.

[Guest djdoylie]

Well I've been running on 'just petrol' for a couple of weeks now - having disconnected the battery to reset the engine management.

It seems to run fine except that whenever I start from cold I get little 'backfires' - usually two or three before I get to the dual carriageway (when, I suppose, the car warms up and the problem is no more).

They are not massive backfires, but they obviously should not be there - and (obviously again) I should get this sorted before moving on to the lpg.

The 'backfires' seem to be at the 'front' of the drivers position (rather than behind, from the exhaust). They also seem to come when the auto changes gear.

Note: I still have the 'big KN type' air filter fitted.

The 'plastic 'T piece' vacuum thingy (see earlier in thread) is still unconnected to anything on the 'leg end'.

Any suggestions guys?