Volvo Community Forum. The Forums of the Volvo Owners Club

Forum Rules Volvo Owners Club About VOC Volvo Gallery Links Volvo History Volvo Press
Go Back   Volvo Owners Club Forum > "Technical Topics" > LPG, CNG & LNG - General Info and Issues

Notices

LPG, CNG & LNG - General Info and Issues Share experiences and problems

Information
  • VOC Members: There is no login facility using your VOC membership number or the details from page 3 of the club magazine. You need to register in the normal way
  • AOL Customers: Make sure you check the 'Remember me' check box otherwise the AOL system may log you out during the session. This is a known issue with AOL.
  • AOL, Yahoo and Plus.net users. Forum owners such as us are finding that AOL, Yahoo and Plus.net are blocking a lot of email generated from forums. This may mean your registration activation and other emails will not get to you, or they may appear in your spam mailbox

Thread Informations

FAQ Faults & Tips for factory Volvo Bifuel LPG / CNG

Views : 56745

Replies : 40

Users Viewing This Thread :  

Reply
 
Thread Tools Display Modes
Old Apr 7th, 2018, 14:09   #1
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default FAQ Faults & Tips for factory Volvo Bifuel LPG / CNG

Here’s an FAQ for factory Bifuel Volvos and after-market conversions running LPG / CNG.

Volvo were just about the first major manufacturer to bring both LPG and CNG cars to market.
The first few pointers will equally apply to those of you with aftermarket converted cars. The remainder are biased towards the rarer factory-fit 1997-2006 Bifuel cars. All the early 1997-2000 P80 cars and the later P2 V70s S80, S60s were fitted the same Necam/Koltec system.


These cars got an unjustly bad reputation. Volvo’s own support to their dealers was poor, and because the cars were not understood, dealers soon became frightened of them. Historically for similar reasons, and parts prices, the LPG / CNG conversion industry also avoided them. This left owners with limited options.

First the general points…
LPG or CNG gases are harder to ignite. Hence, whereas running petrol will be fine, running either LPG or CNG finds the weaknesses of any slightly tired, high-miler ignition system. Look to you plugs and coils first.

1) Steer clear of multi-point plugs. Spark plugs in these cars don’t want to be anything special. Good quality low-spec single-point are fine. Avoid Snake-oil LPG plugs, (NGK & Brisk brand etc). If you have the 5-pot B5244SG engine as fitted to the S80 & V70 factory Bifuels, you need Denso’s or NGK’s most basic plugs:

Denso K20PR-U
NGK BKR6ES

The S40
NGK BKR6es


Delivered to your door, a set of 5 will cost you no more than £10-12. There are no gains with ’so-called’ LPG plugs at 3-4 times the price. Brisk plugs might actually be worse.

IMPORTANT: Running petrol, there is an ongoing dispute about which is the correct plug-gap. Plugs are usually pre-gapped at 0.9mm. Running gas, reduce the gap to 0.7mm or 0.028 thou. Swapped every 15-20,000, I’ve found Denso K20PR-U at 0.7mm gap are best. Some will tell you wider gaps are fine, but often LPG or CNG will cause mis-firing to one or two cylinders. This is all the more prevalent if anything is tired, These cars are getting old. This brings me to…

2) Coil packs: These are a known issue. Combined with a wide plug-gap a car that runs OK on petrol runs lumpy on tired coil-packs with gas. Faulty coil-packs are easy to locate. With the car running, pull the connector from each respective coil-pack. The one that least effects smooth-running is your kiddy. Replace the plugs whilst you’re on…

The Necam System - Overview:
With an unjust reputation the factory-fit Necam system falls foul to many a bar-room mechanic. Mention Necam and you’ll struggle to hear anyone unable to resist telling you to be ripping everything out, and start again.
The issues the Necam system does have are usually sorted for under £200 - £400. A ‘better’ system, even if you install yourself, runs to £6-700 and the hassle. For most of us, the whole point of running LPG or CNG was to save money, and to put something else in there, a pro will want nearer £1700-2000.

The Necam system has a few known issues, and once you understand these, if all you want is for your car to run, it works well enough.

The Necam System
The Achilles-heel of the system is the hard working distributor / stepper motor assembly. Most issues come down to dirt and lack of maintenance and/or heat. Maintenance is made ever more awkward by the daft place Volvo have sited the distributor / stepper motor assembly on the post 2000 P2 Volvos. Pre 2000 P80 P1 cars suffer far less problems simply because the distributor / stepper motor assembly is mounted out of the heat on the bulkhead. More on this later.

Maintenance: Cleaning the distributor. (aka dizzy).
Because getting to it is such a faff, a short-cut on late cars is to pour injector cleaner down via the 16mm dizzy feed pipe. This sometimes works. LPG in particular is dirty stuff. The ‘heavy-ends’ clog the ‘V’ shaped slots found in the distributor giving poor starting and lumpy running. These ‘heavy-ends’ jam the piston of the expensive stepper motor. Hence often you’ll burn it out this way. It’s a hard-working part of your car. On the later cars getting to the stepper is a PITA. If you stepper motor was cheap, and a £40 item I wouldn’t worry. But it’s a £350-400 item, and that’s if you can find onet, he price and rarity of stepper motors makes this job not one to be skipped. Be aware, Volvo dealers want £65 for new stepper.

Cleaning is a 2-3 min job on early cars. On post 2000 cars look to 1-2 hours and grazed knuckles…

For 2001-2005 era S80 S60 V70s:

The stepper motor is even hard to find. It sits between the radiator and the engine block.

With the car running on gas disconnect the solenoid cable under the air box to purge the system of gas. Reconnect before you forget.

Disconnect battery. The distributor is close to some chunky cables that can supply lots of amps if you put a spanner in the wrong place!

Clamp the lower power-steering hose near the pump and disconnect the top hose and move out of the way. (Don't get oil in the alternator) Unbolt the dip stick pipe (10mm socket]. You don't have to remove it but it's easier if you do. Remove the pipes and cables and undo the 2 nuts on the distributor / engine bracket / rubber mount. Careful here, the rubber might be perished. If you do shear the rubber mount, Demon Tweeks Part No. FSEFPA905 - Facet Fuel Pump Mount x 2 will fit). Leaving the bracket on the distributor might be easiest. Remove; some jiggling required. Knuckles will be in fine order about now. Now replace those bracket nuts with wing-nuts. You'll be taking it off again in the future, so make it easy. And do not smoke!
Undo the hose and the two electrical plugs.

For pre 2000 era cars.
Sitting on the bulkhead, you can usually get away with leaving the distributor in place.

Removing the stepper motor from the distributor.
Remove 2 x 3mm Allen bolts and remove stepper motor. Careful here. Two reasons, 1) Shaft of stepper easily bent. 2) A* large spring washer about the size of a 2p bit, a large compression-spring, and if you’re unlucky a ball-bearing will fly around too. Watch yourself.

Unclip piston from the spring on the motor’s piston/plunger-tip* (note which way up piston goes - deeper side away from stepper to accommodate large compression-spring).

I don't recommend ever stripping the dizzy down. There’s rebuild kits sold on eBay for Necam, and usually these are not required. Unless the lower diaphragm goes (in the bottom of the dizzy) you'll not need those kits. If swished out with injector-cleaner. you don't need to strip either. LPG runs dirty compared to CNG but repeated applications usually shift the heavy-ends. Do this every 5-6000 miles.

Fill and leave to soak in injector cleaner. Put a 2p coin over the opening to stop evaporation of the cleaner and leave it for 2-3 hours.
Injector cleaner for petrol is ideal. Wynns or Comma is fine. Specialist LPG cleaner I think is the same stuff, but twice the price. Injector cleaner for petrol works for me.

Fill to 5-10mm from top. Put a large coin, (2p piece is good) over the opening and let it soak 3-4 hours. 2p is there to stop dirt and injector-cleaner evaporating.

You are cleaning the V shaped slots you can just about make out if you look to the bottom of the cylinder/barrel of the dizzy. In bad cases, a 0.15 mm and a pair of fine long-nose pliers to push the feeler through the slots works… just.

Put a pea sized or smaller ball of grease in the keyway on the stepper motor shaft (I do NOT mean the PISTON!). When you’rve done that lubricate the piston with GT85. Do NOT use WD40, it contains silicon. You will damage your 02 sensor. Assemble: Watch for the O-ring sitting on the neck of the stepper (usually Brown in colour). There's 1 x O-ring, a spring and a spring-washer between the stepper and the dizzy. Do not F*CK this up! Wrong assembly will see you cry in your beer. You will fry your control module. So be very careful - put this lot back in the orientation and the order as you found it. Do not omit the large spring washer.

The stepper motor is at the route of most of the bad-mouthing of what is otherwise a very simple system that works well. Keep everything clean and cool, and it all works well enough. Hence…

Moving your stepper motor.
If you own a later P2 2000-2005 car, and most of you do, I would strongly advise you to move your Distributor/ Stepper Motor Assembly. if the distributor is not cleaned ‘heavy ends’ will burn- out these motors, yet there’s another reason…

Sited such that cooked by the radiator, this heat is the source of many BiFuel Volvo problems. This location also turns a 2 mins cleaning job into a major ball-ache., hence it fails to be done. Move the Distributor/ Stepper Motor Assembly out of this heat, I suggest you remount it to the battery area, in cool air.

1) You will need longer hose (if I recall 16 & 8mm).
2) Lengthen the wiring. Solder these wires, DO NOT bodge this!

Use Scotchloks or Chocolate Block terminals or other idiocies. Electronic components need soldering! Do not use heating grade orange butane/propane hose. The stuff you want is marked CNG/LPG. Find the hose you require on eBay.

Volvo should never have located these motors in such a position. Come on, opposite the battery, the main ECU and transmission ECU gets their own air-cooled box! Move your stepper, left where it is, stuck in traffic-jam for 20 mins this summer, it'll cook.

Maintenance: Your stepper.
The stepper-motor is required to whizz a piston up and down in the distributor. It responds to your right foot as you move it.

There’s two versions of the Necam Stepper:
Type A version was fitted to some CNG versions and Vauxhalls, Opels and Transits. You’ll find those for £40 odd. Sadly, they only fit the S40, S60 and pre 1998 V70s.
Type B has a flat top and is unique to Volvo. All P2 V70 and S80 cars have these. it is hard to find. It comes with the aforementioned unique price.

Both CNG and LPG cars use the same stepper motor. The does distributor differs between CNG and LPG. The difference is the size of the V slots in the cylinder. Identified by Red or Green labelling, I think Red is CNG.

Maintenance: Filters
These were often omitted from the large 16mm feed pipe into the dizzy. This made things worse. These can be found on eBay for £5-6 when Volvo want £90.00!?

Common Faults:
Most are cleaning or stepper motor related:

1) Random cutting out:
If your Bifuel randomly cuts out... if you car runs fine, cuts out and then might, or might not, start right away, you have a stepper motor problem. Tomorrow it’s fine, ad infinitum, until it cuts out again. A known issue. Where cutting out is random in car that otherwise fine (once you have it running), it’ll be a stepper motor problem. This problem will gradually get worse, unless your car refuse to run LPG/CNG at all. This distinct from lumpy running and other issues.

2) Rough running only on LPG/CNG fine on Petrol:
Indicate problems with your regulator and/or distributor. First place to look would be a dirty distributor. Don’t leave it, else more costly parts will be damaged. See above.


3) Poor starting on Petrol is often a worn regulator diaphragm.
There’s is a bubble test. Details later.

That’s enough for today. I’ll do more faults later. Please put you queries to another post

WORK IN PROGRESS
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]
CNGBiFuel is offline   Reply With Quote
The Following 4 Users Say Thank You to CNGBiFuel For This Useful Post:
Old Apr 7th, 2018, 14:35   #2
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default

Variants: Necam EGI - Stepper locations.

Easy to keep clean, fire injector cleaner into the dizzy in 2-3 mins.
Attached Images
File Type: jpg CNG Mk1 V70 Alternative Mounting 01.jpg (100.8 KB, 152 views)
File Type: jpg Necam Installation.jpg (249.9 KB, 149 views)
File Type: png Late-P2-Install.png (128.7 KB, 119 views)
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Last edited by CNGBiFuel; Apr 7th, 2018 at 15:17.
CNGBiFuel is offline   Reply With Quote
Old Apr 7th, 2018, 14:50   #3
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default

I forgot to say this system is known as Koltec and/or Necam EGI. There's also a Necam GSI which is a different animal.

Here's one way to get that pricey Necam EGI stepper out of the heat. If I was doing it today, I'd move it to the right, by the battery and put a bit of old vacuum cleaner tubing pointing to it to keep it cool. After all, the ECU box to the left in this picture, gets its very own cooling tube. Why doesn't the stepper? I mean... it works far harder!

WORK IN PROGRESS...
Attached Images
File Type: jpg moveDizzy.jpg (109.7 KB, 156 views)
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Last edited by CNGBiFuel; Apr 7th, 2018 at 15:03.
CNGBiFuel is offline   Reply With Quote
The Following User Says Thank You to CNGBiFuel For This Useful Post:
Old Apr 7th, 2018, 15:07   #4
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default

S40 with cheaper Necam GSI stepper. You are lucky should you have one of these. Later cars are usually a PITA to get to the stepper, and when you do, cost £400.


S40 models share their steppers with Ford Transits and Vauxhalls, and are about £40-50. You can shoot some injector cleaner into the dizzy very easily.

I'll cover DFCO, vapour tests, fault-finding etc later

Be aware, of my prior 'Be aware' typo.

I wrote:

"Be aware, Volvo dealers want £65 for new stepper."

I'm afraid that's £650 at a dealer. As I write, elsewhere, these are £400+ (with a bit of hunting).


WORK IN PROGRESS
Attached Images
File Type: jpg S40.jpg (98.7 KB, 99 views)
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Last edited by CNGBiFuel; Apr 7th, 2018 at 16:31.
CNGBiFuel is offline   Reply With Quote
Old Apr 8th, 2018, 16:01   #5
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default

Necam EGI DFCO valve

There is a valve (DFCO) sitting in the bottom of the distributor. To test this, with the engine running, pull its plug-connector. Your engine should stop immediately.
If this test fails, the DFCO membrane is not working as it should.
Stretch the spring which sits under the rubber diaphragm/ membrane of the distributor. If this fix fails, you will need to buy one of those Necam distributor rebuild kits you see on eBay. Remove the aluminium cap at the bottom of the dizzy. Change the diaphragm/ membrane.

Sometimes the small rubber-tip of the DFCO valve is worn. Fortunately a new DFCO is not an expensive part. Be aware there are two versions of this part. Cost about £40 on eBay.

More on Dizzy cleaning
Clean the dizzy V-grooves with a 0.15 mm feeler gauge, but nothing larger. The kits usually come with one. The slots are soft and easily damaged. If one slot is particularly clogged, being made for a 6-cyl engine, swap it with one of the spare connections on the distributor.

The stepper motor itself is not easy to check without changing the part. Sorry.

To pressure-test the vaporiser and distributor you need an M6 screw thread. I’ll cover that when I’ve a mo’


WORK IN PROGRESS
Attached Images
File Type: png NecamDFCO 01.png (101.1 KB, 155 views)
File Type: jpg Dist Recon Kit 09-08-14 01.jpg (77.9 KB, 107 views)
Attached Files
File Type: pdf CleaningNecamDistributor English.pdf (54.2 KB, 80 views)
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Last edited by CNGBiFuel; Apr 8th, 2018 at 16:10.
CNGBiFuel is offline   Reply With Quote
The Following User Says Thank You to CNGBiFuel For This Useful Post:
Old Apr 8th, 2018, 16:51   #6
CNGBiFuel
Classic P80 1999 BiFuel
 

Last Online: Jul 17th, 2024 11:31
Join Date: Aug 2012
Location: 48mph Middle Lane M4
Default

If you've looked at the pics attached and think ah... maybe this is not for me, contact these blokes, and whilst they're on, have them move the whole shebang, ...

Professionals in the UK
Depending on where you are in the country, the LPG gas conversion specialists with Necam experience are:

Autogas 2000 - Thirsk
CRD Performance - Bolton
Gareth - Littlehampton (used to be AAG, not sure what he trades as now) I have his number somewhere (PM me)


I suspect we can add our very own classicswede of Anglesey to this list too.

2000-2003 cars have less room, madness for an assembly that needs the same maintenance as say, your air-cleaner
Attached Images
File Type: jpg VolvoP2NecamLocation 05-07-16 01.jpg (75.9 KB, 120 views)
File Type: jpg VolvoP2NecamLocation 05-07-16 02.jpg (38.0 KB, 115 views)
File Type: jpg VolvoP2NecamLocation 05-07-16 03.jpg (34.8 KB, 113 views)
__________________
Bifuel V70 Classic 1999 [The Old Grumpy in the Corner, "When I was a lad... blah, bl**dy blah."]

Last edited by CNGBiFuel; Apr 8th, 2018 at 17:07.
CNGBiFuel is offline   Reply With Quote
Old Oct 9th, 2021, 22:20   #7
Andrewrennard
New Member
 

Last Online: Dec 8th, 2021 16:19
Join Date: Sep 2021
Location: Darlington
Default

Dear forum members I am reaching out to you knowledgeable fellows .I am the owner of a 2005 volvo s60 bi fuel CNG model I have relocated my gas distributor and had the stepper motor refurbished. My dilemma is I sent the old step motor away with the piston attached. When I received the refurbished step motor back the piston was with it but not attached how do I connect the piston to the arm of the stepper motor ..???
Andrewrennard is offline   Reply With Quote
Old Dec 23rd, 2021, 13:20   #8
Russki
Junior Member
 

Last Online: Apr 27th, 2023 16:57
Join Date: Feb 2017
Location: Gloucester
Default

Haven't been here for a while. I can share some documentation about Koltec system fitted to Volvos. It is a pretty good guide. The only trick is that its is in russian. If you can't read Russian please use Google translate. Hope it helps
Attached Files
File Type: pdf koltec.pdf (948.3 KB, 31 views)
Russki is offline   Reply With Quote
Old Aug 14th, 2024, 16:05   #9
dikidera
Member
 

Last Online: Yesterday 17:39
Join Date: Nov 2022
Location: None
Default

Some components of the CNG distributor PCB:

Two (potentially) 4946 Dual P-Channel 60-V mosfets.
Two (potentially) 4948 Dual N-Channel 60 V mosfets.
One BL05A - High-side Power Switch IC
One big tantalum capacitor 68535K

On the other side of the PCB:

One PIC microcontroller PIC16C622A with a program stored inside. Will dump later.
One crystal oscillator, potentially 8Mhz, not measured yet.


Last edited by dikidera; Aug 14th, 2024 at 16:13.
dikidera is offline   Reply With Quote
Old Aug 18th, 2024, 17:35   #10
dikidera
Member
 

Last Online: Yesterday 17:39
Join Date: Nov 2022
Location: None
Default

Quote:
Originally Posted by dikidera View Post
Some components of the CNG distributor PCB:

Two (potentially) 4946 Dual P-Channel 60-V mosfets.
Two (potentially) 4948 Dual N-Channel 60 V mosfets.
One BL05A - High-side Power Switch IC
One big tantalum capacitor 68535K

On the other side of the PCB:

One PIC microcontroller PIC16C622A with a program stored inside. Will dump later.
One crystal oscillator, potentially 8Mhz, not measured yet.

The PCB is/was produced by SONCEBOZ. If you open up this link you will find pretty much the same stepper motor, albeit without driver. https://sonceboz.com/product/flowregulation/
dikidera is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 10:21.


Powered by vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.