Misfiring/Power Loss D2 woes - please help

[lifestyler]

Hi all,

I'm not sure if anyone can help me out but I'm having an issue with my 99 D2 V8.

Basically, when I start it in the morning, it runs very rough and if I put my foot on the accelerator while stationary, it splutters and misfires. When it's warmed up then it doesn't splutter (most times - see below).

OK, so now it's idling OK (still a bit rough though).

I drive it and there is a major loss of power - acceleration is really bad - even a 4 cylider car could beat me hands down. If I try to drive it before I let it warm up, it *seems* fires on about 6 cylinders - lots of misfires...grrr.

On two occasions, it has surged at around 60/70km/hr (quite violently - like starting a large lorry/truck wrong - that kind of surge). To stop the surging, I have to take my foot of the accelerator and then accelerate again "slowly".

On the highway when I try to pass a car, it seems to take forever - no "beasty" grunt it should have...this I miss.

On a number of occasions on the freeway, when I'm pi$$ed off at it, I put my foot down and it then accelerates to 120 km/hr at 5000 rpm (approx) and doesn't change gear. I have to back off then accelerate again for it to change correctly.

So the two issues are power loss and misfiring. I've listed all the other things in case anyone can point me closer to the prob.

I put magnecor leads in and no difference. Pulled the plugs and they have a little black soot around them but seem to be fine otherwise. Have "free flow" catalyctic converters in and there is a slight power increase there.

Anyhow, if someone out there can help me, it would be very much appreciated as I'm stuffed if I know what to do.

Cheers from oz.

Erron

 

[Plain2000DII]

My guess, and I emphisize guess, it's your VSS sensor. But lately I've just found it better to wait for Chris to do his previously mullet-headed reasoning and really figure out what it could be..... rock on St. Louis, we'd be lost without ya!

 

[Chris-St Louis]

Hi all,

Oh shoot David, Your making me blush.

I'm not sure if anyone can help me out but I'm having an issue with my 99 D2 V8.

Are they using the Motronic Fuel Injection down under like here in the states?

Basically, when I start it in the morning, it runs very rough and if I put my foot on the accelerator while stationary, it splutters and misfires. When it's warmed up then it doesn't splutter (most times - see below).

Is this car OBD2 Compliant? Do you get a check engine light?

OK, so now it's idling OK (still a bit rough though).

I drive it and there is a major loss of power - acceleration is really bad - even a 4 cylider car could beat me hands down. If I try to drive it before I let it warm up, it *seems* fires on about 6 cylinders - lots of misfires...grrr.

I'm kind of leaning toward fuel pressure at this point.

On two occasions, it has surged at around 60/70km/hr (quite violently - like starting a large lorry/truck wrong - that kind of surge). To stop the surging, I have to take my foot of the accelerator and then accelerate again "slowly".

Still leaning toward fuel pressure.

On the highway when I try to pass a car, it seems to take forever - no "beasty" grunt it should have...this I miss.

At least they make NOISE at full throttle.

On a number of occasions on the freeway, when I'm pi$$ed off at it, I put my foot down and it then accelerates to 120 km/hr at 5000 rpm (approx) and doesn't change gear. I have to back off then accelerate again for it to change correctly.

Still thinking fuel pressure, but starting to sound more like ignition.

So the two issues are power loss and misfiring. I've listed all the other things in case anyone can point me closer to the prob.

I put magnecor leads in and no difference. Pulled the plugs and they have a little black soot around them but seem to be fine otherwise. Have "free flow" catalyctic converters in and there is a slight power increase there.

Whose spark plugs are you using?

Anyhow, if someone out there can help me, it would be very much appreciated as I'm stuffed if I know what to do.

Cheers from oz.

Erron

 

[sammygon]

I'm having this same problem with my 99. No power and backfires until it warms up. Then its ok. It doesn't surge at high speeds though. I'm very curious about what it could be. I've checked the codes I mainly get right bank lean and left bank lean along with a bunch of misfires. I've cleaned the MAF but that didn't help. Currently I'm thinking O2 sensors but am just guessing. I hope someone has an answer.
-Sam

 

[lifestyler]

Hi Chris,

Haven't worked out this "quote" thing yet so I'm using the "old way"

BTW, thanks for your reply.

In answer to your questions:

>Are they using the Motronic Fuel Injection down under like here in the states?

I rang British Parts and they tell me the fuel injection system is Bosch...however my research revealed that Motronic is Bosch so I'm "assuming" yes...although I always tell people to never "assume"

>Is this car OBD2 Compliant?

Hmmm, not sure. I checked the ECU and the landrover model number is NNN100470 (it's a Bosch unit). The only doc I could find with this model number mentioned Motronic as well (an autologic doc). As for OBD2 compliant...hmmm...maybe...the doc I found says this re the ECU:

"Adherence to On-Board Diagnostic II (OBDII) legislation (where applicable)"

>Do you get a check engine light?

I assume you mean a light that indicates the engine needs checking. If this is the case then no, I don't get a check engine light.

>Whose spark plugs are you using?

Apparently they are Iridum plugs (have a thin electrode). When I pulled them, the average gap size was around 1.3 to 1.5mm.

Hope this helps Chris

Cheers and thanks in advance

Erron

 

[bishop13]

Apparently they are Iridum plugs (have a thin electrode). When I pulled them, the average gap size was around 1.3 to 1.5mm.

Sounds a bit overgapped. The Rave CD lists the gap at 1.00mm +/- 0.1mm in the Australian Owner's Handbook (at least I'm assuming its Australian, the file name is "Discovery Series II Owner's Handbook - Aus").

 

[Chris-St Louis]

Agreed. I think the gap is too large too. Get some properly gapped Champions in there....

 

[lifestyler]

Thanks all.

I'll pull the plugs and recheck the gaps - that was a visual estimation but I'm sure I saw some pretty large gaps there. I'll let you know how I go

I was told that they need changing every 100k and apparently they were last changed at 100k (now 150k). Maybe they weren't changed as stated...hmmm...is it every 100k they recommend new plugs?

Would that also cause the surging I was experiencing? Was it a new kind of "resonance" happening in the engine? Maybe there's a new way to design an engine for one of those "bronco bulls" here

Hmmm...

Cheers

Erron

 

[justinhaaga]

100k for plugs?! wow that is way too long, 25k at the lastest? I do mine every 10k though, hopefully a preventive to valve problems. 100k strong....

 

[lifestyler]

Hi again all

BTW, forgot to mention I am using the Champion Platinum plugs.

Before I buy plugs, what do you guys recommend I do?

Some time ago, I purchased Magnecor Electrosports 80 Leads (8mm - 55kV - 98 Ohm/cm) based on feedback on this website and was wondering if I should match the Bosch coil packs with the leads and the plugs.

My problem is that I have an electronic engineering background and I think about these things. Sorry

Based on bishop13's info for the gap to be 0.9mm to 1.1mm, should I make the shorter leads 1.1mm and the longer leads 0.9mm?

Since I have Magecor wires and less reistance, could I increase the gap size to get a bigger spark and more burn?

If I mucked around enough (re wiring so one pack serviced one bank), could I even move the coil packs right near the cylinders and use short leads with really big gaps and an even bigger spark and more efficiency?

Just thinking out loud.

Lastly, is it possible to regap the existing plugs?

Cheers and thanks

Erron

 

[Chris-St Louis]

EEs..... You guys ALWAYS overthink stuff.

You can regap the plugs... Set them all to 1 mm and reinstall. Champions are correct.

Lets try the cheapest-easiest thing first.... Setting your plug gap correctly.

 

[bishop13]

Since I have Magecor wires and less reistance, could I increase the gap size to get a bigger spark and more burn?

I always thought plug gap was independent of resistance from the wires.

 

[lifestyler]

bishop13:

I did some research and thought I'd share

The circuit for an ignition system is called an RL circuit.

The L is the coil that is connected to the spark plug and the R is the resistance of the lead and the gap. The resistance of the lead is minimal and the resistance of the gap is great so, yes you are right - the lead resistance should have little effect unless there is a major problem with the lead that causes extremely high resistance and, as such, no spark. If you have 100% good leads then it's all about the gap size.

The bigger the gap size, the greater the spark and the more effective the burn is...BUT, you have a higher chance of misfires. The smaller the gap size, the smaller the spark and the less effective the burn is...BUT, you have less misfires.

I assume (I did it again) that the 1.0mm gap size is "nominal" as recommended by Landrover.

BTW, the sharper the edges of the centre electrode, the better the spark too

A brilliant paper (Thesis) I found on EFI systems can be read at:

http://innovexpo.itee.uq.edu.au/2000/341482969/Thesis.PDF

Good general info about plugs is here:

http://www.se-r.net/engine/specialty_spark_plugs.html

Cheers

Erron

 

[bishop13]

Good stuff! Thanks Erron!

bishop13:

I did some research and thought I'd share

The circuit for an ignition system is called an RL circuit.

The L is the coil that is connected to the spark plug and the R is the resistance of the lead and the gap. The resistance of the lead is minimal and the resistance of the gap is great so, yes you are right - the lead resistance should have little effect unless there is a major problem with the lead that causes extremely high resistance and, as such, no spark. If you have 100% good leads then it's all about the gap size.

The bigger the gap size, the greater the spark and the more effective the burn is...BUT, you have a higher chance of misfires. The smaller the gap size, the smaller the spark and the less effective the burn is...BUT, you have less misfires.

I assume (I did it again) that the 1.0mm gap size is "nominal" as recommended by Landrover.

BTW, the sharper the edges of the centre electrode, the better the spark too

A brilliant paper (Thesis) I found on EFI systems can be read at:

http://innovexpo.itee.uq.edu.au/2000/341482969/Thesis.PDF

Good general info about plugs is here:

http://www.se-r.net/engine/specialty_spark_plugs.html

Cheers

Erron

 

[lifestyler]

Hi everyone...and a special hello to you Chris

OK, I pulled all the plugs again and I checked the gaps. I think my eyes are going on me as they were all 1.0mm+/- 0.1mm.

I then started the disco and ran it for around 30 seconds while two or more cylinders were acting up.

Turned the disco off and pulled the plugs again and I found 2, 4 and 5 were "medium sooty" while the others were OK.

I then started the disco again and it was rough as guts as usual. Put the foot down and it seemed like it was running on 5-6 cylinders. I even heard a backfire/pop (out the air-cleaner?) from under the hood when I pressed the gas down during the spluttering.

I remember when I did a carby job on my Nissan Patrol G60 and I switched a couple of jets around by mistake and when I put the foot down it was basically spluttering etc due to a rich mixture. Same sort of thing here.

Also forgot - would the "free flow" catalyctic converters reduce the pressue in the exhaust and, as such, cause the O2 sensors to read a lean mixture and then try to make it richer to compensate?

Anyhow, what do you think Chris? Others?

Help!

Cheers in advance

Erron

 

[Plain2000DII]

Sorry to hear your still out of luck. Let's go back to beginning, How long has this been happening? Did it just start one morning or has it been coming on for a while? were you bottle fed or breast fed? - sorry- Perhaps its a gas thing? bad tank of fuel? plugged filter? I'm unfamiliar with the Iridium plugs you mentioned, but many here including myself have good luck with just a plain old champion plug. You mentioned new Magnecor wires? are you SURE they're not crossed up?(hum.. reread your org. post, not likely) Have you pulled the MAF and looked for dirt, crud and the like? We'll keep helping - you keep trying...

 

[lifestyler]

Plain2000II:

It's been happening for a while. I'm going to insert some regular plugs and see what happens.

Here's a URL for plugs for the 99 D2 Petrol:

http://www.championsparkplugs.com/results_app.asp?AAIA=1377806

Cheers

 

[lifestyler]

Hi all,

I'm waiting on the plugs (yes, no-one stocks them) to install and I have found something else.

On another thread, someone suggested I look under the bonnet when it was dark.

Well, I did that and I found a "sparking/glow" at the tops of the plugs (under the boots I think), however I ALSO found light sparking at the left and right back of the engine where all the wires bunch up on the corner of the motor.

Is this normal for wires - to show blue "glows/sparks/lights" midway along the leads?

I did not spray any water on the leads and the leads are 8mm Magnecor.

Any help appreciated if anyone knows about this.

Also, if I had dodgy plugs, would this increase the flashover midway along the wires? When I put the new plugs in, would this flashover along the plugs reduce?


BTW, also testing fuel pressure tomorrow.

Cheers

Erron

 

[bishop13]

^^ I believe thats called cross-firing. I don't think it would cause any of the problems you've been having...unless its really really bad, I guess.

 

[Discoinjapan]

If your plug wires are arking then you need to change your wires!!!!!!!!!
The plugs arent receiving the spark they need.