Help! Multiple misfires AGAIN - Land Rovers Only

bobthebuilder · 11-08-2006, 10:44 PM

Several months ago, on a regular basis, I would drive 50 to 80 miles and then stop for gas or at a rest area. As soon as I would start out again I would feel a strong shudder between 50 and 60 MPH. If I feathered the pedal or floored it hard the misfire would go away in a few miles. Occasionally the ck engine light would come on within a week. Codes were usually P0300, P0303 or 07 and P1316. It would never do this around town or when it was cold.
Last week about 50 miles from home the misfires stared up again. This time they won't go away and were constant between 2400 and 2600 RPMs. I checked the codes: P0300, P0303 and P1316.
Today I replaced the vehicle speed sensor and fuel filter expecting a cure.
I went for a 20 mile run on the freeway. Now it is shuddering and misfiring from 2000 to 2700 RPM and it never quits misfiring. It knocks so hard that I can feel it in the body and steering wheel.
After the warm up, I checked the codes again: P0300, P0306, P1316 and P1313
I drove around the block and the P1316 came back. I can hear what sounds like a rocker arm klack in the exhaust pipe, only one, and an audible misfire at idle.
What have I done to it? hammmered the injectors? bent a valve? developed a rod knock?
I'm about certain that LR couldn't correctly diagnose this, but maybe a forum member has run into a similar problem
97 disco 1, 99000 miles, 10K on LR installed plugs

Disco Mike · 11-09-2006, 03:41 AM

Maybe you have already answered these questions, how old are the plug wires, have you checked the condition and color of each spark plug, how about your coil pack, have you considered doing a decarboning on the engine since excess carbon will cause misfires.
Sound bad enough that you have already lost one cat.
Mike

bobthebuilder · 11-09-2006, 10:34 PM

Plugs have 10K, wires seem good, not weathered or cracked, don't know about coil packs, Can they be tested? I'll pull the plugs Sat and check condition. It was running so good two weeks ago and then went bonkers.

Disco · 11-10-2006, 02:40 AM

Before you start changing out your coil packs, try this little test. After dark, start your engine and spray a fine mist of water around the coils, sparkplugs and leads. If need be raise the engine revs to approx where you think it's missing. If you see an sparks anywhere that's where the problem is.

Disco Mike · 11-10-2006, 04:43 AM

Quote:

Originally Posted by bobthebuilder

Plugs have 10K, wires seem good, not weathered or cracked, don't know about coil packs, Can they be tested? I'll pull the plugs Sat and check condition. It was running so good two weeks ago and then went bonkers.

On the plug wires, looking at them won't get the job done, if they are factory type wires with 40K plus miles on them, they could just be shot. You can look for very small gery dots that would indicate they are shorting out, also do the night test otherwise you need to use a meter and read the resistance in each wire.
There is testing equipment to test the coil packs which should be done before you replace them cause they are expensive.
Mike

Hank · 11-10-2006, 05:29 AM

Carbon in the heads.

I had the same problem on a 99 D1 I had. I changed the plugs, wires, swapped coils, VSS, wires again, and ran BG244K. Come to find out, it was carbon.

Disco · 11-10-2006, 01:45 PM

Quite possible Hank, but it's cheaper to do the perlimenary tests first before tearing into the engine.

bobthebuilder · 11-11-2006, 01:48 PM

It was raining too hard to do much under the hood. I hooked up my 'pro-scan' and read the most recent codes. P0300, P0303, P1316 and P1313.
I set up the ocilliscope to read out all 4 O2 sensors, while test driving it.
3 appear normal but the Bank 1 sensor 2 is a virtual 'FLATLINE'. Could a bad
O2sensor be causing the shuddering under acceleration???

Disco Mike · 11-11-2006, 02:58 PM

Possible, but it won't cause the misfires.
If you do replace the O2's do all 4 of them because of your mileage.
May be time to look at a serious decarbon, may make a big difference.
Mike

bobthebuilder · 11-11-2006, 03:27 PM

Mike: All four? They're $145 to $160 each, unless there is a generic replacement. I looked at DAP and some other sites, any preference?

11-08-2006, 10:44 PM	#1 (permalink)
bobthebuilder Member Join Date: Jan 2006 Posts: 13 Gallery: 0	Help! Multiple misfires AGAIN Several months ago, on a regular basis, I would drive 50 to 80 miles and then stop for gas or at a rest area. As soon as I would start out again I would feel a strong shudder between 50 and 60 MPH. If I feathered the pedal or floored it hard the misfire would go away in a few miles. Occasionally the ck engine light would come on within a week. Codes were usually P0300, P0303 or 07 and P1316. It would never do this around town or when it was cold. Last week about 50 miles from home the misfires stared up again. This time they won't go away and were constant between 2400 and 2600 RPMs. I checked the codes: P0300, P0303 and P1316. Today I replaced the vehicle speed sensor and fuel filter expecting a cure. I went for a 20 mile run on the freeway. Now it is shuddering and misfiring from 2000 to 2700 RPM and it never quits misfiring. It knocks so hard that I can feel it in the body and steering wheel. After the warm up, I checked the codes again: P0300, P0306, P1316 and P1313 I drove around the block and the P1316 came back. I can hear what sounds like a rocker arm klack in the exhaust pipe, only one, and an audible misfire at idle. What have I done to it? hammmered the injectors? bent a valve? developed a rod knock? I'm about certain that LR couldn't correctly diagnose this, but maybe a forum member has run into a similar problem 97 disco 1, 99000 miles, 10K on LR installed plugs

11-10-2006, 02:40 AM	#4 (permalink)
Disco Super Moderator Join Date: Dec 2004 Posts: 1,819 Gallery: 0	Before you start changing out your coil packs, try this little test. After dark, start your engine and spray a fine mist of water around the coils, sparkplugs and leads. If need be raise the engine revs to approx where you think it's missing. If you see an sparks anywhere that's where the problem is. __________________ No hand signals, driver playing with his transfer Knob.

11-10-2006, 01:45 PM	#7 (permalink)
Disco Super Moderator Join Date: Dec 2004 Posts: 1,819 Gallery: 0	Quite possible Hank, but it's cheaper to do the perlimenary tests first before tearing into the engine. __________________ No hand signals, driver playing with his transfer Knob.

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11-09-2006, 03:41 AM	#2 (permalink)
Disco Mike Moderator Join Date: Aug 2004 Location: Parker, Colorado Posts: 5,131 Gallery: 0	Maybe you have already answered these questions, how old are the plug wires, have you checked the condition and color of each spark plug, how about your coil pack, have you considered doing a decarboning on the engine since excess carbon will cause misfires. Sound bad enough that you have already lost one cat. Mike

11-09-2006, 10:34 PM	#3 (permalink)
bobthebuilder Member Join Date: Jan 2006 Posts: 13 Gallery: 0	Plugs have 10K, wires seem good, not weathered or cracked, don't know about coil packs, Can they be tested? I'll pull the plugs Sat and check condition. It was running so good two weeks ago and then went bonkers.

11-10-2006, 05:29 AM	#6 (permalink)
Hank Banned Join Date: Feb 2005 Location: VA Posts: 914 Gallery: 0	Carbon in the heads. I had the same problem on a 99 D1 I had. I changed the plugs, wires, swapped coils, VSS, wires again, and ran BG244K. Come to find out, it was carbon.

11-11-2006, 01:48 PM	#8 (permalink)
bobthebuilder Member Join Date: Jan 2006 Posts: 13 Gallery: 0	It was raining too hard to do much under the hood. I hooked up my 'pro-scan' and read the most recent codes. P0300, P0303, P1316 and P1313. I set up the ocilliscope to read out all 4 O2 sensors, while test driving it. 3 appear normal but the Bank 1 sensor 2 is a virtual 'FLATLINE'. Could a bad O2sensor be causing the shuddering under acceleration???

11-11-2006, 02:58 PM	#9 (permalink)
Disco Mike Moderator Join Date: Aug 2004 Location: Parker, Colorado Posts: 5,131 Gallery: 0	Possible, but it won't cause the misfires. If you do replace the O2's do all 4 of them because of your mileage. May be time to look at a serious decarbon, may make a big difference. Mike

11-11-2006, 03:27 PM	#10 (permalink)
bobthebuilder Member Join Date: Jan 2006 Posts: 13 Gallery: 0	Mike: All four? They're $145 to $160 each, unless there is a generic replacement. I looked at DAP and some other sites, any preference?

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