Massive Misfires

C

capttyler1

Member
Jul 4, 2010
12
0
East Liberty, OH
About a week ago, my Disco started really struggling and vibrating. It did not take me long to deduce it had a misfire. I bought this LR used about 7 months ago. In that time, I have put new Magnecor 8mm wires on it as well as changed fluids and the like. I replaced the plugs a few days ago with Champion Platinums (gapped at .035). The old plugs were not in good shape. That helped a little but I still have the misfires. I always run 93 in the tank and I cannot vouch for what it had run in it before I bought it. The codes are as follows:

PO300
PO304
PO306
PO308
PO314
PO316

So I clearly have misfire issues. I did some searching on here but did not come across the amount of misfire codes I have here. So before I start slinging parts/money, my questions are this, is the coil the obvious next place to go? Would I get multiple misfires on only one side (cyls 4,6,8) with a bad coil? I read somewhere about the vehicle speed sensor having issues, does that have any bearing on this? Any help you guys could give me would be greatly appreciated. Any questions you have that I did not cover here, I can answer quickly.
 
P

peter sherman

Well-known member
May 10, 2004
3,072
0
Fake Forest, IL
hey man welcome!
first thing; do you have a copy of the rave? if not do yourself and us a world of favor find it download it.
the correct wire is in the correct place?
the boots are seated
whats your fuel press
 
azarmadillo

azarmadillo

Well-known member
Nov 7, 2004
795
1
Phoenix, AZ
www.chadmanz.com
I had a fuel injector go bad. It stuck open and was pouring fuel into the cylinder. So much in fact that you could see the exhaust manifold get wet when it was started. Engine ran horrible, vibrated and smoked really bad out the exhaust. New injector fixed it.
 
Last edited:
T

terrormachine

Active member
Aug 5, 2005
38
0
Texas
0316 is misfire at startup. 0300 is random and the rest are misfire on the numbered cylinders.

That being said, having misfires on one bank only can also mean sticking valves. If this vehicle never had a valve job, then it might be time for one.
 
SGaynor

SGaynor

Well-known member
Dec 6, 2006
7,148
162
52
Bristol, TN
If it was a bad coil, you would likely have failures at the corresponding drain side of the coil (see Rave - when a coil sends a "fire" charge, there is a plug it "drains" (sends negative charge) to), so you would expect to see balanced misfires (again, see Rave for the charge/discharge pairs). IIRC, you aren't seeing that.

I don't think you have that, so check your connections again. I misplaced a wire and threw numerous codes when I changed my wires.

Also, the standard gap is 0.40 (although some have recommended 0.50, just replace every year). And high end plugs have been widely panned; I use Champion copper 318/322 plugs, gaped at 0.40-0.50 and replaced every spring.

A bad injector is less likely since you have a whole bank throwing codes. MAFs are also culprits for multiple codes. however, I think you should check your wire connections (proper connections, order) and the plugs.

That said, that's from my limited (4 year) Rover experience, and what you described.
 
SGaynor

SGaynor

Well-known member
Dec 6, 2006
7,148
162
52
Bristol, TN
terrormachine said:
That being said, having misfires on one bank only can also mean sticking valves. If this vehicle never had a valve job, then it might be time for one.
Click to expand...
Didn't see the mileage/vintage...this could also be a culprit.
 
C

capttyler1

Member
Jul 4, 2010
12
0
East Liberty, OH
I have a RAVE but mine does not have the inline coil pack, it instead has the cap/rotor. Where could I get a RAVE for a 97? My connections at the coil and plugs have all been checked and rechecked. They are all in the correct position on the coil. I put the new wires on about 4 months ago and it had run fine since then. The RAVE cites a plug gap from like 0.033 to 0.038 so thats why I gapped 0.035. Per the codes, I do not have a misfire on cylinder 2 so it is not an entire bank. I also realized the strangeness of all the misfires on one side which led to me asking if I really would/could get misfires on one side without the corresponding 'odd' side cylinder having one also.

I am not an expert but would bad fuel pressure in the rail cause a single side failure? I kind of doubt I had 3 injectors go at the same time. And I am with you on the coil, I would have opposing failures. So the consensus seems to be the valvetrain right? If so, what should my next step be? Pull the cover? Or to the shop?
 
p m

p m

Administrator
Staff member
Apr 19, 2004
15,651
869
58
La Jolla, CA
www.3rj.org
If it has a single ignition coil, a distributor, and it's a 97 MY D1, it's a ROW truck.
In this case, forget everything that's been said about two-ended coils - it doesn't apply.
On the other hand, I don't know if a ROW 97 truck would have OBD-2 setup.

Where are you, PT?
 
p m

p m

Administrator
Staff member
Apr 19, 2004
15,651
869
58
La Jolla, CA
www.3rj.org
OK, I got it. Your truck does have a coil pack, like a 97 NAS D1 should, but your RAVE file is for a 94-95 model year.
You've got a wrong RAVE file - look for 96 and later D1.
Everything Scott said about the coils is correct.
 
C

capttyler1

Member
Jul 4, 2010
12
0
East Liberty, OH
Unknown at this point. I do not have the tools for a leak down test. I could probably jump in the fuel line for a pressure test there. Are you suspecting low pressure in the rail? Wouldn't I have more widespread issues than just the 3 cylinders? Please excuse my ignorance. I am fairly mechanical, it is just by no means do I consider myself a master mechanic or an expert on LRs.
 
You must log in or register to reply here.
Top Bottom