Topic: Occasional misfire! (Read 15201 times)

PtP · « **on:** September 17, 2008, 01:45:34 PM »

I’ve noticed over the last couple of months a random occasional misfire on my 4.0 TJ. I can be driving along at a steady speed with virtually no obvious movement in of the accelerator and out of nowhere the engine will give a split second misfire and then carry on. Sometimes the misfire will then repeat after a couple of seconds or it might not do it again!

I fitted new plugs around 10,000 miles ago and that’s about it on the electrical side of things.

I nearly always give the engine a good jet-wash after it’s been in mud and I’m wondering if I’ve got water in the TPS.

The inside of the distributor is dry and has been sprayed with WD40 as have the plug leads etc.

Anyone had a similar problem or where should I start?

eastryjeep · « **Reply #1 on:** September 17, 2008, 02:16:05 PM »

If youve got a crank position sensor on the bellhousing that would be my first guess!

JohnFuk · « **Reply #2 on:** September 17, 2008, 02:26:54 PM »

Just had the same thing on a mates VW. It ended up with it being the HT leads.
They were breaking down with the vibration.

wildwood · « **Reply #3 on:** September 18, 2008, 05:49:16 PM »

Throttle position sensor (TPS) on the throttle body.
Had this same symptom last year, just as you described.
Swapped out the TPS and no probs again.
They don't like extreme saturation, mine got a dunking at Tong was OK up to then.

Dave69 · « **Reply #4 on:** September 18, 2008, 07:21:57 PM »

what you could also do is whip the plugs out and give them a good clean, 10k miles without them being cleaned is alot of miles as i see it

PtP · « **Reply #5 on:** September 18, 2008, 09:36:07 PM »

I've done about 20 miles today and it ran without missing a beat. :-)

Bubba · « **Reply #6 on:** September 18, 2008, 09:41:27 PM »

start it up in the dark wiggle the leads and look closly at dizzy cap see if you can see any small sparks from the ht system.......wear a rubber glove if feelin wimpy

PtP · « **Reply #7 on:** September 18, 2008, 09:44:57 PM »

Quote from: "V8 Bubba"

.......wear a rubber glove if feelin wimpy

I'll wet my hands and I should find it a bit quicker! :lol:

Bubba · « **Reply #8 on:** September 18, 2008, 10:01:18 PM »

if you are feelin tough use ya tongue

PtP · « **Reply #9 on:** September 18, 2008, 10:11:29 PM »

Quote from: "V8 Bubba"

if you are feelin tough use ya tongue

I've got to keep it clean for later! :lol:

Dave69 · « **Reply #10 on:** September 19, 2008, 07:59:03 PM »

Quote from: "V8 Bubba"

if you are feelin tough use ya tongue

i bet you have done that on a 9v battery LOL

Tank · « **Reply #11 on:** September 20, 2008, 12:36:12 AM »

Quote from: "Dave69"

Quote from: "V8 Bubba"
if you are feelin tough use ya tongue

i bet you have done that on a 9v battery LOL

All the time......what a Buzz!!!!! :wink: :wink:

eastryjeep · « **Reply #12 on:** September 21, 2008, 06:01:27 PM »

Sorry I'm confused here, what do you need to keep your tongue clean for :?:

Tank · « **Reply #13 on:** September 21, 2008, 08:01:58 PM »

Sure i heard something about a pussy....... :lol: :lol:

PtP · « **Reply #14 on:** October 01, 2008, 01:16:32 PM »

I’ve just fitted a new set of Bosch Platinum+4 plugs and whilst doing the last one, No. 6 Cyl. I pulled the plug lead off the distributor cap only to find the terminal had pulled straight out of the cap too! :-)

PtP · « **Reply #15 on:** October 01, 2008, 07:55:09 PM »

I’ve fitted a new cap and so far the misfire seems to have gone, :-)

Here is a photo of the problem I had with the cap

This shows the only sign of cracking inside the cap too

I suspect the cap is the original from 1997 with 60,000 miles on it, but I’m wondering if the burning on the end of the terminal is okay. What do you think?

Roland · « **Reply #16 on:** October 01, 2008, 08:01:14 PM »

yup that's normal. Did you change the rotor as well :roll: :?:

PtP · « **Reply #17 on:** October 01, 2008, 08:06:20 PM »

Quote from: "Roland"

yup that's normal. Did you change the rotor as well :roll:

Nope! Should I?

TJMart · « **Reply #18 on:** October 01, 2008, 08:10:11 PM »

i would

MOCAJ · « **Reply #19 on:** October 01, 2008, 08:14:03 PM »

and me

Bishops Finger · « **Reply #20 on:** October 01, 2008, 08:16:47 PM »

Err yes from me as well!

PtP · « **Reply #21 on:** October 01, 2008, 08:23:01 PM »

What is there that can go wrong with it?

scrw · « **Reply #22 on:** October 01, 2008, 08:46:54 PM »

Quote from: "Bishops Finger"

Err yes from me as well!

:lol:

TJMart · « **Reply #23 on:** October 01, 2008, 09:01:22 PM »

Bubba · « **Reply #24 on:** October 01, 2008, 09:02:01 PM »

stew can explain

Author Topic: Occasional misfire! (Read 15201 times)

eastryjeep

JohnFuk

Tank

eastryjeep

Tank

Roland

TJMart

Bishops Finger

scrw

TJMart