Renix back fire and lifter tick

My 87 Waggy XJ got ticked off again today, LOL. It has done that for >10 years, lifter tick that comes and goes, been that way for 70,000 miles.

Today, when still warming up, 0-30 mph, local 10 minute trip, it decided to develop a slight back fire in the intake, and had low power on take off from a light, last maybe 2 minutes, then the tick vanished (as it usually does) and the back fire and power loss vanished.

Once again the rest of the day it ran better than it ever has, like has been for the last 3-4 months.

My first task is check the #1 and #2 spark plugs that are known to foul from leaking valve guide seals (worn valve guides...on the to do list head job that includes new lifters too), and known to cause power loss at the bottom end from oil fouled plugs #1 and #2, but there was no lifter tick those times.

But I thought the short term, weak back firing was worth noting here.

I will update my findings that I come up with as I get the chance to inspect it, etc.

I recall it back firing once, real bad, many years ago and blowing the vacuum hose to the MAP sensor off the throttle body, and then it really ran like shit. That was an EASY fix!!!:clap:

First things first. Do a wet and dry compression test.

Go out at night with no lights around and open the hood. Look for cross arcing on spark plug wires.

Put a vacuum gauge on it.

old_man said:

First things first...

Put a vacuum gauge on it.

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I was holding my tongue, waiting to see what Mike came up with. :shhh:

Hypoid said:

I was holding my tongue, waiting to see what Mike came up with. :shhh:

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It ran perfectly again today, second time this year it has fixed itself with a bizarre issue LOL. Last time it was temp gauge that went into boiling over range and driver's side window that stopped working. When I parked the jeep in Park, they both suddenly fixed themselves, about 8 weeks ago LOL.

I think yesterday was the # 1 and #2 spark plug fouling issue again I have been dealing with for 10 years, that has gotten worse the last 2 years. Hotter spark plug has helped the last year, NGK FR5 iirc. This is worn guides on Cyls 1 and 2, only. It hick ups when the ground to center pin get fouled. Usually a hard run at 3000 rpms for 60 seconds cleans it. After about 1-2,000 miles I pull them and clean them.

Just got a spare head and been rounding up parts for a full head job. But at first yesterday, it seemed a little different, but when I slept on it I recalled 1-2 prior hick ups just like this one that were fouled plugs on 1 and 2.

When the weathers clear up I will pull them, and see how bad they are.

Here is an old post, spark plug photos, from about 4 years ago when it got real bad, before I installed new valve seals.

http://www.naxja.org/forum/showpost.php?p=245795503&postcount=1

A year ago I tried the NGK FR5 plugs per Cruiser54 and added Lucas additive, and got a huge improvement. But the valve guides are an issue.

hows your grounds? could be a faulty wiring to an injector that grounds out the control side and causes the injector to get stuck open.

90xj06 said:

hows your grounds? could be a faulty wiring to an injector that grounds out the control side and causes the injector to get stuck open.

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LOL, you are preaching to the Renix Ground god preacher here LOL.

Problem cleared itself up for two days and about 6 trips so far. Been too much rain to pull the plugs yet. 99.9% sure it is the same old plug fouling issue, that I had forgotten about where one of its tricks when a plug got fouled enough was to back fire a little and give me low power on acceleration in first gear. In my case, the plugs seem to clean them selves quickly in the early symptom flare ups, and I had been cleaning recently before they got the problem state....but I had let them go too long this time I think.