Engine bad lifter? is it possible to test lifter before removing lower intake?

lizzard · Jul 18, 2018

hi
I have a 95 GTS 5.0
For almost five years I'm chasing my bad idle demon. Only at idle the engine is misfiring. from 1500 rpm and up there is no misfiring. Everytime when I stomp on the gas pedal after cruising I get a backfire. furthermore my quarterhorse shows that my fuel error is off by about 20%! (ecm pulling fuel because of misfire). The injectors are dialed in fine. only when I'm accelerating and decelerating the fuel error gets extremely off.
I already checked jrichkers idle surging list, no change
I checked every sensor, every Ignition component, cable, changed ECM etc.
no vaccuum leaks. engine pulls 20 in hg!
I even did check every electrical cable for voltage. yes! some cables were corroded, but I replaced them. Of course I replaced every ground cable with thicker ones.
And I did a engine rebuild one year ago. But: I didnt replace the lifters.
Could they be the culprits? I know bad lifters could cause bad compression and therefore misfiring issues.

So. before I remove the lower intake again and replace the lifters, is there a possibility to check the lifters if they work perfect?
I did also the pour-a-half-quart-atf-in-your-engine-oil-dude-method. I drove for about 100 miles. new oil and filter. no change.

any ideas? questions?

*EDIT*
Yes, I have strange lifter noises

a91what · Jul 18, 2018

pedestal mount rockers?? how did you set the pre-load on them?

lizzard · Jul 18, 2018

they have a preload of 0.20" - 3/4 turn after zero lash - 25 lb ft
I had to put shims (about 0.08") because I have new heads (ford racing x306)
(had the same problem also with the old stock heads)

*edit* and yes, they are stock pedestal mount rockers

RangerJoe · Jul 18, 2018

Only way I would know to check them is to roll each cylinder over with both valves closed, use an oil priming tool on a drill and prime the engine well. Then check and see if the lash is loose. Could also pump cylinders with air with both valves shut and see if you can hear or feel a leak past the valves.

Joe

lizzard · Jul 19, 2018

good ideas. But I don't understand why the second proposal: this is a kind of valve-leakdown-test. it hasnt anything to do with the lifters or am I wrong?

RangerJoe · Jul 19, 2018

lizzard said:
good ideas. But I don't understand why the second proposal: this is a kind of valve-leakdown-test. it hasnt anything to do with the lifters or am I wrong?

I was just thinking it would help rule out a valve being hung open. That can cause backfires as unburned vapors push into the intake.

Joe

Mustang5L5 · Jul 19, 2018

Have you had the engine apart before thisvstarted?

I'm thinking I'd suspect and slipped manifold gasket before a bad lifter

lizzard · Jul 19, 2018

Mustang5L5 said:
Have you had the engine apart before thisvstarted?

I'm thinking I'd suspect and slipped manifold gasket before a bad lifter

No, I had bought the car already with this issue.
I had the engine apart a year ago. I had replaced all bearings, compression rings etc. but not the lifters. the push rods are not bent btw.

If it would be a slipped gasket the engine would not pull strong 20 in Hg vaccuum? and there are no coolant leaks

lizzard · Jul 19, 2018

RangerJoe said:
I was just thinking it would help rule out a valve being hung open. That can cause backfires as unburned vapors push into the intake.

Joe

Yes of course. Thanks!

Mustang5L5 · Jul 19, 2018

lizzard said:
If it would be a slipped gasket the engine would not pull strong 20 in Hg vaccuum? and there are no coolant leaks

It would be an internal leak, leaning out your mixture cause lean backfires. Unsure how it would affect vac reading

mikestang63 · Jul 19, 2018

YOu can test the lifter with the engine off push down on the rocker/pushrod- if the pushrod goes down more than a slight amount the lifter has collapsed
The lifter could also be sticking- pour about 4 ounces of Marvel Mystery oil on each head . That does a good job within a few hundred miles of freeing up sticky lifters.

ALso, if the valves are not properly adjusted with the right preload/torque that will produce a tick. with the valves closed and on the base of the cam lobe- you should see both rockers all the way down, try and move the pushrod up and down and spin it. there should be no movement.

lizzard · Jul 20, 2018

thanks guys. I'll report later with the results.

FYI: I meant afterfire rather than backfire. there are a lot of people who use backfire for both definitions.
In my case I'm very sure it's a afterfire somewhere in the front part of the exhaust.

What could cause this afterfire? collapsed or sticky lifters or both? I'm thinking collapsed lifters would cause the valves to open in a unsufficient amount and duration (lifters=too short). therefore they could cause a lean misfire. Sticky lifters however would cause the valves to stay slighty open when they should be totally closed(lifters=too long with preload). that could lead to bad compression, misfire and maybe afterfire? it that true or am I wrong?

BTW I found a video from scannerdanner. it shows a 2007 Dodge Caravan/Chrysler Town and Country 3.8L with a misfire.
The symptoms are the same like on my car.

View: https://www.youtube.com/watch?reload=9&v=uB9XCDO8oa8

lizzard · Jul 31, 2018

ok thanks for your help guys, I did push down all rockers/pushrods. they all don't go down. but I could twist all pushrods. Is that normal?
I tried Marvel Mystery, absolutely no change after hundred miles. always bad idle and a lot of ticking when the engine is hot. It's very frustrating!!!

I also found out that every rocker has a sideplay (0.02") when pushing from the side. But I suppose that is normal, isn't it? I will load up a movie soon.

BTW the shaft of the dizzy is very hard to turn by hand (see another thread). Of course outside of the engine.
https://www.stangnet.com/mustang-fo...ibutor-shaft-hard-to-turn-bad-bearing.904999/
but I had the ticking noise problem also before I replaced the dizzy.

ok, while I'm at it I will replace the lifters. I already received new ones.
Any other ideas?

***EDIT****

View: https://youtu.be/WJelQ3Kxago
ROCKER SIDEPLAY MOVIE

mikestang63 said:
YOu can test the lifter with the engine off push down on the rocker/pushrod- if the pushrod goes down more than a slight amount the lifter has collapsed
The lifter could also be sticking- pour about 4 ounces of Marvel Mystery oil on each head . That does a good job within a few hundred miles of freeing up sticky lifters.

ALso, if the valves are not properly adjusted with the right preload/torque that will produce a tick. with the valves closed and on the base of the cam lobe- you should see both rockers all the way down, try and move the pushrod up and down and spin it. there should be no movement.

Engine bad lifter? is it possible to test lifter before removing lower intake?

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