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YOUR RESEARCHStuck lifter: symptoms misfire on cylinder 4 intermittent
Reported or suspected cause
either a burned exhaust valve or bent valves
Reported cause
No successful repair reported for this finding.
1
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0
Suspected cause
0
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Reported cause
I know of two cases of persistent misfires, thankfully not with Porsche engines, that was due to either a burned exhaust valve or bent valves.
Stuck lifter: symptoms misfire on cylinder 4 intermittent
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Leading evidence: 'either a burned exhaust valve or bent valves' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'either a burned exhaust valve or bent valves' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Fill of the cylinder lta, or compression lta due' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
They were shipped in individual ,oil-filled snap-top containers.
Stuck lifter: symptoms misfire on cylinder 4 intermittent
Install perfectly
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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Performed · outcome unconfirmed
When they arrived, they had the correct part number,fitted perfectly but have insufficient miles on them to claim a 'win'.
Stuck lifter: symptoms misfire on cylinder 4 intermittent
Use last 7k miles was joe gibbs
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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Performed · outcome unconfirmed · Original poster
Oil used for the last 7k miles was Joe Gibbs, before that I imagine mobil 1 (previous owner).
Stuck lifter: symptoms misfire on cylinder 4 intermittent
misfire was triggered
Suggestion or failed attempt
No successful repair reported for this finding.
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Identified cause
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Suspected cause
In this case I suspect the misfire was triggered because the cylinder was out performing the other cylinders.
Stuck lifter: symptoms misfire on cylinder 4 intermittent
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30 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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So we went through the usual diagnosis for the misfire on cylinder 4. Coil was good, plug was good, injector was good. That left the lifters. Here they are. Misfire gone. Nice set of paper weights now to go with the XXX.
Nice photo and thanks for sharing. Is the center rod rotated since you removed it or it was that way when you removed it (the wear marks suggests the latter)? What were the symptoms again?
The lifter wiping marks being partially "off the lifter" may be on purpose. The lifter/cam lobe interfaces are splashed lubed. By having the lobe intersect/engage the lifter top like that exposes the lobe to a longer edge surface which is intended to supply more oil to the lifter lobe as it begins to press down on the lifter bucket.
Some answers:
Car had 39,000 miles and looks to be normal wear on the lifter surface.
Oil used for the last 7k miles was Joe Gibbs, before that I imagine mobil 1 (previous owner).
Symptoms, intermittent misfire that exhibited itself at idle. P0304. Would miss then go away. Didn't miss at high rpms.
The mechanism of failure was that the plunger in the middle (yes it is just rotated in the picture) rides the middle lobe (low lift), the outer ring rides on the high lift lobes but is pressed down during low lift operation. Once the high lift mode is engaged a pin is hydraulicly pushed in, locking the two pieces (plunger and outer ring) together. So as I would enter high lift mode and come down from it, the inner plunger would stick together with the outer ring, resulting in high lift at idle for that valve. As the cam beat on the lifter it would release and begin up and down operation in relation to the inner plunger resulting in low lift mode and regain proper firing of the cylinder.
The opposite, it would enter high lift and not come out of high lift. High lift at idle on the one valve caused a misfire either due to filling of the cylinder LTA, or compression LTA due to the partially open valve
Thanks.
My memory isn't 100% on this one so don't take this at 100%. I'm sure Jake will chime in and can either confirm or correct me if needed. IIRC #5 has failed historically a lot due to the lack of oil vs the others. I've seen and read about a lot more of 5 and 6 failures.
Gotcha. I remember bank 2 runs hotter hence more susceptible to taper/oval. Not sure about oil supply. I think the issue is the tiny oil hole on the lifter that's a dead end, which can trap debris and it can happen to any of the intake lifters.
Made a guess and guessed wrong. I was too lazy to put aside the laptop and get up out of my recliner and go look at a VarioCam Plus intake valve lifter I have around to refresh my memory of the failure modes.
Generally a misfire signals an under performing cylinder.
But in this case, the misfire was due to the #4 cylinder receiving a larger intake charge than the other cylinders. In this case I suspect the misfire was triggered because the cylinder was out performing the other cylinders.
Glad you resolved the misfire. It could have been worse. I know of two cases of persistent misfires, thankfully not with Porsche engines, that was due to either a burned exhaust valve or bent valves. In either case the head was removed to fix the valve problem.
Thank you ChicagoSpeed996 !!!
I had the exact same symptoms for a single cylinder misfire, except mine was on cylinder number 6.
We did all the "regular" investigating with everything looking good, then we dropped the engine and found one intake lifter seized or close to being seized. I can move the plunger in the other lifters with my hand/thumb force, just not that one.
The engine was put back together with all new lifters on that one bank of cylinders and I have no more misfire ... for now, and hopefully forever, or at least a very long time. It's only been 300 miles with no misfire at this point, but I am cautiously ELATED because we found the one stuck lifter.
Thank you again !!!!
The lifters are made by INA- Germany iirc. There have been several part number changes over the years. Same INA part number is used in other vehicles.
The mode of failure described is the most usual I have read about and my own engine suffered from this.
So the updated part number item should solve the problem.
The Porsche mark-up is very high. I took a risk and bought direct in Europe. I do not have sufficient use on the rebuilt engine to recommend this .I took the risk because the cost difference is huge.
Well, for me it was 8 hours to take the engine out and put it back in. Then 8.8 hours to replace the lifters. The intake lifters cost about $145 apiece and the exhaust lifters cost about $63 apiece.
You can do the math based on the labor rate in your area.
Schnell Gelb, you bring up some interesting points. The intake lifters we took out had 996-105-255-20 stamped on them and the new ones were listed on my invoice as 996-105-255-25, so it does appear there have been some changes, assuming the first number I gave is not a component number for a component of the intake lifter. (I'm just trying not to make any assumptions.)
So, how much do the intake lifters from INA cost?
I went to their website and the picture sure looks like my intake lifter. I've attached a picture of it from their website.
Mark,
I am reluctant to contribute to an engine disaster. So my reply is a bit cryptic. I beat this subject to death with research on the German Forums because I read German. Eventually I found some Interchange data for INA lifters. Then it was a matter of hunting down that part in other German/Jap/Euro cars and buying from the cheapest source for that specific INA number.I could not find any U.S. cars using that number. They may call it a "tappet' or a "cam follower".
When they arrived, they had the correct part number,fitted perfectly but have insufficient miles on them to claim a 'win'. They were shipped in individual ,oil-filled snap-top containers. Most leaked during airfreight !Lucky they were not condemened as a hazmat incident.
The bread crumbs start here:
http://www.elfertreff.de/
Schnell Gelb,
You will not be contributing to my engine disaster because I already had the Porsche parts installed. I'm just curious how much money could be saved. As I said in previous posts, I paid approximately US$145 per intake lifter. How much were yours from INA?
In this situation, unless I had a lot of data, if I have to or had to do it again I would be using the Porsche parts. I'm not a big gambler on items like this.
Since I paid a shop to do the work, most of the job is in labor.
Great investigative work on your part !
Schnell Gelb,
At this point, I can say I have no idea what you are talking about.
A $9 lifter?
Rock Auto only lists the Exhaust lifter for my car and it is at around US$40.
I paid around $63 each for the exhaust lifters. I'm fine with that.
The intake lifter is the expensive one, and that is what I thought we were talking about.
Frankly at this point it is irrelevant for me.
Me and my "new" daily driver are happy as clams with 500 miles under our belts with no misfire.
Good luck to you.
Mark
^I noticed the same thing^ (at Rock Auto)... $40 would have been a nice savings over $143 or whatever you paid the dealer, but it's water under the bridge at this point. At the very least, you can rest assured you got the correct part. Here's to no more misfires
