I think I FINALLY found the source of my dying engine!
8/27/08, 10:17 PM
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I think I FINALLY found the source of my dying engine!
As some of you may remember, I had a problem with intermittent engine dying several months ago. The cause of that issue was eventually traced down to a loose PVC elbow on my JLT CAI.
After fixing that, all was well for several months. Then it came back, but it was behaving differently.
Before, it would happen hot or cold, and usually not very often (once, twice a day). When it came back, it had a very definite pattern:
1) It never happened when cold
2) It never happened when the car was started cold and driven for a long time (say road trip)
3) It ONLY happened after the car had got fully warmed up and then was allowed to heat soak for an hour or so.
4) It would get VERY bad about dying (for the last week or so) shortly after starting up after the heat soak (but it had to go at least two or three blocks before it started to die), but would then get better as I drove until it pretty much went away.
5) Each dying was generally caused by some kind of sharp jolt. Road joints at bridges being the "almost always will" if it was after a heat soak.
Strange behavior, no??
Guess what I found tonight? The aluminum insert (that part that holds the MAF sensor and the air clean attaches to) had pulled out of the PVC pipe by about 1/8". When I went through the car on the original go around several months ago, there was an 1/16" gap between the flange on the aluminum part and the PCV pipe is slides into. I had run a bead of silicon sealant around that bead "just to be sure". Needless to say, the bead had fully pulled away from the aluminum fitting due to the increased gap.
While playing with it, I found that I could slightly twist the fitting in the PVC pipe. I'm sure the sharp jolts where causing it to twist slighly and adding a burp of air into the inlet pipe. Why this small amount of unmetered air could kill the car, I have NO idea. But these cares are VERY sensitive to unmetered air!
So, I took it out and took it to the shop for some disassembly work. What I found was the aluminum fitting had a pair of shallow grooves in them. The part was glued to the PVC pipe with some solvent glue. The glue SHOULD have filled the gaps and basically locked the part together were it can never come apart. It looks like on mine there wasn't enough glue used and it only had a small amount of glue in the groove in a couple of places. And those places had completely worn down due to vibration.
I have a can of Weld-On 4052 sitting on the shelf (plastic to plastic medium bodied solvent cement), so I clean everything up, apply a generous portion of glue to the aluminum and the inside of the PVC pipe, line it all up and press it back together and clamp it to let the cement set up. After letting it sit for a few hours, I went to pull it out of the clamps and take a look at it. Perfect fit. The PVC was tight up against the flange and everything looked beautiful.
Of course, when I went to put it all together, I realized that I STILL managed to get the PVC 180 out of phase with the MAF sensor!!!! Now, the fitting is on top! Needless to say, my attempts at pulling the aluminum part off COMPELTELY failed (using a makeshift slide hammer). That sucker is REALLY on there now.
After cussing for a bit, I went a head and bolted everything back up in my car. It does all fit (even with that stupid PVC fitting on TOP of the pipe now!), so at least I will be able to take it out for it's test spin/lunch tomorrow to see if this fixed the problem.
If so, I guess I need to get ahold of Jay and see how much just the tube will cost me...
And yes, I STILL feel like an idiot!
But it will be ALL worth it fit this does indeed fix the sudden engine quiting problem!!! I'll update tomorrow afternoon, but I am 99% convenced this IS the cause of the problem.
Here is how I see these particular parts being loose causing the symptoms I have seen:
1) When cold, the PVC has a snug fit against the aluminum, preventing any air leaks.
2) When the car is running, the cold air flowing through the pipe keeps both the aluminum and the PVC mostly cool.
3) When the car is heat soaked for a time, the aluminum absorbs heat and expands significantly (aluminum has a VERY large coefficent of thermal expansion). This is MORE expansion than the PVC would do, so the aluminum part stretches the PVC tube slightly.
4) When I drive off after the heat soak, the cold air flowing through the tube quickly cools the aluminum, which contracts back to it's smaller, original size. The PVC is mechanically stretched, so it takes a while for the plastics "memory" to pull it back down to it's original size. It is during this period that I have the sudden engine dying events for every little bump (and often just for the heck of it)
5) As I drive, the aluminum part stays cool (and small) and the PVC pipe slowly contracts back down to it's original size, causing the stoppages to get better and better until they go away completely because the parts are fitting tightly enough together that they can't wiggle enough to "burp" air into the inlet tract, causing the engine to stall.
6) As the alumium part was wiggling more and more out of the PVC tube, and the small amount of glue that was in the grooves got more and more worn away, the problem became more and more of an issue.
This actually makes perfect sense to me. I couldn't figure out how any of the other possible culprits (cam position sensor, crank position sensor, TPS, fuel pump, inertial switch, ECU, etc) could POSSIBLY behave the way the were with get bad after heat soak then getter better until the problem went away. It just didn't make sense! But the PVC/aluminum issue in the CAI DOES make sense!
We shall see!
After fixing that, all was well for several months. Then it came back, but it was behaving differently.
Before, it would happen hot or cold, and usually not very often (once, twice a day). When it came back, it had a very definite pattern:
1) It never happened when cold
2) It never happened when the car was started cold and driven for a long time (say road trip)
3) It ONLY happened after the car had got fully warmed up and then was allowed to heat soak for an hour or so.
4) It would get VERY bad about dying (for the last week or so) shortly after starting up after the heat soak (but it had to go at least two or three blocks before it started to die), but would then get better as I drove until it pretty much went away.
5) Each dying was generally caused by some kind of sharp jolt. Road joints at bridges being the "almost always will" if it was after a heat soak.
Strange behavior, no??
Guess what I found tonight? The aluminum insert (that part that holds the MAF sensor and the air clean attaches to) had pulled out of the PVC pipe by about 1/8". When I went through the car on the original go around several months ago, there was an 1/16" gap between the flange on the aluminum part and the PCV pipe is slides into. I had run a bead of silicon sealant around that bead "just to be sure". Needless to say, the bead had fully pulled away from the aluminum fitting due to the increased gap.
While playing with it, I found that I could slightly twist the fitting in the PVC pipe. I'm sure the sharp jolts where causing it to twist slighly and adding a burp of air into the inlet pipe. Why this small amount of unmetered air could kill the car, I have NO idea. But these cares are VERY sensitive to unmetered air!
So, I took it out and took it to the shop for some disassembly work. What I found was the aluminum fitting had a pair of shallow grooves in them. The part was glued to the PVC pipe with some solvent glue. The glue SHOULD have filled the gaps and basically locked the part together were it can never come apart. It looks like on mine there wasn't enough glue used and it only had a small amount of glue in the groove in a couple of places. And those places had completely worn down due to vibration.
I have a can of Weld-On 4052 sitting on the shelf (plastic to plastic medium bodied solvent cement), so I clean everything up, apply a generous portion of glue to the aluminum and the inside of the PVC pipe, line it all up and press it back together and clamp it to let the cement set up. After letting it sit for a few hours, I went to pull it out of the clamps and take a look at it. Perfect fit. The PVC was tight up against the flange and everything looked beautiful.
Of course, when I went to put it all together, I realized that I STILL managed to get the PVC 180 out of phase with the MAF sensor!!!! Now, the fitting is on top! Needless to say, my attempts at pulling the aluminum part off COMPELTELY failed (using a makeshift slide hammer). That sucker is REALLY on there now.
After cussing for a bit, I went a head and bolted everything back up in my car. It does all fit (even with that stupid PVC fitting on TOP of the pipe now!), so at least I will be able to take it out for it's test spin/lunch tomorrow to see if this fixed the problem.
If so, I guess I need to get ahold of Jay and see how much just the tube will cost me...
And yes, I STILL feel like an idiot!
But it will be ALL worth it fit this does indeed fix the sudden engine quiting problem!!! I'll update tomorrow afternoon, but I am 99% convenced this IS the cause of the problem.
Here is how I see these particular parts being loose causing the symptoms I have seen:
1) When cold, the PVC has a snug fit against the aluminum, preventing any air leaks.
2) When the car is running, the cold air flowing through the pipe keeps both the aluminum and the PVC mostly cool.
3) When the car is heat soaked for a time, the aluminum absorbs heat and expands significantly (aluminum has a VERY large coefficent of thermal expansion). This is MORE expansion than the PVC would do, so the aluminum part stretches the PVC tube slightly.
4) When I drive off after the heat soak, the cold air flowing through the tube quickly cools the aluminum, which contracts back to it's smaller, original size. The PVC is mechanically stretched, so it takes a while for the plastics "memory" to pull it back down to it's original size. It is during this period that I have the sudden engine dying events for every little bump (and often just for the heck of it)
5) As I drive, the aluminum part stays cool (and small) and the PVC pipe slowly contracts back down to it's original size, causing the stoppages to get better and better until they go away completely because the parts are fitting tightly enough together that they can't wiggle enough to "burp" air into the inlet tract, causing the engine to stall.
6) As the alumium part was wiggling more and more out of the PVC tube, and the small amount of glue that was in the grooves got more and more worn away, the problem became more and more of an issue.
This actually makes perfect sense to me. I couldn't figure out how any of the other possible culprits (cam position sensor, crank position sensor, TPS, fuel pump, inertial switch, ECU, etc) could POSSIBLY behave the way the were with get bad after heat soak then getter better until the problem went away. It just didn't make sense! But the PVC/aluminum issue in the CAI DOES make sense!
We shall see!
Last edited by RRRoamer; 8/28/08 at 09:51 AM. Reason: correcting solvent cement type
8/28/08, 09:06 AM
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This is why I do not mess around with oil separators in the PCV system. The tiniest leak can cause the engine to stall out. The OEM-equipped oil separators on ULEV cars and turbocharged German engines are far more complex and designed specifically for this application. The aftermarket oil separators are nothing more than air compressor in-line filters retrofitted for use on an engine.
8/28/08, 09:29 AM
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Isn't that the truth! For the life of me, I STILL can't figure out why these engines are SO sensitive to unmetered air. It only takes a tiny leak for the ECU to freak out and shut things down. Of course, the ECU isn't nice enough to actually write a diagnostic code to let us know WHY it freaked out either...
Last edited by RRRoamer; 8/28/08 at 09:57 AM. Reason: spelling...
8/28/08, 09:44 AM
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I sent an email to Jay Tucker of JLT Performance last night explaining what happened (I gave him the SHORT version!) and asked how much a replacement pipe would cost. Given that this CAI is over one year out of warranty AND the fact that I am the idiot that glued it back together 180 degrees out of alignment, I wasn't even THINKING about trying to get a replacement under warranty.
Here was Jay's reply this morning:
What can I say???
WOW!!!
That is the kind of customer service that will keep me coming back to a business. When he came out with the second version of this CAI, he offered to send the updated pipe to all of his customers for free because some of his customers had problems with the filter slipping on the original design. That level of customer service was one of the reasons I went with JLT in the first place.
It looks Jay hasn't changed his views on customer service over the last couple of years!
Here was Jay's reply this morning:
Always remember I'm here for my customers. If you EVER have a issue with my product contact me.
With that said, did you order this from us directly, meaning will I have your info.
I can send you a replacement pipe at no cost along with a return shipping label to get that one back.
Sorry this happened to you, but rest assured it's not a common problem.
So, what color?
Give me all your info and it's done.
With that said, did you order this from us directly, meaning will I have your info.
I can send you a replacement pipe at no cost along with a return shipping label to get that one back.
Sorry this happened to you, but rest assured it's not a common problem.
So, what color?
Give me all your info and it's done.
WOW!!!
That is the kind of customer service that will keep me coming back to a business. When he came out with the second version of this CAI, he offered to send the updated pipe to all of his customers for free because some of his customers had problems with the filter slipping on the original design. That level of customer service was one of the reasons I went with JLT in the first place.
It looks Jay hasn't changed his views on customer service over the last couple of years!
8/28/08, 11:46 AM
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Nice writeup, glad you figured it out.
8/28/08, 02:25 PM
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I'm just glad I finally found the source of the problem. I took it on an extra long trip before lunch to get it nice and hot for the heat soak. After lunch, I made several short stops before heading home.
No issues at all. I kept expecting the engine to die at certain places because the last week or so it ALWAYS died when I hit those bumps. I even found my hand resting on the key a couple of times... But, today all was good! No dying.
And Jay,
Thank you for stepping up when you literally didn't have too. It means a lot to me.
No issues at all. I kept expecting the engine to die at certain places because the last week or so it ALWAYS died when I hit those bumps. I even found my hand resting on the key a couple of times... But, today all was good! No dying.
And Jay,
Thank you for stepping up when you literally didn't have too. It means a lot to me.
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