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Discussion Starter · #1 · (Edited)
The car: 19 720s performance 15k miles, (i've owned for 5k), fresh oil change 1500 miles ago, fresh 93 octane shell gasoline, never tuned, ryft catless dp's and pure turbo inlets being the only mods.

Car performed flawlessly without any issues for 8 month and over 4,000 miles of ownership.

Then started chasing down a hesitation problem that developed 8 months into ownership occurring at the top of 3rd and 4th gear and p2539 fuel pressure fault. Identical to the problem taw6189 experienced with his car and was solved by replacing fuel pump and filter at mclaren: 720s hesitating/bogging during acceleration (WOT)

We drop the fuel tank find small amounts of metal in it not enough to hurt anything, clean all, replace fuel pump and filter, reassemble and find problem still exists. Next, ordered the superseded part # fuel pump controller from Mclaren and installed it. Did a handful of highway pulls and find problem to be much improved but still present.

Park the car for a couple days, then take it out to dinner, leaving the restaurant at a red light decide to launch it, hit the button and launch 1st,2nd,3rd gear.. then slowing down at the next light I feel a vibration almost like its misfiring. Shut it off at the light, start it back and notice the oil pressure light on. Immediately shut it off..

Get out and see all oil underneath it. Tow it to the shop, lift it and confirm it threw a rod out of the block.

Experienced no abnormal noises, warning lights, or any other issues leading up to it. Just a slight hesitation at ~7300 rpm in 4th gear and sometimes in 3rd.

I am baffled to say the least. I have video of the engine block and video of the highway pulls after the pump controller install.

No warranty due to "previous rental history"

All criticism and opinions or similar experiences are welcome. I feel that Mclaren is responsible for this.
 

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Wow, here I was thinking most problems are worked out by 10-12k miles (usually the warranty period) after which the car's relatively reliable, presumably. I guess I better keep an extended warranty going on till I hit 20k miles considering the engine can potentially self destruct like yours. I've seen several of the m838t units go past 50k miles and these days that's the least exotic car engines should last till. Germany91, sir, my deepest sympathies for you and even though this shouldn't have happened there's very slim chances Mclaren would do anything about it. Theyre notoriously tough to deal with at times especially when mods (even tiny ones that shouldnt be a problem) are concerned. '19 should still be under warranty and the rental history excuse sounds stupid (applicable to extended warranty but DOES NOT MAKE SENSE for factory warranty). The inlet pipes are not a mod but a fix as in it is preventative maintenance and the downpipes need to be proven as the culprit for Mclaren to rightly deny a warranty claim. Perhaps try reaching out to customer services, you can look up the email for north America online, they do repsond be it in a couple of days and they were helpful for my situation. It really sucks having something that gives us so much joy in such a state, i cant fully empathize with you sir, just hope you find some solace.
 

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Tough one. Not all rental cars are abused but a high proportion are. Over the last decade, McLaren engines - powertrains generally - have proven to be close to bulletproof. Certainly very robust. For all the criticisms you can level at McLaren, fragile engines aren't a common theme.

This is ultimately about who picks up the cost for the repair. Dare I ask, have you had a quote yet?
 

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I really feel sorry for you as you have an expensive repair coming (or you can take another gamble and buy an engine off the bay). Maybe look at it like spending the money you saved on the buy on the engine now - hope a rental was cheap to acquire at least. If you watch the videos of idiots spitting flames on rental cars etc you know why McL will never honor the warranty here, especially as you have mods round the engine as well.
 

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Yes I seen the others posts, very rare, if mclaren dont want to play ball. I would go ebay engine, I have seen a few. I think the chances of another one failing are very small. Ive spoken to a development engineer at mclaren and he said "its never happened to his knowledge" it could be a freak accident. either way its fing shit and im sorry.
 

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The car: 19 720s performance 15k miles, (i've owned for 5k), fresh oil change 1500 miles ago, fresh 93 octane shell gasoline, never tuned, ryft catless dp's and pure turbo inlets being the only mods.

Car performed flawlessly without any issues for 8 month and over 4,000 miles of ownership.

Then started chasing down a hesitation problem that developed 8 months into ownership occurring at the top of 3rd and 4th gear and p2539 fuel pressure fault. Identical to the problem taw6189 experienced with his car and was solved by replacing fuel pump and filter at mclaren: 720s hesitating/bogging during acceleration (WOT)

We drop the fuel tank find small amounts of metal in it not enough to hurt anything, clean all, replace fuel pump and filter, reassemble and find problem still exists. Next, ordered the superseded part # fuel pump controller from Mclaren and installed it. Did a handful of highway pulls and find problem to be much improved but still present.

Park the car for a couple days, then take it out to dinner, leaving the restaurant at a red light decide to launch it, hit the button and launch 1st,2nd,3rd gear.. then slowing down at the next light I feel a vibration almost like its misfiring. Shut it off at the light, start it back and notice the oil pressure light on. Immediately shut it off..

Get out and see all oil underneath it. Tow it to the shop, lift it and confirm it threw a rod out of the block.

Experienced no abnormal noises, warning lights, or any other issues leading up to it. Just a slight hesitation at ~7300 rpm in 4th gear and sometimes in 3rd.

I am baffled to say the least. I have video of the engine block and video of the highway pulls after the pump controller install.

No warranty due to "previous rental history"

All criticism and opinions or similar experiences are welcome. I feel that Mclaren is responsible for this.
Sorry for your loss - that hurts.

Metal in the fuel system would have concerned me enough to strip down the whole fuel system.

Catless DPs are a major mod, not to mention illegal for US road use. At least it wasn't that that invalidated your warranty.

It'd be interesting to see the disassembled engine and fuel system. Good luck with your repair.
 

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Since you were running catless downpipes what did you use to eliminate the CEL for the secondary O2 sensors.

HIgh revs and load on the engine in low gears most likely caused the rod to exit. If the oil is not up to temp and it is revved this may have also caused the issue.
This is an outlier case.

I don't think you hesitation problem has anything to do with this failure.
 

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Who fitted the dps? Its poss you experienced overboost a vac line could have come off one of the turbos so the ecu would have no way of controlling it. Have all this checked because these failures are really rare
 

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Discussion Starter · #9 ·
I didn’t eliminate the CEL for the secondary’s. I didn’t think catless dp’s would hurt the car in this way since I had so many trouble free miles and bought the car with the pipes on it.

2nd I believe the turbos are electronic and not vacuum.

3rd the car was at full operating temperature. I never rev a cold engine high. Also the rod bearing that has half of the rod still attached to it is perfectly smooth and definitely didn’t experience oil or bearing issues. I believe the issue occurred above the piston whether overfueled or detonated.
 

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Discussion Starter · #10 ·
The rear o2 sensors are plugged in. After a while set a efficiency fault due to no cats. After replacing the engine do I need to get it tuned to safely run it without cats? Is the computer smart enough to compensate in stock form? Do I need some type of bypass or wire extensions?
 

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I didn’t eliminate the CEL for the secondary’s. I didn’t think catless dp’s would hurt the car in this way since I had so many trouble free miles and bought the car with the pipes on it.

2nd I believe the turbos are electronic and not vacuum.

3rd the car was at full operating temperature. I never rev a cold engine high. Also the rod bearing that has half of the rod still attached to it is perfectly smooth and definitely didn’t experience oil or bearing issues. I believe the issue occurred above the piston whether overfueled or detonated.
yes you are correct sorry they are controlled electronically. if you can share some images, that would really help to determine the cause.
 

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The rear o2 sensors are plugged in. After a while set a efficiency fault due to no cats. After replacing the engine do I need to get it tuned to safely run it without cats? Is the computer smart enough to compensate in stock form? Do I need some type of bypass or wire extensions?
No you dont, the O2 sensors post cat, all they do is monitor emissions, nothing else, the pre cat o2s adjust the fuel, they are the important ones. Putting it simply, they are basically for knowing if the cats are doing their job or not. It would be a good idea to have the code deleted from the ecu after you have replaced the engine so you get no errors
 

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Wow, catless downpipes without a tune specially on a turbo car . Why would anybody do that ? That hesitation in the upper rpms was most likely a detonation
 

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Discussion Starter · #17 ·
you can run DPs with no tune my friend.
That’s what I thought too sir! Thank you. I’ve ran catless exhaust on many stock tune cars and have never had a problem. And they would not cause a fuel pressure fault anyways. I agree, I do believe it was detonation that killed it. But with all that was replaced being a car this new with not that many miles it’s simply not acceptable. We shouldn’t have to worry about installing aftermarket turbo inlets to prevent killing our turbos, we shouldn’t have to drop our fuel tank and clean out metal that wasn’t cleaned out from the manufacturing process. I had a 60k mile 991 turbo s that I beat the mess out of for a year without ever a single issue. I just want to enjoy my damn car and not worry about something going wrong constantly!
 

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It was just bad luck my friend im sorry to say. God only knows what happened. But as we have all being saying its really rare
 

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That’s what I thought too sir! Thank you. I’ve ran catless exhaust on many stock tune cars and have never had a problem. And they would not cause a fuel pressure fault anyways. I agree, I do believe it was detonation that killed it. But with all that was replaced being a car this new with not that many miles it’s simply not acceptable. We shouldn’t have to worry about installing aftermarket turbo inlets to prevent killing our turbos, we shouldn’t have to drop our fuel tank and clean out metal that wasn’t cleaned out from the manufacturing process. I had a 60k mile 991 turbo s that I beat the mess out of for a year without ever a single issue. I just want to enjoy my damn car and not worry about something going wrong constantly!
I am sorry, but the worry entirely comes from the fact you bought a modfied car/modified it. McLaren would have no choice but to honor the warranty otherwise. If the engine would have blown up anyway is another question. Will you open it up to look what happened?
 

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No warranty due to "previous rental history"

All criticism and opinions or similar experiences are welcome. I feel that Mclaren is responsible for this.
Come on man. The initial warranty was voided due to the car being a rental car and it is modified.

I'm sure that the price you purchased the car for reflected this (the question; is the below market price that you purchased the car for still get you ahead in the price department after you get all of this fixed.

At least you were above board with this compared to other forum members.
 
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