Hi all

My 'new' P1 has 85k on the clock and is still on the original engine. It's quiet, smooth and shows no signs of impending failure, but I can't help but feel it might be living on borrowed time before the big ends let go.

Does anyone know whether the dreaded bottom end failure tends to be down to cumulative damage that occurs over time, or whether it's the sudden failure of, say, the MAF or oil pump which causes them to fail?

The car has a new MAF anyway, but I'd much rather also replace the oil pump and any other critical components now than wait for the engine to let go first, assuming that the bearings are still in good shape. On the other hand, if they're already likely to be 90% of the way to failure, then there's not much point - I'm better off putting the money towards a new engine.

 

You could rebuild it before it goes bang.

I priced up the parts from David at API and was looking at £500 - 800 for a diy rebuild depending on spec. New bearings, oil pump and gaskets etc.

Give the man a call.

 

isn't p1 failure due to dodgy stock map? if so a remap will make it just as reliable as any other.

 

Just one little one apart from all the obvious maintenance issues. Change up at 7000 rpm! I know they have an 8000 limit but ..

 

The ECU is obviously the aggressively mapped STi v.5 one ( I think Japan had 100 RON by then). I remember from an old thread about the P1, that Mike from Prodrive had said that Prodrive instructed STi to add a just a tad more knock control. So I suspect it still can't retard enough if the det threshold is breached, which is more easily arrived at with the UK's lower octane 97 (or 95!) RON fuel.

IMO, I reckon this is the most likely explanation for the 'P1 issue'.

 

Depending on who you ask, there are lots of issues which contribute to P1 engine failures: oil pump failure, poor lubrication due to bearing and crank design, inadequate fuel supply at high rpm, and knocking (due to MAF failure or too-low octane rating) are all mentioned.

So, there's no single 'P1 issue' that's responsible for all the failures. The engine builders I've spoken to have pointed to the crank / bearing design, though, so if I were going to rebuild the engine early I'd definitely put in a later crank - anyone know if a newer block is needed too?

 

You will be fine using your original block, my previous block was P1 short block with a Version 9 crank and I ran that for 35k at 390bhp no problems.

Banny

 

looks like your p1 is overdue it's 65k service, which usually involves new crank, rod, shells and if you're unluckly a block!

a preventative rebuild at this point is much cheaper than doing to because you have to.

 

Lol I get the idea, so: which part(s) is it that is (are) likely to actually need replacing at this point? For example, are the bearings OK until the oil pump gives up and wrecks them, or do they gradually wear out over time anyway and definitely need changing?

 

it it's all okay, then you will get away with just bearing shells and gaskets, with perhaps a refresh of the heads (clean/lap inlet valves, possibly repalce exhaust valves, then reshim for clearances). If you do it that way, it will be pretty cheap, especially if you roll in a service too. Pump should be fine, as should oil cooler etc.

Paul

 

Paul. Forgive my ignorance, but I was under the impression that the P1s problems stemmed mainly from the fragility for the MY99 MAF and the STi5 map that is really meant for 100RON fuel.

Would it not be adequate, if the engine still appears healthy to just swap to a mafless ECU such as Simtek, and remap from 99RON or whatever the OP uses most regularly?

If it aint broke etc...

Ns04

 

x 2

 

I very much doubt that would be adequate.

I have only ever come across 1 P1 with more than 70k on the clock on the original engine. We have rebuild a fair few, and I would say that in most cases they were running perfectly at the time of their demise.

 

But is it then not worth delaying the inevitable, as the owner may get many more 100s, maybe 1000s, of miles out of it, before it actually lets go?

Also, the owner may be strapped for cash now (but not later when it does fail)... if you get my drift.

 

AKA start fecking saving!

Maf failure can claim a perfectly good engine quickly through det and ditto running the car hard on lower octane petrol. The OP will be after a simtek or similar as part of a rebuild anyway, so why not bung that in there for now, tell em that a original p1 engine on that mileage is a rare thing and to expect a rebuild, start saving for it, and hope for the best in the meantime.

I just can't get my head around binning a motor that still shows signs of being perfectly good when one could remove two of the chief culprits for rapid and terminal engine failure at a stroke and with an approach one would only eventually adopt when doing the re-build anyway.

Not intended to be taken as having a go or questioning your extensive knowledge

 

Eh?

I'm not especially strapped for cash right now - I'm just trying to minimise my total expenditure over the time I own the car. So, on that basis, I'd rather replace a few parts now that are likely to fail if left, rather than pick up the pieces next year when a bearing shell decides to spread little bits of itself throughout the entire engine.

The car already has a new MAF, and I've heard of oil pumps failing and taking perfectly good engines with them - so that would be one of the first items on my list.

I did ask one respected tuner and engine builder about a remap; his exact response was "Although your car would benefit from a remap it would not protect the bottom end from a bigend failure". Given that I know to run the car on high octane fuel, and that I simply don't drive that hard or fast, I'm inclined to feel that £700 or so spent on a remap would be better put towards replacing the bearing shells and crank with later, better lubricated items.

 

I dissagree that the MAF is the main culprit for P1 engine failures. The only P1 we've had that had a piston related failure due to how it was running, had no problems with the bearings. All the P1's we've rebuilt with failed bearings have had no problems with the pistons or signs of detonation. Although I appreciate the effect that slight detonation can have over an extented period of time.

I would point out though, that refreshing a okay bottom end is a hell of a lot cheaper than rebuilding a trashed one.

 

Ok, but surely if minimizing the expenditure is the goal, then would it not be prudent to go to a mafless ECU having had the engine refresh done? Lest one pays for that work to be done only to have it wrecked by a dodgy maf. I consider myself fortunate and I've gone from 3 in 5 years of ownership!

General question: if it's not the maf and it's not the map that's the route cause of the P1 engine's reliability at 60k + mileage.....then what is it? Surely, the rest should be no more or less reliable than a stock STi 5?

 

Agreed (this is what I meant in the earlier post).

 

Agreed again.

Certainly from the ECU's map point of view i.e. all but the same OEM map (but with a little extra IAM retard)... But, of course, it'd be running on 97 or 95, and NOT the 100 it was designed for.

As far as the motor is concerned, this is the only difference between a regular STi 5 and a P1, is it not?

 

would be interesting to know a very rough figure for the cost of "refreshing" an engine on a P1??

 

I give up.

 

If you think it's hard to fight 'internet wisdom' with science on a car forum, you should try teaching some science to people on a hi-fi forum... it doesn't go down well!

Thanks for the advice Paul, I would be genuinely interested to know which parts you believe are likely to be worn and/or should be replaced in order to best preserve the engine. Please drop me a PM if you prefer.

 

if your comment is in respone to mine i was mearly asking a question ... as i've seen many people say costs of P1 rebuilds (fairly standard parts) are on average anything from 3-5k (depending on who/where does the build and exactly what internal are chosen etc).
Being on 68k miles and NOT wanting to spend that much a refresh sounded very interesting and maybe a very good option for me - and anyone else that is in a similar boat.
Didnt mean to frustrate or annoy with my question mate ...


... on the other hand if it was meant at someone else then no worries

 

It was probably aimed at Ns04 and myself.

 

I know its not a P1 but my MY00 RA has a VF29 and being a WRX it hasn't got an STI engine. Its had ECUTEK mapping but it has a K&N induction kit.

One would suggest that I'm living dangerously? I voiced my concerns about the K&N and was told that this should be OK and its the mushroom type ones they don't like.

The car does have a hesitation between 2750 and 3250 so might change the MAF and see if that cures it.

So, assuming it doesn't let go beforehand, what would the cost be of having some reliability built into the engine? Its still got its TMIC but I would like to change to FMIC. I don't really want it that much quicker than it already is, just reliable.

 

It wasn't my intention to frustrate.... just that for me, personally, unless it was very significantly more to rebuild than refresh, I would stick with the if it aint broke, don't fix it approach. If any checks it was feasible to perform on the engine suggested all was well, I would simply address the known map problems (Mike wood from Prodrive came on here and said that they weren't asked to do any revisions to the STi 5 map for the P1 IIRC) and the notorious maf worries by getting a mafless ECU and having the car remapped by someone like Paul for UK fuel. Then I would start saving... just in case.

TBH If I were to take my car in to have a "engine refresh" I'd only end up upgrading it anyway , so there'd unlikely be much of a saving for me!

Was/am in a similar position with my gearbox, my MY99 is running 343ft lbs torque and I coud sell it and put the money towards a 6 speed conversion, or see how it goes. 3 years ago, some said I was on borrowed time with the std box, 3 years later it's still going strong.....touchwood!!!!!!

 

I'm in the same camp as you Ns04 - but that's only my 'weighed up' opinion (however flawed).


Yes, and I also think he also said that Prodrive instructed Subaru or STi (don't know who would attend to the ECU map) to dial in a little more IAM retard capability into the P1-destined ECUs - presumably to account for the UK's 97 (or 95!) RON.