Shawn O

In the hunt for a car. Owner says dealer says compression test is a waste of money since the CEL would be on if the car had low compression. Owner is very nice and I believe them.

CEL light coming on sounds legit to me but then again Apple has computer issues and they aren't 100% correct all the time.

Is the reason for a compression test besides wear on the cylinders just the 100% peace of mind? If there was a problem shouldn't the CEL come one? I guess I know the answers to the question I'm asking but if the car looks, sounds, and smells right would you roll with it?

How many of you had it done?

PS Sorry for the ton of posts here recently and search function may be my friend but I promise to settle down after vehicle in hand.

Nooch

Compression and leakdown #1 in your PPI checklist

Ridin Dirty

Your probably right. is probably good enough?

it would throw not a compression code, don't think there is a code for that, but a misfire code should be seen. That is "should be".

Further is the ECU OEM? You never know with tuners out there if it has been modified would it still throw a misfire code as readily .

These cars are OBD 2's but I think there are levels of sensitivity effectiveness...example my 993 never throws codes my Cayenne Turbo never stops.

Further a compression test, more specifically a leak-down test is never a bad idea and it could forewarn of inconsistencies before a misfire code is thrown.

mickfluff

Small step, and long shot but also have the tech check the bulb behind the "check engine" indicator... heard of some low lives removing these. Thus no light will ever come on....

OverBoosted28

Doing the leakdown and comp test is a must if you value your spent dollar. The DME will not store or have a code for compression. A misfire code is an ignition problem. Compression problems are pre-text to one of 2 things, valves or rings. So is it a top end rebuild or an overhaul? I know the seller may be a really nice guy, but will he pay for this work if it's needed? Good luck

P.S. usually, if the dealers mouth is open it's a lie or ignorance

Quadcammer

compression and leakdown, no exceptions. If the seller doesn't like it, he can go find himself a new buyer.

Turbodan

if you were a scammer with a bad engine, wouldn't you try to appear to be a really nice guy?
or...so you are saying the used car dealer is a really nice guy so you trust him with over 50k purchase no warranty? if problem do you think he will give you your money back?
I ppi'd a car few years back that had no codes, no cel, even drove great but needed 15k rebuild.
hey it's your money, go for it....but don't cry on this forum when you need an engine rebuild and could have known by a leakdown (as others have done here).
good luck.
IMO leakdown and compression and full ppi including paint meter test necessary to know what you got.

UserA

Shawn, search for how much a top and or bottom end rebuild costs on these cars and see if you still want to save the extra $2-300.

Shawn O

Thanks guys - I really needed some "tough love" to push me to spend the extra money. Enough of you guys chimed in to let me know this is a must do item (It's a lot of jack in my world). Hopefully the car is clean and I'm not flushing money down the toilet.

$1,237 + tax for the local Porsche dealer with new plugs. Told him to give me the old ones for my information.

If PPI checks out you'll have pics Friday. Thanks!

Shawn O

And yes, $1,237 seems stupid high but it's right next to the guy's house and it's at a Porsche Dealer and not an independent mechanic.

nrubenstein

The CEL only comes on if you have a sufficiently extreme compression issue that it impacts firing. You can have a lot of leaking before then.

Knight

The PPI $ relative to the price of the car is well worth it when you think about it.

Always good to have this sort of info on file for piece of mind, reference point and helpful if you ever sell the car in the future too.

Good luck, looking forward to pics on Friday!

Turbodan

I wouldn't take it to a dealer even if it is next to his house, or especially if next to his house. you may want to be present for the test and ask for the old plugs back because many are too lazy to do all 6. $1200 is more than double what it should cost.

Turbodan

how many hours are they booking?
there is something wrong here, and I don't think it is coincidence.

doc_porsche

$1200 is high..... but i do say do it