i have a 2002 cavy with 250k on it. and i noticed that due to its age and mileage it's lost quite a bit of performance. so my question is can i do anything to regain some back?

wow 250k in a 2002! Thats a lot of miles. I'd say check your cylinder compression. If it is low then you can do a few things. You can have your block torn down get new pistons and rings, or just get a different engine. With that many miles you might have worn rings, or leaky valves weak coils or a multitude of things. But I don't know for sure there may be some one or a lot of more knowledgeable people who can answer your question better.
I had 221k on my engine I never noticed it losing power until the #3 rod bearing took a dump.

Bet the timing chain is stretched the hell out of. Might be improveemnt in replacing that alone. Lord knows when the chain on mine closed-in on the failing point, it lost mileage.

If you do decide to apply my advice, go all the way & use the GM replacement pieces. Don't cheap-out even the slightest, you'll regret it like I did. I installed a GM set in one app & it worked beautifully. I installed a Cloyes in another of the smae engine (LN2) and had small troubles ever since. Why does the Cloyes trouble me? And how? Simple:
The Cloyes pieces & other "Cheapo" non-GM versions are all made by the same manufacturer on the same line & of the same stock. The only difference between them is the box they're placed in.

As for troubles, the tensioner sets when it sees hot engine oil but then slacks when the engine cools & slap results. It's not supposed to do that. It's supposed to set the first time it sees hot oil & keep that way, even after engine cool-down. This slap results in me needing to crank the engine excessively during dead-cold start-up to keep it from sneezing, which totally halts it & results in even more cranking otherwise to get it started. With the GM pieces, I barely gotta crank it for it to catch properly & keep goin'.

250,000mi... Wow. I always theorized that if it weren't for the lack-luster life span of the timing chain in the LN2 (At least in S-truck apps, it seems. Don't ask me why...) that it could easily last every bit as long as a Small-Block Chevy (Try 300,000mi, or more before needing a rebuild). I guess this is proof. Makes me wonder how long it'd last w/o worries if it had a double-roller chainset in it, like the '82 (Only) OHV 1.8L it's based upon does.


Go beyond the "bolt-on".

One more thing came to mind: I'll bet the oil pump is pretty worn too. Replace it with a Mellimg M98, which was used in the '90-93 enignes. It'll be available at your local Autozone.


Go beyond the "bolt-on".

if you want performance back out of a 250k motor, either do a full rebuild or buy a new engine


____________________________________
Primer Counts as Custom Paint Right?
BTW: This is my Sig.

hes canadian too, 250 k is km. thats a lot but not so bad. Use Seafoam to clean the engine. (google seafoam). replace every maintanence part. maybe put a new cat. i hope this is done but airfilter, and, (2) O2 sensors, sparkplugs, ignition wires, thermostat. you might want to switch to synthetic oil too. synthetic makes a big difference on all levels of an engine, more than most people know. theyve even done dynos on TV and made a good hp by switching to synthetic just because of the loss of friction from the superior oil. cant think of any warn out parts that would screw up you performance....


Working on obtainting an M-Class license... ?? Hint: 2 wheels.

If you haven't changed your fuel filter in the last 80k or so, change that first - and check your air filter. I found that around here, 50k is usually about the limit on original AC filters, and about 30k on the orange box variety before they start to become restricted. With my car, at least so far, any loss in performance has usually been restored between one of these two items.

I assume that you don't have any codes setting for anything - so I would then do a compression test. At 175k, mine read about 180psi on its "good" cylinders (I had a burnt exhaust valve on the other - only 75psi), so I would expect a number near there. As long as they're all relatively even (within about 10, I would consider them to be "okay". I don't like to tell you to look for specific numbers, as I'm suspect to the accuracy of different gauges.

If you find that compression is down, or that a specific problem exists on one cylinder, I would start to consider your options. You could either try to get the problem fixed with your engine (rebuild at least part of it), or replace it with either a rebuilt or used engine (depending on your budget, and the condition of the rest of the car). As I'm sure you're aware, our cars aren't worth much with high mileage, so it's probably worth more to you to fix it, rather than replace (as long as you still like the car). If you don't do the work yourself, the labor charges to do work on your existing engine can quickly add up - and as mileage increases, doing a fix on only one part becomes less and less worthwhile. I had the head rebuilt on mine at 175k - but I kind of wish I had spent a bit more on a rebuilt engine instead. I haven't had any specific problems yet since, but it has sounded rather like a diesel when it's cold (piston slap maybe?) for the last few winters. I would consider replacing the timing chain if it gets noisy, but anything else internal and I'll probably look for a rebuilt engine (since everything else in there is likely worn similarly).

Assuming from your mileage that you do a fair bit of highway driving, I wouldn't expect things to be too gummed up in the combustion area, or with the injectors if you use decent quality fuels. My 2200 (currently with 235k) seems to respond best with Shell gas around here - especially the higher grades with less ethanol content.

I must say, that my experience with different oils hasn't found much difference in performance. I use synthetic oils in the winter because I know that they flow more quickly (and I live VERY close to the highway), but I really can't say that they feel any different power-wise, or help with fuel economy. I also like them because if the weather's too crappy when it's "time" to do the next change, they've got some more reserve available to be able to go a few more weeks if necessary without risking anything.

I wouldn't throw too many other parts at it without proper diagnosis. O2 sensors and converters can be checked for proper performance. Ignition wires can be inspected and measured for resistance if necessary. If you've changed the plugs when you were supposed to, and used proper replacements, then they aren't likely the cause (but you could inspect them while they're out for the compression check). Typically plugs or wires will set a misfire code if a problem is occurring there.

Good luck! You should let us know if you find the cause (for future reference).
John

Yeah, catalytics are supposed to be replaced after 100,000mi. But most folks don't know that so...

A couple more things to consider... Since it unlikely that the engine will be coming apart in any way... is either the addition of Restore engine oil additive to restore compression (I know... Questionable) or, as many who've driven older vehicles have done when the mileage gets high, run a lil' heavier weight of oil. Nothing crazy, just one with a little higher minimum viscosity than what was called for by the factory (10w-40 vs. 5w-30). this will help seal the rings & make up for whatever added clearance has worn into the bearings. There are high-mileage oils designed for applications with more than 75,000mi, including synthetics, which are a perfect choice in this case. Just follow the viscosity guidelines I suggested when choosing & you'll be okay. Just do it after running Seafoam thruogh the engine, if you choose to do that.


Go beyond the "bolt-on".

Thanks guys for all the imformative reponses. Well, I try to take care of my car so I do my maintenance regularly. I only use synthetic oil, just cleaned my cone air filter and oiled a month ago. spark plugs and wires were changed about 100k ago (with NGK irridiums) as well as I ran seafoam this summer. I believe what causes this lag is one of 2 things, like you guys pointed out it could pretty much be a clogged cat (along with O2 sensors) and it may as well be reduced compression in cylinders. Because i don't exactly drive calmly. I will get these things checked out when I preform my next scheduled maintenance after New Years. I want this car to keep going and stay in shape because it's been nothing but good to me.