Noleman

Hey fellas (and ladies),

New here. Used to have a 96 Z28 back in HS. Thinking of buying a 2000 SS. It has 106k miles. It's in pretty good shape. No rust anywhere. Leather seats are in really good condition. The only real blemishes on the car is a 4in diameter spot on the spoiler where the clear coat is pealed away and the black paint across the B pillar that goes over the roof is wavey (I can't explain it). They just replaced the ac compressor and the water pump and belts.

Anyway, the only reason I'm hesitant is because when I test drove it today, it felt like it was down on power by about 75 hp. It threw a code and the dealer said the code was a cat converter. I asked if they've done a compression test and they said they have not. They're will to take $300 of of the car so o can fix the converter. My concern is that a cylinder might be down for whatever reason, either a ring or a cracked sleeve, or even worse a cracked block.

My question to you all is, can a blown cat cause a loss of, what feels like, 75 hp or more? And what are the chances that the motor is blown? I told the guy I'd split the cost of a compression test and if the motor is good I'd buy it. If they don't test it, is it worth the risk?

Any feedback would be appreciated.

They're asking $7700 out the door.

JD_AMG

$300 will not buy you a new replacement cat and installation...
Strange to me they would sell a car with a check engine light on throwing codes.
A compression test is a good idea, I wouldn't buy that car without that. Also wouldn't buy the car until they replaced the cat and got the car to run right.

Noleman

The problem is that they are already into the car for as much as they want to be. They've already replaced the compressor and water pump, so if they have to put any more into it, they're just going to send it across the auction block.

So, unless I offer to something, I think they're just going to punt it. I think the car is worth saving.

RPM WS6

iTrader: (3)

Ask them to see the exact code that the PCM is generating. Their claim that it's a "cat code" could be misleading (might be an O2 sensor or fuel trim issue rather than the actual cat itself) and/or there could be other codes they're not telling you about (or don't know about themselves since last scanning - once the SES light it on, you don't know how many other codes may have been tripped since your last scan.)

A compression test is OK, but wouldn't be my first thought for diagnosing power loss (without any other offending symptoms) on an LS1 with only 106k miles - for example, this test won't help if the issue is fuel system related. It might be down on power due to poor fuel pressure under load, maybe it needs a new pump. That would be more likely in my experience, and would be much more costly than $300 to correct if you pay someone to replace it with a quality piece.

Is power loss the only issue? Are there any alarming noises coming from the engine at various rpms/conditions, something beyond typical LS1 piston slap at idle/low rpm? Or perhaps smoke/smells from the exhaust system than might indicate significant oil burning? If you are seriously concerned about the health of the engine itself, it would be better to insist on a leakdown test as it will give you a better indication of where a problem might be than a simple compression test.

Regardless, I'd first want to see the exact code or codes being tripped if I were the one considering this car.

Also, the roof issue is unfortunately a much bigger issue than you might realize. The roof panel will need to be replaced to permanently and properly fix this issue (all '99+ and some late '98 cars are affected.) The repair can be done cheaply if you source a good used panel from an earlier car and do the labor yourself, but it's a tough job - especially if you've never done it before. The other option is to purchase a new reproduction panel and have it installed (cost will depend on whether it's a hard top or t-top roof, but either way you can expect to spend close to or beyond $1000 for a new panel plus shipping and install/paint. Here is a link with comprehensive discussion and details regarding the condition and repair options:

https://ls1tech.com/forums/paint-bod...e-dummies.html

Noleman

There were no other issues or concerns I had with the motor. It sounded fine. No smoke, noises, smells or any other issues that I noticed.

An wow! I was unaware of the roof sail issue. Thats a disappointment. Thanks for the info. Changes things a bit.

Noleman

Do you know if the Firebird was effected by this issue also?

Spamfritter

iTrader: (1)

It is.

RPM WS6

iTrader: (3)

Yes, as stated in the post above me, it is.

The link I included above gives complete details on this condition. ALL '99+ F-bodies (regardless of trim level or make/model) are subject to this condition unless they are convertibles. Dark colored roofs see this the worst as they absorb more heat (heat is the catalyst.) If you were to get a model with a very light colored roof, such as white or perhaps silver, and it wasn't constantly exposed to direct sunlight, you might not have to worry about this but, regardless of color, the issue is still a possibility for any '99+ car. The transition occurred very late in the 1998 model year, so only 05/98 and later built '98s have ever presented this condition in my research. This is further confirmed by the fact that the GM TSB was issued only for "1999-2002" models, though they seem to be unaware that some of the very late '98s were also affected.

williehank

One of things muffler specialists have told me is when a cat breaks down (usually in the + 80K range), the element breaks down and clogs the exhaust, which could be a likely outcome in power loss. Of course, if that has actually occurred, you may now be looking at collateral damage. A compression test would be inline, to be sure, as already recommended. Does the exhaust rattle? That is also a symptom of a bad cat. I kept throwing Bank 1 efficiency code (P0420 I recall), and replaced all the upstream and downstream O2 sensors, and it still kept coming back. At 35K miles the muffler guy said no way is was the cat(s). I ended up removing my Diablo programming, reset the OBD, and it did go away. However, when I reloaded the Diablo, it came back after another 2000 miles. I was told replacing dual cats would run me about $1000.


I was also told there is no such thing as hi-flo cat.s, but I keep getting differing opinions on that.

RPM WS6

iTrader: (3)

This is not the typical failure mode for the stock F-body cats. What usually happens is the coating wears off the substrate, marginalizing their ability to "scrub" the exhaust, resulting in increased tail pipe emissions. This failure mode does not include any reduction in flow or clogging effect (which would be a separate type of failure which is much less common for these cars.) GM even extended the warranty on the '00-'02 V8 F-body cats because of this known issue, but again this does not necessarily indicate a clog and therefore isn't a certain explanation for the power loss.

I would not recommend starting with a compression test, especially if the OP has to split the cost with the seller. This would be a potential waste of money without first knowing more about the condition, such as the exact DTCs being tripped and doing a simple Infrared/heat test on the cats (even a visual inspection might be enough, one or both could be glowing red with heat if they are clogged enough to cause massive power loss.) There should not be a fee for any of that as the seller appears to be some sort of dealer. My next actions would depend on the data gathered from those inspections. Based on what has been stated so far, and possibly depending on information gathered from the above inspections, I would still most likely look at the fuel system (PSI under load, injector data and fuel trims) before doing a compression test.

Again, the P0420/P0430 codes are quite common on these, especially the '00+ cars (exhaust system was revised for 2000 and above.) My '02 car had this problem, just beyond the warranty extension that GM issued for these regarding the loss of substrate coatings. I knew there was no clog based on zero change in performance or MPG and no elevated surface temp readings on the cat shells at the time. I just disabled the codes and continued to drive it that way for several years without an issue.

Ultimately, even if the car the OP is considering displays the P0420/P0430 codes along with power loss, it doesn't necessarily mean that the power loss has anything to do with the codes. He may simply have the usual substrate coating deterioration (which is only harmful to emissions) as well as some other separate issue that is causing the power loss. Hard to tell without some further diagnostics as outlined above.

Noleman

Hey fellas. Thanks for all the info. You all helped out a lot. Due to all the information you all provided, I ended up not buying the Camaro. I drove an extra hour away and picked up a Silver 2002 Pontiac Trans Am with 99600 miles. The car is completely stock and is mechanically sound. The sail issue is there, but it;s only noticeable when you look for it. No other cosmetic issues. The chrome wheels weren't even pitted. The clear coat still has its glossy shine. It's in great shape and I picked it up for $8500.00. I have pics and will post up in an intro thread. Thanks again!