1998 Infiniti I30 Failing Exhaust System?

My beloved Infiniti I30 had a serious setback this weekend. I wanted to get your take on whether the exhaust system is to blame. I was told by the dealership shop that the entire exhaust system needed replacing for $2000, which was nearly the cost of the car itself.

Saturday: we’re in NYC (I live in DC, we get there no problem) when all of a sudden the car starts bucking like a horse. I couldn’t accelerate and the RPMs were stuck at 2000. We find a place to stop and check out things. We’re able to get home but the car bucks again and loses the ability to accelerate, except after coming to a complete stop.

Monday: We’re driving at 60 MPH and it happens again and I can’t accelerate so we begin slowing down. I pull into a gas station where I call AAA to have the car towed to my grandma’s. The car we keep on for a/c while we wait–but all of a sudden, the car shuts off. I turn it on again and while it idles at 900-1000 for a while, it suddenly drops again to 300 and the engine starts to sound like a Diesel engine. It does this for a few minutes and then shuts off. I start it again and it keeps doing the diesel noise. There was smoke. That was pretty much it.

Is this a direct result of having a bad exhaust system? I read on the Internet something about idle valves causing this problem.

Thanks for your insight!

Did you check the engine oil level?


Hi Tester, I pulled up something from the engine and didn’t see anything on the strip. Also, I’m terrible with car stuff.

Did have a yellow handle? If so that’s the oil dip stick. And if there was no oil on the dip stick the engine is out of oil and probably ruined.




At least u don’t have to buy a 2000 exhaust

Did any trouble lights come on the dash when it first acted up?
The oil light in particular.

Before you write it off, see how much oil has to be added to register on the dip stick and report back. If you are only down a quart or two the engine may be ok. Three quarts or more, there is probably damage to the motor.

Ed B.

1st point - when a car isn’t running right and shuts itself off several times, you don’t restart it just to run the AC or anything else. The original problem could be compounded by more problems and more significant problems.

2nd point the car is a model year 1998, making it about 15 years old. A new exhaust system in a 15 year old car is something you’d have to accept as reasonable, given the age of the car. Now, $2000 for a new exhaust system, that might not be reasonable. The OEM exhaust system is stainless steel, which is why it lasted this long. The quote for the replacement sounds like another stainless steel system. You could buy a cheaper conventional exhaust system, just expect it to last about 5 years instead of 15. A conventional exhaust should be about $700 to 1,000 installed. Call a Midas shop for prices.

You need to find out if there was significant damage to the motor from the round trip from DC to NYC and back before you spend the money for a new exhaust. If the motor was run with no oil in it (causing the diesel noises and smoke) then I’d think the motor is shot now it isn’t going to be worth the money to repair the car. It might be time to look for another car to buy and send this one to the junkyard.

It was a one-way trip thankfully! I really don’t plan to spend the money to repair as it’s 15 years old and I’m moving to Brooklyn. That money can be spent elsewhere. It’s my late father’s car that he passed on to me, so I’m feeling a little guilt that it’s come to this so to speak. Now, how can I sell it? I just had all these other repairs done and the battery is brand new. Help me car guys. My Dad’s gone so I need some expert advice! Thanks for your input this far.

By the way, no CEL came on or service soon light. Nothing!

One more comment: I am pretty sure I know the source of the problem and the dealership quoted me $800 to repair the valve cover gasket. Is that unreasonable too?

isnt this the dealer that wants to fix your exhaust for $2000? now they want to fix your leaky valve cover instead? did your motor run low on oil? dealer says motor is fine, you just need a new valve cover gasket? what is their estimate for parts and labor? $55 gasket and $670 labor?

I would get a second opinion from an independent mechanic to determine if the engine is damaged goods after running low on oil. An independent mechanic would be considerably less expensive than a dealer also. Check with family, friends, and coworkers for a recommendation or the Mechanics Files link on this website.

Ed B.

Well, they can’t add oil until valve cover gasket is fixed. Than they can tell you if motor is ok.

I was told about the valve cover gasket problem before I took my trip but I didn’t understand just how low on oil the engine was. Like I said, no lights went on, it just smelled funny and bucked before giving out eventually. I’m pretty sure why this is happened is because of the valve cover gasket. I cannot understand why it’s an $800 repair. It sounds like if I could get that done for less money I could still have a car. But the car is parked in NJ and I won’t relocate to the area until July. Would I have to have the car towed to a mechanic from where it is, or could oil be added and I drive it over? Thanks again everyone!

How much oil did it need?

No cel leads me to rule out catalytic converter, and exhaust system to me, time for a second opinion!

First, the OP shouldn’t use a dealership for this particular problem. Any good inde mechanic is usually the better option for fixing older cars, or for problems that don’t require manufacturer-specific diagnosis scan tools. OP should ask friends, coworkers, fellow church goers, etc for a recommendation on who they use. Try to find a shop that does a lot of work on this particular make. Be sure, on the first visit, to tell the inde shop who recommended you. The OP will see an immediate improvement in advice, service, and quoted prices I expect.

Second, a poorly running engine could be caused by many things. A problematic exhaust system is just one of them. But it could be the exhaust system, for a couple of reasons. The exhaust gases produced in the engine are supposed to be entirely contained in the pipes, and isolated from the normal air, from the exhaust manifold through the cat and out the tailpipe. If there’s a hole in the exhaust system somewhere, air getting into the stream will confuse the ECM ( engine computer), because the O2 sensor will say there’s a lot of O2 coming down the exhaust pipe, which there shouldn’t be if the fuel/air mixture inside the engine is correctly adjusted, and the ECM will try to compensate by injecting more gas to eliminate the extra O2, which will flood the engine and make the car run poorly. The second reason would be if there is an constriction of exhaust flow. That would cause the engine to run poorly. The problem with all this is that this would almost certainly turn on the check engine light. Which is why the OP should consider to bring in an inde mechanic for a look-see. Hopefully it will be something simple.

Best of luck to the OP.


First of all, valve cover gaskets almost never leak oil so profusely that the engine runs out of oil in no time flat

And if the valve cover gasket was leaking that badly, you should have seen ENORMOUS puddles of engine oil on your driveway

Or you should have CONSTANTLY smelled the burning oil on the hot exhaust manifold

With all due respect, it sounds like the main problem is that you didn’t check and correct the engine oil level often enough.

If that engine is damaged, I’d not want to be the next owner.

I certainly hope that you fully disclose this incident with any prospective buyers.