only9k

Hello All,

I have a MY2000, with a 35k low mileage motor installed, after my last one went boom after 15 years. Stock CAT/Factory Original Exhaust

My problem is recently (fairly sure this is recent), where anytime I go WOT (even from 3k to 5.5k in 3rd for example), or do a run to 9k, I immediately get this extremely strong smell of EXHAUST (not gasoline), but the kind I would smell if I was running like open header or something. No Codes

Now, I have been used to the rich smell coming when I ran to 9k, but that was much different than this. That smell was like exhaust getting processed through cat, and coming out the other side with the traditional AP1 Rich smell.

This smells like, someone piped the exhaust manifold right into the cabin. When I drive normally, I don't smell it, ONLY when I put my foot down- even for 2 seconds. There is very little lag, and I can immediately smell it in the cabin. The unburnt gas, kind of makes me nausious. I have owned my car for 4 years, this is not the smell I had before when I would be going WOT.

Now recently, I switched transmissions, and noticed that when we did the engine swap, we did not put in a exhaust manifold gasket, but that would mean I would have smelled this after the swap, and this is only recently.

Other Symptoms

• When I start my car in the morning - the engine wants to die - RIGHT as the air pump goes on. Starts sputtering, and It will recover in 1-2 seconds, or I can hit the gas pedal and then it stabilizes.No Codes
• When the air pump goes off after about 40 seconds of a cold start, it then usually turns on again for a 2,3 seconds and off, and then on, and then off again. Then finally goes off.

What could it be?

• BAD Cat? (I mean this this is original from 2000 to 2016 now)
• My missing Exhaust Manifold Gasket (but this has been the case for 2 years now)
• Gasket between manifold and exhaust/cat pipe bad (hondapartsnow shows there is a gasket) (also called donut gasket?)
• Bad Engine PCV Valve
• Manifold not connected to exhaust pipe all the way? (because of missing gasket, maybe metal expands or contracts letting exhaust gas escape. I think I am missing one or two bolts for the mani)
• Bad/Damaged o2 sensor leaking exhaust gas.
• Maybe bad oil cap gasket, leaking that pressure- and smell of oil/gas - although I smell mostly exhaust gas, not so much actual gas.
• Something wrong with the air pump, or the whole clean air into exhaust business.

Things I have tried to alleviate this

• Change Spark Plugs
• Tighten the bolts holding exhaust mani to cat/exhaust pipe - in case this was the source of the leak.

Since immediately smell it after I go WOT - even for 2 seconds - I doubt that this is coming from the back of the car.

Any Ideas? I just don't want to replace parts that aren't worn or damaged and throw money away so will look for suggestion as to the cause of this problem.

windhund116

"We did not put in a exhaust manifold gasket."

Why was this not done?

only9k

Not sure. Mustve slipped through the todo list.

You think it could be this? I mean wouldnt it be noisy since so much exhaust would be escaping.

windhund116

Yeah, I'd replace the exhaust gasket.

realblag

You didn't use a new exhaust mani gasket or you didn't use one at all?

starchland

You have an exhaust leak. Probably only can smell it when your on it hard

only9k

didnt use one at all.

only9k

you know, I realized that I had 2 bolts missing from the manifold.

I added two bolts and tightened everything down and now, the engine doesnt stutter at startup, but I can still smell the exhaust when I get on it hard.

I will try add the gasket first thing and see if that takes care of the smell.

windhund116

Think the gasket will do the trick.

Good luck!