LS1 strange "putting" exhaust note
07-31-2011, 04:21 PM
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LS1 strange "putting" exhaust note I have an LS1 from a '99 Camaro SS swapped into a '75 Datsun 280Z. Stock internals, with shortie headers, CAI, and a Texas Speed Ported/Shimmed LS6 oil pump. ECM has a generic LS1 tune from wait4meperformance.com, and rear O2 sensor delete, VATS/skip shift delete, etc. In other words, mostly stock. Transmission is a T-56.
I have had no engine problems whatsoever up until this point. I was driving it to breakfast this morning, a total distance of maybe 3 miles. I had let the car warm up, and jumped on it maybe twice on the way there, never exceeeding 4000 RPM or so. I've never over-revved the engine before, and other than a couple of cold revs so someone could hear the car, abused it. As I said, no issues.
Anyway, as I was pulling into the parking lot, I noticed the exhaust note had changed. The only way I can describe it is a "putt-putt" sound. If you've ever heard an original VW Beetle, you know what I mean; or maybe a Subie - the boxer engine sound. It gets somewhat worse when you rev it; I didn't go past 3K or so on the way home, as I wasn't sure what was wrong.
I initially thought either a cylinder was mis-firing, or I had a bent valve. I did some Googling, and found that a bent valve was unlikely due to the volume/intensity increasing with RPMs. I couldn't find an exhaust leak (besides, this is a brand new system - I've driven the car maybe 200 miles), and I couldn't find any issues with the coilpacks or plugs. Besides, the exhaust pulses coming out of the pipes seem pretty rhythmic and steady.
Other possibilities I read of were stuck lifters, or malformed pistons. The engine when I bought it had around 35K on it (supposedly - the motor doesn't burn any oil, anyway), however, the clutch and flywheel were absolutely toasted, indicating the P.O. ran the hell out of it.
Ideas?
I have had no engine problems whatsoever up until this point. I was driving it to breakfast this morning, a total distance of maybe 3 miles. I had let the car warm up, and jumped on it maybe twice on the way there, never exceeeding 4000 RPM or so. I've never over-revved the engine before, and other than a couple of cold revs so someone could hear the car, abused it. As I said, no issues.
Anyway, as I was pulling into the parking lot, I noticed the exhaust note had changed. The only way I can describe it is a "putt-putt" sound. If you've ever heard an original VW Beetle, you know what I mean; or maybe a Subie - the boxer engine sound. It gets somewhat worse when you rev it; I didn't go past 3K or so on the way home, as I wasn't sure what was wrong.
I initially thought either a cylinder was mis-firing, or I had a bent valve. I did some Googling, and found that a bent valve was unlikely due to the volume/intensity increasing with RPMs. I couldn't find an exhaust leak (besides, this is a brand new system - I've driven the car maybe 200 miles), and I couldn't find any issues with the coilpacks or plugs. Besides, the exhaust pulses coming out of the pipes seem pretty rhythmic and steady.
Other possibilities I read of were stuck lifters, or malformed pistons. The engine when I bought it had around 35K on it (supposedly - the motor doesn't burn any oil, anyway), however, the clutch and flywheel were absolutely toasted, indicating the P.O. ran the hell out of it.
Ideas?
08-06-2011, 12:55 PM
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https://picasaweb.google.com/stephonovich/280Z A few pictures of it coming off the trailer, one of the engine bay, and some showing what happens when your wheel wells don't quite fit the tires.
It still looks like garbage - paint is horrible, interior is pretty much non-existant, etc.
The donor car was not wrecked, just parted out.
The air comes in through the elbow you see in the engine bay picture, then another elbow - filter sits directly in front of the radiator. So, filter --> elbow --> elbow --> straight --> elbow --> intake. No resonators. The stock filter screen which supposedly straightens turbulent airflow before the MAF is still installed, as I don't have the straight-in intake like F-bodies do.
It still looks like garbage - paint is horrible, interior is pretty much non-existant, etc.
The donor car was not wrecked, just parted out.
The air comes in through the elbow you see in the engine bay picture, then another elbow - filter sits directly in front of the radiator. So, filter --> elbow --> elbow --> straight --> elbow --> intake. No resonators. The stock filter screen which supposedly straightens turbulent airflow before the MAF is still installed, as I don't have the straight-in intake like F-bodies do.
08-06-2011, 01:32 PM
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Is it possible that you do indeed have an exhaust leak somewhere? You mention that it is new, but perhaps some connection has worked it's way loose in the initial break-in?
I only mention it since my '99 Z also has a slight "putt-putt" sound, and I do know that one of the tail pipes is rusting thru.
Cool car, BTW. I ignored the 240 and 280Z's when they were new ...... only recently have I developed an appreciation for them. Classic cars.
I only mention it since my '99 Z also has a slight "putt-putt" sound, and I do know that one of the tail pipes is rusting thru.
Cool car, BTW. I ignored the 240 and 280Z's when they were new ...... only recently have I developed an appreciation for them. Classic cars.
08-09-2011, 07:27 PM
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Maybe I'll get some Seafoam and look again for leaks.
As to the car itself, I will say that while it's fun, I almost enjoyed my stock '78 280Z I had previously (it caught on fire... battery short) more, if only because I could drive it at 10/10 knowing exactly how it was going to handle. A 280Z chassis is not exactly setup for almost 400HP - it's downright scary sometimes. Still, the ability to get into triple digits in the blink of an eye is fun.
As to the car itself, I will say that while it's fun, I almost enjoyed my stock '78 280Z I had previously (it caught on fire... battery short) more, if only because I could drive it at 10/10 knowing exactly how it was going to handle. A 280Z chassis is not exactly setup for almost 400HP - it's downright scary sometimes. Still, the ability to get into triple digits in the blink of an eye is fun.
09-02-2011, 06:19 PM
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So, I ran it again tonight and listened more carefully. There is a definite ticking noise that seemed to be coming from the left driver's side. I did some research, and aside from the "LS1 Tick" that is common, I read that a leaking oil gasket can cause this particular symptom.
I checked the torque of all the header bolts; they were all fine.
I checked the torque of all the header bolts; they were all fine.
