First off its a camaro with 87'TPI motor and t-5 tranny. Car is modified and has no emissions, Im running Edelbrock TES header to a 3" Catco Converter with air tube but not using an air pump. to flomaster 80 series catback. Upon acceleration theres this chattering sound coming underneath the car, Could it be due to the cat being clogged since i dont have an air pump connected? The motor and exhaust have about 700 miles on it. This chattering noise came the next day after i changed the tranny mount. On highway its smooth but when u accelerate it has a annoying noise(teh teh teh teh) Is there anyway to test if a cat is clogged beside removing it? I put my hangds by the tailpipes and it seems like its flowing enough. Another issue is when i start the car it runs that immediatly shuts off, This happened b4 and i upped the idle and lowered it back again and it went away, now its happening again. It goes away only if i have the idle high. I checked for vacuum leaks and there arent any, Theres fuel going through so what could it be. Im confused, any help would be appreciated.

 

Your headers have air tubes you said. Are they plugged? If they aren't, then thats the clattering noise. Small amounts of exhaust gasses slipping out.

I would also check for any exhaust leaks. That would also make the sound.

My opinion.

 

Could the sound you're hearing be the air leak from that air tube on the cat? I've owned a few cars that didn't have an air pump, but still had a cat, it shouldn't have clogged up just because of that. Use a block and hammer and flatten that tube out and then roll it up. Don't really have any idea about the other problem.

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"NOV8Z28" - '87 20th Anniversary Iroc-Z Convertible, leather, 1200 watt stereo, Spohn torque arm/tranny mount,6 pt. roll bar, 5 pt. harness, 4" cowl hood, '92 Z28 Rear spoiler, 3.8 SFI Turbo/200R4 from '86 Buick T-Type, 42# (009) Injectors, Custom chip, RJC power plate, Dutweiler neck IC, Adj. FP Reg., 14" K&N, Walbro 340 FP, 3" exhaust with gutted crossflow flowmaster, 17" Boyds, 4.11 rear end.

Http://CamaroZ28.cardomain.com/id/roc87

 

Thanx for the reply guys and there is slight exhaust leak. The Header tubes are blocked off with a 1/2 cap and the air tube in the cat is also blocked off, nothign seeping from either of them. Im clueless.

 

Is it consistent with engine RPM? Just for the hell of it, check your torque converter bolts. Happened to me a few weeks ago, swore it was a rod knock till I listened to it again, turned out a bolt loosened on the converter

 

uh i have a manual, Its idling is unusual, Had the MAF screens removed. I still have Filters, hope nothing went inside

 

Damn JD, your problems dont' ever seem to go away do they?

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-Jason
"Get this, no man with a good car needs to be justified."

91 Z28 305 TPI/ 5 spd (15.301 @ 88.31 mph)
92 Formula WS6 305 TPI/ 5 spd (14.639 @ 95.44 mph)
My 3rd gen Headache

 

No. One of the reasons why im scraping the TPI unit and motor and working on a carbeurated 406. Ah well guess i'll put the TPI up on ebay.

 

It sounds like an exhaust leak.

What kind of tranny mount did you put in? If it was poly it could be the extra vibration because it is harder than the stock rubber one.

Why not make it a TPi 406?

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I WOULD RATHER PUSH A CAMARO THAN DRIVE AN IMPORT

1983Z28
Superramed roller 406 10.5 compression, AFR 195's and custom cam.

future mods:
N20 waiting to be installed

Wifes new car:

1995 Z28
AT, leather, T-tops bone stock for now. 250 RWHP 300 RWT 14.0 @ 99 MPH on a 2.2 60'

future mods:
header to tailpipe replacement and a cold air intake. Then I am just going to leave it alone (maybe)