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Russell James · 03-29-2010, 08:19 PM

Ran into a strange quirk after installing long tube headers and a catback. No codes or CEL light after the header install. But if I rev it hard in nuetral with the clutch out, sometimes the speedo jumps up. If the DIC is set on speedo it will jump up to 20 ish and then count down as the revs come down. If the brake is on I get a DIC warning to release the brake.

Possibly not related to the headers, never really rev'd it hard before putting the headers on. But now that it sounds so good, of course had to romp it a few times in nuetral. Not even close to red line, just a second or two quick rev up to 5K or so. The only wiring messed with was the O2's and extensions... Maybe they are tied off to other wires too close or something interfering with the speed sensor signal?

Just curious if anyone else has seen that. Doing it when the clutch is out, wonder if something is spinning up in the trans. Car is brand new tight, 100 miles.

03-29-2010, 08:19 PM	#1
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	Anybody's speedo jump up when rev engine in nuetral? Ran into a strange quirk after installing long tube headers and a catback. No codes or CEL light after the header install. But if I rev it hard in nuetral with the clutch out, sometimes the speedo jumps up. If the DIC is set on speedo it will jump up to 20 ish and then count down as the revs come down. If the brake is on I get a DIC warning to release the brake. Possibly not related to the headers, never really rev'd it hard before putting the headers on. But now that it sounds so good, of course had to romp it a few times in nuetral. Not even close to red line, just a second or two quick rev up to 5K or so. The only wiring messed with was the O2's and extensions... Maybe they are tied off to other wires too close or something interfering with the speed sensor signal? Just curious if anyone else has seen that. Doing it when the clutch is out, wonder if something is spinning up in the trans. Car is brand new tight, 100 miles.