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Old 12-02-2017, 03:13 AM   #1
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Intermittent rough idle slight jerk/ hesitation 95 z28

Hey guys new user to the forum but love it my 95 z28 seems to have a slight idle problem and studder/hesitation the idle on cold start is at 1000rpm but will slightly surge a bit til warm then for odd periods of time it will hesitate and studder at what i noticed around 1500 to 2000 doin 40 to 70mph other than that runs good 95k original has mods though also did stall once few weeks back when driving it about 80 miles wouldnt start voltage was fine then as me and my brother were pushing it in neutral out of the way i heard the pump prime? So i turned the key and it started right up? Any advice is greatly appreciated guys dont you just love lt1s...
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Old 12-02-2017, 10:47 AM   #2
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Welcome to CamaroZ28.com ! !

What engine mods? How old are the plugs, wires and Opti? What brand Opti, if not original? How old are the O2 sensors?

Has the ignition switch ever been replaced? When it "wouldn’t start", what did it do when you turned the key to "run" (e.g. - did the dash lights come on briefly)? What about the "SECURITY" light? What happened when you turned the key to "start" (e.g. - did the starter engage and crank)?

After it stalled, did you scan for codes?

Manual trans or auto trans?
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Old 12-02-2017, 11:33 AM   #3
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Hey thanks! mods arent anything major hardly internal long tube headers accel coil accel opti pcm for less tune k and n cai magnaflow exhaust just had head gaskets plugs done and header gaskets about a month ago mechanic said my wires were still good but those and the opti were on the car when i bought it 3 yrs ago and i have a gut feeling one of the wires might have been roasted by one of the headers?? I dont think the ignition has been changed to my knowledge and the o2s have been on there since i got the car also i believe they might be bosch 02s i wish i could scan it need a scanner that can read obd1 hardware with obd2 connecter when stalled power steering went out check guages light and i think maybe ses light i cant remember if security light did i went up to like 3000rpm in first and just click engine cut off the only thing is it fires right up when i start it if the optis on its way out wouldnt it be hard to start? Me and my buddy did my driver side plugs months ago and before idle in park was 900 after plug change 1000 was a tiny bit of smoke when first start after plug change like maybe burnt rubber hence why i think wires getting new ones today i can do them tomorrow so i guess well see also im not sure if it has anything to do with it but my right side tailpipe has a sort of tap tap tap coming from it could it be 02s and a messed up cat converter?
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Old 12-02-2017, 11:40 AM   #4
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Went to turn key all lights radio etc came on voltage good turned key and wanted to start but no turnover did it for like 5 min then like i said fuel pump prime and fired up 4l60e auto trans rebuilt about 3k miles back shifts fine though
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Old 12-02-2017, 05:27 PM   #5
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Free dowload of Scan9495 software - best thing out there for scanning/data logs. All you need to buy is the correct 16-pin OBD-1 cable. Author is a member here, and can help with any install or setup problems.

https://www.camaroz28.com/forums/com...95-lt1-874306/
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Old 12-02-2017, 10:18 PM   #6
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Ill definitely try it out got to get my hands on an old laptop or something unless i find someone with the right scanner anyways thank you for the link
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Old 12-03-2017, 11:13 AM   #7
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

If you have access to an OBD-1 scanner, with only a 12-pin connector:

Courtesy of Shoebox

http://shbox.com/1/xraycable.jpg

Avoid Innova and Equus dual OBD-1/OBD-2 scanners. Their database for the LT1 PCM is corrupt, and they typically produce a list of seven codes you either don’t have, or don’t even exist.
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Old 12-03-2017, 05:23 PM   #8
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Its a 16 pin ob2 connecter with obd 1 hardware was thinking that bosch obd1300??
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Old 12-03-2017, 09:02 PM   #9
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

I know about the 95 paradox. Shoebox's photo shows how to connect a 12-pin cable to your 16-pin connector. We've been doing this for 20+ years.

No experience w/ Bosch 1300.
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Old 12-04-2017, 02:48 PM   #10
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

So i could just get an obd 1 scanner with this xray cable and where would i find this cable at?
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Old 12-05-2017, 12:42 AM   #11
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

No.

You get an OBD-1 scanner. It should come with a cable with a 12-pin connector. You make the two little jumper wires to "jumper" between the OBD-1 scanners 12-pin cable connector and your 16-pin connector. Just the two short whiteish lengths of wire, with the blue and pink connectors shown in the photo.



Shoebox referenced the Auto Xray cable in the file name, because he had an Auto Xray scanner, with its cable. Way back (probably ~20 years ago) when he took that photo, that was a popular OBD-1 scanner. Still a good unit if you can find a used one that still works cheap.
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Old 12-06-2017, 12:43 PM   #12
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Think i found the hesitation problem had my #7 plug was finger loose still crappy idle when in drive foot on the brake at a light or something usually when warmed up?
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Old 12-06-2017, 12:48 PM   #13
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

That plug may be fouled since it wasn’t firing. 2 cents
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Old 12-06-2017, 05:15 PM   #14
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

Yea it was a little rough looking around the insulator but i replaced it with a new one would coolant temp sensor have anything to do with rough idle
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Old 12-06-2017, 05:56 PM   #15
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Re: Intermittent rough idle slight jerk/ hesitation 95 z28

It is logical to me that if it was not functioning correctly that it could cause it to run rich at idle
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