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kurfbird Member
Joined: 02 Mar 2005 Posts: 866 Location: Whidbey Island
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Posted: Fri Jul 23, 2010 5:53 pm Post subject: 91 firebird 3.1 rough idle and tires to die |
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Car runs good except.
When you come to a stop want to die has a miss, Studders on take off will die.
Okay had a bad motor so I replaced it with a good one with new heads. Head gasket head bolts and intake gasket. Trans has 6,000 miles on it.
Replaced the following parts during installation
Rebuild distributor with NEW Cap rotor wires, plugs, Igniton module and pick up coil. New coil
NEW
MAF sensor
Throttle position sensor
Idle air controller
Fuel injectors
Alternator
Belts
Water pump
Heater core
Hoses
Rebuilt 3.1 throttle body kit installed.
Collant Temp Sensor'
Starter
Fuel Filter
Inspected vaccum hoses etc. Anything that was suspect was replaced.
Check compression has 150-180 PSI
Checked fuel pressure has 40 PSI
Sprayed throttle body spray to see if there is any increase.
Vaccum is 15-17 if you ramp on it will try to die.
Sunday to check
Recheck compression.
Found a broken ground wire
Is there anything that I could be missing ??
Runs well on the raod except when you come to a stop. _________________ kurfbird
1991 Camaro 3.1 v6
1991 Firebird 3.1 v6
1992 Formula 350 5.7
700r4 Transmissions
brucesthirdgenparts.com |
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turbo_jimi Member

Joined: 23 Feb 2004 Posts: 1206 Location: Tacoma
1985 Chevrolet Camaro Z/28
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Posted: Fri Jul 23, 2010 6:35 pm Post subject: |
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Clogged CAT or Exhaust? if it was a 5-speed, would might be a bad clutch, but it's not. sounds like what johns car was doing _________________
1985 Z28 Crate 350, Hurst T-5, 3.23s, Flowmaster Under previous set-up: 143.82 rwhp 216.98 lbs. torque @4390 rpms 3/12/11 |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Jul 23, 2010 6:37 pm Post subject: |
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Clogged exhaust should show up on a vacuum gauge.
Timing correct?
Get some carb caps and kill everything at the plenum. That will rule out any external vacuum leaks. |
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IROCDave Member
Joined: 16 Jan 2010 Posts: 957 Location: Snohomish WA
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Jul 23, 2010 8:11 pm Post subject: |
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| Reset idle manually then adjust the TPS. |
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kurfbird Member
Joined: 02 Mar 2005 Posts: 866 Location: Whidbey Island
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Posted: Fri Jul 23, 2010 8:35 pm Post subject: Trouble Shooting |
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Cat has been gutted No polution control here.
Timing is right on.
Got a code 22 for TPS. Check the voltage was .22 Checked for range and there was None. Had a used TPS and installed that. Again checked voltage it wa .29 and went up thropugh 2.61 volts. Checked my other camaro 3.1 has the same results.
Runs better but still has a miss. Will be looking at it sunday _________________ kurfbird
1991 Camaro 3.1 v6
1991 Firebird 3.1 v6
1992 Formula 350 5.7
700r4 Transmissions
brucesthirdgenparts.com |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Jul 23, 2010 8:38 pm Post subject: |
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| TPS is reading too low. Should be .54v. Should also go up higher than that IIRC; something like 4.5v at WOT. |
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kurfbird Member
Joined: 02 Mar 2005 Posts: 866 Location: Whidbey Island
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Posted: Fri Jul 23, 2010 8:49 pm Post subject: TPS |
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According to GM service manual for 91
TPS should be .29 and go through 2.68 volts _________________ kurfbird
1991 Camaro 3.1 v6
1991 Firebird 3.1 v6
1992 Formula 350 5.7
700r4 Transmissions
brucesthirdgenparts.com |
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91camaro_rs Member

Joined: 03 Dec 2008 Posts: 1712 Location: Fox Island, Wa
1991 Chevrolet Camaro RS
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Posted: Sun Jul 25, 2010 12:04 am Post subject: |
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| that sounds like what happened when my fuel injectors went bad |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Sun Jul 25, 2010 8:21 am Post subject: Re: 91 firebird 3.1 rough idle and tires to die |
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| kurfbird wrote: | | NEW ... Fuel injectors |
| 91camaro_rs wrote: | | that sounds like what happened when my fuel injectors went bad |
Bruce is way ahead of you.
Unless there was some radical change for the TPS when they went to a speed density ECM, those TPS voltages are no bueno.
There is also still a good possibility of a vacuum leak elsewhere. I have seen vacuum leaks in the brake booster, in the HVAC system under the dash, between the intake ports and the crankcase; all kinds of weird places. Spraying ether around the throttle body is a good start, but you can have vacuum problems anywhere. |
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RSFreak The other "John"

Joined: 23 Jan 2004 Posts: 2946 Location: Renton
1989 Chevrolet Camaro RS
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Posted: Sun Jul 25, 2010 9:28 am Post subject: |
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Mine did that when the IAC was dirty. Cleaned the whole TB and that fixed it. _________________ '86 Trans Am - 5.0L TPI - LT1 cam - 700R4 - WS6
'85 Camaro Berlinetta - IROC clone
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kurfbird Member
Joined: 02 Mar 2005 Posts: 866 Location: Whidbey Island
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Posted: Sun Jul 25, 2010 10:21 am Post subject: Okay found bad NEW TPS sensor |
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Okay it was a bad TPS sensor. Drives fine except for a miss.
Thing that gets me is my other bird has the same TPS sensor reading and runs fine no miss. So How can it be TPS voltage being bad.
I made a extra throttle body adjustable. Drilled out the holes elongated them it it idles fast 1500-1800 RPM. Going to aqttempt to drive it and see if the computer learns the sensors and it slows down.
Also going to issolate the throttle body out of the system. Disconect the cruse the vaccum booster etc and see what happens.
Also going to check the spark plug wires cap rotor etc a miss is usually spark related. and seems to get worse when the car gets warm. _________________ kurfbird
1991 Camaro 3.1 v6
1991 Firebird 3.1 v6
1992 Formula 350 5.7
700r4 Transmissions
brucesthirdgenparts.com |
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kurfbird Member
Joined: 02 Mar 2005 Posts: 866 Location: Whidbey Island
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Posted: Sun Jul 25, 2010 10:22 am Post subject: throttle body |
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| RSFreak wrote: | | Mine did that when the IAC was dirty. Cleaned the whole TB and that fixed it. |
Throttle body has been taken part and cleaned and new gaskets installed _________________ kurfbird
1991 Camaro 3.1 v6
1991 Firebird 3.1 v6
1992 Formula 350 5.7
700r4 Transmissions
brucesthirdgenparts.com |
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