87 Buick will not run right
August 20th, 2017, 10:25 PM
#1
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Join Date: Jun 2016
Location: Los Angeles, CA
Posts: 170
87 Buick will not run right
Very recently my brother's 87 regal (307 olds) started to run really rough when restarted warm, sometimes stalls, but then when hot it runs fine. A few days ago I was driving it and I floored it and the damn car got stuck at 50% throttle. Shut it off, and started it back up and it was back to regular idle.
I checked the code, since the CEL came on, and I got code 21 - TPS signal voltage high
I checked the wires at the TPS and here's what I found:
With the key on
Ground wire - I connected the positive lead of my multimeter to the pos terminal on the battery and the negative lead to the ground at the TPS, I have 12V which tells me that the ECM is providing good ground.
Reference wire - I have 5 volts at the reference wire
Signal wire - when I backprobe it, at idle the voltage is at 0.8-0.9. I increased the throttle slowly and the voltage increase without jumping around. The max voltage at WOT was 3.5. Not sure what the factory specification is, but it seems to me that the range is completely off.
Then when I disconnect the connector, the signal read 4.7v, not sure if this is normal or not.
I would appreciate it if someone could chime in with any advice/ suggestions.
Is the range from the signal completely off? Or does it fall within specifications.
Are there any problems such as a gummed up carburetor that can cause this code to go off?
Honestly am considering ditching the computer for a non computer carb and dist.
I checked the code, since the CEL came on, and I got code 21 - TPS signal voltage high
I checked the wires at the TPS and here's what I found:
With the key on
Ground wire - I connected the positive lead of my multimeter to the pos terminal on the battery and the negative lead to the ground at the TPS, I have 12V which tells me that the ECM is providing good ground.
Reference wire - I have 5 volts at the reference wire
Signal wire - when I backprobe it, at idle the voltage is at 0.8-0.9. I increased the throttle slowly and the voltage increase without jumping around. The max voltage at WOT was 3.5. Not sure what the factory specification is, but it seems to me that the range is completely off.
Then when I disconnect the connector, the signal read 4.7v, not sure if this is normal or not.
I would appreciate it if someone could chime in with any advice/ suggestions.
Is the range from the signal completely off? Or does it fall within specifications.
Are there any problems such as a gummed up carburetor that can cause this code to go off?
Honestly am considering ditching the computer for a non computer carb and dist.
Last edited by 77ricbaez; August 20th, 2017 at 10:28 PM.
August 21st, 2017, 06:30 AM
#2
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Join Date: Oct 2012
Location: central massachusetts
Posts: 1,541
it's unlikely the tps is causing any hard starting or rough running,i would look closely at the choke operation.is it open when hot when restarting?check the hot air tube to see if it has vacuum,the port in the baseplate of the carb that feeds the choke housing can get clogged with sludge and won't draw hot air by the spring.also a common problem on those cars is when the purge valve goes bad it causes vacuum to draw fuel out the bowl vent.there shouldn't be any fuel/wetness in the bowl vent hose.
August 21st, 2017, 08:20 AM
#3
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Join Date: Jun 2016
Location: Los Angeles, CA
Posts: 170
it's unlikely the tps is causing any hard starting or rough running,i would look closely at the choke operation.is it open when hot when restarting?check the hot air tube to see if it has vacuum,the port in the baseplate of the carb that feeds the choke housing can get clogged with sludge and won't draw hot air by the spring.also a common problem on those cars is when the purge valve goes bad it causes vacuum to draw fuel out the bowl vent.there shouldn't be any fuel/wetness in the bowl vent hose.
August 21st, 2017, 08:34 AM
#4
'87 Delta 88 Royale
Join Date: Dec 2010
Location: Margate, England
Posts: 2,513
Just because it's throwing a code, don't take it as gospel. Over here 6 cylinder Jaguars will run rough and throw up a faulty O2 sensor code, when all that's wrong is a breather hose split or come adrift.
Check the simple stuff first, rather than throw money at the car.
Roger.
Check the simple stuff first, rather than throw money at the car.
Roger.
August 21st, 2017, 08:40 AM
#5
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Thread Starter
Join Date: Jun 2016
Location: Los Angeles, CA
Posts: 170
Just because it's throwing a code, don't take it as gospel. Over here 6 cylinder Jaguars will run rough and throw up a faulty O2 sensor code, when all that's wrong is a breather hose split or come adrift.
Check the simple stuff first, rather than throw money at the car.
Roger.
Check the simple stuff first, rather than throw money at the car.
Roger.
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