How exactly can I tell if the throttle is stuck??
08-03-09, 03:45 AM
#1
How exactly can I tell if the throttle is stuck??
This might be a stupid question to you guys, but to me the only stupid question is the one left not asked.
When I start the 7 up, it shoots up automatically to 3000 rpms. Just like its supposed to with the AWS. But after an alloted time of about 15 seconds, about the time the idle should drop back down, the idle remains at not 3 but 4000 rpms.
I wanted to check my TB but wasn't sure what to check for. Any help would be great!
Car is an 87 turbo with a new rebuild.
When I start the 7 up, it shoots up automatically to 3000 rpms. Just like its supposed to with the AWS. But after an alloted time of about 15 seconds, about the time the idle should drop back down, the idle remains at not 3 but 4000 rpms.
I wanted to check my TB but wasn't sure what to check for. Any help would be great!
Car is an 87 turbo with a new rebuild.
08-03-09, 02:54 PM
#6
The idle speed increasing is pretty weird, but a similar problem was fixed in this thread: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/high-idle-loping-idle-questions-854949/. The secondary throttle plates were sticking open slightly and allowing engine speed to approach redline on startup. This was on a car without a BAC or AWS valve however, so if you have them, they could be a factor as well.
08-03-09, 03:25 PM
#7
well disconnecting the cables is just the lazy way to check that. What you really need to do is check the TPS voltage. It should be 1 volt max with the engine warmed up or the fast idle cam manually rotated down. If it's higher than that (and your sensor was calibrated correctly) your throttle plates are open too far.
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08-03-09, 04:44 PM
#8
I'm kind of paranoid about leaving my car on at this point since its a rebuild with no miles on the motor. I suppose another question to ask is, if leaving the car running while the idle is set this high will have ill affects to the engine if I left it running to check the engine?
The idle speed increasing is pretty weird, but a similar problem was fixed in this thread: https://www.rx7club.com/showthread.php?t=854949. The secondary throttle plates were sticking open slightly and allowing engine speed to approach redline on startup. This was on a car without a BAC or AWS valve however, so if you have them, they could be a factor as well.
Thanks for taking the time to help me out guys.
08-03-09, 10:36 PM
#11
The one I believe you turned will adjust the secondary throttle which was my problem. Unscrewing it will let the butterflies close more or open later if they are closed all of the way already. If you screw it in it will open the butterflies a little allowing air in at lower rpm or idle. I had to unscrew mine almost all of the way out but my engine was approaching redline when I started it. My tps was at 1 ohm at idle so that wasn't the problem. You should check that to be sure.
08-04-09, 03:02 AM
#12
The one I believe you turned will adjust the secondary throttle which was my problem. Unscrewing it will let the butterflies close more or open later if they are closed all of the way already. If you screw it in it will open the butterflies a little allowing air in at lower rpm or idle. I had to unscrew mine almost all of the way out but my engine was approaching redline when I started it. My tps was at 1 ohm at idle so that wasn't the problem. You should check that to be sure.
08-05-09, 04:42 PM
#15
just tapping the throttle should take it out of AWS phase also.
if you want to try seeing if the throttle is stuck just be sure both throttle and cruise cables have some small amount of slack then turn the throttle cam back manually by pushing on it in the reverse direction of the cables pulling on it.
i suspect your thermowax is fubar though, i have had a few that had poor or no coolant circulation through the thermowax on the back of the throttle body resulting in a stuck high idle. you didn't do a throttle body mod and leave it installed did you?
if you want to try seeing if the throttle is stuck just be sure both throttle and cruise cables have some small amount of slack then turn the throttle cam back manually by pushing on it in the reverse direction of the cables pulling on it.
i suspect your thermowax is fubar though, i have had a few that had poor or no coolant circulation through the thermowax on the back of the throttle body resulting in a stuck high idle. you didn't do a throttle body mod and leave it installed did you?
08-05-09, 05:13 PM
#16
just tapping the throttle should take it out of AWS phase also.
if you want to try seeing if the throttle is stuck just be sure both throttle and cruise cables have some small amount of slack then turn the throttle cam back manually by pushing on it in the reverse direction of the cables pulling on it.
i suspect your thermowax is fubar though, i have had a few that had poor or no coolant circulation through the thermowax on the back of the throttle body resulting in a stuck high idle. you didn't do a throttle body mod and leave it installed did you?
if you want to try seeing if the throttle is stuck just be sure both throttle and cruise cables have some small amount of slack then turn the throttle cam back manually by pushing on it in the reverse direction of the cables pulling on it.
i suspect your thermowax is fubar though, i have had a few that had poor or no coolant circulation through the thermowax on the back of the throttle body resulting in a stuck high idle. you didn't do a throttle body mod and leave it installed did you?
08-06-09, 02:58 AM
#18
This is absolutely weird. Earlier I had shut the car off and made a post on the forum. Then I went back into the garage about 20 minutes later and turned the car back on, and the idle went from a steady 1400 rpms, to 5000 rpms. Even higher than the original problem had started out as.
The BAC is screwed in all the way and won't lower idle anymore. I'm going to remove the throttle cable tomorrow and see if that reveals anything. Thank you Karack and to everyone else for the help.
The BAC is screwed in all the way and won't lower idle anymore. I'm going to remove the throttle cable tomorrow and see if that reveals anything. Thank you Karack and to everyone else for the help.
