Rebushing '84 throttle bodies
Thread Starter
Intermediate
Joined: Oct 2020
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Rebushing '84 throttle bodies
Still fighting my idle problem. Replaced the already new TPS and it helped a bit but not satisfied.
Has anyone installed new bushings in their TBIs? It appears mine are not settling down in the same position every time so, I believe, this is part of my problem. The idle varies up to 300-400 rpms then might settle down to 800.
I would like to give rebushing a try if it's not way too hard.
Are the shafts 3/8" like other GM vehicles?
Thanks for any info,
Has anyone installed new bushings in their TBIs? It appears mine are not settling down in the same position every time so, I believe, this is part of my problem. The idle varies up to 300-400 rpms then might settle down to 800.
I would like to give rebushing a try if it's not way too hard.
Are the shafts 3/8" like other GM vehicles?
Thanks for any info,
Safety Car
Joined: Jul 2003
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From: Saratoga Springs NY
2024 C4 of the Year Finalist - Modified
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Honestly just spray the throttle shaft as its running with a water bottle and see if it affects it. Then spray all your vac lines to see if they leak....If you put a vac gauge on it that'll tell you also if you have a leak (as well as a number of different issues with engine- online you will find a vac gauge chart that shows various readings and problems).....As far as re bushing it you need to mic it out and have the bushings made. Highly doubt they are exactly 3/8.
Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
IF your TB's are actually worn to the extent that they're causing the problem, which I doubt that they are, it would probably be easier to just go to the bone yard and get a couple TB's off some "iron duke" (2.5L 4 banger) engines and adapt the linkage to work on the CFI.
Thread Starter
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Thanks. I have a leak detector I used to find only one vac leak so far. Using a water bottle is a good idea and I will try that. I tried choke cleaner when I was cleaning the TBIs but didn't find anything. But, that sure doesn't mean there aren't leaks I missed.
Idle issues seems to be a popular problem with these cars. I think most people wouldn't mind but it bothers me.
Idle issues seems to be a popular problem with these cars. I think most people wouldn't mind but it bothers me.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
A good idle is important, I hear you. Did you check for leaks all the way around the plenum lid? Also, make sure that your TB's are synced. There is a procedure that involves a water manometer, but honestly, you can set 'em damn accurate and have a perfect idle by simply ensuring that they both "bottom" in the bores at the same time, then re-setting your minimum air and then TPS. Easy.
Thread Starter
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Thanks for the reply. I tightened the plenum and checked for leaks--found nothing. I followed all the instructions for synching and bought a manometer. I think I have them pretty close. I'll check a fourth time tomorrow. Since I am at 5280 feet, vacuum readings are quite a bit lower than sea level. I bought a new TPS and set it exactly. I think both throttle butterflies bottom at the same time.
What is minimum air setting? Not sure about that one.
I am definitely missing something but I'm sure getting better at working on these.
What is minimum air setting? Not sure about that one.
I am definitely missing something but I'm sure getting better at working on these.
Thread Starter
Intermediate
Joined: Oct 2020
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Thanks. Good idea.
I take your word for doubting the problem are the shafts--I'm sure you have a lot of experience with them. The parts to install new bushings are expensive and I don't want to spend that much money and time to find it didn't help.
I take your word for doubting the problem are the shafts--I'm sure you have a lot of experience with them. The parts to install new bushings are expensive and I don't want to spend that much money and time to find it didn't help.
Thread Starter
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I think I got a pretty good deal on the car at $4400. The previous owner had it 17 years and put quite a bit of money in it. New tires and battery are good. He had the overdrive unit rebuilt. I don't remember how much that was but it was probably 25% of what I paid for the car. I bought it for a daily driver which it is perfect to do--it's a blast to drive with the quick steering option and it shifts real smooth with the Nash T10. The body and interior are both 50 foot car which is fine for a driver. I'm one of those guys that want a car to run perfectly just like new. Caused me a lot of problems in the past.
Does this sickness ever end?
Does this sickness ever end?
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Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
Basically, setting the "throttle stop", there is a procedure for that:
Block off both IAC inlets or bottom the IAC's -either way to stop airflow through the IAC passages. Then set the idle speed to spec. (I believe it's 400 RPM for manual tran...IDK automatic) using the throttle stop screw. Re-adjust TPS after that, then re-activate the IAC's.
Block off both IAC inlets or bottom the IAC's -either way to stop airflow through the IAC passages. Then set the idle speed to spec. (I believe it's 400 RPM for manual tran...IDK automatic) using the throttle stop screw. Re-adjust TPS after that, then re-activate the IAC's.
Thread Starter
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Thanks again. I did all that when I was synching the TBIs. I could not get it to idle down far enough but I did get the final idle at 800. I set the TPS exactly and synched the TBIs with the manometer. The last thing I did was set the final idle and make sure the TPS was set to spec. Then again, I might have made a mistake in there somewhere. I can't believe the car is supposed to run like it does.
I am missing something somewhere. I want to get the adapter to hook it up to my laptop to check everything.
I am missing something somewhere. I want to get the adapter to hook it up to my laptop to check everything.
Drifting
Joined: Nov 2018
Posts: 1,767
Likes: 648
From: USA
Thanks again. I did all that when I was synching the TBIs. I could not get it to idle down far enough but I did get the final idle at 800. I set the TPS exactly and synched the TBIs with the manometer. The last thing I did was set the final idle and make sure the TPS was set to spec. Then again, I might have made a mistake in there somewhere. I can't believe the car is supposed to run like it does.
I am missing something somewhere. I want to get the adapter to hook it up to my laptop to check everything.
I am missing something somewhere. I want to get the adapter to hook it up to my laptop to check everything.
Thread Starter
Intermediate
Joined: Oct 2020
Posts: 33
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I had it at 12 btdc then set it back to 8 btdc. I'll probably bump it back up but I hear a bit of pinging right now. I don't think the last owner used 91 octane. I am wondering if there is something going on with the way the ecm is adjusting the timing.
Drifting
Joined: Nov 2018
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From: USA
Unplug HEI connector
Thread Starter
Intermediate
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Thanks for both posts and I appreciate the pictures. I agree with the timing thoughts and I will check again--no insult taken. It is the tan wire with the tracer that I need to disconnect? At least that's what I did.
The bushings must be real bad to leak fuel. I'm going to look more closely at those--I still suspect something there also.
The bushings must be real bad to leak fuel. I'm going to look more closely at those--I still suspect something there also.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
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From: New Jersey
Thanks for both posts and I appreciate the pictures. I agree with the timing thoughts and I will check again--no insult taken. It is the tan wire with the tracer that I need to disconnect? At least that's what I did.
The bushings must be real bad to leak fuel. I'm going to look more closely at those--I still suspect something there also.
The bushings must be real bad to leak fuel. I'm going to look more closely at those--I still suspect something there also.
Thread Starter
Intermediate
Joined: Oct 2020
Posts: 33
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Thanks again. I took it for a ride just now and it ran really bad. At times it idled to about 400, at other times 1500. If I put it in neutral while coming to a stop, it will idle about 1100 then when I stop, it will back down to about 800. Still pinging and very rough off idle at a slow cruising speed, in fact it bucks until I get up to speed.
I wish I didn't buy this car!
I wish I didn't buy this car!