IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: SuperSix on June 13 2009, 08:19:58 AM
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Seems like all the TR's I have had had very lopey idles, is this inherent to the engine design?
What can be done to these to get the smoothest idle?
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Stock V6's are balanced to allow the vibration to exit at the soft motor mount. When you build a fresh motor and have it rebalanced most shops use a formula (50%) that sets a vertical imbalance instead of the stock 36.6 horizontal. Not much you can do about this since you are trading off on up and down or side by side engine imbalance. The short answer is make the fueling a little richer at idle and open the plug gap. :rolleyes: Also check the basics like a vacuum leak, bad plug wires, worn plugs, bad maf and the other usual issues
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I guess I have been driving them too long with too many different combinations because I don't seem to notice it anymore once the car is warmed up. :)
Modern chips from Turbotweak or Bob Bailey seem to have improved the idle as far as my experience goes. They run open loop, or quasi open loop, at idle and this allows a richer air/fuel which makes a big difference if everything else is in good order.
One thing that often happens on cars with older injectors is that they may get some deposits on the tips, or gum build up, and they don't spray correctly, or uniformly. Given the very small duration of the pulsewidths at idle, this can be very noticeable at idle, but, not so much during normal driving. Removing and cleaning the injectors will usually make a difference, but, on a very old injector, it is probably better longer term to buy new injectors.
Our cars control the idle air with a solenoid (IAC) that is pulsed by the ecm. The lower the iac counts, the less input the ecm has on the process. Sometimes, reducing this number will smooth an idle somewhat as the engine is not reacting as much to perceived load.
If you are not familar with the process, you might read the tps and iac adjustment sections of this page on my site and see what happens
http://www.vortexbuicks-etc.com/tuning.htm
And as Ed stated...all the basics, leaks, etc.... :)
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Nice - thanks. Seems like the usual culprits.
Is it a given that the #3 cam lobe will wipe eventually? My TR has 130k on it.
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I had one with 210,000 miles on it for a short time...it had not failed at that time.
My experience is that if they are installed correctly, they don't fail.
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The cam in my 170k engine is still good as well. I don't belive the
stock cam had that problem. I think that was only the early flat tappet aftermarket cams.
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Is it worth getting a measuring tool and checking the lift?
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no...look at the base of each lifter...if none are scrubbed off, there is no significant damage to the lobe
Lifters are convex to begin with....it will be obvious if anything has been eaten away