XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Slight hesitation on quick revving

Old Mar 19, 2017 | 09:56 AM
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Default Slight hesitation on quick revving

Having replaced a faulty injector yesterday, Jesse is running great! Much smoother and a bit more power. Barked the tires by accident using my normal throttle demand.

But im going to try to get a small hesitation out of her today. By hesitation I don't mean she stumbles at all. In park engine warm a quick punch of the throttle shows a very brief delay before revving quickly and smoothly.

I know now that all my previous tweeking is likely needing to be rechecked after correcting the injector. The idle adjustment on the ECU has never been right. ECU seemed to see the miss as unburnt oxygen and rich up the mix then oscillate trying to solve its unsolvable mixture issue.

With all 12 firing properly hopefully I can meter that and get it set properly. Does anyone know if clockwise or counterclockwise is leaner?

The TPS will get rechecked because I always suspect it what else should I suspect?
 
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Old Mar 19, 2017 | 11:14 AM
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Originally Posted by JigJag
The idle adjustment on the ECU has never been right. ECU seemed to see the miss as unburnt oxygen and rich up the mix then oscillate trying to solve its unsolvable mixture issue.

With all 12 firing properly hopefully I can meter that and get it set properly. Does anyone know if clockwise or counterclockwise is leaner?


I can't remember which way is lean vs rich.....and all my notes are 83 miles away with the car. I'll be going thru this process myself in a few days. Someone will come along soon with the answer.

I DO remember, from previous experience, that with every adjustment you should wait a minute or two for the system to respond and stabilize....but you probably already knew that


The TPS will get rechecked because I always suspect it what else should I suspect?

Make sure your throttles are clean and set to .002" gap and make very sure that the throttle linkages are *perfectly synchronized with no free play*. I've found this to be very important.

Cheers
DD
 
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Old Mar 19, 2017 | 11:29 AM
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Originally Posted by Doug
I can't remember which way is lean vs rich.....and all my notes are 83 miles away with the car. I'll be going thru this process myself in a few days. Someone will come along soon with the answer.

I DO remember, from previous experience, that with every adjustment you should wait a minute or two for the system to respond and stabilize....but you probably already knew that





Make sure your throttles are clean and set to .002" gap and make very sure that the throttle linkages are *perfectly synchronized with no free play*. I've found this to be very important.

Cheers
DD
DING! DING! DING! DING!

Man that really rang a bell for me! I always make sure to keep those throttle rods separate when I pull them off. Yesterday they got together and I wasn't sure which was which. When I put them back something felt off.

Im going to go swap them. I'll reset them if that doesn't bring things right.
 
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Old Mar 19, 2017 | 11:30 AM
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I was going to suggest what Doug beat me to. Mechanical delay of pedal to butterflies.


Kudos on resolving the miss issue.


Carl
 
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Old Mar 19, 2017 | 06:13 PM
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Throttle rods. Thanks again! Got them dialed in. Now for a test drive...
 
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Old Mar 20, 2017 | 04:26 PM
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I need to go through my linkage also as I have a hesitation from every stop. I know that somewhere on here is the total procedure. My question is about the .002 feeler gauge. What type of gauge are you using. A flat gauge of .002 will cause a gap of more than .002 due to the cord of the circle. I can't find any wire gauges that small.
Or maybe it doesn't mater that much as long as both are the same?
 
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Old Mar 20, 2017 | 04:58 PM
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Originally Posted by catterwaller
I need to go through my linkage also as I have a hesitation from every stop. I know that somewhere on here is the total procedure. My question is about the .002 feeler gauge. What type of gauge are you using. A flat gauge of .002 will cause a gap of more than .002 due to the cord of the circle. I can't find any wire gauges that small.
Or maybe it doesn't mater that much as long as both are the same?
a flat .002 is so thin the butterfly curves it.
 
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