Detonation. The music of a 1977 Buick.

[Purloined]

I'm once again inclined to test the normally sweet, polite temperament of the many here with another bout of my stupid questions. 

I did sift through countless posts about the issues that induced this, to be clear.

I was stunned at the fuel consumption of my 2000V11 at +/- mid-thirties when I purchased it five years ago. My 1980 Le Mans averaged in the mid to high forties. A recent post regarding average mileage has assuaged my assumption that something was seriously amiss. My VDub TDI, even with fat, sticky tires manages closer to 45.        It is possible that a performance disparity exists between the two, though not empirical, I've good reason to believe it true. They're both balls-of-fire in their own way; I don't feel a need to belabor the differences at a drag strip or elsewhere.  

I, as others have also noted, experience some detonation on hard acceleration. I don't tend run the motor at higher RPM generally. It does not feel like it is lugging at lower RPM in sixth gear, pulls strongly, and I often don't downshift when hard on the throttle. Perhaps the detonation is a result of the way I'm riding it and I should expect that this is a normal given what I'm asking of it.

But given these characteristics and possible remedies, I'm wondering about the balancing of fuel supply and ignition timing. Someone here suggested a Tecmate Carbmate fuel injection synchronizer. This appears a more sophisticated version of the old mercury tube vacuum balancer I used to use on my old, carbureted two cylinder motorcycles. Is there a port on the throttle bodies that this would attach to and is it a purely mechanical adjustment of the throttle cable assembly? Worth the price of purchase?

And ignition timing? Monitored by the sensor reading the position of the camshaft? Not the dual points version on my old Le Mans of days of yore that looked like caveman flints? No tweaking necessary?

In the old days I would mechanically address the state of these and other adjustments given detonation and 'poor' fuel mileage. I have gone through the bike, i.e. valve lash, fuel/oil/air filters, spark plugs and new leads etc and the machine runs to my mind well and sounds great. I get burbling when I'm off the throttle, the exhaust is (I think OEM) somewhat loud and seems fine. I'm not sure what the ~3000RPM 'cough' people describe is. I'll talk to my therapist about accepting the fact that is guzzles fuel, but the detonation is not cool. I took it on a spirited ride today (roughly 45ºF); the achingly cacophonous detonation a sharp lil'needle in my ear.

I can't stick to a script, a couple of questions in a succinct paragraph. Sorry to the pummeled few who managed to hold on to this linguistic roller coaster in order to get to here. Hardy thanks. 

 

[docc]

Have the throttle bodies been balanced at "some rpm?" No mention of TPS baseline. Or CO Fuel Trim.

What fuel are you running?

 

[Lucky Phil]

Hard to say about the pinging but if your shifting into 6th gear at anything below 100kph/60mph then you're looking for trouble in that department.

Ciao

 

[Purloined]

51 minutes ago, docc said:

Have the throttle bodies been balanced at "some rpm?" No mention of TPS baseline. Or CO Fuel Trim.

What fuel are you running?

 

I read (tho 'glazed' prlly more descriptive) the link you sent (I can't find the underwear in my drawer any given morning, how are you able to conjure a six year old post? Kudos). I'll read and re-read. Thank you.

High-test fuel available here in Connecticut, which I exclusively use, is 93 octane. I think. Maybe it is 91. I need to pay more attention. 

[Purloined]

1 hour ago, docc said:

Have the throttle bodies been balanced at "some rpm?" No mention of TPS baseline. Or CO Fuel Trim.

What fuel are you running?

 

Found a pic. 93. Tho an old pic. Fuel price double $ now.   

 

why is it so difficult to clip a tiny image to a post here?

[footgoose]

1 hour ago, Purloined said:

I'm once again inclined to test the normally sweet, polite temperament of the many here with another bout of my stupid questions. 

I did sift through countless posts about the issues that induced this, to be clear.

I was stunned at the fuel consumption of my 2000V11 at +/- mid-thirties when I purchased it five years ago. My 1980 Le Mans averaged in the mid to high forties. A recent post regarding average mileage has assuaged my assumption that something was seriously amiss. My VDub TDI, even with fat, sticky tires manages closer to 45.        It is possible that a performance disparity exists between the two, though not empirical, I've good reason to believe it true. They're both balls-of-fire in their own way; I don't feel a need to belabor the differences at a drag strip or elsewhere.  

I, as others have also noted, experience some detonation on hard acceleration. I don't tend run the motor at higher RPM generally. It does not feel like it is lugging at lower RPM in sixth gear, pulls strongly, and I often don't downshift when hard on the throttle. Perhaps the detonation is a result of the way I'm riding it and I should expect that this is a normal given what I'm asking of it.

But given these characteristics and possible remedies, I'm wondering about the balancing of fuel supply and ignition timing. Someone here suggested a Tecmate Carbmate fuel injection synchronizer. This appears a more sophisticated version of the old mercury tube vacuum balancer I used to use on my old, carbureted two cylinder motorcycles. Is there a port on the throttle bodies that this would attach to and is it a purely mechanical adjustment of the throttle cable assembly? Worth the price of purchase?

And ignition timing? Monitored by the sensor reading the position of the camshaft? Not the dual points version on my old Le Mans of days of yore that looked like caveman flints? No tweaking necessary?

In the old days I would mechanically address the state of these and other adjustments given detonation and 'poor' fuel mileage. I have gone through the bike, i.e. valve lash, fuel/oil/air filters, spark plugs and new leads etc and the machine runs to my mind well and sounds great. I get burbling when I'm off the throttle, the exhaust is (I think OEM) somewhat loud and seems fine. I'm not sure what the ~3000RPM 'cough' people describe is. I'll talk to my therapist about accepting the fact that is guzzles fuel, but the detonation is not cool. I took it on a spirited ride today (roughly 45ºF); the achingly cacophonous detonation a sharp lil'needle in my ear.

I can't stick to a script, a couple of questions in a succinct paragraph. Sorry to the pummeled few who managed to hold on to this linguistic roller coaster in order to get to here. Hardy thanks. 

 

Personally I DO tend to run at a high RPM through all the gears and I nearly always downshift for hard throttle. The thing positively sings at higher rpm's as well as shifts effortlessly. It's made to rev IMO. My bike loves me for it. I ride all my bikes this way. Also I don't give a hoot about mpg OR tire life. (other than to determine a fault) This is my toy, not my investment.