Is there any DFI system for a GN that allows one to alter base timing? I have been having problems with my GN and finally took it to someone in the Chicago area to look at. Only thing he came up with is that possibly the balancer shifted and my timing is off. Car exhibits all the symptoms of late timing (low vacume, low rpm, and no power). I am looking for a new balancer right now but wanted to explore this option as well. Sorry for the newbie DFI question.
Aftermarket DFI question
- Thread starter GNandTTA
- Start date
If you align the balancer mark with the timing tab and pull the #1 spark plug you can reach in either with a small finger or tip of a small screwdriver and feel the piston while someone else rocks the motor back and forth, and do a pretty good job of stopping at top dead center. Then look at the balancer mark and timing tab and you can verify that they are still aligned. Then put the plug back in and crank it up with a timing light and you should see about 20 degrees of advance at idle. If you have directscan you can see exactly what it should be, but the stock table is about 20 degrees and most chipmakers don't change this. I'd rather do all this than buy a new balancer and change it and maybe not have the problem get fixed 
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.Stock ecm? You can put the ECM in "diagnostic" mode (which is different than ALDL mode), which fixes the timing at 15 deg. You put the car in diagnostic mode by jumpering the ALDL pins A and B (same as pulling codes via the service engine light). "ALDL mode" doesn't fix the timing, it just adds 8 deg to the normally calculated advance, so that doesn't help.
If you look at the timing tab on the timing chain cover, most of the marks and numbers runs down the outside edge. There is one mark and number on the inside edge; coincidentally it is at 15 deg.
So, fire up the car, jumper the A & B pins, and get the timing light going. If the balancer mark doesn't line up with the 15deg mark on the timing tab, you know the timing ring on the balancer has moved, and the actual timing vs. the commanded timing will be offset by that amount.
John
If you look at the timing tab on the timing chain cover, most of the marks and numbers runs down the outside edge. There is one mark and number on the inside edge; coincidentally it is at 15 deg.
So, fire up the car, jumper the A & B pins, and get the timing light going. If the balancer mark doesn't line up with the 15deg mark on the timing tab, you know the timing ring on the balancer has moved, and the actual timing vs. the commanded timing will be offset by that amount.
John
Except the fact that the waste spark, sparks twice do the timing light will show double the actual timing. Glad i went to a distributer and crank trigger i can adjust the base timing to what i want and move it anywhere. The amount of ve on my maps has increased quite a bit since the installation of the distributor.
With a dial back timing light I think you are right, the timing won't get shown correctly. With standard old style timing light that is just reading off the plug wire the light will get triggered at the 15 deg point every time the TDC mark on the balancer comes around instead of every other time. I've checked mine and had no problem confirming that 15 deg commanded was giving me 15 deg actual, this being after I had to move the timing ring on my balancer to the proper point (it had gotten installed a few deg off).
John
John
I put the new balancer on the car and nothing changed. Kind of figured so when I compared the new balancer to mine off the car and they looked identical. But figured I would give it a try.
So I was thinking of doing what ijames said. Pull the #1 plug and get to TDC and examine that the mark on the balancer lines up with the timing tab. In doing this, should the balancer mark line up with the 0 mark on the tab?
I do not see how this alignment could be off. Balancer is connected to the crankshaft and the pistons are connected to the crankshaft. So the only way the timing could be off is if the timing ring moved (shifted) or something is bent in which case there would probably be other signs of problems?? Am I wrong on this??
JDEStill, I will try the diagnostic mode. Maybe this will show somw difference either positive or negative.
So I was thinking of doing what ijames said. Pull the #1 plug and get to TDC and examine that the mark on the balancer lines up with the timing tab. In doing this, should the balancer mark line up with the 0 mark on the tab?
I do not see how this alignment could be off. Balancer is connected to the crankshaft and the pistons are connected to the crankshaft. So the only way the timing could be off is if the timing ring moved (shifted) or something is bent in which case there would probably be other signs of problems?? Am I wrong on this??
JDEStill, I will try the diagnostic mode. Maybe this will show somw difference either positive or negative.
Can you elaberate on this a little. How did you move the timing ring?JDEstill said:
The timing ring on the stock balancer is just pressed on. You can pull it off and press it on in a different spot. I had gotten a new balancer several years ago, and it didn't come with a timing ring. A mechanic was working on my car at the time (this was before I started doing all my own work), and he pulled the timing ring off the old balancer and pressed it on the new one, but apparently missed getting it into the right spot by a few degrees.
A post to the old mailing list (from pudd'n I believe) said "The edge of the ring should be lined up perfectly with tdc mark on the harmonic balancer. With age they seem to move. They are only pressed on."
Mine didn't look like that. Mine looked like this (the string is in the balancer 0 deg mark):
http://pages.prodigy.net/buickv6/CarStuff/balancer1.jpg
It looked close, but not close enough. The difference between 22 deg and 18 deg could be significant at full boogie after all.
Now I never got to check the timing with that method I described while the balancer was set as in the picture (I was in the middle of doing a cam swap I think), but I thought there might be a problem, and I didn't want to put the balancer on, check it, find a problem, and have to pull it off to fix it. So I risked pulling the ring off, moved it to where I thought the right spot was, and installed it, hoping I wasn't going to have to pull it apart to set it back where it originally was
So I don't know just how many degrees the ring was off in that picture. I do know that I moved it, checked it when the car was running again, and it was spot on at that time.
John
A post to the old mailing list (from pudd'n I believe) said "The edge of the ring should be lined up perfectly with tdc mark on the harmonic balancer. With age they seem to move. They are only pressed on."
Mine didn't look like that. Mine looked like this (the string is in the balancer 0 deg mark):
http://pages.prodigy.net/buickv6/CarStuff/balancer1.jpg
It looked close, but not close enough. The difference between 22 deg and 18 deg could be significant at full boogie after all.
Now I never got to check the timing with that method I described while the balancer was set as in the picture (I was in the middle of doing a cam swap I think), but I thought there might be a problem, and I didn't want to put the balancer on, check it, find a problem, and have to pull it off to fix it. So I risked pulling the ring off, moved it to where I thought the right spot was, and installed it, hoping I wasn't going to have to pull it apart to set it back where it originally was
So I don't know just how many degrees the ring was off in that picture. I do know that I moved it, checked it when the car was running again, and it was spot on at that time.
John
If you swapped balancers and nothing changed you have pretty much done the equivalent of my tdc check, unless you found a second balancer with the exact same problem as your first one . How many miles on the timing chain and gears; maybe it jumped a tooth and the cam is now advanced or retarded? It is possible you also have a cam lobe going flat.
. How many miles on the timing chain and gears; maybe it jumped a tooth and the cam is now advanced or retarded? It is possible you also have a cam lobe going flat.It has a new timing chain, comp cam 206 hydraulic cam, and fresh heads. This problem surfaced way before changing this stuff. Car just went from running great one day to sh*t the next. Factory heads were fine, cam was fine (slight wear on #3 exhaust), and chain was fine. But didn't know what else it could be. Had exhausted everything else. Car passed IL emissions easily (30 seconds on the rollers). Guy who looked at it in Chicago said it is definetly spark/gas timing. He had mentioned putting an aftermarket fuel system to adjust the timing. And that is where I am at. If anyone has any ideas, please mention them.ijames said:If you swapped balancers and nothing changed you have pretty much done the equivalent of my tdc check, unless you found a second balancer with the exact same problem as your first one
If you always run the same exhaust, maybe something is plugged up there. The cat could be be breaking up and plugging, and still let you pass emissions at the low flow of the test. You can get an adaptor to screw into the O2 sensor bung to connect a pressure gauge to check this, or uncap it at the end of the downpipe if you can (just be careful the first time you boost up, because if it was plugged it will go way up).
Going to an aftermarket EFI system seems a little extreme and unlikely to fix whatever problem you have. If this just started one day, I'd say that something broke somewhere, and you just haven't found what it is yet! Only thing an DFI or FAST system is going to fix is what, a bad MAF or a bad ECM? You can swap those with known good ones to eliminate those. I saw you had a previous post that said you got low compression on all cylinders, did you resolve that? You might want to post all your symptoms under General Tech and see what ideas everyone has.
John
John
I did resolve the low compression issue - it was a bad gauge. The guy in Chicago ran a compression test and it was fine. He said the motor is %100 mechanicaly sound. So it has to be something electrical. but I have changed/swapped every single bolt on sensor/part with the TTA (which runs perfect). So I thought maybe the wiring? I know the DFI is extreme but that is where I am at. I guess it would be more of a bandage. But if it works, I don't care.JDEstill said:
I tried the exhaust idea a few years ago, ran it open after the downpipe.
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