Play in drivetrain (ah and tuning issue)
Discussion
I am falling from one issue into another, but I believe I aqm close to having her sorted.
First: I cant find my old topic about throttle body's and light throttle kangarooing, but there I have been helped out by Paul at Austec: In the end the big issue was that the throttle bodies needed a lot of work to give them equal and more stable readings ater which Paul also put in quite a bit of work to smooth the map, all resulting in an as smooth a ride as I have had so far. I have to say that I have been amazed by the patience of Paul sorting this out and not cutting any corners: very happy with service.
With that sorted I have now have another issue which I am not sure is normal:
From a cold start the cerb will feel smooth an tight, however after having had a good workout (Mostly after more than 1-2 hours of driving!!)I am getting the feeling that there is more play in the drive train, mainly in the differential or in that area. I have no idea what may cause it as one would expect the oil in the differential to have heated up more earlier.
The end result is that that I hear a distinct clonk when releasing the throttle and stepping on it again and it also affects slow driving (more shuddering).
Any ideas?
thx
Wiebe
First: I cant find my old topic about throttle body's and light throttle kangarooing, but there I have been helped out by Paul at Austec: In the end the big issue was that the throttle bodies needed a lot of work to give them equal and more stable readings ater which Paul also put in quite a bit of work to smooth the map, all resulting in an as smooth a ride as I have had so far. I have to say that I have been amazed by the patience of Paul sorting this out and not cutting any corners: very happy with service.
With that sorted I have now have another issue which I am not sure is normal:
From a cold start the cerb will feel smooth an tight, however after having had a good workout (Mostly after more than 1-2 hours of driving!!)I am getting the feeling that there is more play in the drive train, mainly in the differential or in that area. I have no idea what may cause it as one would expect the oil in the differential to have heated up more earlier.
The end result is that that I hear a distinct clonk when releasing the throttle and stepping on it again and it also affects slow driving (more shuddering).
Any ideas?
thx
Wiebe
on the tuning question, what ECU are you using? A standard mapping error is to add a little advance at lower rpms on neutral throttle as it improves the output and makes the curve look better. It also makes them (4.5 V8, can't speak for others) kangaroo with accompanying drive train clonks at circa 1800 to 2500 rpm on when cruising. The retarded ignition was there for a reason to do with throttle body flow reversion at a small throttle angles. The purpose was to force the throttle open a little wider to effectively map around the problem area. You can't tweak it out, time it out of enrich it out but a good lump of retard in the lowest 2 throttle bins at 1500-2500 rpm will cure it. It will also make it pop and crackle, now there’s a coincidence putting paid to the theory that pops and crackles were a marketing idea, they are really a result of using huge independent throttle bodies to make massive power and accidentally creating a tractability problem down low.
Sounds exactly like what mine was doing, rear diff mount broke, replaced that with all the bushes, after about 200 miles it developed a knock coming on and off power. With it on jacks with wheels off, handbrake on I could re-create the clunk by bringing clutch up to bite point quickly. I could see the driver side diff output flange moving up as well as turning, which it shouldn't do. Turns out the diff was shot. Shims, bearings, spider fingers (all internal) were bust up good and proper. Just got it re furbed at Readman racing.
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