tminer
Not quite normal
- Joined
- May 25, 2001
- Messages
- 761
I have a problem with the TTA and the symptoms are very much like the common grounding problems. Throws a bunch of malfs, goes into backup mode and doesn't run well. It is very intermittant and so far only happens when engine is running.
I've replaced the ECM and chip, but not the calpak. I've soldered all ground wires at battery/chassis, G117 & G118 (both at RH rear of intake). I've even run battery cables from battery to G117 & G118. I also have the bottom cover off of the ecm so that I can measure & scope C1 & C2 at the pcb. The only odd reading is EGR Diagnostic (D9) at B+ instead of 0* like reported on gnttype, but it is pulled up within ECM and the switch is NO in the wiring diagram. Also looks the same with the EVRV disconencted.
when this happens all of the A/D convertor functions go wacko. Volts shows as 0.2-1.6 or so, tps doubles, rpm goes up, speed goes up, mat goes up and coolant temp goes down. also get false readings for P/N, 3rd, 4th, etc. This can happen for just a frame or for several minutes while sitting at idle. Can also be normal for long enough for me to think that I've fixed it, only to reappear on an extended test drive.
I've observed this with Maf, O2, TPS, EGR, A/C, cannister purge, and esc (maybe other things) disconnected. I haven't pulled coolant temp, but have observed it at the ecm.
I've swapped out the coil pack and ccci.
I've observed injector B+ lines on O-scope, and they are consistant.
I don't think that it is T-link because I had drivability issues and then started using T-link and observed that drivability coincided with the wacko readings.
I suppose that I could try the GN calpak, but I would think that with a bad calpak it would run really bad in backup mode. It doesn't run good, but drivable, what I would expect for limp home.
I know to keep eliminating things (divide and conquer) but thought I'd see if anyone has something specific based on prior experience and/or more intimate knowledge.
BTW, when the reported volts goes low, all of the ground to B+ voltages look good at C1 & C2.
Thanks,
Tom
I've replaced the ECM and chip, but not the calpak. I've soldered all ground wires at battery/chassis, G117 & G118 (both at RH rear of intake). I've even run battery cables from battery to G117 & G118. I also have the bottom cover off of the ecm so that I can measure & scope C1 & C2 at the pcb. The only odd reading is EGR Diagnostic (D9) at B+ instead of 0* like reported on gnttype, but it is pulled up within ECM and the switch is NO in the wiring diagram. Also looks the same with the EVRV disconencted.
when this happens all of the A/D convertor functions go wacko. Volts shows as 0.2-1.6 or so, tps doubles, rpm goes up, speed goes up, mat goes up and coolant temp goes down. also get false readings for P/N, 3rd, 4th, etc. This can happen for just a frame or for several minutes while sitting at idle. Can also be normal for long enough for me to think that I've fixed it, only to reappear on an extended test drive.
I've observed this with Maf, O2, TPS, EGR, A/C, cannister purge, and esc (maybe other things) disconnected. I haven't pulled coolant temp, but have observed it at the ecm.
I've swapped out the coil pack and ccci.
I've observed injector B+ lines on O-scope, and they are consistant.
I don't think that it is T-link because I had drivability issues and then started using T-link and observed that drivability coincided with the wacko readings.
I suppose that I could try the GN calpak, but I would think that with a bad calpak it would run really bad in backup mode. It doesn't run good, but drivable, what I would expect for limp home.
I know to keep eliminating things (divide and conquer) but thought I'd see if anyone has something specific based on prior experience and/or more intimate knowledge.
BTW, when the reported volts goes low, all of the ground to B+ voltages look good at C1 & C2.
Thanks,
Tom
