Z32 Dash Tach ECU mismatch

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ZleggedBeast
Posts: 1
Joined: Tue Jun 14, 2016 11:18 am

Z32 Dash Tach ECU mismatch

Postby ZleggedBeast » Tue Jun 14, 2016 11:49 am

Hi all,

I am new to the forums, new to tuning, new to haltech. I have managed to get my Z driving fairly well with a couple exceptions (not getting all but 5 psi of boost until 5k rpms). I have a multi-part question because i think they are all related. My boost issue still may be a boost leak as i am not convinced its not even after a boost leak test. I dont start getting any boost until about 4500 rpms. I have a fresh built up long block, new GTX2863 turbos, 1000cc injectors and (among many other supporting modes) a Haltech Pnp pro ECU. I am thinking that i could have a cam timing issue and either overlap or exhaust advance is not correct, putting my spool way late in the RPM range. At the same time im dealing with issues that im sure allot of people deal with on big builds, one of them that troubles me is that my dash Tachometer does not match the ECU reading for RPM. The dash reads about 200 rpm more than the Haltech software. This doesn't seem to be linear either. At idle it seems to be less than 200 RPMS.

My question is this: is it possible that my timiing (either crank or cam) is contributing to the RPM discrepancy? I have the stock value of 6 pulses per engine cycle set for my crank angle sensor (came with my factor Z32 ecu map). I will try to fiddle with the filter levels of the signals but i figure now is as good of time as any to get on the forums and start talking. I have many questions.

I am assuming that my CAS sends a signal to the ECU, so my ECU should have the "correct" RPM reading. The ECU then sends a signal to the dash, or the CAS sends a split signal to the dash. Depending on which is the case will depend on the severity of my problem. Does anyone here know how this signal works with this ECU?

Thanks
Dave

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HaltechMatthew
Haltech Staff
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Re: Z32 Dash Tach ECU mismatch

Postby HaltechMatthew » Thu Jun 16, 2016 10:50 am

You have a Z32 or Z33? This section is for the Pro Harness models... Z33 and R35.

the_bluester
Posts: 175
Joined: Wed Oct 24, 2007 3:19 pm

Re: Z32 Dash Tach ECU mismatch

Postby the_bluester » Sun Jun 26, 2016 12:13 pm

Regardless of if this is in the right section or not. I would say that the error is on the part of the factory tach. A couple of hundred RPM error would not surprise me much at all.

Without knowing the individual setup (Which goes to Matthews question) on a Z32 I would imagine the ECU would output a tach drive signal to the dash, Z33 I would assume it would be outputting the RPM in a CAN bus message and the dash is taking it from there. In either case the meter movement in the dash would be the least accurate part of the train.

I am just wondering though, what is the AR of the exhaust housings on the turbos? (Again goes back to Z33 versus Z32 to some degree as well, engine capacity wise) I have a GT2860RS on an RB20 with a .63 exhaust housing and it is snappy on that engine, but even with that small housing I would expect it to be a bit on the doughy side on a 1.5L (Extrapolating out to two of them on a 3L engine.)


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