I am in need of some help with this one. and if anyone as the knowlage, it is the members of this group

this started in July, See Post Here I thought it was a reset, but turns out it was just a sync loss. the car is a street legal track car, so it does not get much use, even less with the reset problem. It is a '94 with a 2001 head (with slight work), 11:1 pistons, flat top IM, RB 4-1 header, VVTuner and diyautotune DIYPnP, v 1,5.

what I have done so far:
Looked at every log I have to determine when this started.
reverted to 3.2.1 with the last good tune, no change.
reset the crank sensor gap from .059 to .040",
bought a scope to look at the signals, looked at the sensor signals to the VVTuner, they looked good to me, (let me preface that with me learning how to use a scope)
Then I had to get the car thru emissions to keep it streetable. I installed the '94 CAS, put MAF and ECU back in. reset base timing and idle speed. passed emissions no problem.

removed the stock ECU and reinstalled the DIYPnP and CAI. drove the car around and logged, never lost sync,

I spent some time the other morning with the car, I set it back up to use the VVTuner cam & crank outputs to the ecu. first I tried VVTuner set to the 90-97 CAS simulation, car would not even start, composit log was all over the place. then I tries 01-05 pass through, again no start. last, was the 01-05 inverted, car starts and idles. but if you give it some revs, massive sync loses, see logs. slowly add throtte it will rev. i scoped the output from the VTuner to the ECU, (Iwill post them in next post). I am thiking about the cam signal crossing over the crank signal at this point. Next I unplugge the OCV, now the car will rev with throttle blip. but, when ever the OCV is plugged in or unplugged, the engine losses sync.

Thinking I might have a VVTuner box issue, I built a jumper plug to run the car
without the VVTuner, just a 15-pin with the sensors jumped and routed 12v and gound to them. car starts and runs fine with no loss of sync. please see logs. This test makes me think it is the VVTuner.

I know the car will run from the CAS, but I would really like to use the 99-00 crank & cam signals to the ECU because of the better timing stability.

any help on this would be apprciated very much. Thank You

 

scope shots of signals from the VVTuner

 

It looks like that with the VVTuner attached, the cam signal sometimes crosses a crank tooth. Contact DIY.

 

Thanks for looking at it, I have contacted them, but I have not yet received a solid reply.

How does the scope shot of the cam signal look? To me I see false triggers, (but what do I know)

Can you tell, from a composit log, if the cam is still physically timed correctly? Maybe by comparing it to a known good composit log?

 

Is the cam messed with? If not, this shouldn't physically happen.

 

No, bone stock,
here is a photo of the engine going together. if you zoom in you can see the timing marks.

 

This one has been a bit tricky. We've sent an RMA number as we will need to have a look at your VVTuner box ourselves.

 

well I got my VVTuner back from DIYAutotune, "no fault found" but it says they replaced the main board anyway. I reinstalled it and it is better with the free reving problem, but my intermitant sync loss issue remains. If I remove & replace the VVTuner with a jumpered 15pin connector, the car never losses sync.

can someone look at the two photos? they are scope shots of the CMP & CKP, red is directly from the sensors, yellow is the VVTuner output that is going to the ECU.

Am I looking in the right direction? at this point I don't know anymore.

 

Did you check the gap between the crank sensor and the trigger wheel teeth. It is supposed to be between 0.5mm to 1.5mm.

 

Why on earth are the VVTuner output signals 12V high?

 

Quick check: Are you having sync loss above about 3500rpm on the stim and 4500 on the road?

 

What exactly is pin 9 wired to?

VVTuner output is open collector. The pullup is provided by the engine ECU.

 

I was wondering about that;
The opto uses a 12v pull up in the DIYPnP. The ECU was originally built for a 94-95 using a CAS, but the build sheet for a 99-00 has the same pull ups.


This is a DIYAutoTune DIYPnP and does not use a stim. Running, the sync loss is very random,mostly below 4000 rpm, with the exception that it occurs a couple of times right after most cold start ups.

The gap is correct, checked it a few time now

Thanks for looking at this

 

Pin 14 is grounded to the ground stud on the engine block (by the TB) at the same location as the ECU. 9 is going to the gnd inside the ecu. Do you feel that it would be better for pin 9 to go to the SG inside the ECU ?

Is pin 9 the signal ground and pin 14 the system ground (that the ocv uses)?

 

It looks like it is fixed now, thank you Reverant for your guidance.

Last night and today, I went over the wiring with a fine tooth comb, no faults found. It is wired EXACTLY as recommended in the installation instructions. Also removed and opened the DIYPnP looked over all the connections. Using a bonding tester, checked the grounds, all okay.

Put it all back together again and started the car with no change, sync loss 3 or 4 times.

Again drove the car around with the vvt box removed, no loss of sync. Next I changed the VVT map to all zeros, short drive and no sync loss. Loaded the base map again, sync loss returns.

Upon Reverant's recommendations, I shared the sensor signals with some mods to the VVTuner and I changed the opto pull up in the DIYPnP from 12v to 5v. Test drove the car for a long time with no sync loss.

It looks like the VVTuner, as it is, is not capable of cleanly simulating cam/crank signals. It only took 12 weeks to resolve.

Graeme,
Golden, CO

 

I'm glad I was able to help!

 

What does this mean?

 

And the fun continues here

 

Sorry to bring back a dead thread but I used the info in post #15 to fix my issue with a new install. I was lazy and didnt wire it up like in the documentation. I only installed 12v to pin 7 and ground to pin 9 and 14 from inside the DIYPNP. Then I shared the cam and crank signal and obviously the OCV. Tried firing up and no spark, no pulse. Unplugged VVTuner and engine fired. Composite logger showed cam signal but no crank signal with VVTuner plugged in. Did a search and ran across this thread after trying to wire it up as the documentation had it and still no crank signal. Changed opto resistor to 5v and all is well. Thanks to Graeme for having the issue and to Reverant for his help.

 

Glad you found it useful. I have to think this is more prevelant than reported.
My car has been running great ever since. Finally go it on the track this weekend, the extra torque of the VVT is amazing. It turned two 2nd gear corners into 3rd gear corners, but now I have to use 4th more!