ECMlink Finally caught the car going crazy on a log please help

[davetheman81]

here it is, im just driving normal, then every once and a while the car sputters and the tach shoots to zero and then it back fires, i shut it off and start it again and usually im good to go, its very intermittent, some people have suggested coil pack, wires, plugs, cas, transistor, any idea

 

[steve]

Look at the RPM and MAFRaw in the log. I doubt your hitting 12k RPM or 1300HZ from the MAF. Given that both values depend on the base timing information from the CAS I'd start looking there and make sure I had a good sensor and good wiring to the ECU.

 

[jcart953]

What is everyone looking to see these logs because everytime I click on the log it usually says cant find or brings me to windows media or something. Is it because I dont have link or something?

 

[Talondvr]

You need ecmlink. You can download it at their website.

 

[jcart953]

You need ecmlink. You can download it at their website.

Thanks for the information.

 

[bradselph]

CAS or CPS could be going out or there shorting out somewhere.

 

[davetheman81]

CPS as in coil pack system?

And by shorting out do you mean a frayed or broken wire or maybe just need to be replaced?

 

[bradselph]

CPS as in Crank Position Sensor

check for frayed wires or it could be just going bad

 

[steve]

All DOHC 1G's have a Crank Angle Sensor (CAS) mounted on the intake cam that provides both the crank angle (TDC) and cam angle signals to the ECU. The crank angle signal is used as the major timing signal for RPM and airflow per rev.

I can't figure out how a noisy CAS signal could create both a high RPM and high MAF HZ. If you assume the MAF signal is unaffected I would expect the MAF HZ to be low since the ECU would see less of them in the shorter time period caused by the noisy CAS.

There is little in common with the signals until they reach IC4 in the ECU which I have seen go bad from time to time.

Does this happen enough that swapping ECUs might identify if the problem goes away?

 

[davetheman81]

Wait, so the CAS and CPS are the same unit?

Here is a brief in a nutshell style history of ECUs in my car. I bought the car and it drove like crap, the ISC made alot of noise when the key was in but car was off. I found the caps were bad, replaced them, car drove great, few months later, my timing belt snaps due to being saturated in oil leaking from the front case.

I get the car back with new motor and mods and i buy a DSMLink v3 lite chip in an EPROM ECU from a forum member. The ECU pulls back 30 percent fuel when the car is running and the front O2 never cycles.

Get a friends ECMLink v3 lite chip and his ECU, put it in and the car can be tuned but now does this weird thing where every 5-10mins or so the car bucks and the tach hits zero and it back fires and then stalls. And on DSMLink, even though I'm only going 30 mph it says I'm at 12,000 RPMs and the MAF is at like 1500 hertz, as you can see i have had a few electrical issues.

Any ideas maybe need more engine grounds.

Ok so i have been having CAS issues, and I believe there is a short some were in my engine harness, what i would like to do is directly wire the CAS into the ECU, 12v, and ECU ground directly, here is my idea.

I will get shielded 16/4 wire and on the correct pins on the 92 CAS plug I will go to 12v ignition and ECU ground, then I will cut the CAS and CPS sensor wires about 2 inches at the ECU connectors and solder my wires in.

My question is not only will this work, but do any of the 4 wires T off anywhere or go anywhere else other then there said destinations at 12v ignition, ECU ground, CAS and CPS inputs on the ECU?

I didn't know if they went to any other sensors first, or the cluster or anything, thanks. I have a new CAS and I would like to get this one in all wired up correctly. I also could test all the wires at the CAS plug to find a short, but how would i go about that?

Also my issues are intermittent so it might only be when a certain wire is pulled or flexed, thanks!

 

[DSMlover2011]

It sounds like you should test out the coil pack and power transistor. Both are know to periodically act up with they start to go bad. This could easily explain your car's symptoms.

Here is a link on how to test the coil pack (main info is 3/4 way down page) > http://www.dsmtuners.com/forums/newbie-forum/130662-back-firing-wot-maybe-fuel-cut.html

Here is a link on how to test the power transistor > http://www.dsmtuners.com/forums/articles-electrical-wiring/229419-how-test-power-transistors.html

 

[91vr4galant]

I've never had a cam sensor go bad but if its reading that much rpm I would suspect that, But ive also never had a coil pack problem either! Just a thought.

 

[davetheman81]

thanks guys, im going to test stuff out tommorow