2G How to install 99 ecu in 95

[shifty2006]

I have been trying to fix my issue l losing spark on 1 and 4 I have changed ptu, coil packs and cas also pig tail for cas. I have 95 motor 98 cas. The car runs for about 15 min and then drops 1 and 4 spark I wait about 10 min and it runs for another 15. I'm looking to swap ecu but I have picked one up from a 99 I just need to know if I can just plug it in or what the steps are..

 

[luv2rallye]

Sounds like a heat issue. The ptu MUST be mounted in it's original bracket to transfer heat to the head (or at least have it's backside flush tight against something solid metal that can absorb heat). Note that the ptu backside is connected to it's negative terminal so don't place it on anything that could produce a short. Having it in it's bracket against the head is best because a large negative current can flow through the backside instead of through the smaller negative wire which can also produce heat. Also, aftermarket ptu's are known for failure upon heating up. Coils also need to dissappate heat trough their brackets. You can test these by heating them up with a hair dryer to see effect. Another possibilility is the CPS (different than CAS). Also the ptu driver circuitry inside the ECU.

The 99 ECU will probably work if you don't mind getting a couple CEL codes due to emission differences (http://www.dsmtuners.com/threads/99-gsx-ecu-in-a-97-gst.380404/#post-153296068). At minimum it should work good for testing (see if same problem is still there).

PM Steve if want complete answer on ECU swaps.

 

[shifty2006]

I have the ptu in the stock mounting location. I never thought of the cps I thought cas controlled spark not the cps thanks for the info I won't mind the check engine light I guess as long as I can swap it to see if that's my issue.

 

[cheney]

I have the ptu in the stock mounting location. I never thought of the cps I thought cas controlled spark not the cps thanks for the info I won't mind the check engine light I guess as long as I can swap it to see if that's my issue.

Hey bud, what did you end up figuring out on this? I have loss intermittent now on cyl 2&3. Aiming at CAS or ECU, just gathering what my best odds are

 

[shifty2006]

No still a work in progress.. I haven't figured it out I've spent hours looking at diagrams and testing things but I only get a few min window each time it drops to test things. My next attempt is I'm swapping from 97 cas and crank sensors to the blacktop 1g that controls both. I picked up another ptu and ecu once they are all installed I'll try it out tried them all separately now I'll see if they work replaced all together also I'm trying out whay someone suggested and putting arctic silver 5 heat dispersion gel on the back of the ptu mounting point..

 

[cheney]

No still a work in progress.. I haven't figured it out I've spent hours looking at diagrams and testing things but I only get a few min window each time it drops to test things. My next attempt is I'm swapping from 97 cas and crank sensors to the blacktop 1g that controls both. I picked up another ptu and ecu once they are all installed I'll try it out tried them all separately now I'll see if they work replaced all together also I'm trying out whay someone suggested and putting arctic silver 5 heat dispersion gel on the back of the ptu mounting point..

I'm in the same boat. Replaced the PTU, connector, plugs, wires, coil pack....still no spark on the cyl 2&3. So i'm looking at a new ECU now. Praying that I don't have to mess with the CAS or CPS. I don't have the time for that mess

 

[shifty2006]

If the ecu doesn't do it just buy the 1g cas and the pigtail that plugs in the install is all lined out with pics if you just find the post..

 

[cheney]

If the ecu doesn't do it just buy the 1g cas and the pigtail that plugs in the install is all lined out with pics if you just find the post..

Good deal thanks!