now i may be mis-understand about the trans temp, but im picturing a sensor in line with the trans cooler.

this is what i used for an electric fan controller. yeah it looks like chit, but it was more operation than looks, that i was concerned with.


this is about as crude and simple as it gets but here ya go. this is just pipe fitting tee, and hose barbs. the wire is soldered to the tee for a ground.

Might as well go with a Gen 3 M62 while you are at it.

I've already done the Gen 2.5 conversion...against my better judgement

I would love to do the full Gen 3, but I have to find a matching TB.

Tonight I worked on the OBD2 harness, going over areas that needed repair or needed modification.

First, for my disclaimer (which I should have stated at the very first post), the older the engine is, the more modifications that need to be done to it to make it OBD2 ready. Typically, the 1992 and earlier crowd will have the most difficult time, mainly due to the crank sensor and harmonic balancer setup...those need to be 93-up pieces.

Now then, on with the harness pics...

This is the complete harness, save for the firewall connector missing. Unimportant since it is a completely different head.


See this? It'* the linear EGR connector. It needs to be much longer for it to work on an S1 as the EGR valves on those engines are on the front bank, not the back bank as the S2 models.


Maybe about this long...


After soldering, heat shrink, encasing in tape, and covering with loom, here is the finished extension


Now here is another difference...the temp sender head. S2 models use only one sender, where the S1s can use up to two, depending on what car that motor is used in.


It too will need to be extended, but not by much. Before that happens though, I need to research which sender on the S1s controls the dash gage, and which one is for the computer. I also need to determine if the resistance-to-temp ratio is the same between the two models. If so, I can eliminate one sensor from the setup. If not, the three-prong sender will have to go into the computer circuit, and the older two-prong will stay in the indicator circuit.

This is meant for the starter relay on S2 models. Since S1s have a different setup, this is not needed in the harness at all. Off with its head!!


That'* all I have for tonight. Tomorrow I may work on modifying the neutral safety switch connection, and extend and repin the trans connection.

For the record, 94/95 L27'* and L67'* don't have two knock sensors. Clearing that up from a comment made above.

Ah...I was thinking of the '95 L36...thanks for that clarification.

But...these blocks CAN support two. Remember...the blocks are the same regardless of them being supercharged or not. The locations of the knock sensors were different. L27s had them up front, L67s in the back. And there is no boss drilling to be done...simply remove a blocking plug, and pop in the sensor.

What'* interesting on the '95 L36s....the dual knock sensors are on the same signal line from the schematics I have looked at. If I am not mistaken, the OBD2 computers have separate lines for each sensor.

You are my hero! I'm hoping that you succeed. I apologize for not having any valuable input since the stuff that has been mentioned pretty much exceeds what I was aware of concerning sensors. But this is awesome! I feel like I'm back in my sub-10-post days, learning all sorts of goodies.

EDIT: Also, the moment I follow your steps to get this done, I'm heading to Intense for some tuning.

Intense, the good company that they are, can't help you. Their expertise is Series 2 tuning. Almost all the tables, from MAF to fuel trims, even shift points, will need to be custom done. GM Tuners (Sinister), from what I have seen, have done this already or are able to do so.

This mod is not for the faint of heart. It is NOT a plug and play setup, and far away even from being a plug and pray. This can't even be considered a mod yet because it has yet to be proven. This is more of a proof of concept than anything at this point. And one must have skills in electronics, soldering, and imagineering to accomplish this. But most of all...patience. I can't begin to tell you how many wires I had to redo last night because I looked at the schematics wrong. But I have a habit of checking and rechecking every step of the way when it comes to something like this.

And it'* far from over. Once I have the sensor parts of the harness modified to work on the S1, I still have to graft it to the firewall connection. And most of the wires coming from the firewall on the SSEi will not be used for their original purpose. Remember, no S1s came from the factory with their PCMs on the outside...meaning all those wires you see coming from that firewall are purely for engine operation and monitoring, and AC. S2s, on the other hand (with the sole exception of the 95 L36), have their PCMs on the outside. So very little coming out of the connector is actually used for engine operation. BUT...much more data needs to flow through there, along with power and ground connections.

Now, nothing stopped me from locating the OBD2 PCM on the inside, and use a simpler conversion harness fashioned from an OBD2 harness and the original PCM female connections. I still might go that route if this external harness doesn't work the way I want it to. These are just a few of the many challenges one faces when re-engineering things that aint supposed to be there. I've got nothing but time on this car since it isn't the daily driver...or a driver at all for that matter.

Radomir, there is no need to appologize. This is one area that nobody has tread on yet, and I fully understand what I have gotten myself into. I also fully understand that all this work may very well be for nothing. That'* the thing with experimentation...you never know until the very end whether or not your efforts will bear fruit.

sandrock, you are the leader in innovation of something that many of us have considered. myself included. i wish you the best of luck. and i would also like to thank you for sharing your experiance with us.

-Wes