Just another LQ9 swap

[Blasphemy]

Ok so temp and oil pressure you can use your old sensors. I got this adapter from speedway motors for the oil pressure and reused the old sender. For the temp, I rethreaded a stock 95 sensor so it would fit in the head M12x1.5 IIRC. Tach, white wire from PCM goes to white wire in cluster connector. Speed, dark green wire from new PCM goes to dark green wire going to cluster (there may be 2). Voltage just worked since I didn't touch the wiring for that. Fuel should also work as before.

Well, like I said, I tried hooking the white wires together for the tach but nothing happened so I'm thinking that I might be missing a ground somewhere or I need to install that resistor. I didn't want to re thread my coolant sensor so I decided to use the 3 wire sensor from a '98 camaro LS1 (done elsewhere on here by another forum member)and that seems to be working fine. I'll have to look in to the oil pressure sensor adapter if that's the only solution. But where does the signal from the current sensor go? I don't have a wiring diagram for my current harness so I can only go off the pins going into the pcm. And yes, I do have two wires for the vss I just wasn't sure which ones to hookup.

[Jeebalow]

Well, like I said, I tried hooking the white wires together for the tach but nothing happened so I'm thinking that I might be missing a ground somewhere or I need to install that resistor. I didn't want to re thread my coolant sensor so I decided to use the 3 wire sensor from a '98 camaro LS1 (done elsewhere on here by another forum member)and that seems to be working fine. I'll have to look in to the oil pressure sensor adapter if that's the only solution. But where does the signal from the current sensor go? I don't have a wiring diagram for my current harness so I can only go off the pins going into the pcm. And yes, I do have two wires for the vss I just wasn't sure which ones to hookup.

Yeah try the resistor, looks like every 2003+ PCM may need it. You probably already saw this, but I'll put it here anyway: http://lt1swap.com/lsx_tach.htm.

3 wire sensors should be fine, I just read that it may be a little off. I didn't want the PCM to read the incorrect temp so I rethreaded, they also make adapters. Regardless, yours is working.

When you say current sensor for oil pressure I am assuming you mean the 98. It goes straight to the gauges, the old PCM (and new PCM) don't need oil pressure to run the engine. I think in the newer trucks the oil pressure signal went to the BCM and gauges to inform you if pressure dropped. Which means you would need to find and correctly wire a BCM to get it to work form the new sender. It's much simpler to get an adapter and stick with the stock sender that works with your 98 gauges.

Do not mess with the VSS circuit that is not where you will be getting speed data. Your gauges cannot use the A/C signal coming from the VSS. That is what the PCM does and corrects for your wheels and gear ratio then sends the corrected signal to the gauges. When I say 2 wires I meant 2 dark green wires going to the gauges. Only one will be the speedo wire, the other will control the temp gauge (at least in my 95 that's the way it's wired).

[Blasphemy]

After much deliberation, I received an email from Brendan on LT1swap.com and he verified much of what you said. I'll try the resistor thing with the tach to see if it works because my PCM is definitely a 2005 model year. Unfortunately the oil pressure sender was still on the 350 when I sold it, so now I'll have to wait for a new one and the adapter to get here...more waiting on the ol mail man. I miss those days when I could just drive down to Summit Racing (I lived in Reno) and pick up whatever go fast parts I needed. I'm not too worried about oil pressure though considering I redid every single gasket and seal on that engine and it only had 96K on it when I did it. This whole swap process has been one long learning curve, but I'm still really happy I did it. Even without the final tuning done, the engine has a boatload of power (even stock) over that tired old 350. My next swap will be a 5.3 into my old '80 chevy shortbed.

[hokeplaya05]

just read through your thread, maybe i missed it but what headers are you using? i saw in a pic that you are running longtubes (looked like pacesetters) but i have not been able to find any longtubes that fit 4wd trucks.

[Blasphemy]

just read through your thread, maybe i missed it but what headers are you using? i saw in a pic that you are running longtubes (looked like pacesetters) but i have not been able to find any longtubes that fit 4wd trucks.

Yes I am running pacesetters for a 4WD. I wasn't too impressed with the fit though because I had to grind the frame where they rubbed on the passenger side. And getting the rest of the exhaust to work was a pain because I found out that my trans crossmember was bent and the headers dump at awkward angles. My recommendation for you is to save up the cash, buy the ceramic coated headers (mine aren't) and pay a reputable exhaust shop to do the install after the headers are on. And to save the coating on the headers, wrap them in something.

[hokeplaya05]

are they made specifically for ls swapped 4wd obs trucks? i will look into them. i am surprised they didnt fit that well, i have their ceramic coated lt's on my truck and my camaro and they fit perfectly. i was really hoping to find stainless ones since i drive my truck in the winter

[gagliano7]

https://www.holley.com/products/ls_p...st/ls_headers/ These are for the 73-87 trucks but I would think the would fit the 88-98

[hokeplaya05]

i highly doubt they would fit since the 73-87 4x4 trucks have solid front axles compared to the 88-98 4x4 with ifs. but could be worth a try. i was thinking that maybe a longtube from a 99-07 4x4 truck may fit since the front suspension is very similar to obs trucks

[GreyChevy]

I used coated pacesetter longtubes part #72c2267 on my 92 k1500 LQ9 swap. I had to do the same though....dimple one primary by the passenger side frame. I also cut off one of the unused transmission ears. Fit like a glove then.

[Steve A]

Hey Brandon,
How's it going? Got that truck done yet? If you do how about some pics man?