# Need some help on a LQ4/LS swap **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [October 12, 2016, 7:18am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321 "2016-10-12T07:18:58Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 12, 2016, 7:18am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/1 "2016-10-12T07:18:58Z")
Having an issue getting my swap to run. 2003 DBW LQ4/ T56 vats has been removed, rear 02’s are gone as well as egr, and evap. Have 55-60psi at the rail. It was running the ther day for 15-20 min trying to cycle through for a DBW relearn, shut it down for an hour came back and now the most I can get out of it is a quick fire idle for a few seconds then it shuts down. Will do this as many times as I crank the key. This is as far as I have gotten. Not throwing any codes. Does anyone have any ideas? I’m lost. Thanks Adam ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [October 12, 2016, 8:58am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/2 "2016-10-12T08:58:11Z")
Sounds like VATS, are you able to confirm through HPT or something? ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 12, 2016, 9:06am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/3 "2016-10-12T09:06:29Z")
I had the guy that did the tune verify it. Also probably would have never ran for extended periods of time if it was vats. Does anyone have HPTuners I could use to verify nothing is wrong with the tune? ---
**Author:** ![dsherw00d](https://avatars.discourse-cdn.com/v4/letter/d/a88e57/32.png) [@dsherw00d](https://forums.speedlife.net/u/dsherw00d)\ **Post date:** [October 12, 2016, 9:40am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/4 "2016-10-12T09:40:05Z")
Oil pressure or oil level sensor? Unplug the MAF? Since it ran fine for a bit, maybe a loose wire or failed sensor. Otherwise, it does sound like VATS. ---
**Author:** ![SOLITUDE](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@SOLITUDE](https://forums.speedlife.net/u/SOLITUDE)\ **Post date:** [October 12, 2016, 10:22am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/5 "2016-10-12T10:22:04Z")
You can always just bypass vats with resistor. Just measure at the key cylinder and eliminate it for the time being. ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 12, 2016, 2:44pm UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/6 "2016-10-12T14:44:32Z")
I dont believe it is VATS but I am willing to try just about anything at this point. I get nothing different going around and unplugging sensors one by one. Where am I wiring a resistor in? Do i have a way to test without having the key from the donor vehicle? This motor is now into a 1997 Chevy Silverado so Im not sure that I can pick up a resistance reading at the key cylinder. Set a lofty goal back in May to use this as the getaway vehicle at my wedding this saturday, but as with most swaps things just didnt go as planned. Figuring this out is just about the last step to having it on the road. - - - Updated - - - I should add it never “ran fine” by any means. It idled around 400-500 rpm with map sensor unplugged and had a max rev of 1400rpm, wouldnt run with map hooked up. Replaced MAP, got nothing. Then grounded out c1-32&34 to get rid of the Park/Neutral rev limiter and now it wont idle at all. lol. Is it possible for VATS to not delete/come back after initially firing and idling? - - - Updated - - - This is what i got from the guy that tuned it. ![http://www.nyspeed.com/attachment.php?attachmentid=36792&stc=1](http://www.nyspeed.com/attachment.php?attachmentid=36792&stc=1) ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 12, 2016, 7:31pm UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/7 "2016-10-12T19:31:09Z")
What are the possibilities of clogged injectors keeping it from firing? Motor sat for 2 years in my shop. We ran it in the donor vehicle before we pulled it. Checked injectors with with a noid light and they are never going out when the motor dies. Leads me to believe it’s not a Vats issue? Would a cam or crank sensor cause anything like this? ---
**Author:** ![BDR5oh](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/bdr5oh/32/7315_2.png) [@BDR5oh](https://forums.speedlife.net/u/BDR5oh)\ **Post date:** [October 13, 2016, 4:12am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/8 "2016-10-13T04:12:38Z")
did you try and start it on starting fluid ? and see if it will stay running … that will at least verify a fuel issue … - - - Updated - - - and unplug the MAF not the MAP sensor ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 13, 2016, 4:59am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/9 "2016-10-13T04:59:15Z")
Thinking it’s an injector plus issue. Noid light test would give one bright pulse then dimmer after that. Verified it would run on starting fluid. ---
**Author:** ![Norb\_O](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/norb_o/32/5189_2.png) [@Norb\_O](https://forums.speedlife.net/u/Norb_O)\ **Post date:** [October 13, 2016, 5:59am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/10 "2016-10-13T05:59:16Z")
If the VATS is tuned out then it won’t come back unless you go back in the tune and turn it on. Possibly a wiring issue, especially since you have fuel at the rail, since it ran for 20 mins and now died. Wire may have come loose somewhere. Is it possible that old rusty sediment got stirred up in the tank and clogged the pickup/pump? Maybe pull the fuel rail off the manifold and crank it to make sure injectors are spraying. ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 13, 2016, 7:14am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/11 "2016-10-13T07:14:53Z")
I don’t think the injectors are getting a strong enough pulse to fire past the initial crank. Any noid light test videos I saw held a steady flashing light the same brightness, I’m getting one bright flash then dimmer flashes after that. ---
**Author:** ![Norb\_O](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/norb_o/32/5189_2.png) [@Norb\_O](https://forums.speedlife.net/u/Norb_O)\ **Post date:** [October 13, 2016, 7:35am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/12 "2016-10-13T07:35:36Z")
How are the injectors wired? Any changes to the factory harness? ---
**Author:** ![LZ1](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@LZ1](https://forums.speedlife.net/u/LZ1)\ **Post date:** [October 13, 2016, 8:54am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/13 "2016-10-13T08:54:12Z")
Have you checked to make sure the tank has gas and isn’t full of water lol someone else recently had the same issue. If the tune isn’t locked you can have someone read it with HP tuners(not using any credits) and verify VATS is off as well as monitor PCM data. ---
**Author:** ![boardjnky4](https://avatars.discourse-cdn.com/v4/letter/b/96bed5/32.png) [@boardjnky4](https://forums.speedlife.net/u/boardjnky4)\ **Post date:** [October 13, 2016, 8:59am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/14 "2016-10-13T08:59:08Z")
I would start by checking the voltages at the injectors if you think that’s the problem. You could also try and get the injectors tested. ---
**Author:** ![nitroinsane](https://avatars.discourse-cdn.com/v4/letter/n/d26b3c/32.png) [@nitroinsane](https://forums.speedlife.net/u/nitroinsane)\ **Post date:** [October 13, 2016, 11:15am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/15 "2016-10-13T11:15:14Z")
Vats will shut down in 1-2 sec. I love that everyone blames vats. Let’s start with. Is this a bone stick engine no cam, no injectors? Is this a maf car? Is the maf hooked up? Are the plugs fouled? Are the cam/crank sensors fully seated? Is the pcm setup for an auto. It could have the wrong parameters. ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 13, 2016, 1:41pm UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/16 "2016-10-13T13:41:47Z")
Bone stock engine. Maf makes no difference plugged or unplugged. New spark plugs initially and have changed them again since diagnosing these problems. Cam sensor was never out, crank sensor was out at one point not sure if it’s seated correctly or not. Pcm was set up for manual trans. All I have is the tuners word on that though. Willing to to pay someone $$ beer food to come hook up hptuners and see where we can get with that. ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 13, 2016, 5:53pm UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/17 "2016-10-13T17:53:24Z")
> [@Norb O](#): > > How are the injectors wired? Any changes to the factory harness? +12v from the fuse block and the control from the PCM. Deleted all unnecessary things from the harness, egr, evap, rear 02’s, auto trans etc. > [@LZ](#): > > Have you checked to make sure the tank has gas and isn’t full of water lol someone else recently had the same issue. > > If the tune isn’t locked you can have someone read it with HP tuners(not using any credits) and verify VATS is off as well as monitor PCM data. gas tank was off and emptied dry. New gas new fuel pump. ---
**Author:** ![BadnewsMike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/badnewsmike/32/7419_2.png) [@BadnewsMike](https://forums.speedlife.net/u/BadnewsMike)\ **Post date:** [October 15, 2016, 6:55am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/18 "2016-10-15T06:55:39Z")
sounds like a ground issue. I have HPtuners if you want I can do a rip. but doubt this is tune issue. ---
**Author:** ![Birdman64](https://avatars.discourse-cdn.com/v4/letter/b/c37758/32.png) [@Birdman64](https://forums.speedlife.net/u/Birdman64)\ **Post date:** [October 27, 2016, 7:55pm UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/19 "2016-10-27T19:55:16Z")
@BadnewsMike wish i would’ve seen this!! Thanks for the offer though. Turned out to be a bad MAF. Must have damaged it during removal/install. Would not run with it unplugged because it had not done the DBW relearn and it starts off with a ~500rpm idle. Might get to drive it before the salt flies… ---
**Author:** ![Norb\_O](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/norb_o/32/5189_2.png) [@Norb\_O](https://forums.speedlife.net/u/Norb_O)\ **Post date:** [October 28, 2016, 5:55am UTC](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321/20 "2016-10-28T05:55:16Z")
:bigtup: Burnouts! [Next page](https://forums.speedlife.net/t/need-some-help-on-a-lq4-ls-swap/274321.md?page=2)