aaronsjeep

Hello All I have dug through LS1tech for tons of help on my swap and gotten the motor and trans in and running but now need some help,

A little about my swap:

1987 Grand Wagoneer, swapping in a 2003 5.3 with matching 4l60e and a NP 241c from a 95 1/2 ton Chevy.

Using Advanced Adapters motor mounts, Novak rebuilt the stock harness and reflashed the computer removed the rear O2 sensors and EGR and VATS. I am using 99 5.7 exhaust manifolds.

Currently the motor is in and starts and runs for about 10- 15 seconds and then dies. It runs a little rough. It has/had new plugs. (seems to be running rich) It seems to be going into limp mode. The throttle body responds to gas pedal input before starting but then nothing after it's running... until you clear the codes then it repeats the scenario. I am getting codes:

P0120
P0220
P1516
P1518

I have checked the wires 4 to 6 inches before the throttle body and they appear to be fine. (digging through the archives I found a service bulletin that suggested inspecting the throttle body wires) I also own a 2003 Yukon with the same drivetrain so I have tried the TAC, Pedal Assembly and Throttle Body from the Jeep on the Yukon and each component works when plugged into the stock Yukon.

My next thoughts are to... try the good throttle body from my Yukon on the Wagoneer.

Remove and clean the fuel injectors.

Tripple check that I have all the grounds hooked up correctly.

Replace wires and check plugs.

Planning on calling Novak tomorrow to go over everything with them, but hoping someone here can help while I have shop time

One more thing... Although the VATS were suppose to be removed, is this how a vehicle acts when they are not?

Any and all help is GREATLY appreciated!

aaronsjeep

I am using a walbro gsl392 fuel pump from summitt mounted by the tank in the rear of the Jeep.

I tried swapping throttle bodies from the Jeep to the Yukon I have both work on the Yukon, neither work on the Jeep, kind of suspected this, but with the p0120 and p0220 TPS codes I thought it was worth ruling out a bad or malfunctioning throttle body.

Searching to find more about the VATS and how vehicles act when they haven't been removed, but no luck yet....

aaronsjeep

bump for some help, reading lot's of tsb's about p1516 and p1518 on 2003 lsx motors. Does anyone here have experience with p1518 and p1516 issues?

aaronsjeep

Tried a new tac module (12589923) which is the part number that my VIN calls for. I previously had the 3059 TAC. Same results. Runs for 10 seconds than dies. Throttle body responds to gas pedal before start up, but vehicle seems to go into limp mode as soon as it fires. Now it is only setting a P1516 so maybe the new TAC sorted some of the issues

Going to go through all the grounds and all connectors again today. Then??? Maybe take the throttle body, gas pedal, and tac out of my wifes 03 Yukon and see if they work together in the Jeep.

Any help would be greatly appreciated.

thanks- aaron

pdsq98gt

Do you have a maf on there?

aaronsjeep

I do. I have the original MAF sensor from the donor truck. I have it connected directly in front of the throttle body now until I can build an intake. I am planning on buying the plumbing for the intake this week. Could that be the problem?

pdsq98gt

Sometimes not having a maf can cause a similar issue, but you have one on there. Could be a harness issue. Check your grounds. Make sure you have good power and ground to the tac module.

74novacustom

I went through some issues with my DBW System as well, not really the same because a new TAC fixed my issue. BUT. here are a list of things my Hours of researched turned up.

As You have already heard, Grounds... Double check these
Behind Pass head by temp gauge sender
back of engine by oil sending unit
Front Driver side down by Power Steering Pump.

Maybe a dumb Question, but is your MAF on backwards? It was just another thing my research turned up.

Check the Yellow wire at the TB, follow it for about a foot and check for it being limp....or brittle. The wire inside is known for breaking.

Using the wifes SUV is what i did to find my Issue. 03 Escalade worked as a good donor.

Goodluck

74novacustom

Now that i think about it im not sure the problem is with any of the DBW system, now that my system is running i can unplug any one of the three components, TB/TAC/Pedal and the only response is low idle.

Grounds

Programming.

aaronsjeep

Thanks pdsq98gt and 74novacustom...

I am planning on getting back out to the garage this weekend. I have checked my grounds at least three times but I am considering disconnecting the complete harness and starting from scratch. (I mean checking every connection) I am not completely confident that I have all the grounds exactly where they should be. (more searching) My computer and Tac both need to be bolted down better as well as some other organizing.

I think when I pull the harness I am going to strip all the insulation and look for any burned or damaged wires too.

I also need to hook up my VSS. Could this being disconnected cause the problem? If it is I am going to feel pretty stupid, but my understanding is the VSS wouldn't put it into limp mode???

I am sure it's something simple and stupid, it usually is. Exhaust and driveshafts are done now, so as soon as this is sorted I am driving!!!

Thanks again, I will update with what I find and some pics...

psiconversion

iTrader: (5)

I have had some truck applications go into limp mode without vss signal.

Jon
PSI

aaronsjeep

Well, I haven't had a lot of time to spend on the Jeep, but I did recheck the grounds and got my VSS squared away. I am using a NP241c transfer case so I was able to use the VSS at the back of the case. It has a different connector than the wiring harness from my 2003 but both VSS's are two wire units and based on searching through several build threads it seems the 241's VSS is compatible with the 2003 ECM.

Regardless, it doesn't seem to have had any effect on how the truck is idling (rough) and the throttle is still not working. Believe it is going into limp mode right away. I have tried the tac and pedal on the wifes truck both work fine for her truck so I THINK?!? I can rule those two components out?

Current trouble codes are p1514 and p1518.

More internet searches for p1514 and p1518 keep bringing up TSB's for replacing the yellow wire at the TB, so I may try that next... Any and all help is MUCH appreciated.

74novacustom

What about the 2ft harness between the TAC and pedal? did it ground out where it is passing through the firewall?

aaronsjeep

BTT
for some help. Had to let this sit for awhile (life

But now getting after it again with a clear head. I pulled the harness and am going to go through it (on the dining room table) with an Ohm meter looking for bad wires starting with the yellow wire off of the throttle body. Also going to check the small lead between the TAC and the pedal. Have called Novak (who built the harness) a couple of times but they haven't been much help, yet.

Any help is greatly appreciated.

I found a good thread about the TPS voltages being off and causing the ECM to put the vehicle in "Reduced Power Mode." And this sounds a lot like what's happening. Just don't know how to check those voltages without a TechII.

TomM

iTrader: (56)

How are you obtaining these codes, by what reader?

Ask your tuner if he did a "write entire" or a "write calibration" when he deleted the VATS. I have seen some PCM's revert to VATS enabled, unless you do a "write entire" when defeating VATS.....

T,

aaronsjeep

Hi TomM,

I have a little Actron OBDII PocketScan I am using to read the codes. It will read the codes and erase them, but I don't think it's good for much else.

I will call Novak and ask them if they did a "write entire" or "write calibration." Thanks for the tip, I have wondered what the symptoms are when VATS are not disabled.

Have the harness apart now and not noticing any obvious burnt or broken wires, yet... And the ones I have tested with an Ohm meter seem to be fine, lot's more hunting to do. Thanks again. aaron

TomM

iTrader: (56)

VATS not disabled = car runs aboout 3-6 seconds then dies.......

I have heard of several causes for limp mode. The wiring you are working on, VSS not connected, bad 02(s), bad connection at either coil harness, bad connection at injector harness.

The last two particularly...check the pins at the connectors, one of my friends had a car that would go into limp mode, and one of his pins was bent at the coil harness connector, causing a misfire...

Have your tuner rescan your PCM and see if VATS is re-enabled. If so, disable it and do a write entire...

T,

pdsq98gt

You need to monitor data with a good scanner to see if a sensor is reading something funny. I had a vehicle the other day that the MAP sensor nipple was broken off, but the sensor was still held down. This caused the vehicle to go into reduced power mode when the throttle was pushed. Something to check

aaronsjeep

Update...

Stripped the harness of all the insulation to search for broken and/or burnt wires and check all connectors. Went through a few of the wires with an ohm meter and everything appears legit.
Bought a single membership to alldata...WOW a ton of info for 27 bucks! Should have done that a long time ago. Reading on alldata it seems that all my codes are indicating that I have a problem in the TPS circuit. Need to buy a scan tool that will give me TPS voltage readings anyone have an economical suggestion?

Got everything back together tonight... still no joy

Runs (kind of rough) for about 20 - 30 seconds but has zero response to stepping on the gas pedal. Only trouble code presently is p1518. Alldata says low battery voltage can cause p1518 so i placed the battery charger on... try again in the morning. (it's a fairly new Optima so I am doubting that's the issue)

Maybe it's time to start investigating a switch to a drive by cable throttle body?

Anyone have a source for intake plumbing? Going to build that in the meantime.

Thanks again for all the help.

aaron

OldCreek

iTrader: (1)

Aaron,

I have similar issues. Maybe my post will help you/us. I'm stilling having issues...intermittently.

My 2005 6.0L conversion will run just fine. Then, the gas pedal will go dead. Sometimes, it happens on start up...dead pedal. If I turn off the car and wait a minute it will return back to normal and run fine. If I reset the codes the car will run fine. It has occurred while I was driving, also....it goes to a rough idle then the engine might die. All the while the gas pedal is dead.

Once, I couldn't get the pedal to work/reset and the car wouldn't start. When I put a new pedal sensor in the car fired over. It ran perfect for a few months and then it started doing it again.

Is something failing the pedal sensor? Maybe the yellow wire in TB?

My codes are P1125 (Accel Position Sensor), P2120 Throttle Ped position sensor "D", and P2125 position "E".

I, too, have consider switching to cable throttle but I read that may require a new set of issues...i.e. new harness/computer/ etc.

Anyways, I'm still working through this. I did my own Vats delete, etc. with hptuners. I, too, am running a new optima.

Good luck,

Wil