ls1railguy

Im new to the group and the ls1 thing. I built a sandrail and put a motor from an 04 Gto in it. 23k miles never been torn apart. I bought a complete harness and mefi 4b computer with a stock program on it. Its suppose to be a plug and play unit. The engine has been in my garage for 1 1/2 years and im finally done with the project. Here is the problem....it wont start. I have searched everywhere for troubleshooting tips and have tried several of them but with no success. Upon cranking, four cylinders are warm (1,7,6,8) and the others cold. Spits and sputters and backfires through intake. New plugs, new wires, changed around coils to see if cylinders changed. They didnt. Im really confused. Any help would be awesome. Thanks

rotor vs. piston

iTrader: (3)

Only time that's happened to me, I forgot to plug in the connector to that bank of coils. Make sure you have power and ground to the coils.

ls1railguy

connectors are plugged in. Ive checked and cleaned them a dozen or so times. How would only half of the cylinders not fire if it was a bad ground? I have the computer grounded directly to the block, block to the tranny, and tranny to frame. Would the starter work if the battery had a bad ground? I could go get a larger ground strap for it. A little more info: Bosch fuel pump recommended for this application, mallory adjustable fuel regulator set at 58
psi, oddysey 925 battery. All emisions were stripped as well.

oct03gto

iTrader: (15)

Have you checked the basics? Like actual spark to the cylinders that aren't firing? And even removing the fuel rail and checking to make sure the injectors are flowing properly? You could have gunk in some injectors not allowing proper fuel or even any fuel to flow. Sitting as long as it did, you could have some troubles.

Also, you said something in regards to a plug and play system for the engine management. Did it include another ECM? Is it programed for 58x or 24x reluctor wheel? The LS-1 from the GTO is a 24x.

ls1railguy

Its got spark. When I pull plugs they are fuel fouled. The ecm is a delphi mefi 4b. I dont know about the relucter wheel. What year did they change? or are they all 24x? How can I check if mine is a 24 or 58?

-Joseph-

iTrader: (12)

04 LS1 will have the older 24x reluctor wheel as will all Gen III LS engines. Gen IV have timing cover mounted cam sensors and the swap to 58x crank gears was in most 2006 vehicles, they will have gray cam and crank sensors as external identification, 24x has black sensors.

If the motor sat for a long time, the fuel injectors may be plugged. Another thing could be a bad coolant sensor, I'm not that familar with the MEFI operation although it is popular for sandrails.

Rick Speed

iTrader: (55)

I had one doing this and found out the guy that did the install missed one wire that was supposed to get power when cranking did not have power while cranking. It had power when key on but not while cranking. To the coils.. I think they were pink wires on his.

Pocket

iTrader: (22)

All the coils on a bank share the same IGN and ground

Intake backfire sounds like a timing issue but timing is controlled by the PCM. Check the firing order in the tune

Rick Speed

iTrader: (55)

Sorry my bad .. I thought he said 1,3,5,7..

ls1railguy

How come when ls1 troubleshooting is googled there are a ton of issues with 04 gto? Isnt this the same as all ls1's? I know the intake is different because no air temp sensor port in the top by the throttle body. I have the sensor plugged into the harness and zip tied next to the valve cover.

rotor vs. piston

iTrader: (3)

The wiring is a bit different, seems the boys down under do their own thing for a large part. I didn't have any issues getting mine running w/ the stock ECU... Only the one time I forgot to plug in the right side coil pack connector.

LS1MCSS

iTrader: (18)

I found an article about a MEFI 4B being used on a 58X reluctor LS7. If it's for a 58X and your motor is 24X, that's probably the problem.

http://www.gmperformanceparts.com/Racing/ls7_camaro.jsp

dpd069

iTrader: (1)

I have an LS1 in my sandrail and when I got the motor for it it had sat in a junkyard for about 18 months.

It did the same thing as yours. Some of the headers you could touch with your hand and others were really hot.

I pulled the injectors and took them to a fuel injection specialist to have them cleaned and flowed and put in new plugs - problem solved

I've used SeaFoam on other motors to soak the injectors, and it doesnn't work quite as well, but is a whole lot cheaper

dpd069

iTrader: (1)

I don't know about the Delphi box, but the regular PCM grounds each of the injectors to fire them - they are always hot with the pink wires but they are only grounded to fire them,

I'd go through my schematics and make sure all my grounds were correct. That PCM has got to use one of them to ground the injectors

dpd069

iTrader: (1)

These guys supply a lot of LSX motors to the sand rail crowd and I think they use the Delphil box exclusively on their motors-

http://www.turnkeyenginesupply.com/E...6&key=packages

You might want to give them a call and ask about the reluctor wheel tooth count compatibility of the MEFI

ls1railguy

Thanks for all the input. I ran a crapload of tests tonight to see what might be going on. It appears that on TDC of #1 I get spark way too late. Thus throwing of all cylinders. #3 and #4 have no spark. I have been talking with the company that makes the harness and tunes the computer. He has offered a ton of help but wants me to tow this thing from Sacramento to L.A. Once its done completely that is ok. But I still want to hear this thing run. Ran compression tests tonight and all seemed fine. My sensors are black so that tells me its a 28x reluctor wheel. But all ls1's are right? The numbers come back as an ls6 but I know there is a goofy thing with that whole deal. Cam sensor? Crank sensor? how do i check without spending the cash and time to replace?

oct03gto

iTrader: (15)

I would check to make sure the crankshaft posistion sensor wires are not damaged, or even the sensor itself. The 24x has 2 pickup's. It is possible one is not functioning.

As far as the GTO's having issues. I guess I haven't had that issue with my cars (I have two 2004's).

All the GTO's use 24x reluctor wheels till late 2006 when GM had to use actual Vette 58x engine to finish production.

All of the LS-1 engines from 2002+ will have the block coded for an LS-6. They all use LS-6 bottom ends. Just 241 heads,and a smaller camshaft. They also use (at least all the LS-1 GTO's) an LS-6 intake manifold.

ls1railguy

Still looking for answers. I have checked for crank sensor. It is a 24x. The map corresponds. Everything checks out. Harness issue?

jeeperanthony

iTrader: (1)

Make sure the coils are plugged in right from the bulk connector to each coil. I took mine apart to repaint the brackets, and ended up hooking up the coils reverse of what they are supposed to be.