Hello Everyone I am in need of some help or advice. I have a 98 sunfire that I have installed a 3400 with a 4T45-E tranny and the car starts very easy but only runs for about 2-3 seconds then shuts off. I have read many posts about vats and I have sent the computer to get reprogrammed twice. The first time it seamed like nothing changed then I sent it in again and still nothing changed. The company said they wanted to try two different setting in the HP tunner program, Neither one help. I have read about Jo MX adding a BCM to send the pulses to the Serial data line. Do you think that is the route I have to take to get this car running. One other note when the car does start for the 3 seconds I have no gauge movement on any thing. I have tried hot wiring the fuel pump relay and that did not help. I am sure the computer is shutting off the injectors. I am looking for some advice is the BCM route the way to go? Which BCM's will work the key I have not does not have the pellet in it. Thank you in advance for any help.
Axel
you have to use the J BCM to get the gauges to work. and that'll allow it to start and continuea to run, AFTER, the company with HPT turns off the VATS.
I was under the impression that the 3400 pcm used serial data to run and the gauges ran off the uart data line thru a microprocesser in the gauge cluster. I thought I might have to piggy back the pcm's to get the gauges to work but after I had the engine running. I also remembered reading do not piggy back 98 plus cars because it causes the milage to jump? I can understand having the piggy back to get the engine gauges working but to get the engine running? I installed the 3 wire temp sensor but the third wire is not connected yet and the URAT wire is not connected to anything either. Do you think if I piggy back the pcm power up the J body pcm and connect the ground and UART it will run??? Thanks to all of you who can help.
Axel
Brad wrote:you have to use the J BCM to get the gauges to work. and that'll allow it to start and continuea to run, AFTER, the company with HPT turns off the VATS.
I didn't say anything about the PCM there did I?
no trying to be rude at all, but, it's just in my nature to be an ass.
I'm pretty sure you have to have the Grand Am BCM in the car. PM Kardain, he had an issue with this back in the past but got around it.
BTW, the pre-00 j-bodies don't have a BCM, so you don't have to worry about the requirement of using it in your car. Things like this make me glad that I went with Megasquirt.
www.gmscf.com
I reread you post and you are correct there was no mention of a PCM. My 98 sunfire does not have a BCM in it. The Micro processer that controls the gauges is in the gauge cluster. I think the newer cars have the BCM from the factory. I am starting to think I will have to add the BCM to the wiring to get the engine to stay running? Dont worry about your nature, I have meet all kinds of people already. Just looking for some answers. Thank's again for any help provided.
Axel
I added a bcm to get around the vats. When I got my first PCM from milzy motorsports, asked that the vats be deleted. Apparently it wasn't, and was also programmed wrong anyway (98 PCM, 2001 engine... Different injector pulses) Well after much hassle, sourced a bcm on eBay just for that single purpose. Stuffed it in my glove box, problem solved.
http://www.j-body.org/forums/read.php?f=30&i=49824&t=49820#49824
Edited 1 time(s). Last edited Sunday, August 02, 2009 12:11 AM
I sent the Pcm back to get it reprogrammed for the third time and it works this time! The programmer was not sure which setting the engine wanted for the vats delete so it took 3 times to get it right. Does that make any sense? Any way its working now. The rear O2 sensor , VSS and Vats was deleted by the Programmer. My plan is to drive the car on a stock tune and work out any problems then have it retuned in the spring. I have added The J body Pcm to get the gauges working. I have connected
1. C1-14 to uart
2. C1 -20 to Pwr all time
3. C1-61 to Pwr all time
4. C1-19 to Pwr in run and start
5. C1-60 to gnd
6. C2-64 to gnd
7. C1-18 to gnd
8. C1-54 to Eng cool temp Sens used a three wire for this
9. C1-64 to VSS Yelow
10 C2-62 to VSS Purple
11. C2-16 to VSS output
I started with a 98 sunfire that came with a 2200 3 speed. When the engine is running the only light on is the Theft light. The question I have now is did I get all the wires going to the J body Pcm. I still have to wrap the harness, connect the radiator hoses and mount the 2nd Pcm. Thank you for all the help I have read many posts to get the car this far.
Axel
