My neighbor had the opti go out on his 93 Z28 M6 and let it sit for 7 months. So I bought it off him and replaced the part myself.

It’s a 93 with 171k miles. The motor and trans were rebuilt about 30-40k ago after someone had messed with his fuel. When it was rebuilt it was bored 30 over and a new slightly more aggressive cam put in.

Ever since then it’s had issues starting. It always starts, but needs a lot of cranking. Once it’s going it runs great, maybe a little rich. I tried checking to see if it’s a fuel issue, but doesn’t seem like it.

From what I’ve read on forums and mechanics I’ve talked to it looks like I need to have the timing adjusted. I could have the chip reprogrammed, but the mechanic doesn’t have paperwork on what cam was installed

What options do I have to fix this? I’ve tried a couple local (San Antonio) speed shops and most can only adjust 94+. Will the mail-order chips work without specs on cam?

 

Well I found a place in town that does dyno's ($500) and they can make the changes without knowing what cam is in it. As soon as I save that up I'll take it in and see if it fixes it.

 

My buddy has a big cam in his LT1. I roughly doubled his 'crank timing' table's values and it starts MUCH easier now. $500 to adjust this is absurd even if they have to reflash an EEPROM chip.

 

What speed shops are u talking about i also live in san antonio and i havent found one wit a good rep yet. I have a 94 z28 that i am trying to fix it and I wouldn't mind visiting one of those shops for some advice

 

Send a message to PCMFORLESS.COM and tell them your problem. They do mail order pcm for under $300 and can probably tune a few other things for that price. $500 for a dyno is insane.

Hal

 

How did you determine it may be running rich? Read the plugs? Check the long term fuel corrections (BLM's)? What are the symptoms - smell of raw fuel, sooty tailpipe?

How did you determine its not a fuel issue? Did you check for pressure bleed down on pump shutoff?

 

The 2 places in San Antonio that I heard about most were Lethal Performance on Nacadoches and Fuel Injection Specialties on Wye Dr., 210-654-0774. There are a couple more, but haven't talked to them yet. Lethal Performance is the one I heard the most about, but for 94+.

I'll try calling some of PCMFORLESS.COM and a couple others, I thought they would need the specs of the cam to adjust anything, but I don't mind trying them out especially if it saves a few dollars for another project.

I did read the plugs, and the tail pipes are very sooty. It's hard to say with the raw fuel, since I have to drop the tank and change the gasket so it contributes to the smell. As far as the fuel issue, not very scientific, just tried the key trick, turn key wait 10 secs X3, and it was still difficult to start. I need to check the vacuum, so may check that and the fuel pressures at the same time just to verify.