Big Cam tune issue

[jpliss]

OK so maybe someone can help me with this.

I have a 5.3 retrofitted in a 56 nomad.

Injectors are DW 18U-01-0042-8 42 LBS injectors.

It has a comp cams Muther Thumper cam in it. ( NOt my doing )

I have tuned cams before and never had this much of an issue.

I cant even get this thing to fire and idle at all.

I seem to only be getting 4 cylinders to fire and it is pig rich when trying to run.

When I open the throttle to 10% or 100% this thing will not even run at all.

Since I was having an issue I thought ill go back to basics and read any docs I can. What brought me to hear.

I followed the guide but this thing wont staty running. It fires like on 4 cylinders but no go.

I have verified all cylinders coils are firing and engine has compression.

Im lost on this one, even willing to pay for some help here.

I currently have no MAF installed either so it does not get in the way.




Attached are the tune and the cranking scan.

[5FDP]

Plug in your IAT sensor, they don't like to start and run that well when it thinks it's at the north pole. If that is built into the MAF, you need to plug that back in. Then set the MAF fail high to 0hz under the engine diag tab and set all 3 MAF dtc's to MIL on first error if you don't want to use the MAF.

Go back to your stock timing tables, this is not a small block 350. Both of those curve looks terrible.

Zero out all that negative timing advanced pull in the spark correction ETC table.

See if it starts and runs with the IAT working the MAF failed correctly. If that doesn't help, make sure you have power at all 8 injectors.

[jpliss]

Ahh good point il try reinstalling the MAF

I have verified power at all 8 injectors.

I was focused on the 400 to 1200 to get it running. I will revisit the timing table and remove all - timing I will reinsert the stock timing table and zero out the spark correction at the points you mentioned.

I will update this morning on the findings.

[jpliss]

5FDP thank you for all the help.

Just as anyone should say always look at the basics. I had not looked at the basics like I should have.

Turns out that the rail pressure was under 20 psi and finally dropped to 0. Discovered that the FP we had a qs 135 from walbro seems to have stopped sucking fuel from the tank. Installed a new FP, powered it up and FP went 58 psi. Moral is check the basics if it does not seem right.

Following the Big Cam idle tune guide which I have done before and 5FDP suggestions, fired right up and actually idles close to what I would expect. Needs final VE and timing tuning and adjust base idle for the right IAC counts but so far so good.

Thanks for the help and sanity check.