5.7 issues

[crazyd88]

Got a 99 Yukon and got two codes popping up camshaft sensor and low voltage MAF. I've replaced both and code still there also shudders between 2000 and 2500 rpms random back fire. Yes I replaced plugs and wires also. Any ideas anyone

 

[mountie]

Got a 99 Yukon and got two codes popping up camshaft sensor and low voltage MAF. I've replaced both and code still there also shudders between 2000 and 2500 rpms random back fire. Yes I replaced plugs and wires also. Any ideas anyone

Frustrating……. check the wiring? Hopefully, someone here will advise…….
Welcome to the forum !

 

[SpareParts]

When i bought my 99 Express van 5.7 it would also backfire and shudder around the same rpm's. Checked wiring, sensors, replaced some things. Turns out it was a bad ecu.
Changed that and that fixed it. Give it a look.

 

[Eman85]

Have many miles on it? Did this just suddenly start? Do you have a way of reading data> Have you checked anything or just replaced parts as a guess?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum, and other folks will chime in.

 

[exp500]

Check that your coil and ICM are GM units, aftermarket known to throw codes.
Plus, on these an ignition miss first check is ALWAYS dist cap/rotor. (GM here also).
Do you have basic troubleshooting tools? Basic toolkit?
Try driving while monitoring Live Data from your scanner.Try Steady state at various RPMS normally encountered to see if anything shows. Codes usually don't set until a Too Much threshold.
Also check braided ground wire that runs toward heater at firewall.

 

[Tonyrodz]

When i bought my 99 Express van 5.7 it would also backfire and shudder around the same rpm's. Checked wiring, sensors, replaced some things. Turns out it was a bad ecu.
Changed that and that fixed it. Give it a look.

I also had to replace the pcm on my 01 Express van. It was doing weird stuff too. No more issues after that.

 

[YukonGTmaster]

I always replace cap and rotor when doing the plug wires. Cheap insurance.