Rough Driving

[slipping]

1999 2wd 4dr Tahoe
Happened a couple months ago and brought to the shop, thought had it fixed.

I'm going to try to describe as best as possible, I didn't have a SD card for my video to take. Started up in parking lot, sat for a few seconds and died. Started up again and drove out. Driving home from work tonight it started to stall/choke out. It would stumble and you could feel it decelerate then the RPMs would drop to zero. Took foot off the gas and moved to the side of the road and bam, RPMs back up to speed and kept going. Did this 3 or 4 times (30 minute drive on section of free way with no lights less those from few other cars and nothing around but desert). A few times it would stumble but not try to die out.

Has 420 and 430 codes with CEL light
security light is lit, but has been since i acquired truck over a year ago
Has new Delphi fuel pump
has new ignition coil, starter relay, fuel pump relay, die hard battery
within last 6000 miles new cap, rotor, spark plugs, wires, heater control valve, kn intake, serpentine belt

Have not had the chance to do the fuel spider upgrade yet

thanks for looking

 

[Monstar_est87]

Did u double chk and tighten down all the clamps on the k&n CAI..? Clean out the MAF..? T
If that dosent do the trick try checking the fuel pressure with a reader gauge...

 

[slipping]

Did u double chk and tighten down all the clamps on the k&n CAI..? Clean out the MAF..? T
If that dosent do the trick try checking the fuel pressure with a reader gauge...

Yes. Clamps tight, MAF cleaned as well. Fuel pressure monitored and is good. Mech last time I was in said cats need replace soon but hadn't thrown codes at that time.

 

[Monstar_est87]

Hummm... This is a tuffy... Egr nice and clean..? Im not sure if that cats would lead to these symptoms... But wat do I kno im just a simple cholo... Where's sunlit when u need him..? Retorqs pretty good with these things but hes probably guarding his bridge like the troll he is... ( retorq u kno ur my boi )

 

[slipping]

Hummm... This is a tuffy... Egr nice and clean..? Im not sure if that cats would lead to these symptoms... But wat do I kno im just a simple cholo... Where's sunlit when u need him..? Retorqs pretty good with these things but hes probably guarding his bridge like the troll he is... ( retorq u kno ur my boi )

Have not checked egr. Would bad cats cause rich fuel cause in unburnt fuel smell? I Dont know, still in that learning phase. Love their duels. Big fan of their work.

 

[SunlitComet]

Ensure a clean egr system and make sure the ground behind the battery on the wheel well and on the thermostat housing are clean. Cats would have to be clogging to stall the engine but not randomly. rich fuel can be cause by electric or sensor issues but the post sensors could not effect the fuel that much. See if you can get your O2 wave forms checked. It will tell you a lot. And if you can test your fuel pressure while driving that would help to. What did the shop do that it was thought to be fixed?

 

[slipping]

Ensure a clean egr system and make sure the ground behind the battery on the wheel well and on the thermostat housing are clean. Cats would have to be clogging to stall the engine but not randomly. rich fuel can be cause by electric or sensor issues but the post sensors could not effect the fuel that much. See if you can get your O2 wave forms checked. It will tell you a lot. And if you can test your fuel pressure while driving that would help to. What did the shop do that it was thought to be fixed?

OK. Will start by checking egr and grounds. How do I check the wave forms? I will try to setup something to check the pressure while driving. Ignition coil at first - ran good for a week. He had it for a week teying to pin point. Then replaced starter relay and fixed some of the wiring to the starter. Ran great for almost 2 months now.

 

[slipping]

Will check connections in morning

 

[SunlitComet]

poking it slightly, does it have free movement?

 

[slipping]

A little yeah, going to clean it tonight when I get home and put new gasket on. Then test it out with ye ol volt meter. Haven't had time.