Moter

iTrader: (20)

Well the dealer thinks its the fuel pump. Part is supposed to show up today....will see. Spoke with South West States Chevy distict manager..he is involved now. Will see what happens after today

girshwald2000

I'm having a similar issue with my 2009 Silverado. Could you tell us what finally solved your issue?

Moter

iTrader: (20)

Dealer had it for 8 days...installed, fuel pump,fuel pump module...coolant temp sensor. Gave it back...did the same thing....backfires and pops thru intake cold..smooths out after it warms up. It also set an evap code now since they had the tank out.. So took it back again..had it for another 7 days..said evap line was loose..started ok today. Will see what tomm brings.

girshwald2000

To clarify, here is my issue - when the truck starts cold it runs like crap for about 30 seconds, then smooths out and runs fine. Depending upon how bad the engine runs it might throw a code 1400. As long as the engine is warm the truck runs great. However, if it gets cold, i.e. sits overnight, the problem returns.

I had the opportunity to speak with a GM mechanic. He told me the problem is epidemic and it is due to fuel. He had three in his garage with the same issue. Apparently the 6.2 and 5.3 engines (what I drive) are so tight that the valves get gummed up and stick. I only have 27K on my engine even though it is a 2009 model, meaning it stays parked a lot. He didn't go into details but said it had something to so with off-shore fuel storage.

The bottom line is this: He said I had two options. (1) I could have GM do a Top Engine Clean on the vehicle to remove the gunk from the valves. He said that it typically isn't covered under the 5yr/100K drivetrain only warranty (all I have left) so I opted for the second option. (2). He said I should put a fuel system cleaner through my engine. He recommended Techron Concentrate Plus Fuel System Cleaner. I found it at an El Paso, TX AutoZone for about $13. It's a black bottle and has the Chvron logo on it. He also recommened I switch to Chevron (since it has detergents in the fuel) or keep using this cleaner periodically.

While I've only run about 3 or 4 gallons through my engine thus far, I can already see and hear an improvement on cold starts. He said that depending upon the level of buildup it might take 1-2 tanks of gas (with the treatment included) to clear things up. I don't drive much so give me a few weeks and I'll let you know whether or not it solved my issue. If you are still struggling with your problem hopefully this will help you out as well.

girshwald2000

I've now run about 8 gallons of fuel (with the Chevroin additive) through the engine and I can tell a difference. This morning I started the truck cold and while it idled a little rough, it was nothing like what I was experiencing before I began using the additive. The best part is that the DTC P1400 disappeared from the instrument cluster this morning. From what I understand, if the vehicle passes a self test consectutively for 4 times the code will disappear from the instrument panel though remain in the computer's history for a while longer (40 starts?). Hopefully this all means things are getting better inside the engine. I'll post another update as things progress.

Moter

iTrader: (20)

Just started using the additive you spoke of...Wally world had it. Still on first tank thru it but shouldnt be long as fast as this thing guzzles fuel. The p1400 code came back this last weekend and it was backfiring bad...will see how things go

chevrolade

iTrader: (22)

im having this problem on my 09 Denali as well...sucks

Moter

iTrader: (20)

The chevron additive and Chevron super unleaded took care of this one. Never would have believed it unless I experiened myself.

chevrolade

iTrader: (22)

Thanks buddy yea right now mine is idling like at 1000-1100 while driving I recently cleaned the kn filter and tb along with maf... And I put one of them techron that treats 20 gallons with 93 is all I run I'm going to take it on a lil trip and see if it helps

girshwald2000

Moter, glad it worked for you. I was waiting a few days to post an update. So far I've had 5 cold starts and no issues. The truck starts up like new and throws no codes. All it took was two bottles of the 20 gallon fuel treatment from Chevron and about 30 gallons of their 91 octane gas (they don't sell 93 in El Paso, TX). I plan on dumping in a bottle every 1000 miles as recommended on the back of the bottle. Chevrolade, hope this fix solves your issue too.