Any idears? Hard to start.

I recently put LT's on my 08 and have noticed my truck is running very rich. I am in the process of getting a retune right now. The last couple of days my truck has turned over for 5-6 seconds before starting... and sometimes it doesn't even start then. It always starts on the second turn and I smell a lot of gas. There is a possibility that my plugs are semi fouled because I have noticed a decrease in mileage as well. I would assume that this would have started a week ago when I put my headers on if that was the issue. I'm thinking that this is tune or spark plug related. I thought it may have been a fuel pump at first (only 27k miles), but I tried priming it before starting and it actually made it worse. I have a feeling it is dumping too much fuel at start up. Any ideas?

personally wouldnt think the headers would be the culprit, not by dumping that much fuel, weeds out the fuel pump concidering youre getting to much fuel.. cant see a 08 model truck being that hard to start mine always starts on the first turn of the key, you running the stock injectors?

Yes, stock injectors. I've had a 9.5 AFR at WOT for no telling how long. I just now got a wideband on it. With it dumping that much fuel at WOT, I can only imagine what it's doing at startup.

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Originally Posted by pl4yboy

Yes, stock injectors. I've had a 9.5 AFR at WOT for no telling how long. I just now got a wideband on it. With it dumping that much fuel at WOT, I can only imagine what it's doing at startup.

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ouch man!! thats filthy rich!! get it tuned!! 9.5 afr?

Virgil tuned it... Someone else will be sending me a base tune in the next few days.

Corvette post-cat 02 sensors usually help with correcting the AFR after installing long tubes.

Greg, can you get them at parts stores or will I have to order them? Dealership? Summit?

I buy them off Ebay but you can get them anywhere that sell 02 sensors. I always buy the Delphi sensors. They will have the wrong connectors on them, just splice them into your old connector with heat shrink type crimp connnectors.

I'll wait until my tuner takes a look before I do anything. Expect a PM within the next week. I'll let you know how things go.

when I had the tune in my truck with the 408 it was hard to start. I put the stock 4.8 tune in the truck after putting the factory 4.8 back in and it fires off first bump every time now. Weird. :nutz:

Oh yeah, I even have the 42 lb lucas injectors on the 4.8L engine.

plug your coolant temp sensor back in. I had the same problem after installing my headers.

Why would I have removed my coolant temp sensor? Why would it become hard to start after a week of running them?

First, my tune has been pulled and is going to be sent to my tuner in about 5 minutes. Secondly, I ran a brief scan on the truck today at idle and guess what? Greg was right. My o2s are slow. Now, my o2s could be slow because the truck is running so rich. I believe the main issue here is fouled plugs. I'm going to wait for my base tune, then change the plugs and do some scans... hopefully tomorrow.

Edit: Coolant temp sensor was fine by the way.

Changed plugs today and it didn't help much. Also got a new base tune at the same time.

New developements:

1) Worse on hot starts.
2) If I kill the truck and start it again immediately, it starts fine.
3) Wait 10 seconds and it cranks for 5+ seconds again.

No ideas?