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Greengenes

2004 Silverado -- Lousy cold start performance

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Hi folks,

 

        I remember posting this as a topic awhile back , but wasn't able to

        search & find it here .. 

 

        I still get some bad knocks with my 5.3L  Silverado during early morning

        starts .. Haven't tried to pull a  sample from the tank to find out what's

        really in there, but I'm real tempted now.  Over the last 3 months, cold starts

        have been attempted each day, only once was the temp below zero.

 

        I have had best results mixing 4 gallons UnL  to a full tank of E85(25g cap.)

 

        I got real tired of the thing bucking and choking with straight E85, not to mention

      what it was doing to the valves/pistons/rods/etc.  ( some very nasty sounds).

 

        Anybody else have this trouble with their  FACTORY EQUIPPED FFV ???

 

        I'm thinking of adding a device to warm the induction air to about 90 degrees,

      just before I crank the engine. Some sort of hair-dryer or Ceramic heater

      contraption, to see if this might help the first couple of strokes..

 

        I had this truck in the shop last week,  for a inst. panel changeout (speedometer)

        and a leaking waterpump,  so GM has seen the truck plenty. They reprogrammed

        the ECM ( I think) and it was better for awhile. But not now.

 

        I'll stick to the extra 4gal input for now,  to keep things moving acceptable.

 

        Anyone know if it's possible to take a fuel conductivity reading from the wiring harness

        somewhere ?? Any GM mechanics out there ?? 

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Greengenes- I know of several 2004 Tahoe, Suburban, and Yukon owners who had issues w/ cold start. One theory a GM rep had was that they started with partially fouled injectors that the alcohol started cleaning but in the transition period they would experience poor spray or leak down-- this situation was suggested for new e85 users. This was never confirmed- It was recommended to the owners to use Chevron Techtron to speed the cleaning. I doubt this was the issue as it seemed to be limited to '04s. I do not know if any of vehicles ever got better- the average consumer just says the heck w/ it. Like you- I would be afraid also- especially if your 04 is like my 2000 and already has a mild case of piston slap on startup.

 

Personally I would see how difficult to pull a quart sample of E85 from the fuel rail- a mechanic should be able to do this for you. Either do the water test or take the sample to a Colorado state fuel inspection station ( i assume they will do this as Wisconsin would for any consumer or station owner). Do this only if you are in doubt as to when you bought the fuel or what the station was stocking.

 

We went thru a couple of periods with the company Taurus where starting was flaky and we knew our blend was right. One turned out to be a fuel pump (low pressure) and the other situation was cured with a ECU update flash.

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Well !!! I posted a while ago about the '04 suburban running on E85 (9 months now). I have had no cold start issues (temps down in the high 20's) BUT have had lousy overall mileage. (12mpg). We are working on the mileage... we'll be reprogramming the engine computer in a couple of weeks. Most agree that Chevy/GM changed something in the fuel type sensing hardware or firmware in the '04s since other years don't seem to have the problem.

We'll keep everyone posted...

:)

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Paulc- Seems like I read somewhere that GM changed the alcohol sensor model# about that time. A former Chrysler engineer I have met who worked on ethanol in the 70's and 80's has his Suburban tuned to operate at 1.5 mpg difference in a 1/3 hwy, 1/3 country road, 1/3 city mix. So far he did this all with ECU programming. He plans to install larger exhaust in the future. He gets 17 mpg (summer) on e85.

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Well, my dad's 2006 F150 FFV has had absolutely no problems running E85 in cold weather.  Even below zero (farenheit) it starts right up and runs like a top on 100% E85.  It might lose a couple MPG on E85 compared to gas, 15mpg on gas down to 13mpg for E85.  No strange engine noises or anything.  The only problem he's had with the truck has been some of the black peeling off the F150 emblem, which was fixed at the dealer at no cost.

 

From what I read on other sites, GM's E85 implementation leaves something to be desired.

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