olharleyman

OK so here's the deal

Lately my truck has been getting horrible gas mileage I mean like 8-10 mpg so I cleaned the throttle body and butterfly with tb cleaner and it got a bit better for a day.

Next morning I wake up and go to start the truck and it starts a bit hard I wright it off to it being 17 degree's outside , once it gets running and idling good I go to step on the gas and release the clutch but the rpm's stay at 800 so I put it to the floor and it takes about 3-4 seconds for the rpm's to rise then it go's up to 4300 rpm.

Now I think ok just real cold and step on the throttle again and it is a bit sluggish but comes up fairly well start to release the clutch and start backing up and BAM it dies. I go to start it and it takes a few seconds to start again almost killing the battery and a puff of blue smoke out the tail pipe and a very obvious smell of gas.

Now it's running fine everything is working good start driving down the road and it is so sluggish it's not funny rpm's barely rising speed is like what's that? It finely catches up to itself and running fairly good so I drive about 2 miles and pull into the store for something to drink push in the clutch and start to make the left and all of a sudden truck dies so I think ok still cold look down at the temp gauge and its showing 1/2 way to red so I just coast in and restart the truck fires right up so I let it idle while I get my O.J. come out and drive to work and it just will not get any speed up in 4th gear tuning 4,000 rpm I was running 50 and it was straining to do it had to drop to 3rd for a second and get the speed back up grabbed 4th and it all seems to be fine so at 3200 rpm I go to 5th and it falls flat on it's face again.

Anyway it's been a real bit*h I have no cel codes and have checked timing , fuel pump and filter and cleaned the intake system again any ideas would be nice Thanks Guy's

Marc

I'll give you a bump here.

You'd think it would show a code with the diagnostic connector jumpered if it was running so bad.

thook

Realize just because it's cold EFI's don't work like carb'd vehicles. IOW, I've had my EFI's long enough to know that even in 17*F weather it shouldn't act up or need to go through a "warm up" period like a carb for it to run good.(Extreme cold areas may be a different story. Have no experience with them). If you had no problems starting, then the cold start system is working. So, I would assume it's something throwing off your fuel/air mix. Timing is also being affected. My first thoughts would be AFM or TPS, but still not necessary for a code to be present for one of them to be going bad. For instance, you could have a dead spot on the TPS VTA track, but the ECU is still getting a contact signal.........albeit a bad or intermittent one. IOW, you press the throttle, the needle hits the dead spot, contact to the ECU is still being made/info is getting there, but the ECU thinks the throttle is still only slightly open when you physically have the throttle wide open. Follow?

Possibly........

Marc

Any chance there could be moisture in the fuel system and it's freezing?

olharleyman

That is actually what I have been leaning toward but just thought that maybe there was something I was missing and wanted to get a 2nd 3rd even 4th opinion to verify what I thought.
Thanks all for the replies.

abecedarian

Thank you Matthew for saying that.

Several things happen when cold starting one of our trucks.
When cranking, the ignition switch sends voltage to the starter (obviously- to turn the starter on) and also sends voltage to the Cold Start Time Switch and the Circuit Opening Relay. If the CSTS is cold enough (< 65 F) it should trigger the Cold Start Injector while cranking for a little enrichment when cold like the choke does for a carbureted engine. Hopefully, the auxillary air valve works properly, causing the idle to rev higher because the engine is cold. One has to realize that the CSI / CSTS only helps get the engine started when cold... and the ECU reads the coolant temp sensor to determine how the engine should run once it's started and the auxillary air valve determine the cold idle speed.
The CSTS / CSI is only like a "jump start" when cold- just a little boost to get it running.... they could've programmed in those little bits but it was more simple to have it mechanical than electrical.

gary96360

the same thing happens to me if its cold outside and i try to drive off like 15 secs after i start it sometimes it feels like truck is gonna die so i floor it for like 2 secs then the rpms start to buildup. truck revs at 1500 rpm cold. i just got used to waiting a couple of mins for the truck to warm up.

olharleyman

Well I can almost live with that but when I get going and the throttle is to the floor it still barely gets going even after letting it warm up for 5 to 10 mins and the mpg is atroshis.
I just filled up the the tank and have 30 miles on a half tank of fuel so I need to find the true issue and correct it asap.

space-junk

iTrader: (1)

if the mileage is that bad, maybe the injectors are toast and leaking or not being controled correctly, thus dumping in an extreme amount of fuel which bogs the motor down trying to compress it? that would also somewhat explain the puff of smoke...

djkeev

Hi,

While I'm fairly new here, I've had my truck for 4 years and do my own work though.
It is obvious that this problem is directly related to what you did on the throttle body. (except for the fuel mileage) I assume it ran great before you clean the TB only gave poor MPGs?
Did you mess with or get carb cleaner in the TBS ? This controls timing and can really mess things up if not set properly.
The gasket to the intake horn. What shape was that in? is it torn and sucking in air?
The air filter rubber pipes to the throttle body, loose, cracked, reinstalled poorly?
Vacuum lines knocked off or incorrectly reinstalled?
Did you bump wires on the coil or ignitor or AFM?
Did you reinstall the TBS wires?

Unplug the cold start injector and see if that helps.
Stupid, obvious question, did you replace or clean the air filter element?

EGR valve stuck open?

Spray some carb cleaner around the entire TB as the engine idles and listen for speed changes which would indicate a vacuum leak.
Check your firing order on you plugs, even if you think they are right, double check them, I once had a #3 and #5 reversed and you've never seen such a bad running truck! I don't know how or when or who did it but I overlooked this one for weeks!

Good Luck
Dave

djkeev

Hi,

Also check you plug wires for leaking voltage, very easy to do on a dark night, just pop the hood and look for small fireworks at any metal contact. Spray some water on the wires to enhance the leakage.

Also how are your plugs?

Dave

thook

And, thank you for saying that, Kirk. One can't think of troubleshooting EFI's in terms of carburetor mechanics what with all the electronic input going on.

olharleyman....your 4rnr sounds like it's doing what mine did until I tested the AFM. Run an advanced thread search using my name and look for "AFM testing". I ran a test not covered in the FSM and found mine was bad. It had eluded me for a long time, too. Of course, it could be the TPS instead. So, if you don't find an issue with the AFM, run the same type of "sweep" test on the VTA track. I suspect since either component is sensitive in response to throttle action that somewhere you're getting a bad signal when you press the throttle and it's flooding out and affecting acceleration so heavily.