Warm up problems

[Daveymisbehavey]

'99 Explorer XLT. When I start the truck in weather colder than 35F degrees it tends to idle like crap/barely idle/stall out. If it drop it in gear and go it's fine by the time I get to the end of my block. If I leave it idle it will run like garbage until it gets warmed up to normal operating temperature. Scanned it for codes. I have codes for bank1 lean condition, bank2 lean condition, ECT out of range, and TFT out of range. The TFT and ECT read -2C degrees and -5C degrees. The IAT was reading -11C. The actual outside temp is around 17F degrees. Am I having a problem with my ECT sensor or is it a fuel pressure problem and the codes are setting from the fact that it's way too cold in PA right now? Truck runs and drives perfect, just wont idle until you drive it about a block. After it is warmed up it will run great and idle great. I should note the timing chain is hanging on. Its making the "noise of death" but only very slightly when first started up for about 1-3 seconds. I've been running synthetic oil and lucas friction modifier ever since the noise started. I've put about 30k miles on it with no worsening of the noise. I have a feeling that the cold coupled with the heavy oil I'm using may be effecting the chain tension when it's cold out... but I'm baffled because after you start it up, the noise dissipates in less than a second but the engine continues to buck and dip and try to stall until you either drive off or warm it up by holding your foot on the gas.

Has anyone has this same issue? Or know what I should do? I've already tried cleaning the MAF and IAC. No change. HELP

-Davey

 

[James909]

What engine? Was the ECT and TFT out of range codes stored in the memory or did they show up during a KOEO or KOER test? If the truck was not warmed up and you did a KOEO or KOER test then those codes would most likely show up. Assuming that this is what happened and there is not a problem with the ECT or TFT sensors then I think the problem is leaking intake manifold O-rings.

 

[Daveymisbehavey]

It is the 4.0L SOHC. The lean bank condition codes are hard stored in the memory after a few dozen starts. I can clear them out but they come back after a few days. I was able to borrow a scan tool and thats where I found out the tft ect out of range codes. They came up when I did a KOEO test. But if I let the truck warm up then clear them and do another KOEO test they don't come back. Thats why I was thinking it's just the sheer cold that's setting those. I questioned the intake gaskets but if that was the problem wouldn't it idle bad in warm weather too? And after being warmed up? This problem only seems to exist if you start the truck from dead cold, under 35F degrees outside. If it's mild or warm out it wont do it. If it's been warmed up it won't do it. Only does it when it's stone cold and cold outside. The other reason I'm looking other places besides the intake is that I have a good 18hgs of vacuum at the manifold and I can soak the runners down with carb cleaner and there's no change. I'm getting ready to pull the fuel rail and see if it's gummed up inside...

 

[James909]

Since the ect and tft sensors out of range code went away when the KOEO test was done on the truck after it was warmed up it seems like those sensors are fine. Doing a KOEO or KOER test on a cold engine will usually cause codes saying that a sensor is out of range. This is because these tests are supposed to be done on a warm engine. I still feel that it is the intake O-rings leaking. When it's cold out the rubber O-rings shrink and cause a vacuum leak to form. Then when either the ambient temp or the engine temp is warm the rubber expands and seals the leak. This is why the truck acts fine when it's warm. That seems to be the general consensus around here because quite a few members have had the same problem and replacing the O-rings cured the problem. Just my $.02.

 

[mrboyle]

Since the ect and tft sensors out of range code went away when the KOEO test was done on the truck after it was warmed up it seems like those sensors are fine. Doing a KOEO or KOER test on a cold engine will usually cause codes saying that a sensor is out of range. This is because these tests are supposed to be done on a warm engine. I still feel that it is the intake O-rings leaking. When it's cold out the rubber O-rings shrink and cause a vacuum leak to form. Then when either the ambient temp or the engine temp is warm the rubber expands and seals the leak. This is why the truck acts fine when it's warm. That seems to be the general consensus around here because quite a few members have had the same problem and replacing the O-rings cured the problem. Just my $.02.

What he said. Common problem with the plastic intakes.

 

[Daveymisbehavey]

Next chance I get I'm gonna rip it down and see what they look like. I'm the original owner of this truck and it's got 71k miles. never had any major engine work done aside from normal maintenance stuff so being that it's all original under there... there's a good possibility. But you're probably right when I did the vacuum leak testing the engine had been running awhile already. It's hard to mess around when it's -2 degrees outside and you don't have a garage to work in I'll let you know what I find out! Thanks for the $.02!