98 Explorer XLT Cold Start Issues

[davew_]

To start things off approx. 2 months ago I bought a 98 explorer xlt used for 1500 bucks and couldn't be happier. I did however start having an issue when cold starting the truck after 8+ hours of not driving. The issue im having is that it will crank, start and immediately die. Usually on the second or third try it will stay running and seem fine. the other day I was about to drive and the truck repeatedly started and died, the only way to keep in running was to hold my foot on the throttle slightly. If I rev'ed it, it would climb in rpms no problem and then die. after around 15-20 times, and almost every time letting in run for 20-30 seconds with my foot on the throttle and consistently dying, it started to idle on its own. a few times on initial start up I would hold the key in the start position and it would still die, I did this to rule out the key switch, also when its running and driving I have no issues, so I was thinking of ruling out the fuel filter as its not sputtering or idling rough when warm. The truck seems to be very well maintained and reliable, except for this one issue, if anyone has come across this issue before or has an idea of what to check, im all ears. thanks

 

[2000StreetRod]

which engine?

It would be helpful to know which engine is in your vehicle: V8, SOHC V6 or OHV V6?

Also, is the check engine light illuminated? If so, what are the codes?

My SOHC V6 will start and then immediately die with a non-functional IAC valve. You might try cleaning it.

 

[davew_]

it is a SOHC v6, I actually was looking around a little on the forums here and I heard about cleaning the IAC valve and I popped it off today along with the little felt piece in the black cap, it looked pretty dirty and I cleaned it and the spring inside seemed to move more freely after and to answer your question the CEL comes and goes occasionally for an 02 sensor and I believe the code was a p0156, o2 sensor malfunction, bank 2 sensor 2

 

[2000StreetRod]

bank 2 sensor 2

The bank 2 sensor 2 is the post cat sensor on the driver side. It mainly checks the effectiveness of the catalytic converter and should not affect cold start. The fuel pump is energized for a couple seconds when the ignition key is switched from off to run and any time the crankshaft is rotating unless the fuel shutoff sensor disables it. Your symptoms indicate a lean condition at cold start which could be due to low fuel pressure, malfunctioning engine coolant temperature sensor or incorrect MAF sensor reading. You might clean the MAF sensor with MAF sensor cleaner. If you don't have a scanner then performing a fuel pressure test would be easier than testing the engine coolant temperature sensor that the PCM depends on to richen the mixture when the engine is cold.

 

[schaffnerb]

Hi Dave,

I had the SAME problem you do. I purchases my explorer in 2011. When I got it the ce light was on with a vengence. It was throwing codes for o2 sensors. It was also not wanting to start cold. ie after the engine sits for more that eight hours. I would need to hold my foot on the gas to keep her running.

Solutions that will work ( they worked for me )
1. UPPER AND LOWER INTAKE GASKETS. This is why she spits and sputters when cold. this was a ford recall. The gaskets shrink when cold thus letting unwanted cold air into the engine upon startup. A quick test I did to confirm this was to unplug the Mass air flow sensor then start the truck up. It should run great when this is unplugged.
2. Clean IAC and MAF.
3.Replace or clean o2 sensors. ( I did away with mine altogether)

Good luck dave.

Just so you know you are going to have timing chain problems with this motor as well. (they used plastic guides))

 

[2000StreetRod]

deleting O2 sensors

. . .
Solutions that will work ( they worked for me )
1. UPPER AND LOWER INTAKE GASKETS. This is why she spits and sputters when cold. this was a ford recall. The gaskets shrink when cold thus letting unwanted cold air into the engine upon startup. A quick test I did to confirm this was to unplug the Mass air flow sensor then start the truck up. It should run great when this is unplugged.

As you state, the intake manifold gaskets leaking is a frequent problem with the SOHC V6 during cold weather starts after the gaskets have aged a few years. However, the DTCs associated with that issue are normally P0171 and/or P0174. An unplugged MAF sensor is detected by the PCM and forces it to rely on engine RPM and throttle position to set the air/fuel ratio since it has no air flow reading and therefore no accurate way to determine "load". It usually runs rich to be safe. Since replacing the upper and lower intake manifold gaskets takes an hour or more the first time, I suggest waiting until you know they are leaking: see Lean condition procedure

2. Clean IAC and MAF.

I agree.

3.Replace or clean o2 sensors. ( I did away with mine altogether)

I strongly advise against eliminating the precat O2 sensors. The PCM will detect they are missing and stay in open loop since it has no feedback for the air/fuel ratio. Open loop mixture values are usually rich for engine safety and fuel economy will suffer.

Just so you know you are going to have timing chain problems with this motor as well. (they used plastic guides))

Unfortunately, this is true. Almost all overhead cam engines requires periodic replacement of timing belts or chains. The Ford SOHC 4.0L V6 camshaft timing components typically last as long or longer than timing belts on other vehicles but the Cologne made engine requires removal of the engine or transmission to replace the right cassette. A significant design deficiency in my opinion.

 

[davew_]

I cleaned the iac at work yesterday and I am about to go to work now and its sat for 12 hours or so, so well see how it fires up ill keep you guys posted, I was thinking that the iac was the culprit after seeing that it looked rather dirty inside, the fuel pressure seems fine to me, bc wouldn't it be causing more driveability issues and rough sputtering rev's during driving or maybe not reving over a certain point if I were having pressure issues?

 

[davew_]

so after the 12 hour window from driving and cleaning the iac, it started up perfect first try not touching the pedal, leads me to believe it was the iac being dirty that cause the issue, if anything happens again or it continues to act up, ill post the details on here, but for now it seems good, thanks again

 

[schaffnerb]

Street rod,

I left the precat o2 sensors. The after cats however have been eliminated along with the cats themselves.

this procedure greatly improves performance in my opinion.

Have you replaced the timing guides yet in your explorer?? Mine are rattling so im planning on pulling the motor and redoing them. Just wanted to know how hard the job is if youve done it.

thanks

 

[2000StreetRod]

replaced camshaft timing components

Street rod, . . . Have you replaced the timing guides yet in your explorer?? Mine are rattling so im planning on pulling the motor and redoing them. Just wanted to know how hard the job is if youve done it. thanks

Yes, I replaced all of the excessively worn or failed camshaft related timing
components. I pulled the engine and took my time. If you plan to do it, PM me your email address and I'll send you the 2005 Mustang SOHC V6 assembly instructions.