Does anyone know if an autopart store, such as Autozone, can pull diagnostic codes when the CEL is not on? I have read other posts that said error codes can be stored even without the check engine light being on, but don't know if I have to take my SportTrac to the dealer or if I can take advantage of the free service at Autozone for this.

The reason I'm asking is because I recently replaced my IAC due to shudders at idle, which makes it feel like the engine wants to die. I still have the same shudders with the new IAC. I figured that the next step is to see if there are any trouble codes to work from (which in hindsight is what I should have done in the first place!).

Thanks for the help.

Andy

 

Yes, there can be codes stored even if the CEL is out. Most Autozones will pull them for free. Call ahead to confirm.

 

Thanks for the reply marragtop, I appreciate it.

 

If you do have codes stored, post them to the forum. Don't let Autozone sell you something you may not need.

 

What year Explorer?

OBD-1/EEC-IV (pre '96) has many cases where codes can be present without lighting the CEL. My limited experience with places like Autozone and EEC-IV is that they are not very useful, except for pulling codes (if they can even do that much. sometimes seems hit and miss as to whether they know how to handle the older vehicles). With EEC-IV, you can pull codes with nothing more than a paper clip (assuming you are smart enough to count the flashes of the CEL). IMO, you'll be better off in the long run to learn how to pull codes yourself than to rely on Autozone or similar.

OBD-2/EEC-V ('96+) is a lot more "sensitive" and usually doesn't have codes stored if the CEL hasn't come on. I haven't dealt much with EEC-V, I've heard of "pending codes" (faults the computer thought it saw but is waiting to see them again before lighting the CEL), but I don't know if Autozoners are able to access pending codes or not.

 

Mrshorty -- it is a 2003 Explorer SportTrac, 4.0 SOHC. Marragtop -- If I am able to get the codes, I will definately be back to the forum to post them.

 

Yeah, newer than 1996 is an OBD II system that you nead a reader for. There are two different ways the do-it-yourself guy could go. Get a "code reader" or get a "scan tool". One of my best tools is a code reader I bought for about a hundred bucks. Some are cheaper. I wish I could have afforded a scan tool!

 

They have the OBD-II code readers at Walmart for jut under $100.00. You might try Amazon or Ebay for a slightly better deal. It's the best $100.00 you'll ever spend IMO. They are very easy to use and come with a book tht lists the codes.

 

BTW - two things I would check if I were you. First - take a quick look around to make certain you don't have a vacuum line disconnected somewhere. Second - check or better yet, replace your fuel filter. The vacuum leak would probably throw a code but I doubt the semi-plugged fule filter would and it certainly could cause it to idle rough. You can also check fuel delivery presssure to make certain it's correct.

 

Thanks for all the replies...you guys are great. I went to Autozone after work last night, and and the code reader did not find any error codes. As for the fuel filter suggestion by Texan2004, I should have noted in my earlier post that the filter was the first thing I changed.

Also, I don't know if this makes a difference or not, but when the truck starts cold and the RPMs hang around 1000 until it warms up, it doesn't shudder as badly. But as soon as it warms up and the RPMs drop to about 650-700, the shudder is much more prominent while sitting still at idle. I also notice that at a complete stop when the truck is cold, once I let off the brake it "rolls" forward a lot faster than it does after the engine warms up. Sometimes after its warm and I let off the brake following a complete stop, I have give it some gas for it to move at all. Does any of this mean anything?

I'm starting to believe that a trip to the dealer is in my immediate future (UGH!)

 

I would also disconnect the battery and clean the MAS. If you ran on a bad IAC for a while, you PCM could have picked up a bad setting and not cleared itself with the new one. Let the PCM recycle itself to make sure it is reading correctly.

 

Sorry for the ignorance CobraXP, but what is the MAS? Further, do you think since the truck is still shuddering at idle like it did before I changed the IAC, that there was nothing wrong with the original IAC when I changed it?

I am just worried that this more of a fuel delivery problem rather than being associated with the amount of air flow. To me, it feels like the truck isn't getting enough gas while idling. It really bugs the *%@# out of me that I don't know much about cars.

 

MAS = mass air sensor. It is the sensor by your air filter that is inside the intake tube.

Since it is doing the same thing now as before the IAC was replaced, the original IAC could have still been good. Who/what told you to replace the IAC?

The problem could be anything from a bad fuel pressure regulator, a dirty or bad MAS, fuel pump problem, to a vaccum leak, to bad plugs or wires, etc. If you are not getting any codes, then usually you have to have a shop put the vehicle on a reader to see exactly what is happening. I have found it is cheaper to spend the $50 to let Ford read it and tell you exactly what is wrong instead of buying parts and guessing.

Before I took it to the dealer, I would start it and let it warm up. Then take a can of carb cleaner or ethenol and spray around the upper intake, the lower intake, and all vaccum lines. This will test for a vaccum leak. If the engine studders or jumps rpms while you are spraying, you probably have a leak in that area. If you don't get anything from that - the possibilities go up from there.

How many miles on it, and when was the last tune up done?

 

Thanks for the tips Cobra, i really appreciate it. I replaced the IAC on a guess after reading some posts on this site and starting my own thread on the topic:

https://www.ford-trucks.com/forums/4...iac-issue.html

I have never experienced another idle surge as I described in the post above after I took the IAC off and cleaned it. I also performed the electrical test on the IAC as described in Wolfmeister's (sp?) post, which it passed, but then I read some of the follow-up posts that questioned the testing procedure. The truck continued to to idle rough after cleaning the IAC and appears to have gotten worse.

I have an uncle who is a general mechanic (who hates Fords), but will probably have time to help me take the carb cleaner to the upper and lower intakes and vaccum lines. If this doesn't produce the problem, it's probably off to the Ford shop next week.

The truck has 59K on it now, and had 38K on it when I bought it used in August of 2005. I have never had a tune up performed, and doubt that the previous owner did either. I spoke with the previous owner before I bought it, and he said he never had any trouble. He traded it in on a F-150 Lightning that matched his Harley.

I'll post again after I've learned something. Based on the threads, it seems like there are a number of people on here with similar problems.

 

Carb cleaner will work as a testing fluid but can eat up some plastics. I would recommend using starting fluid/ether.