Hey everyone, new to this site so I apologize if I'm posting in the wrong place or bringing up a dead subject, but I have browsed and haven't come across another thread stating my exact problem, also browsing the internet for the answer I seek has left my head spinning. So as stated my 98 4.2 is pulling two different (possibly related?) codes... I'm hoping it's JUST the IMRC valve stuck(reason for the 1538)that is causing the 174 code as there the same bank. I suppose I'll be replacing the upper and lower intake gaskets as I believe I have to remove the upper to get to the IMRC. Also should I purchase isolator bolts just to be safe? I've read they go out prematurely in these trucks and cause lean codes. Don't want to throw parts at it and I would really like the opinion of someone more experienced than I. Thanks in advance.

 

Also I could smell raw fuel the other day while running the vent, never happened before but I do smell 'rotten eggs' faintly from time to time while running the vent.... maybe the IMRCV went out and is throwing off my O2 sensors on account of lean fuel system due to IMRCV and burning up my cats? Could really use some advice.

 

This link from another post may help:

https://sites.google.com/site/fordf1...P0171P0174-Fix

 

OK first the system isn't running lean. The code you have is for "lean condition detected" which means the PCM has tried to correct that by richening the a/f ratio, (you're running rich). If you have been driving with the "lean"code for quite a while, then yes you may have damaged the cat.

P0171/174 are most commonly caused by an air leak after the MAF sensor, a stuck open IMRC would fit that scenerio. So would an intake manifold leak.

I'm not sure, but I thought the '97 had the aluminum plenum. If that is the case then I think you are at least looking at intake gaskets, (I don't think the aluminum plenum used isolator bolts).

If you have the composite plenum then you need to replace the isolator bolts if you remove the plenum. Pay the price and get the ones from Ford, no aftermarket.

The IMRC has 2 little arms that can fall out when the bushings get worn. Take a flashlight and an inspection mirror and see if you can see if the arm is out of place on that side. A borescope would work better, but not everyone has one, haha! If you have small hands there are cases of guys that have replaced the bushing and arm without removing anything, I don't think I could do it myself though.

With the IMRC code and the lean code it's like- which came first, the chicken or the egg. One can cause the code for the other to be thrown.

Do the visual inspection first and make sure you get the correct parts for your type of intake.

BTW that link above is an excellent how to!

Good luck, and welcome to the site.

 

I would replace the upper and lower intake gaskets and the front cover gasket on general principle - 4.2's built before 1/16/98 have defective gaskets.

You sure it's not a P1538? P1358 is ignition-related.

 

glc, I think it's a typo in the title of his thread, he says 1538 in the post.

Was I correct about the plenum on his being aluminum?

 

I believe so. I don't know exactly when they switched to composite.

 

Sorry for the confusion guys, I was up all night researching my problem before I posted this lol. It's an aluminum plenum and the second code is a 1538. I will be doing my gaskets just based on the fact I have to remove the upper intake to get to the IMRC as stated above. Theres no way I can get my hands back there. Ill try to check it out with a mirror, thanks for the advice everyone

 

Make sure you do the lowers and front cover too. Get the updated gaskets from Ford.

 

Thanks for the tip glc!

 

Finally got a check I can spend on something other than bills, just ordered the gaskets and the IMRCV, next available spending money will replace the driver side cats with the magnaflow bolt in kit ;]. Should I pick up some gasket sealer for when I do the intake? If so what would some of you fellas recommend?