resetting computer after FPR

[oahrens]

Hey Guys,
After encountering the infamous "check engine light" after 10 mins of driving on my 91 xlt with 75000 miles, I searched the boards and think I solved the problem.

There was 50% loss of power and gas mileage!!!

I cleaned the MAF with Gumout and replaced the Fuel Pressure Regulator. After replacing I drove about 30 miles on the highway to reset the airflow in the MAF.

I am still getting chk eng lt and power is only a little better.

Question: Do I have to reset the computer by disconnecting the neg batt cable? If so then how long and what driving conditions are the best to reset everything?

Thanks All.

 

[Stephen S]

I see this is one of your first posts!! Welcome aboard!! I'm sure you'll fine just about anything you'll want to know about your truck right here! Enjoy your stay!!!

Now on to your question: Yes, disconnecting the battery for a little while (30 minutes or so) will cause the computer to reset, and forget all stored codes. When you start the truck back up, drive it around like you normally do so the computer can relearn the engine's air and fuel needs. The check engine light will not come back on, unless there is still a problem with the engine. But then it will be easy to track the code with a scanner to find out what the problem is.

 

[oahrens]

Thanks Stephen S.

I appreciate the welcoming and the reply.

I will reply with results tomorrow.

 

[Stephen S]

No problem, glad to help. Let us know if you can tell the difference!!

 

[oahrens]

Uh-OH

Hey all...

Just an update to this painin the a**.
I reset the computer...still no good.

I went to my buddy and the dealership and hooked up to the computer diag reader.

After all O2 sensors...MAF...EGR...and FPR...here comes the bad news.


Bad/Clogged Cats!!!!

Is there anything that might help clean them out without replacing them.
The price for just the cats from the dealer is 690$ cost.
Please any help .

 

[SteveVB]

New cats

You can get a new "high flow cat" from Summit for 150 I think, maybe less. I would call and check.

I would also check non dealer parts houses to see what they have.

I replaced mine in a few minutes when I installed my Borla cat back system. ( put a little liquid soap on the rubber isolators- the hangers will slide right off)

Good luck

 

[fordkrazy]

you might want to reclean the MAS with brake cleaner rather than carb cleaner. and you should get the high flow cats. or you could get a muffler shop to cut them open and remove the innerds but i would replace them and be kind to OUR air. i would check to see if they are really clogged. should smell bad and they will more than likely be melted down. to check to see if they are melted down crawl under there and hit them with your fist (not your nuckles and when its cool....duh) you should be able to hear the core rattle arround in there. the dealer might not have found an expensive fix so they made one up so they could fix the cheap problem and do an expensive unneeded repair.

 

[oahrens]

NIcey Nice

Hey Guys..

Sorry so late.

Here's the finale....
I got OEM cats from a local parts place for $95..(good deal).
I installed myself in about 45 mins.
As soon as I tuned the key I knew this was it. The power/gas mileage went back to norm.

So after all O2's...MAF sensor....Fuel press reg....full tune up and hours of frustration....this was the fix...
BTW---- It all started with CEL after about 10 mins and the codes saying MAF and FPR were bad.

Thanks for the help.

 

[Triton46]

oahrens,

Sounds like the same problem as me. I had a check engine going off as soon as I reached 20 miles on a long trip. I could stop and restart however the check engine would come on at 20 miles. As soon as I got to my destination (400 miles) I changed the FPR and cleaned the MAF.

Check Engine came on at 200 miles this time.

When I got home, I replaced the O2 which was full of carbon. The Check Engine went away and has not been back since.