Boy this vehicle sure keeps me on my toes. I thought I was getting caught up and the service engine light comes on today. It reads PO734 Gear 4 Ratio Incorrect and that is all. It seems to run just fine. Does this necesarily point to the MAF? I am using a paper filter.
I did just replace the tranny fluid a week or two ago and have been replacing all the other fluids perthe 60kservice list. This sounds like a tranny code.
If it is the MAF, how long do I have. Can I keep driving it before it is really shot? I'd like to take it on a trip this week and probably will not have time to get a new one.
Thanks.

 

Yes, you can continue to drive it, it will slowly start running worse with time.
Good news is you can buy a new MAF on line for about $130 .

 

Thanks Mike, that's pretty good news. At least it's easy.Although I was hoping you would say that I need to tighten my gas cap.

 

Well, the engine code went away for a few weeks, now it came back today with a few more codes thrown in(there's nothing like hooking up your OBD readerand getting a whole list of codes): P0305-306-307-308 and P01300 and P0734.

Can I assume it's time to get a new MAF asap?

 

What has been done tune related wise to your truck and how many miles ago? Are you running factory plug wires still?

 

About 1500 miles ago: I replaced thewires with Magnacor's and plugs with Bosch+2 (after bad misfires). I also cleaned the throttle body, BG inductioncleaning and ATF engine flush at about the same time.

One apparent no-no I did when I first got the truck was to pull the air filter out to see what it looked like, banged some dust out of it and put it back in. I've since replaced it with another paper filter a month or two ago. Maybe the MAF got dirty? This was a few months ago though.

 

So, it looks like there are 2 things going on, for misfire codes, the 1300 which is a general emissoin misfire and your 4th gear issue which is usually the first sign of a failing MAF. I wouldn't change it out yet though.
How is the truck running right now?

 

The truck is running fine. Ierased the check engine light and went for two short trips this afternoon. It ran fine and the light did not come on again.

 

Strange, let me know if they come back on and what codes.

 

My 99 was having the same problem. I found a store on e-bay that sells used MAF sensors for about $70, I usually would not have gotten used parts (especially electrical), but they said that it has a lifetime warranty. Being a skeptic, i made them send that to me in writing, replacement (if they have it) or full refund. Still throwing misfire codes.I assume it's due to running bad maf for about 6 months, plugs need replacing. It's been progressively getting better, codes haven't come on in more than two months. Good luck, if you want i'll dig through my files and find the name of the company.