I had similar problems with my truck awhile back. My is a 4.0 1994 and the MAF went when I had about 120,000 miles on it. Although mine was an automatic I remember when I would slow down to a lower gear it would correct itself. My check engine light came on and the codes read the MAF so I tried cleaning it which didn't work so I ended up changing it and all my problems were solved. I hope you can fix your problem.

 

Since I've changed the rotor/cap, my truck has been running as if there was never a problem. (However, I've learned through experience that this doesn't always mean the problem has been fixed.) It has only been about four days though, and I've only taken it on the freeway twice. I pushed the truck a little bit, even taking it up to 75 mph or so, and it runs well. Originally, I had been having problems once I got into fifth gear or if I went faster than 45 mph or so.

Black Ranger, I was going to clean out my MAF, JUST in case that could still be potential culprit, but even with a torx security bit, I could only remove on of the screws on the MAF sensor. The other screw has a tiny plastic cap on it, and when it was removed, the plastic broke off, filling the grooves on the screw head. (Arggghhh!) I'm going to try to remove the screw with some pliers though. I did the "tap test" thing, with the MAF, and the idle didn't change, so I don't know whether it might have been the problem or not. (or at least part of it) My truck does have almost 170,000 miles on it, and I don't know how well the truck was maintained by the previous owner. (it starting to seem like it was poorly-maintained though) I think I'll change the MAF in the next few weeks, if I can't clean it that is. With such high mileage on my truck, it can't possibly hurt. I also think that I'm going to clean the IAC too. My truck still has a slightly, and I mean very slight, "rough" idle. ("rough" is the only word that comes to mind)

Actually Black Ranger, my CEL did come on twice during my first drive after I changed the cap/rotor. It came on then went off, during my test drive. The other night, Sunday, the CEL light came on while I was driving again, but after I stopped driving for the night and drove the truck the next day, the CEL has not come on since.

As I said though, I'm going to change the MAF. Also, earlier in this post, KEN00 mentioned that it might be the TFI ignition module. As per his suggestion, combined with what I've researched, I think I'm going change that in the next couple of weeks too. I'm just trying to do a component at a time, so as to be able to more readily pinpoint what might have been causing the problem. I'm also trying to not spend money needlessly. (although it's probably money well spent, considering the big picture of wanting my truck to last...) I guess the only other thing I'll end up changing will probably be the 02 sensors. After all, it's probably something I should change due to the mileage. I'm also going to change the transmission fluid as well. I bought the last July, but I haven't changed the fluid yet, and there's no telling when the previous owner(s) changed it, if ever.

Ken00, since you mentioned the crusty stuff on my distributor cap was dielectric grease, should I take the cap off and put some of that stuff on the contacts? I didn't do that when I changed it. Also, should I put some dielectric grease on the rotor contact as well?

Black Ranger, how much did your MAF cost? The cheapest I've seen has been at partsmamerica.com for $63 or so. (remanufactured) Actually, that brings up a good question... the phrase "You get what you pay for..." does anyone think this applies to the MAF? I not exactly sure whether I shoul get a new one or a remanufactured one. I've had other remanufactured parts from vehicles I previously owned, and those parts worked fine. Any opinions on whether "You get what you pay for..." (about vehicle parts that is) is true or not?

Until the my post, (which I hope will be a bit less problematic in origin) take it easy everybody.

-Mike-

 

You should be fine without it, I always put it on the plug boots.

 

I go by the if it isn't broke don't fix it when it comes to electrical parts. No reason to change the maf & TFI if there fine. I've seen more then a few vehicals that wouldn't run good at a higher load being caused by a bad cap/rotor/plugs or wires. The reason is the engine is under more strain to pull a higher gear. If it's not getting enough spark to burn the combustion mixure you won't have power. If the cap had lots of carbon in it once it gets hot enough it could arc all around inside and not fire on the cylinders it supposed to, once again causing a loss of power. If the contacts on the rotor and/or inside of the cap was black/grey or rust colored then it was ready to be changed.

good luck, hope you fixed it.

 

BigMackZac,

Get the codes pulled from the CEL going on, that should help. I paid about $65 for a remanufactured one and had no problems with it. A lot of people will tell you otherwise, but I've never had any problem with the remanufactured parts. I figure in the case of the MAF, it was much cheaper and easy to change, plus the part came with a warranty. I bought mine from partsamerica also, which is what Checker Auto uses.

If you use a dremmel you can cut through the security torx heads and take them off with a regular screwdriver.

 

Grab a Haynes manual and then you can test the MAF along with most other sensors under the hood with a cheap digital muti-meter. No sense spending money replacing parts that aren't bad.

A small pair of vise grips worked for the epoxy filled security torx bolts on my 97 4.0's MAF.

Don't use carb cleaner to clean the maf either. It does leave a film. Use something like Electrical Cleaner from CRC. You can find it at most autopart stores. Plus you can use it to clean the rest of the connections on all your sensors if needed.

Use some di-electric grease when you plug your MAF connectors back together. For that matter use it on all your electrical connections you take apart and on both sides of your plug wire boots. Makes it easier to take'em apart later on.

Also, There's lots of talk online about different plugs/wires and what to use on the 4.0's. Not sure if it applies to the 3.0 but from what I've gathered from reading everything most people that have some type of miss or stumbling idle are the ones that used bosch platinum plugs and/or cheap wires. I had a miss due to Bosch wires.