Low RPM miss on 2.9

[djunkie]

1990 Ranger 2.9L 2wd, 5spd. The other day It developed a low idle miss. At idle it'll miss then smooth out out when the engine is revved up. When driving its fine above 1500-2000 rpm's. When I come to a stop then take off again it'll miss till it gets above 1500rpm then it smooths out and runs perfect. Fuel pressure is good, Its got a new ignition module and fuel pressure regulator too. Also I put in new plugs/cap/rotor/wires. I pulled the codes and I got a 67, 66, and 41. I think the 66 came from when I pulled the intake tube off to squirt throttle body clean in the intake to clean some of the carbon build up. Also the IAC valve is less than a year old and I took it off today and cleaned it and still the same problem.

I disconnected the O2 sensor just for the heck of it and drove it. Seemed good for about 2 miles then the problem came back. That may be the reason for the code 41. Any ideas?

 

[IMenriched]

Look at the Tech Library it has a HOST of information.

Not sure what the "codes" are/mean...I'm sure that someone here can explain them.
this can be difficult to run down...because it can be sooo many things.

Just Seems/Sounds to me your having a vacuum leak of some kind....spray vacuum lines include the brake booster and around the intake where it bolts up to the block with carb cleaner when running...listen...for the idle to flaten out.

Also could be electrical, bad ground cable for example and any of the other ground wires.... or a poor connection at one of the sensors...or a faulty sensor themselves..or the pick-up coil which is below the distributor cap BTW.

Or simple as changing the fuel filter


It does look like you're on the right track...How many mile on this critter?

 

[IMenriched]

1990 Ranger 2.9L 2wd, 5spd. The other day It developed a low idle miss. At idle it'll miss then smooth out out when the engine is revved up. When driving its fine above 1500-2000 rpm's. When I come to a stop then take off again it'll miss till it gets above 1500rpm then it smooths out and runs perfect. Fuel pressure is good, Its got a new ignition module and fuel pressure regulator too. Also I put in new plugs/cap/rotor/wires. I pulled the codes and I got a 67, 66, and 41. I think the 66 came from when I pulled the intake tube off to squirt throttle body clean in the intake to clean some of the carbon build up. Also the IAC valve is less than a year old and I took it off today and cleaned it and still the same problem.

I disconnected the O2 sensor just for the heck of it and drove it. Seemed good for about 2 miles then the problem came back. That may be the reason for the code 41. Any ideas?

Ok found the code list..out of the Chiltons (didn't think they were there or couldn't find them right away)

#66= TOT sensor below test minimum TOT??

#67= Neutral drive switch open A/C input high

#41= EGO/HEGO circuit shows system lean
& or#41= No EGO/HEGO switching detected, system lean

hope that helps

 

[djunkie]

Problem solved. It was out of gas. Well not completely. Apparently my gas gauge is on the fritz and it was low on fuel and I think I may of had some water in the fuel. I topped it off with some fresh stuff and its runs fine now.

 

[IMenriched]

Problem solved. It was out of gas. Well not completely. Apparently my gas gauge is on the fritz and it was low on fuel and I think I may of had some water in the fuel. I topped it off with some fresh stuff and its runs fine now.

Yeap...the ole "not enough fuel/cruddy fuel" will make the best of them run...poorly to say the least.

does your truck have 1 or 2 fuel pumps? 2=1 in the tank &1 on the frame rail.

If your's has 2 you may want to check the one in the tank...you may need a buddy to listen for it to cycle/prime.

Glad to hear that it doing better