Weird idle

[csbuckn]

Hey ya'll, I have a 94 B2300 thats acting a little weird to me. Ever since I got the truck about 8 months ago, the idle has been rough. Off idle has been good, but idle will be rough. Well, the other day, I hopped in the truck to go somewhere and the idle was smooth and the truck was running great. The check engine light came on and the truck idled smooth with no miss, it was like this all day and the check engine light was on, off, on, off but ran smooth the whole day. The next day, it ran rough again and no check engine light. I didnt get a chance to read the codes because I forgot how. It has only happened once. I have replaced the TPS, IAC, MAF sensor and vacuum line chasing down another problem. Any clue what would cause the engine to be rough, then one day idle smooth, then back rough again? It has a rough idle and a small hesitation off the line.

Thanks, Sam

 

[tbirdsps]

Just guessing but a EGR valve sticking? Take it off and clean, put back on. I'll bet you have an EGR code when the light is on.

Again, just guessing.

 

[csbuckn]

Thanks, I'll look into it.

 

[Tagg]

Sounds like the Right Answer EGR Valve

Just had the same problem with my 95 Ranger. No CEL, Would NOT Pass Pa Emissions. Idled Extremely Rough at idle but ran extremely well when driving. Replaced IAC, MAF, TPS, Tuneup, Wires , Plugs, Fuel Pump and repaired broken wire to solenoid to canister. Had truck to 3 different shops. Checked for vacuum leaks and intake gaskets, etc....... unable to locate problem. Truck sat for over 6 months due to problem. Finally, Found the problem myself, as usual, it was the EGR Valve. The top of the valve was totally separated from the base. It was able to be totally lifted up, the only thing connecting it was a 1/8" metal tube under the dome to base. Had to crack old EGR valve body to separate from lower metal tube and drill out mounting bolts to get off of intake tube line. However, now it runs like a 2011 Caddy.

 

[bblatch69]

Could be the pcv possibly as well supposed to be replaced at 80 k

 

[Mullins81]

check for vacuum leaks had that problem with my 94 b3000, they can be a bugger to find and cause weird problems

 

[Rembrandt]

I had a similar prob with mine and also when I had over about 2500-3000 rpms and let off if I didn't feather the throttle til it lower it would die. It ran great other than that and threw no codes. It turned out to be my IAC valve

 

[modelageek]

Hey ya'll, I have a 94 B2300 thats acting a little weird to me. Ever since I got the truck about 8 months ago, the idle has been rough. Off idle has been good, but idle will be rough. Well, the other day, I hopped in the truck to go somewhere and the idle was smooth and the truck was running great. The check engine light came on and the truck idled smooth with no miss, it was like this all day and the check engine light was on, off, on, off but ran smooth the whole day. The next day, it ran rough again and no check engine light. I didnt get a chance to read the codes because I forgot how. It has only happened once. I have replaced the TPS, IAC, MAF sensor and vacuum line chasing down another problem. Any clue what would cause the engine to be rough, then one day idle smooth, then back rough again? It has a rough idle and a small hesitation off the line.

Thanks, Sam

1) add as many details to your signature as you can fit

2) the first rule in auto repair is DXing

3) the first rule in auto DXing is checking for codes even pending codes

4) you did not mention what your "other issue was"....but dollars to donuts they are related......you have spent at least $200 on parts so far and the first thing you should have invested in is a scanner for $20........if you have the OBD I you can read them without a scanner.........I know all 1995 rangers are obd-II and I think some california 1994 are obd-II also but I am not positive


your issue could be many things even a faulty ECT sensor or low coolant level(depending on where your ECT sensor is located)..........I solve man issues just by catching a pending code

 

[ForOffRoadDriving]

pull the codes as modelageek suggested, it could be an evap system code caused by a stuck open or stuck shut egr solenoid, or a vaccum leak in the intake tube where the valve cover breather hose connects to it. i found a leak in my tube right on the seam wehre the intak ehose was molded, took forever to chase it down but it fixed my low vaccum problem.

 

[csbuckn]

An update...it was the EGR. The way I found out was pulling the vacuum line off the EGR valve, the idle went right to normal. My EGR looks really rusty so I dont think its coming off easy. I now have a little hesitation off the line but its better then the truck wanting to stall. Thank y'all for all the help!

 

[modelageek]

An update...it was the EGR. The way I found out was pulling the vacuum line off the EGR valve, the idle went right to normal. My EGR looks really rusty so I dont think its coming off easy. I now have a little hesitation off the line but its better then the truck wanting to stall. Thank y'all for all the help!

could be the egr or hoses,however the most common failure of that system is the DPFE

 

[csbuckn]

Alright, good to know. I'll vacuum check the EGR first when the time comes for repair but I'll check the DPFE also.