Starts with a stutter, then idles smooth

[Jackofalltrades1980]

I have a problem with my 93 Ranger, where upon starting, whether the truck is warm or cold, will start with a sputter, then ramp up the rpm's until it reaches idle speed, sometimes itll sputter down a few rpm's for a second then come back up and level off after a couple of seconds, running smooth from that point on.

When the A/C is turned on, you can detect the change in idle when the compressor kicks in, especially at cruising speed, the motor will react when the compressor kicks in.

I put my scanner on the computer and the thing comes back with a 111-pass code on the KOER, KOEO and a 327-EGR pressure sensor trouble code in the memory codes. I already changed the spark plugs, fuel injectors, timing belt doesn't have that many miles, fuel pump is new, and based on the lack of trouble codes, all of the sensors I'm assuming, are ok.

After getting the EGR error, I did some dicking around with the EGR, removing the vac line from the EGR valve, and starting the truck, with the same effect, I also removed the wire harness from the sensor mounted on the valve, and the check engine light came on to indicate that the computer did see (or in this case, didn't see) the sensor. I didnt check anything else at this point since I dont know what else to really check at this point.

The truck runs just fine otherwise, itll accelerate smoothly with no missing or stuttering, itll go 85mph on a level surface, doesnt smoke or run lean or rich at any time, all in all the truck runs fine, given that it has 250k miles. The only thing is that rough starting issue, which is a concern of mine, since everything else doesnt matter if I start having problems getting the engine started.

 

[2.3slow]

hi jack

i am experiencing the same issue. sometimes it stalls out. i have noticed that the volts drop on the volt meter when this happens. like something is drawing more amperage than necessary. and thus larger drag from the alternator. (one would be surprised at the drag that is created when the alternator is at full field) i have replaced a myriad of stuff. they are: plugs, wires, coilpacks(acell), mass air flow sensor or meter(i regret that move it was expensive). i know about cleaning it but the rough idle would improve for a day or two and go back to rough so thats why i changed it. i put in a new t-stat as a cheap try me because if your not running the right temp the ect sensor cant tell the processor how hot you are to meter fuel correctly. it has had a new O2 sensor a couple years back. i also have replaced the fuel pump and pressure regulator. when i pulled the intake manifold to clean it out and the throttle body i checked the egr valve and sensor. both hold vacuum just fine so i figured it could be dirty or a chunk of carbon holding it open. the plunger and seat looked fine. anyhow i got some gumout cleaner and did a good cleaning on it. the whole time i had vacuum pulled on it. the only thing i can think of is it has to be the idle air control valve. or idle air bypass valve. i inspected it when the intake was off and it wasnt full of carbon. it was seemingly clean for 99k miles(not like new but clean) any how a blew it out with compressed air because i didnt want any chemical getting into the solenoid motor half of the valve.(old tech-school teacher beat that into my head) thats the only thing i can figure. i have no check engine light on and my star tester reads no codes and the IABV is the only thing that controls the idle fluctuation. i am going to put in a new ect sensor because it is old. maybe its lazy? who knows. i am going to try a seafoam treatment in the fuel tank. i cannot condemn the alternator because it is newer. (the best one at autozone) if you find any fixes let me know i will do the same

john

 

[2.3slow]

i just had a crazy wild ass guess. maybe the vacuum solenoid valve for the EGR is allowing vacuum to the EGR valve at startup causing it to stumble when it shouldnt be open. then it thinks about it for a while and then it energizes and it shuts off vacuum to the valve. we did a recall on certain vin break rangers in 91-92. it was so long ago i cannot remember why. but you installed a black plug spacer thing inbetween the wiring harness plug and the solenoid valve itself. they never told you what it did or what it prevented.

 

[BobbyB2300]

I would clean the MAF with an entire can of MAF cleaner and replace the DPFE. Make sure the two hoses that feed the DPFE are intact. It's a fairly inexpensive maintenance. If you're experiencing an occasional bucking\jerking, this is indicative of a bad DPFE.

With the problem being at idle, I wouldn't rule out a flakey Idle Air Control(IAC) valve either. For that matter, I wouldn't rule out the Fuel Pressure Regulator(FPR) either. In fact, pull off the vacuum hose on the FPR and see if leaks out the hole, that would be a bad thng, it's located on the fuel rail right on top.