Low/searching Idle and stalling

[sleslie17]

How do you test it?

[hfx_guy]

hi disconnect the dark blue wire from the sensor (it's around the oil pan gasket depending on the year either near the oil filter or the starter its round & looks like an oilpressure sender)it has a 100k ohm resister in it measure res between the terminal on the sensor & the block it should be 1.5k to 10k (88 to95)and 90k to 110k ohms(96 to 00) to check it when running hook it up and thump the engine block with a SOFT hammer the idle should change the other test is to probe the wire with the neg meter lead and check for ac voltage it will increase as the engine speeds up if not its hooped. info from a haynes manual#24065 . another thing to check is the star shaped pickup under the rotor buton the distributor shaft will come apart spining the star & messing up the timing .good luck jj.

[sleslie17]

Thanks hfx - I will ask give this idea to the mechanic. Shouldn't it throw a code?


Shawn

[sleslie17]

The saga continues - the fuel pump was apparently not the problem. It has been stalling on my wife a week later. It was running good for a week. She said the air bag light has been interrmittantly coming on and off. It flashed when she was moving froma stop and she said it sputtered a bit. It stalled when putting it into gear hours later after having been off. Once it was hard to start. It is hard to diagnose this b*tch. It is back at the mechanic - I am out of ideas and tired of this. I hope he finds something. Any ideas from out there?


Shawn

[hfx_guy]

hi my 94 gmc is a complete bag of shi* last night i changed the wires cap & rotor the distributor shaft broke under the rotor button there is a star wheel it should be affixed solidly to the shaft these DO break and move on the shaft if they spin your timing will move and cause the truck to sh** the bed, put a flat screw driver near one of the points and tap it gently its cast&a magnet it should not move if it spins its hooped and must be changed the gm dealer sells the shaft seperate from the dist and is $95 cdn. this is what i must pick today.good luck jj. (the knock will not set a code in my p.o.s.)

[scubatomm]

try to hook up a fuel press gauge , then turn the key on ,wait until the pump stops, about 3 or 4 seconds, if it holds press there are no leaks, but if the press goes down in just a second or two one of the cheap,built in failure mode GM plastic pieces of junk fuel lines inside the intake plenumn may have sprung a leak like mine did. Tom

[sleslie17]

Thanks. Did yours have symptoms like mine?

[scubatomm]

Mine would start good only if it sat for a couple days, or if I restarted it after sitting only about 5 minutes or less. Otherwise it was always very hard to start (cranked for about 10 seconds). When it did start it ran pretty smooth for about 1 minute, then it would start to miss, and the idle speed was low, and sometimes hunting arround. I disconnected the battery then took off the top plenum and turned on the key on then touched the neg battery term so the fuel pump would run, BE CAREFUL , A GOOD WAY TO CATCH YOU AND YOUR CAR ,GARAGE ,ETC. ON FIRE. got a flash light to look for leaks. don't use a drop light if the gas hits the bulb it could pop and start a fire!! I immediately saw the leak. The repair kit is a GM item acdelco part no. 17112705, costs $44 from rockauto.com, However it is a pain in the butt to change . GOOD LUCK, Tom

[sereilly]

I am having the EXACT same problem with a 93 Suburban with 350 engine. I have so far eliminated TPS, IAC, O2 sensor, loose rotor cap or rotor, wires, plugs, walking cam, vacuum leaks, PCV valve, timing, and fuel pressure. I believe I am down to MAP, EGR valve, or computer. I plan on doing EGR and possibly MAP sensor tomorrow. I'll let you know if either works.

[clay1937]

I see that this thread is about 4 years old, but I am having the same problem described by sleslie17 with my full-size 1991 GMC Jimmy (same as Blazer) with a 5.7 litre V8.

Does anybody know if sleslie17 ever got a resolution?

I always warm the engine to 100 degress plus before I drive, and it runs perfectly until it gets hot (operating temperature). I can general drive 2-5 miles before it starts acting up...with the low and bouncing/searching idle, such that it feels like the engine going to die.

Once the engine is at it's hottest, the stumbling also occurs during decelleration from about 30mph down to zero.

The carburetor has been cleaned many times, and the engine has had a Motorvac service.

So far I have already replaced the following parts with no improvement:

Tune-Up (GM cap, GM rotor, AC Delco plugs, GM wires)
ECM (computer chip)
Distributor Module
IAC and gasket (this is the only part that isn't available from GM)
TPS (Throttle Position Sensor)
EGR Valve and gasket
MAP Sensor
Knock Sensor
TBI Injectors

I've read in the Haynes books that if the temperature sensor is bad (not the temperature sender), that nothing in the injection system will work properly, so the next thing I'm going to try is replacing the Temperator Sensor, once it comes in (the 4x4 version of the GM part was only available on special order). I also have a GM O2 sensor to try after that.

I've had trouble finding the correct EGR solenoid, but have thought that may be a possibility too.

Other thoughts I've had include replacing the distributor, or even the thermostat (I'm running a 180 rather than the factory 190, but I've been running a 180 for the last 14 years I've owned the truck). I have even considered that replacing the A/C/Heater temperature controls might help, (although this was replaced about 5 years ago).

There don't seem to be any vacuum leaks anywhere, and the intake manifold gasket was replaced about 5 years ago, and isn't leaking again yet.

Even though the truck has 209,000 miles on it, I can't imagine that there's a problem with the fuel pump (i.e., low pressure), coil, or timing chain (i.e., play in chain), because the truck runs perfectly until it's hot.

And since this is a 1991, there's no MAF sensor, Crank/Cam Position sensor, or even an air pump.

I'm running out of ideas.

[ZL1power69]

Start a new thread with a link to this one in the full size forum. That member has not been on the site since June of 04 so i doubt anyone knows if he fixed his issue.