92, Problem with Idle while in drive(new egr, FPR, nut kit)

[neverendingninja]

My sisters 1992 Jimmy, 99,999 on the non-functioning odometer, recently started acting up, and knowing her routines, or lack thereof, I figured a full tune up would acknowledge the issue, and solve it. Spark plugs, wires, rotor, fuel filter, air filter, oil, pcv, etc...

Anyway, that didn't work. So, I come here. I read that a common cause for a rough, rich idle is either the nut kit, or the FPR. I replaced both tonight, along with the EGR valve(not brand new, but the actuator works).

The truck idles ok in park, but when its in drive and you come to a stop, the idle is much rougher, the lights pulses a bit, dimming and whatnot. The exhaust smells much better, but is still richer than I'd like, but I believe she may be catless.

If anyone has any insight into this, please let me know. I've sunk $300 into this so far, and don't want to put too much in without actually solving the problem. Thanks guys!

[Chris Stewart]

If the idle speed is less than 700rpm, the Idle Air Control (IAC) valve may be sticking ...it's mounted on the left side of the air inlet to the intake manifold next to the throttle cables. You can take it off and spray some carburetor cleaner in the manifold and spray some on a rag and wipe off the IAC plunger

[neverendingninja]

Cleaned the IAC to no avail. Someone suggested the injectors could be "fried" if the EGR valve was stuck open at idle. Would this "fried" refer to overheating, or fouling due to carbon cycling through? Also, if they are indeed fried, are the injectors on a 92 rebuildable?

Thanks again guys. I've done everything I know to do so far

P.S. Sorry for posting in the wrong forum.

[DelCoch]

Check and/or replace the MAP sensor.

[Chris Stewart]

Is the Check Engine light on?

[neverendingninja]

Originally Posted by Chris Stewart

Is the Check Engine light on?

The only light I recall seeing was the ABS light. I'm going to diagnose the MAP sensor ASAP. What should volts read? 0.5 to 1.5 volts at idle, 3.0 to 4.5 at accel?

[old_master]

If the MAP sensor is out of range, it will set a code in the OBDI and turn on the check engine light. If the EGR valve does not close, it will also set a code but will not damage the injectors. With the exhaust smelling rich, I would suspect fuel delivery or secondary ignition. Fuel pressure and secondary ignition are not monitored by OBDI. You made no mention of replacing the distributor cap, a very important part of secondary ignition. When was it last replaced? Check fuel pressure and the systems ability to hold fuel pressure. Post back with the 8th character in the VIN if you need fuel pressure testing procedures and specs.

[neverendingninja]

Sorry, thought I put the engine code up. Its W.

Dist cap was also replaced in the service I performed...about 2 weeks ago. Has been mostly just sitting since the service, besides being driven once to her work, about 1.5 miles from her house, and back and forth between our houses, which isn't even an 1/8th of a mile.

Test procedures would be appreciated. Thanks a lot guys!

[old_master]

Fuel pump operation and fuel pressure testing

The fuel pump circuits are designed to energize the fuel pump continuously any time the key is in the START position. When the key is in the RUN position the fuel pump will operate provided the engine is running. If the engine stalls, or is not running for any reason, the ECM will shut off the fuel pump after approximately 2 to 3 seconds.

Fuel pressure test:
Install fuel pressure gauge to the test port near the distributor. Turn the key to the RUN position, (do not start the engine). While the fuel pump is running, fuel pressure must be 60-66psi. After approximately 2 to 3 seconds, the fuel pump will shut off. Fuel pressure must remain between 55-60psi for several minutes. A drop in pressure below 55psi indicates a leak. Most likely the fuel pressure regulator, lines, (nut kit) or the injector under the upper intake manifold are leaking.

[riptide44]

i'm gonna go ahead and say the injection unit is the problem - been there done that on so many w engines including my own - and trust me on this - get a delco or delphi unit

[Chris Stewart]

Here's the fuel pressure test port on your '92 W motor.
A fuel pressure test kit is available at most chain type auto parts stores.
An old R-12 freon refill kit with a gauge will fit the test port valve too.

[ericn1300]

Originally Posted by Chris Stewart

Here's the fuel pressure test port on your '92 W motor.
A fuel pressure test kit is available at most chain type auto parts stores.
An old R-12 freon refill kit with a gauge will fit the test port valve too.

it's a shraeder valve, i just use a cheap dial type air pressure guage that holds the high reading until reset. not the most accurate but good enough for basic trouble shooting. a lot harder if you use a regular air pressure guage as it will be spraying fuel while you bend over to get a reading. wear eye protection.

hey Chris, you ever think about cleaning that engine?