When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Please help! I just got a '94 Ford Ranger XLT that jumps like a rabbit and tries to stall out while idling. It's a 4-speed manual with overdrive and four wheel drive. Finally got to do some decent research and discovered the problem may be the EGR valve. Have a suspicion that it may have been bypassed a long time ago (I'm the third owner of this truck) but I don't see any spare loose wires or tubes in the engine bay. My hubby is pretty mechanically inclined (just not with Fords). He's teaching me a bit but this part needs to be fixed and not only can we NOT find it, the owner's manual that comes with it when purchased new doesn't even have it on the engine bay drawings. This is where we suspect it goes. View is from driver's side. Holding the new part next to the only similar piece I can see, but it's about 1.5 or 2 times the size.
UPDATE: Suspicion on location was correct, however we still don't see any loose wires or hoses, let alone where they would even be plugged in. Suggestions on where to look are greatly appreciated!
1994 may or may not have an EGR valve, it depends on what State it was sold in when new, its was an emissions requirement in some states but not in others
Does the CEL(check engine light) work, it should come on with key on and then go off after engine starts
If Computer is programmed to use an EGR Valve then CEL would be on all the time and you would have EGR codes
So if no CEL then it didn't come with EGR valve
The EGR Valve is connected to the exhaust manifold on that side of the engine by a Metal pipe, so you should see a threaded hold on that manifold with a plug screwed into it
EGR system also has an EGR solenoid and a DPFE sensor as the electrical parts, solenoid had a 2 wire plug, DPFE a 3 wire plug
EGR system lowered the cylinder temps to reduce NOX(toxic gas) emissions when engine was under a load, i.e. accelerating or at highway speeds
And it was only used after engine was fully warmed up
So any stumbling from lack of EGR would only occur after warm up
And no EGR really wouldn't cause symptoms as described
Pinging/knocking is a symptom of high cylinder temps, 87 octane gasoline(regular) can pre-ignite if cylinder temps get too high
Non-EGR computers have a different spark advance than EGR computers to try and prevent pinging/knocking
IAC(idle air control) Valve should be cleaned, computer uses that to control idle RPMs
Base spark timing may need to be checked and reset, 1994 was last year 3.0l had a distributor
Luckily, the paperwork and owner's guide that comes with a new vehicle actually came with it when I purchased it, and that paperwork says it was sold to a dealership in Baltimore, Maryland so it should have the EGR Valve as they require emission tests every two years. In the first photo of my original post, there's a plate (about 1/2 inch thick) directly under my hubby's finger that is actually covering the hole for the valve. However, we still don't see the wiring or tubing that is needed or where they would be plugged in so I have a feeling it was probably bypassed, but I would think there'd still be some evidence of where to plug things in if not loose wires/tubes.
The CEL does work and comes on when the truck is started, but will shut off after a max of 10 minutes only to come back on moments later. The jumping starts after about 20 minutes and only appears when we press on the gas pedal and are going at least 40 miles per hour.
I will definitely look at cleaning the IAC Valve (as well as other things on my list - i.e. fuel injectors, etc.), but I may put it in a shop for the spark timing to get checked and/or reset since I'm not comfortable with messing with anything to do with timing.
03-06-2022
