I’m not very good with diagnosing stuff, but I can pretty easily figure out how to fix stuff. On this truck I’ve taken apart the dash to fix the hacked radio wiring the previous owner did, made my own little wiring harness thing to extend the ignition control module to the fender because ford put it on the distributor so it overheated easily, fixed the broken filler neck (a tube got disconnected inside), swapped out the A/C heater box for a non-ac box (previous owner mangled all the AC stuff and I don’t use AC anyway), set the timing, replaced the lower intake manifold gasket, tested/replaced fuel injectors, replaced trans pan gasket, had to unbolt engine and trans and lift them up to replace the oil pan gasket, fit an explorer 4.0 2 core radiator in instead of the original tiny 1 core 2.9 rad (that was also leaking) and had to make the original fan shroud attach to that rad, ect. Basically, I can fix just about anything on it, my problem is I have no idea what is wrong and neither did the shop I took it to. I’ve just never really needed to use a vacuum pump/gauge. For any tools I would use maybe once or twice, I’d rather just rent them then buy them since its free.
Thanks for the explanation, sounds like you are good to go diy’er-wise. I have a 50 year old Ford truck and I’ve had to diagnose many vacuum related problems over the years, so grabbing the vacuum pump and vacuum gauge off the shelf is a pretty common task. If I had to go to the parts store to rent those tools would too much of a chore for me, given how inexpensive they are and how often I need to use them. .
That could cause problems because (I believe in this case) the ignition module inputs a small signal from a sensor in the distributor and outputs a drive signal to the ignition coil consisting of 100V+ pulses.
Those lines could interfere if running side by side un-shielded.
That’s why they put the module next to the distributor, to avoid long wiring.
I made sure to shield it, it ran just as bad before I did that. It overheated on 30+ minute drives and started misfiring worse but extending it fixed that. I made the extension 100% reversible too if I ever want to remove it. It just plugs into the stock harness so I could just unplug the extension then put the module back in the stock place if I wanted to
Given the ignition system wiring harness modifications you’ve made, it might pay off to find a shop that knows how to do o’scope diagnosis of your Ranger’s ignition system. Years ago most shops knew how to do this, and had special equipment (usually made by Sun) on hand just for that purpose. These days they tend to rely on scan tool diagnosis for that purpose, but for your older pre-OBD truck, an o-scope method may be better.
I did find some things when doing a smoke test. There’s a small leak at the EGR valve and also a small leak in the crankcase breather’s plastic casing. I tried to measure manifold vacuum and the gauge shot to -20 in Hg immediately and maxed out so it might be -20 flat or it could be more, can’t tell. One thing I found though is that unplugging the IAC valve didn’t change the idle at all. Also confirmed with a guy who owns the same truck that the IAC valve should be increasing the RPM back up when the alternator is being loaded up.
Is the vacuum system configured so there’s a way to clamp off the paths showing some smoke-leak temporarily, as an experiment, to see if the engine runs better? Small vacuum leaks in those locations could possibly be normal. What is the IAC operation method? Vacuum actuator, vacuum controlled electrically? Or is it done electronically only? The throttle valve is moved by an electric motor? Has any of that been replaced?
That means the engine computer is unable to control idle speed, so mind those leaks!
Clean the IACV & make sure its not stuck.
Not really
I don’t think vacuum leaks at the EGR is normal and I know the crankcase breather valve isn’t normal because its a crack in the plastic itself causing the leak. I’m not 100% sure, but I’m pretty sure the IAC is electronically only. The throttle valve is controlled by just a cable though. The IAC valve was replaced by the previous owner, no idea when it was replaced or what brand it is. It still looks like it’s in good shape so I’m assuming not too long before it got to me.
If you are certain there are significant leaks in the vacuum system, and visible cracks seen in a vacuum-related hose is pretty certain, suggest fix all of those first, as that may well solve the entire problem.
If your EGR system is like the one on my Corolla, in certain driving conditions (like cold idle) the EGR valve is completely disabled , done by bleeding off its vacuum signal using an electrically actuated solenoid air-bleed-valve. Done to prevent engine stalling. That could possibly show up as an EGR vacuum system leak in a smoke test, when in fact it was normal operation.