Surging Idle

[Cole94]

Alright, so I cut that off a little prematurely, I was able to get the videos up. Here's the links.





Let me know what you think.

 

[FR-425]

The ECT does look good.

Listening to the video, what you have is not "surging" but a dead misfire.

Start with the basics, pull the spark plugs. Run the engine in a very dark garage and look for spark leak.

 

[mgmgmg]

2 things I want you to do while Explorer is idling........

1. Unplug Electric Connection on IAC to see if helps idle.

2. Unplug Vacuum hose on back of EGR Valve to see if idle is normal

I had same bucking and rough idle on in my 1994, but I had a CEL on. CEL pointed me to EGR sysytem......Almost 75% of idle issues are vacuum related......

 

[Cole94]

Thank you for the help so far.

FR-425:
Would a dead misfire clear up when the engine is throttled past 1k rpm? I forgot to mention, but it runs fine otherwise. Replacing the spark plugs was a PIA. What are the steps to finding the spark leak? I would like to try it as I am running out of options.

mgmgmg:
I have unplugged electrical connectors on a lot of things, MAF, TPS, EGR, IAC, nothing seems to help it. I will try again, however. I am not at the truck right now, but I will try both suggestions at about 3:00 when I get back to the truck.

Thank you. I forgot to mention that prior to the failure, my mpg was going downhill. It got to 11 before the truck started acting up.

 

[Cole94]

Yeah, it didn't make it any better.

 

[Cole94]

I guess my best bet is to take it somewhere to get it fixed or ignore it then.
I've already taken it to the ford dealership near me and the mechanics were just scratching their heads at it.

 

[410Fortune]

Pull all 6 plugs and see what they look like, my guess is one will have signs of not firing

It maybe a bad injector
A dead miss is very obvious at a warm idle and will "appear" to clear up at higher RPM although it is always there
The spark plugs will tell the tale

Have you tried cleaning the MAS sensor?

 

[Cole94]

Sorry for the late response.

Did you mean MAF sensor? If so, then no.

I guess I'll pull all of the plugs tomorrow if I get time. We'll see.

 

[mcfixstuff]

Alright, so before I replaced it, I took some pictures of my fancy computer readings. All of these were taken with a warm engine.
Idle

View attachment 165631


35 mph

Am I seeing live data from a 1994 Explorer? Just want to confirm that the Bosch 1300 supports live data from the OBD1 Explorer without any modifications, before I shell out the cash for one.

 

[Cole94]

Am I seeing live data from a 1994 Explorer? Just want to confirm that the Bosch 1300 supports live data from the OBD1 Explorer without any modifications, before I shell out the cash for one.

Yes, that is OBD-I live data as the bosch displays it straight out of the box.
There's more data it also displays live not pictured.

 

[mcfixstuff]

Yes, that is OBD-I live data as the bosch displays it straight out of the box.
There's more data it also displays live not pictured.

HMMMMMMM interesting! I might just have to spend the money on one of those.
What do you use to compare the data to see if it is good or bad numbers?