1995 Bronco 5.8 low idle speed stall after warm up

[freedomgirl]

Rons beast...i looked at a few ground connections tonight and your right. I need to clean them all. Yuck. Its overwhelming all the work i have to do. I just hope skinner is right and its an easy fix. I do not want to tackle switching out another motor. The last one nearly killed me.

 

[Skinner95]

OK

Here is something really ODD

I noticed yesterday that when I am driving the truck there is a direct reaction to the Tachometer when I move the accelerator pedal..

OK - OK Don't Laugh... Not what you think... Thought you all would like that description

While driving the truck when I let off the pedal the tachometer jumps up 200-300 rpm then immediately back to rpm speed.

While cruising if I let off it does the same jump, and if I apply additional pressure it will spike up 200-300 rpm then go back to actual range while...

There is no significant reason for this unless like indicated earlier it is a ground feeding back through the system...

Any thoughts...

 

[Bully Bob]

Have no personal experience with this but, I've seen reports where a faulty tach can mess with

the vehicles ignition.

 

[Skinner95]

Ok

Went and replaced all of the common ground wires with new wires with bare metal contact points as well as cleaning several existing connection points.

Still the exact same condition... Really getting the best of me ...

The exact same process... Start up runs fine no missing or backfiring... After a minute or so it kicks down from high idle and either runs perfect or runs like crap with hesitation sluggish acceleration, and popping back through the intake .. once it gets over that **** it smooths out and runs fine ...

Again clearing the entire system has no change and no error codes are coming up...

Any last suggestions ???

 

[Rons beast]

Have you changed the Ignition module?  The tach gets it's signal from the module. It's important to get the correct module there are 2.

 

[Skinner95]

Swiftly  approaching the part swap out cost of $1,000.00 with all of the suggestions.

Really thought there would have been someone with past experience with this issue... Having difficulties believing the ignition module would start the truck warm up cause the truck to misfire then warm up even more and fix itself... Even harder to believe that it is anything outside the warm up operation since this occurs almost every time the engine is started regardless of operating temperature...

Guess I will replace the relays and the three vacuum relays next to the coil.

 

[freedomgirl]

Dear Skinner,

I replaced my ECM, and my issue is resolved. I am still knocking on wood of course. LOLOL

Not sure if you already tried this.

 

[Elmo]

Sorry Skinner but you are replacing parts without determining the part to actually be faulty. this kind of issue would kick my but as well but I wouldn't replace it if it is not bad.

 

[Seabronc]

I hear your frustration, but nobody on the forum is on site to actually see the problem.  They are not Ford employees, just well meaning volunteers.  You have spent a lot of money shotgunning the problem which obviously hasn't worked.  It is possible that you even replaced the failing part with a bad one off the shelf, that happens a lot with parts from the Big Box parts sellers.  As you have found out, you can spend a lot of money with your current approach.  Many problems have the same symptom so it is not possible for some one to say, "I had that problem and changed X part which fixed it", and be accurate for you.  It may have fixed it for them but it may not be the fix for you.  When you are on a forum, you just have to take what people say as something that  may or may not do it for you and be pretty certain that it is prior to spending your hard earned money.  The alternative is take it to a local professionsl mechanic and from what it looks like in this case, save a batch of money.

I'm going to take you back to the issue of grounds.  Bad grounds, especially the battery to frame, engine block and engine block to fire wall have caused a lot of strange problems.  I realize you did some rewiring of grounds.  however you did not say anything about what you did with the battery (-) cable.

So, please answer these questions and put your response to each question as a reply to this post.

1. Did you remove the battery (-) from the battery and clean the post and lug?

2. Did you disconnect the battery (-) cable from the frame and clean the lug and contact surface?

3. Did you disconnect the battery (-) from the engine block and clean the lug and contact surface?

4. If you removed the cable from the above locations, did you inspect the lug to cable connection point where they are soldered together for corrosion?

5. Was there any corrosion at any of those points?

    If so, did you replace the battery (-) cable?

6. Did you check the ground strap from the top rear end of the intake manafold to the bolt on the firewall for the above mentioned conditions plus disconnect and clean all points of contact?  (usually on the right side as looking from the front of the truck)

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