Idle issue - About ready to sell this old girl

[Dprocks100]

This whole problem started 3 weeks ago. I started my truck and let it idle for about 5 minuets and took off down the road. About 1-2 min later when I went to put the clutch in, it stalled as it went down to idle. Tried 4-5 times to start it, and it ran like normal. Drove it another 1-2 min and it stalled again when I put the clutch in. Started on either the first or second try, and I tried to limp it back to work. Pulled into work, got out letting it idle, checked it over, it seemed fine. Turned it off, checked oil, coolant, etc, nothing seemed wrong. Pull out of my stall at work, and it stalls again with clutch in. Starts right back up and I drive the whole way home with out a problem. I replace the fuel pump, because its under warranty, and It runs fine for three weeks, with just a little bit of a high idle every now and then (1000 rpm) and sometimes its slow to come back down to normal idle (7-800 rpm). I figure I'll look at it next chance I get and drive it daily. This brings me to saturday, I finally get around to trying to find the reason for my idle, and I find a vacuum line that has melted quite a bit on the exhaust. Replace the whole line from the manifold to the air box. Start it up, and it runs like sh*t. Exhaust sounds like this ...*..*..*.*...*.*...* at idle, kind of like its misfiring. Idle won't come down from 1000 rpm. If you rev it, the exhaust sounds fine and it doesn't seem to have lost much, if any, power. Still drivable around the block, and It hasn't stalled since the initial problem three weeks ago. Today I wen't out to check it and it was running the same. had a miss and would not go under 1000 rpm. when reved, it would be very slow to come down. Exhaust had a hint of an eggy smell to it as well.

Things I have done so far:
Checked for vacuum leaks in all hoses
replaced exhaust side plug wires and checked plugs (looked all the same)
had the coil or whatever its called on a DIS checked, and it passed
fuel pump
checked resistance on the IAC, passed and idle drops to 5-600 when unplugged. cleaned as well
MAF is new as of a year ago, unplugging it doesn't help

Things I will be doing:
TPS voltage test
Compression/leak down test

What can I check and rule out on this? Anyone have any suggestions? Ive done a ton of looking on this and no one ever comes back with an answer, and It could be tons of different things from what I've read. I don't have a lot of money to throw at this in parts, and I just fixed the head 1,500 miles ago. Since its my daily, I need it working asap or I will have to get rid of the old girl.

 

[tomw]

I would double check two things: 1) the vacuum line that was melted, as things kind of went bad after replacing and re-connecting it, and 2) plug wire routing and connection to the correct spark plug. You disconnected the coil, and have misfire. If you missed any of the bolts that hold the coil in place, you may have removed a ground. From reading, it needs all the bolts installed properly to get ground for each individual coil in the assembly.
If the plug wires were flipped, you'd have a good steady miss at idle. If the miss is intermittent, and it runs smooth between misfires, plug wires are likely not misconnected.
Have you checked fuel pressure and regulator for proper pressure and volume? Pressure should bump when the vacuum line is disconnected, engine running at idle.
Did you clean the IAC? It can cause high idle, and slow return to normal if gummed.
tom

 

[Dprocks100]

I had a miss before messing with the coil pack or plug wires, so it should be grounded, and the plugs are in the correct order.

I have not checked fuel pressure, I will do that next chance I get.

And I did clean the IAC. Cleaned it as part of mantinence 6 months ago, and again last sunday. Also unplugged it before start up and idle went to 5-600 rpm.

I checked all my lines last night with my vacuum pump, and they all hold vacuum. Need to still check the pcv and brake booster though. I used an unlit propain torch and ran it over them, and nothing changed though.

 

[adsm08]

I agree with Tom. The IAC is the most likely culprit for the idle issues, and the stalling.

I also agree that double checking your plug wires is a good place to start with your misfire. And that should be a dual plug engine, so it should have two coil packs. And a misfire at idle can smooth out at higher RPM.

 

[Dprocks100]

Aren't the exhaust side plugs the Ignition plugs? I didn't check the Intake side because from what I've read, they only fire on the exhaust stroke and wouldn't be the reason I have a miss. Just to make sure, I'm going to pull the intake side plugs and check them along with the wires and coil pack tonight I guess.

And an IAC wouldn't be causing it to miss right? Because the air that goes through the IAC is still metered by the MAF and is sealed off. The engine was missing before I did anything to the spark plugs, wires or coil pack. It didn't have a miss before when the vacuum line was melted, and started missing after the line had been replaced.

 

[JiKeidan]

... I don't have a lot of money to throw at this in parts, and I just fixed the head 1,500 miles ago. ...

What did you fix about the head?

Sent from my Z970 using Tapatalk

 

[Dprocks100]

The head cracked allowing coolant to enter the cylinders. Replaced it with a new one with new valves, springs, seals etc.

 

[Dprocks100]

To follow up with this issue so that this isn't just another dead end thread, I found that the reason I was stalling out that day is because my crankshaft position sensor wasn't connected. One of the inner pins in the connector decided to back out and not make a secure connection. That was fixed, but didn't fix all the issues.

The hanging idle I believe to be because of an intake manifold leak where it attaches to the head. I found that out today when spraying around with a can of carb cleaner. When the area was sprayed, the miss would stop and the idle would smooth out. This was not fixed because of the following thing I found out today.

I finally got around to doing a compression test today, and the results showed that cylinder #3 compression is at 110psi, 19% lower than the highest, 135psi. When tested with a bit of oil in the cylinder, It jumps up to join the others in pressure. I assume that this is the reason for the miss at idle after the engine has warmed up, along with the intake leak. Obviously, at this point it would not be worth putting time and money into doing the intake gasket, right?

 

[Mark_88]

You're probably best to check out ring replacement...or find another engine to swap in...

Sounds like a nice little truck to play with so I'd be wanting to keep it...

 

[tomw]

It might not run perfectly at idle, but you have compression, and you never know if the rings are stuck or are damaged or have lost their tension. Check the price & time for an intake manifold gasket. I doubt it is real expensive.
Who knows, fixing that would make it run for a long time, even with a semi-contributing cylinder.
It's not perfect, but a $10 gasket might make it work well enough that you can either start saving for another ride or consider purchase of another engine to work on for a 'swap' later down the road. This one will keep you on wheels with a small investment.
AND you know recent service history and treatment of the one you have should you decide to swap that one and fix it while running a used from a boneyard... Lots of choices.
tom

 

[Mark_88]

It might not run perfectly at idle, but you have compression, and you never know if the rings are stuck or are damaged or have lost their tension. Check the price & time for an intake manifold gasket. I doubt it is real expensive.
Who knows, fixing that would make it run for a long time, even with a semi-contributing cylinder.
It's not perfect, but a $10 gasket might make it work well enough that you can either start saving for another ride or consider purchase of another engine to work on for a 'swap' later down the road. This one will keep you on wheels with a small investment.
AND you know recent service history and treatment of the one you have should you decide to swap that one and fix it while running a used from a boneyard... Lots of choices.
tom

Well, glad you went into that detail...I was going to say something similar but then I remembered it was pretty much what I went through for the last two years or so...the truck ran fine, even had pretty good power...but started using way too much oil and eventually started smoking every time I let my foot off the gas (typical of valve seal issues)...

If the truck isn't smoking too much now or losing oil then it might be a cheap short term fix to keep it going until a replacement or rebuild is possible...which I was intending also at the time...but things took a very serious turn for the worst at some point and it just went downhill from there...until the engine blew and I was left in a very tight situation...

That's sorta why I leaned towards the short answer...get it fixed while you can and it will save you a tonne of headaches...

 

[Dprocks100]

Thanks for your suggestions guys. I don't think it would be worth the time to throw a intake gasket in it, I haven't been driving it for the last month, so my transportation has been worked out for a little bit longer. I'm leaning towards dropping a junker engine into it at the moment. Reason being is that I love this truck, and have put a lot of work in to her, and also the fact that I don't really have the cash at the moment to replace the whole truck. Thinking of putting in a 95+ 2.3 in it using my current intake. The only problem I can't seem to figure out is if the 95+ block has the mounts available to use my original Crankshaft position sensor. They seem to be drilled and tapped from the factory on my block, and somewhere I read that ford didn't put them on the newer blocks because the Crank position sensor changed. I guess I could always drill and tap them myself, but I don't really like that idea since it has to be so precise. If anyone has done this swap knows how to make that part of the system work with the newer motor, please let me know.

 

[Mark_88]

Good choice...

As for the sensor, I do recall someone on here did exactly that and it worked out OK from what I remember. Trying to remember who it was but it was a while ago...so search on the crank position sensor and you should find it...even if you have to go back a few months...

There wasn't actually much detail on how it was done...but I guess if you had the engines side by side you would be able to see where it needs to go...there are parts from the older engine that require removing or changing out the pulley also...I will try a search since I haven't done it for a while and post a link if I find one...also try Youtube...amazing what is on there...

 

[Dprocks100]

I spent a good amount of time yesterday trying to figure this out. I think I found the thread you were talking about, Rebuild - 94 or 95? and there is a link in that thread to this one 2.3 oil pump in 2.5 Where tinman_72 explains how he did it, but the pictures have lost their link. There are 2 95+ engines around me at the moment that have under 110k miles, and all the 94 and older are unknown or bad. So thats why I like the idea of the 95+. Hopefully I can find some more info on the conversion to bump up my confidence. I'll post more if I find anything else helpful.

 

[BlackBII]

I wouldn't even think about replacing the engine when the compression in the "low" cylinder is still at 110psi. If it were like 85psi then sure.

I recommend you replace the intake manifold gasket and keep driving it. Gaskets are cheap and easy to replace so I think it's worth the time.