Stumble at idle

[sheltonfilms]

A member on another forum has a truck with an identical powertrain (even uses the same PCM calibration code) and nearly identical truck overall. If anything, it's heavier than mine. He also lives in the same area as I just moved from but his city only gas mileage beats my best highway only mileage by a couple mpg and his highway only beats mine by a long shot. This is before I started having problems with my truck. Right now his his city only beats my combined by almost 10mpg. This has me puzzled as well. I know driving habits play a big role but since the 2.5L basically has no power I don't exactly hot rod it. The big difference in mileage between our trucks from the get go makes me wonder if there is another major underlying issue.

Your truck is lighter than mine. You have the lighter weight hood. I think that is something with the Sport trim. BTW I have a different name on here. eThe diver name is just on RPS. The others is this one.

 

[Earl43P]

Your truck is lighter than mine. You have the lighter weight hood. I think that is something with the Sport trim. BTW I have a different name on here. eThe diver name is just on RPS. The others is this one.

I wondered where ^you^ came from.
You brought "good tech" over here with you.

Welcome to The Ranger Station.
I do realize you've been around for over a year, but have a low post count.

I had a similar problem as Primer88's, but less dramatic, on this 2000 2.5 (a few months new to me). I was servicing up the AC and kept hearing a sharp snap every once in a while from the PS side and the idle would judder and vary. Eventually found one plug boot completely split, letting it arc in the perfect hidden from view spot. I didn't hear anything like that in the OP's video, though. I'd still pull the plugs and "read them" and really check out the plug wires with an ohmmeter. (if you haven't misted them in the dark, do so)

I never did get a misfire code on my Scangage II, which is always in the truck, connected. I only replaced that one wire and it made a world of difference. I yanked it out of a spares box from the old 2.9 I pulled out of the 90 out back (not finished). I realize that you have replaced the plug wires already.

The only other problem I've had is (still ongoing) EGR. I put a new DPFE on it and it smoothed out some, but I like the way it runs so much better with the vacuum line removed from the EGR valve (and plugged). Had no effect on MPG leaving it disconnected. I'd try that to rule out EGR.

That Scangage is a handy device. If you want to bounce any oddities about its readings by me, send a PM with the conditions and I'll see what mine says for comparison. I drive it every day and I'm on here a lot.

 

[sheltonfilms]

I wondered where ^you^ came from.
You brought "good tech" over here with you.

Not sure if I completely understand those statements.

 

[Primer88]

Thanks earl, Ill be sure to let you know if I have any questions about the scangauge.

driver, I figured your truck was lighter purely because at the very least you have power windows lol. All the 98-00 hoods are the same from what I've seen. My sport's is the same as my old 00 4.0 super cab xlt. if I'm not mistaken you cant get any lighter than my truck unless you have a manual transmission.

I will be pulling the plugs tomorrow and doing a compression test. I'm really kicking myself for tossing the old plug wires now. I'd like to have at least one long one to try out on cylinder 3 before I get too far into this. cant seem to find a single wire at the parts stores here, only full sets. sucks because I've bought a single wire before in TN............I really miss TN, I hate bama.

If I just plug the egr vac line will I get a code? I forget and Im on my phone right now so searching will drive me insane. I'd love to get rid of the egr all together. The amount of shit I cleaned out of my intake from it a couple months ago was rediculous.

 

[sheltonfilms]

I bet your truck doesn't have the door panels with the pockets does it. Buddy of mine has a 00 red sport but it was v6 manual, he didn't have the pocket door panels.

I don't know what the code is but it should be "EGR insufficient flow", the DPFE will sense the EGR being closed.

I really hope that compression test shows something, otherwise I think we are gonna hit a dead end.

 

[Primer88]

Nope, no door pockets. The only "options" I can figure out that this truck has is the automatic, cd player, stepside bed and 4.10 gears.

 

[sheltonfilms]

4.10's must be a standard with the 2.5 A/T. Every one I've seen has them. Probably has to have them.

 

[Primer88]

I stand corrected then. Weak engines require low gears to move themselves out of the way.

 

[sheltonfilms]

They barely do it with the 4.10s.

My quartermile time at Bristol Motor Speedway was 20.3 seconds. Yeah you read that correctly. Ran that so consistently that my friend told me I should bracket race....lol. Even had my buddy drive and he ran 20.3

Dude a dump truck ran at the quartermile one night and ran a 23.0. A dump truck

 

[Primer88]

Compression test results.

I started with cylinder #3 and here are the results.
105, 120, 130 then I tested the other cylinders and came back to this one. Second test I got 120 then 115. I added a small amount of oil to the cylinder and got these results, 175, 170 and 160.

Cylinder #2 results: 145, 145, 145
Cylinder #1 results: 150, 150, 150

I didn't test cylinder #4 because I tried for over half an hour to tread the test hose into it and I just couldn't get it in there. I also couldn't remove the DPFE sensor bracket which was the main problem with getting the test hose screwed on.

All of the spark plugs on the passenger side looked fine and the gaps were still within range. I didn't mess with the driver side because after I did the compression test I realized I have bigger issues than a possible faulty plug wire or plug.

 

[rrbrian222]

I've been following this thread on and off, and may have missed it but how many miles are on the engine?

So what are you thinking is next, maybe a leak-down test?

 

[Rackster]

Speed Demons!!!

They barely do it with the 4.10s.

My quartermile time at Bristol Motor Speedway was 20.3 seconds. Yeah you read that correctly. Ran that so consistently that my friend told me I should bracket race....lol. Even had my buddy drive and he ran 20.3

Dude a dump truck ran at the quartermile one night and ran a 23.0. A dump truck

I was looking into how to make the 2.5L more spirited off the line and better on fuel performance. Once I figured out that I had the 4:10s, I figured that I'd better just focus on better mpg. I was wondering though if someone had taken their stock truck to the track to find out.

Back on topic - fuel, spark and oxygen all present (lots of new parts). Leaning towards the timing belt. With the timing code, seems that things aren't present at the same point...some of the time.

 

[Primer88]

I've been following this thread on and off, and may have missed it but how many miles are on the engine?

So what are you thinking is next, maybe a leak-down test?

There are 133K miles on this truck. I need to figure out if I've got the money to do anything to my truck right now.

 

[Primer88]

Back on topic - fuel, spark and oxygen all present (lots of new parts). Leaning towards the timing belt. With the timing code, seems that things aren't present at the same point...some of the time.

If the timing belt was the problem why would I have bad compression in only one (possibly 2) cylinders?

 

[Rackster]

More than one issue at play...perhaps

Keep in mind that you might have a couple things happening. Re: the compression loss, you might have a bad valve or something. It would explain your engine running rough, but not sure if it would affect your gas mileage to the extent your experiencing.